Modern combat vehicles 4 - M48

Geoffrey Tillotson

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Geoffrey Tillotson 1981

Published by Ian Allan Ltd . Shepperton. Surrey, and printed by Ian Allan Printing Ltd at their works at Coombelands in Runnymede , England

ontents

Preface 4

.-\bbreviations 5

From World War 1 to the Patton - The M47 13

~ The M48 27

- \148 Variants 60

" :\148 in US Service 75

:\'148 in Foreign Service 88

- Parallel Developments 99

Appendices 110

6

Preface

When 1 was asked to write this book on the M48, I must admit that I had cel1ain reservations. 1 knew of others working on the same subject, and over the years the M48 has received considerable coverage in reference books and in magazines. Much of this material concentrates on the Vietnam War and on the two Middle East Wars. The M48 is now nearly 30 years old and cannot in all fairness be regarded as a main battle tank of the current generation - that is, the T-62, Leopard, M60 and Chieftain. The M48 belongs with the T-54 and Centurion. I have therefore treated the M48 largely from a historical point of view. Since the design of the M48 began before I was born, some might think that there are other good grounds for taking this view. However my main reason for taking the historical perspective is that it is the approach which 1 find the most interesting and for that I make no apology. Where possible I have used the official designations and nomenclature for tanks and other components. The US Ordnance standardised nomenclature system largely avoids confusion, but it makes for repetitive reading and lacks the appeal of. say, the variety of tank names in the British Army. When describing measurements I have kept to the units originally quoted and in most cases these are in 'imperial' units. There are two exceptions: the ton, which in this book refers to the US (,short ' ) ton of 2,000lb, and the gallon, which is the US gallon (0.83 Imp gal) . Metric units are also given and are in the Sl system , conforming as closely as is reasonable. Brief notes on nomenclature and units are given at the end of the book. Spelling and terminology are other grey (or 'gray') areas. The American spelling is used only in titles, for

4

example '2d Armored Division ' , ' Secretary for Defense ' . There have always been differences in usage on each side of the Atlantic, but these need not cause confusion . I have used 'petrol' rather than 'gasoline', and for this I apologise to my American friends. lowe a considerable debt to the many firms and individuals who have helped in the preparation of this book. William Auerbach, George Balin , Gary Binder, Paul Handel, Javier de Mazarrasa, Nathan Shiovitz and Russ Vaughan have all gone to great lengths on my behalf to provide photographs, and 1 am grateful to Thomas Mayer for his reminiscences. Armor Magazine , The Military Engineer and Military Review have all kindly allowed me to quote passages or to use photographs . Colonel Robert leks and Richard P. Hunnicutt (whose books on the Sherman and Pershing provided a detailed account of American tank development between 1930 and 1950) have patiently answered my questions and generously provided photographs , and I am proud to acknowledge the assistance I have received from the two foremost experts on American AFV development. Christopher Foss originally suggested the book and his further suggestions , advice and the unlimited use of all his material have been invaluable. I am glad to have this chance to thank these individuals and to apologise to any friends I may have inadvertently overlooked. Finally I wish to acknowledge my family's tolerance and support throughout the progress of the book. To Joan , Clive and Anne: thank you for letting me get on with it.

Geoffrey Tillotson

Abbreviations

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Army Ground Forces Armour-pierci ng Armour-piercing , capped Armour-piercing, discarding sa bot Anti-perso nnel Armour-pierci ng , fin stabilised , discardin g sabot Aberdeen Proving Grou nd Army Radar/Gun Air Defense System Armoured Recov ery Vehicle Army of the Republi c of Vietnam (South Vietnamese Arm y) Anti -tank Guided Weapon Armoured Vehicle Launched Bridge Bowen -McLaughlin -York Company Battalion Landing Team (USMC) Chemica l, Bacteriological and Radiol ogical (US) Canister Continental (US) Army Command Division Air De fen se Gun System Expedited , Non -S tanda rd , Urgently Required Equipment Fire Cont rol System Federal Rep ubli c of Germany (Wes t Germany) Fisca l Year Gun Low Altitude Air Defense System

GOCO HE HEAT

HEP HESH HVAP, HVTP, etc IR MACOV MBT MAP NBC NVA PCF PI RISE ROKA SAA SHORADS SMK SP -T TP, TPDS , etc VC WP

Gove rnment Owned. Contractor Operated High Explosive Hi gh Explosive. Anti-tank (s pecifica ll y refers to shaped charges) High Explosive , Pl asti c (US term fo r HESH ) Hig h Explosive , Squash Head Hi gh Velocity AP , TP, etc Infra- red Military Assistan ce Command . Vietnam Main Battle Tank Mil itary Aid Program Nuclear, Bio logical and Chemi cal (US-CBR) North Vi etnamese Army Pac ific Car & Foundry Com pany Produ ct Improved Reli abi lit y Improved. Selected Equipment Republic of Korea Arm y (South Korean Army) Small Arms Ammunition Short Range Air Defen se System Smoke Self-propelled Tracer Training Practi ce, etc Viet Cong White phosphoru s

5

1. From World War 1 to the Patton Today's Main Battle Tank (MBT) is a far cry from the lumbering monsters which made their debut at Cambrai in November 1917, The tank of the 1980s is a co mplicated machine, the design of which depend s on many factors all of which in turn depend on each other. It is traditionally held that the tank combines the attributes of mobility , firepower and protection, and on this point practically everyone can agree, The US Army defines the MBT as a tracked vehicle providing heavy armour protection and serving as the principal assault weapon of armoured and infantry troops, The relative importance given to each attribute is another question altogether and almost every expert has his own view, This is illustrated fairly well if one compares two of NATO 's MBTs , the German Leopard and the British Chieftain, Leopard is exceptionally agile but lacks protectio n while on the other hand Chieftain has excellent protection, a gun which is second to none , and is less mobile, It was the difference between the German and British users' perception of the way in which thei r tanks was to be used which resulted in two very different tanks . It might still be rel atively simple to agree on common characteristics for a tank if it were only a case of choosing the right balance of mobility, firepower and protection, Howeve r, other factors have to be considered. The weight must be kept to such a value that the tank can still cross the average bridge . The cost must be kept within a rigidly defi ned budget or the user may not have the tank in sufficient numbers. The chassis may have to perform other roles, such as recovery veh icles or self-propelled artillery. The tank must be easy to maintain ; th e training of crew and maintenance personnel must be si mple. Sometimes even the number of the crew must be considered, for in some armies manpower, rather than fin ance, is the limiting factor. This book makes no attempt to compare the M48 with present day MBTs, This would not be a valid comparison unless these other tanks were described in similar detail and even then the comparison could not be entirely objective. For this reason no comment was made on the rel ative effectiveness of Chieftain and Leopard when some of their differences were mentioned earlier. As a tank , the M48 is not new . The first production of

6

M48s began in 1952 and ended in 1959, but there have been several models , most of which have also been supplied to foreign armies as well as the United States Army , Many of these armies have made various improvements to their M48s just as the US Army has, and the latest M48A5 model is expected to remain in service until at least 1987. During its time in service the M48 has seen action throughout the world; in the Indo-Pakistan Wars of 1965 and 1971, the Middle East Wars of 1967 and 1973 , and in Vietnam . Despite the publicity which greeted its announcement, there was little about the M48 which was revolutionary , It evolved from an established line of design and its features were continued into its successor. The M60 is the current US Army tank and was a logical development from the M48. A description of the M60 is outside the scope of this book but several other experimental tank types are covered when they have featured in the story of the M48. For thi s reason the history of American Medium Tanks has been traced back to the 1920s to show the succession of models and the changes , large and small, which resulted in the M48. The practice of giving names to American tanks arose during World War 2 when tanks were supplied to the British Army, Un accustomed to referring to its steeds by impersonal alphanumerics such as M3 and M4 , the Royal Armoured Corps preferred to have a name for each type of tank , Out of courtesy to their American benefactors the models received were given the names of famous American generals , although 'General' was soon dropped and the tanks were referred to as 'Grant', ' Sherman ', ' Chaffee ' and so on, The name ' Patton ' was first given to the M46 Mediu m Tank which first appeared in 1949, but this time the name was given by the US Army. As the M46 was only intended to be an interim design it is sometimes called the Patton I, indicating that there would be another tank with the same name. This later tank was the M47, which followed in 1950. The M48 then assumed the name Patton III when it appeared in 1952. The name has found little favour with troops although it is convenient to use it as a genera l name for any US medium tank over the period from 1950 until the mid- l960s. The M48 is not a glamorous tank, It has none of the

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sleek deadliness of the Chieftain, the cavalry background of the AMX-30 or the dash of the Leopard. Perhaps it is not very dramatic, but it has been the Free World's equivalent of the T-S4, and of the tanks so far mentioned onl y the Centurion, T-S4 series and M48 series have seen Jction.

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Early developments The bomber of the late 1920s was a flimsy contraption 'xhose appearance and performance clearly indicated its beginnings in World War 1. Similarly , most warship designs of the time reflected the same concepts as those which had prevailed a decade earlier. On land the picture was very much the same. In the US Army, tanks were the province of the Infantry and in 1930 all that existed was a handful of Liberty Tanks and some Renault light tanks, both of which types were of World War 1 vintage. Efforts to equip the Infantry with more modern tanks during the 1920s and 1930s were hampered by financial di fficulties and by opposition from some of the rival fac tions within the US Army. It was not until 1940 that the Infantry gave up its control of medium tanks, but four years earlier a step had been taken in the right direction . In : 936 approval was given for the development of the TS \1 edium Tank. This tank combined for the first time a gun with all-round traverse, a rear engine and a new

Above: The Soviet T-SS Medium Tank. An improved version of the T-S4, the T-SS was in service throughout the Warsaw Pact during most of the service life of the M48 series. C. F. Foss

suspension known as the Vertical Volute Spring Suspension (VVSS). Directly or indirectly, the Infantry's control of tanks had led to them being regarded as mobile pillboxes, to accompany infantry. This negative thinking meant that tanks were not appreciated as being able to take on other tanks , or to fight in their own right. It was not until the closing months of World War 2 that this fact was fully assimilated into tactical doctrine. From the TS were developed in fairly rapid succession the Medium Tank M2 and then the Medium Tank M3, for by this time it was apparent that the coming war would require a new generation of tank. Thus by 1939 the American medium tank had taken on a completely new appearance. The 'mobile pillbox' form of hull gave way to the lower, more angled hull of the Medium Tank T6, later to become the M4 and known to all as the ' Sherman '. Today the result of such a transformation would be described as a second generation tank.

7

The M3 was armed with a 75mm gun mounted in the hull, with limited traverse, and with a 37mm gun in a turret. The Sherman dispensed with the 37mm gun and mounted the 75mm gun in a turret with all-round traverse. Later models introduced different hulls and engines for convenience of mass production, but the American medium tank was still characterised by the same general appearance and features. Even the introduction of a modified suspension known as the Horizontal Volute Spring Suspension (HVSS) did little to alter the silhouette or characteristics of the Sherman, but by 1944 the Ordnance Department and Army Ground Forces realised that piecemeal improvements to the Sherman were not the answer. A completely new tank was needed. There was a school of thought which held that while the Sherman may have lacked the hitting powerof its Gennan counterpalts, it was durable and reliable and, more importantly , it was in mass production. However , a new tank was on the way. As far back as 1942 battle experience with the Sherman in North Africa had shown the need for a better tank and the Ordnance Department had begun the design of the Medium Tank T20. A mockup was examined by senior officers from AGF and. was enthusiastically received. The Ordnance Committee gave approval for the construction of two pilots of the T20 and a few months later for two pilots each of the T22, with a different transmission, and the T23, with a ' gas-electric' drive. Various additional models of the T20, T22 and T23 were built with variations in

8

armament, suspensions and transmissions. Eventually the new medium tank series was refined to a point where one or two models could be considered for standardisa­ tion and ordered into production. The T23E3 and T20E3 were therefore proposed for standardisation as the M27 and M27B I Medium Tanks respectively. At the same time the Ordnance Department was asked to modify the T23 to mount the new 90mm gun then under development. Two versions of the modified T23 were to be built; the first with armour similar to the T23 and the second with heavier armour. These two tanks were designated the Medium Tanks T25 and T26. Reports from the European Theatre of Operations showed that the thin armour basis of the T25 would be inadequate and the emphasis shifted to the T26E I, which was redesignated as a heavy tank in June 1944. This was a paper transaction which did not reflect any change in characteristics. After troop trials were complete the Ordnance Department was authorised to build 250 tanks, and by February 1945 I 10 of these T26E3s had been produced. The T26E3 went into action east of Aachen in late February, and in March 1945 was standardised as the Heavy Tank M26. From this point the evolution of the M48 and indeed the M60 can be clearly traced. Fully loaded, the M26 weighed 4lton and carried a 90mm gun. Its hull was assembled from sections of rolled plate and cast armour and the suspension consisted of six pairs of rubber-tyred roadwheels on each side supported on torsion bars. In this form of suspension the springing

: : ...es from the resistance of a high-tensile steel bar to a ing force. The track was driven by a sprocket at the :-~ .:r of the tank and the engine was mounted in a : .:-:npartment at the rear of the hull , with very little ::~c) tru ding above the line of the top of the track. The M26 was given the name 'General Pershing ' , after Gene ral John J. Pershing, who had been responsible for :'::e creation of the American Tank Corps in World War 1. : was. however, more commonly known simply as the Pe rshing'. The Pershing arrived too late to make any ;reat contribution to World War 2, but production ~ ominued after the war and when the Korean War broke o [ the Pershing was still the mainstay of the US Army. Towards the end of World War 2 a board of senior oificers was assembled at the Headquarters of Army :-.. :5

Left: A small number of M26 Pershings were supplied to the British Army , although nothing like the 1,610 reported by one authoritative American journalist. This particular M26 has been renumbered under the scheme introduced in the early 1950s. !WM Below: The bow machine gun opening of this M46 has been blanked off and the hull is practically the same as thaI oflhe M47 . The five track return rollers give the game away. US Army

Ground Forces in the Army War College in Washington . The Post War Equipment Review Board looked at every aspect of Army material and equipment , and recom­ mended the way ahead. The development of the M48 generally followed their recommendations , and from time to time in succeeding chapters further reference is made to the report of this Board.

From the Pershing to the Patton In the years that followed the end of World War 2 , production of the Pershing continued and in all nearly 2,500 were built. Minor improvements were made and considerable experimental work was carried out. The M26 was used as a testbed for various modifications to fire control equipment, armament (including rocket launchers and machine gun cupolas) and to engines and transmissions. As various shortcomings became obvious in the M26, development of a replacement tank was begun. This new tank was originally designated the M26E2 Medium Tank , but subsequently redesignated the T40 in 1948. Ten pilot models were authorised for the purpose of engineering test and in anticipation of these being found acceptable , the rework of 800 Pershings was scheduled to start at Detroit Arsenal in July of 1949. By November, 16 tanks had been produced and the T40 had been standardised as

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9

the M46 Medium Tank. The name 'General Patton' was bestowed on the new tank as was mentioned earlier. It was mainly intended that the M46 should be more reliable and have better mobility than the M26, so the armament and armour protection were largely un­ changed. In the T40, the Ford GAF engine of the M26 was replaced by the Ordnance-Continental AV-1790-3 engine and a crossdrive transmission was incorporated. This new engine was one of the first of a range developed around the Common Component Concept, a scheme forced upon the Army by postwar budget strictures as much as by common-sense . By settling on two basic cylinder sizes it was possible to build up a range of engines to suit almost any military purpose, from a one-cylinder engine for an auxiliary generator to a 16-cylinder tank engine. The M26E2 had in fact used the AV-1790-1, the first in the new series. This used the larger 5 .75in cylinders. In a similar fashion to the range of engine components many other components such as roadwheels, track shoes, fire control instruments and vision devices were standardised. The advantage of this

10

approach was that it was then possible to assemble a variety of vehicles relatively cheaply in the knowledge that each of the components was satisfactory in itself. The CD-850-2 crossdrive transmission of the T40 was another product of the common component concept. The Pe rshing had had a ' torqmatic' (sic) transmission, although the M26E2 had been used as a testbed for the crossdrive unit. The new transmission gave control of gear selection and steering by means of a single ' wobble stick', while other refinements to the engine allowed the vehicle to operate with the engine submerged, or at temperatures down to -65°F (-54°C). A new design of track gave the vehicle more traction in heavy going, and a small track tension idler was added behind the rear roadwheel on each side to reduce the tendency to throw tracks when turning . Tests of the M46 were conducted at Aberdeen Proving Ground and at Fort Knox , Kentucky, from December 1949 until April 1950, and revealed two serious failings. The mechanical reliability was disappointing and certainly no improvement over the M26, and there was

: nadequate control over the steering of the vehicle. It is ot c lear what action was taken to improve the reliabi lity, . ut it was found that a simple modification to the routeing of some hydraulic pipes in the transmission rectified the steering defect. The Patton was popular with its crews in Korea. ..lJthough largely used in static defensive positions or as armoured artillery , it proved its superiority over the Russian T-34176 and T-34/85 used by the Communist forces. It also compared favourably with the Centurions in service with British Commonwealth forces. While the 20pdr gun of the Centurion was superior to the 90mm gun of the M46, American tank drivers were confident that they could put their tank anywhere a Centurion could go, and probably faster, although it compared less favourably with the Sherman in difficult terrain . In generaJ, the Patton was felt to be reliable by this time, particularly in the transmission and oil cooling. There were problems of course. The cooling fans often failed in the hot, dusty summer conditions. A driver had to take care in his choice of gear ratios and soon learnt that neutral turns on rocky or soft ground would break or throw tracks. Anti-tank mines were a constant hazard and the escape hatches in the hull floor were too easily blown in. By welding old track sprockets on the outside of the hatch the problem was overcome.

Left: Tile Soviet T-34/85, tile main adversary of tile Perslling in Korea. US Army Below: The first pilot model of tile T42 medium tank from which the turret of the M47 originated. US Army

BadJy damaged or worn-out tanks were returned to the Tokyo Ordnance Depot of the US Army's Japan Logistical Command. Here the Japanese workforce could refurbish two Pattons each day at a reputed cost of only $700. Even if this figure is wrong by a factor of 100, making the cost of rework $70,000, there is still a considerable saving over the cost of a new tank at $245,000. The last 360 Pershings to be reworked were fitted with the A V-1790-5B engine and CD-850-4 transmission and were known as the M46A 1, but the differences in engines and transmissions were minor. The M46 programme had been rushed through as an expedient to meet an urgent operational requirement in 1948 and resulted in what was essentially an updated Pershing. The same requirement was considered by a Panel on Armor whose work resulted in proposals for a family of three tanks which were designated Light Tank T41, Medium Tank T42 and Heavy Tank T43. At a conference at Detroit Arsenal on 2l September 1948, the Military Characteristics of the T42 were established - although the earlier AGF Equipment Review Board of 1945 had also given consideration to a new medium tank to replace the M26. (' ... a medium tank, for light assault action, exploitation, and pursuit'). The new tank was ' . . . to meet an urgent requirement for a medium tank having a completely integrated fighting compartment and incorporating modem components in the hull. This new medium tank (is) to weigh approximately 36ton , a l3ton saving of weight compared to the Medium Tank, M46.' By February 1949 the basic layouts were about 15% complete. Layout drawings are intended to show the relative positions of the major components and to ensure that the design does not appear to require undue emphasis

11

to be placed on anyone feature. From these drawings the positions of the engine, transmission, radiators , exhausts and turret ring can be determined and designs for the hull and turret castings worked out. Development of the T42 was approved up to and including the construction of wooden mockups and by June 1949 a mockup was nearly complete. It showed the tank to be conventional in appearance , with a suspension consisting of five pairs of roadwhee ls supported by torsion bars, and a long, narrow turret mounting a new 90mm gun, and it looked as if the original weight estimate of 36ton would be satisfied. One unusual feature of the T42 design was the large amount of secondary armament. The coaxial machine gun was the .50in Browning as opposed to the more usual . 30in and there was in addition a .30in machine gun in a remotely controlled blister on either side of the turret. These blister machine guns worked as a pair but were elevated independently ofthe main armament and, with a maximum elevation of 45°, could be used against aircraft as well as ground targets. The customary .50in Browning for the use of the commander was mounted on the turret roof but the bow machine gun mounting was eliminated in the T42 . This reduced the crew from the five men of the M26 and M46 to four men and made more space available for the stowage of ammunition. Another conference at Detroit in mid-1949 recom­ mended that the turret blisters be eliminated from the design until an effective control mechanism could be demonstrated. At the same time an increase in weight to 38.25ton was allowed and it was specified that the turret armour should be better sloped. The increase in weight meant that the requirement for a speed of 35mph had to be reduced to 30mph, and to get an idea of the new tank's

performance before pilots were built a mobile test rig was assembled. This used the new AOS-895-1 engine and General Motors CD-500 transmission in a turretless M46 tank. The detailed mockup of the T42 was completed in about October 1950 , the drawings having been already approved for production two months earlier. Six pilots were authorised and in December 1950 detailed characteristics were published. The Korean War had broken out in June 1950, but the T42 had arrived too late to be of use as production could not have been underway in significant quantities. Instead the US Army had to get by with the Pershing and the M46. However, the T42 did play its part in developments leading up to the M48 tank, as the next chapter will show . The six pilots were used to prove other components in the continuing development of a medium tank- for example , the T69 tank mounted a 90mm gun in an oscillating tutTet on the hull of the T42 , and a T42 turret was used by the Chemical Corps at Edgewood Arsenal to develop a flamethrower version of the M47. In fact the T42 programme was resutTected in April 1953 with the aim of producing a smaller, lighter and cheaper 90mm gun tank under the designation Tank, 90mm Gun, T87 . Little more is known of thi s project but it may perhaps indicate that already the M48 was getting too big, too heavy and too expensive.

Below: The 90mm Gun Tank T69, consisting of the hull of the T42 with an oscillating turret. US Army

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Development of the M47 By 1950 the US Army found itself between the horns of a dilemma - whether to continue with the M26/M46 line with its reliability and familiarity, or to elect for the superior T42 then available for production. The eventual decision was something of a surprise. The turret of the T42 was combined with the hull of the M46, and in one step a new tank appeared, combining the proven components and mechanical sturdiness of the M46 with the radically new turret of the T42. The new tank was ordered into production on 17 July 1950 although at that time no drawings existed. This was clearly a gamble, but it was hoped that any problems arising from the forced marriage of hull and turret could be overcome without interrupting production. It should be pointed out, too , that there was an historical precedent for this. In 1943 the Ordnance Committee authorised the installation of the turret of the experimental Medium Tank T23 on the hull of the Sherman to accommodate the new 76mm gun, and from this the new model went straight into production. In fact the production of the new tank was not as simple as it may have sounded . One of the requirements was for a better engine cooling system and electrical harness, so modifications had to be made to the M46 hull. The characteristic long shape of the T42 turret was in part due to the fitting of the hull ventilating blower in the turret bustle, so the protruding rotoc1one housing between the driver' s and co-driver' s hatches on the M46 was superfluous. The elimination of this housing and better sloping of the glacis improved the ballistic protection of the hull. The T42 tank had introduced other new features, among them a turret rangefinder and a new 90mm gun. Production of range finders and guns was lagging behind tank production by several months, and the Office of the Deputy Chief of Staff for Administration took note of this when work was authorised to proceed on the application of the T42 turret to the M46 hull on 13 July 1950. The various changes to the M46 hull were specified and directions issued that the new tank should supersede the M46 as soon as gun production would allow. Tanks from initial production would be issued without rangefinders but were to have provision for subsequent installation.

The first trial modification to the M46 was known as the M46E1 , and thi s was later accepted for service as the M46A I, with the hull modifications but retaining the original hull casting. The new tank consisting of the T 42 turret on the new hu]] was designated M47 and it is interesting to note that there is no record of a T-designation ever being assigned. Since the M47 never went through a prototype stage this is perhaps understandable . The new gun and rangefinder of the T42 have been briefly mentioned previously. The 90mm Gun T119 was a completely new high velocity gun developed in parallel with the UK 20pdr tank gun. It had been intended that the 20pdr should be trialled in the M47, and it was hoped that the UK would test the T119 , known at the time as the TX-1, in the Centurion Mk 3. It does not appear that this interchange ever took place. Although superficiall.y similar to the 90mm Gun M3A 1 of the M46, the Tl19 differed internally and ballistically, having a larger chamber. It could thus fire any ammunition approved for the M3AJ gun, but the latter could not fire all the new ammunition developed for the T119 gun. There was another significant difference between the old and new turrets and guns. While the 90mm guns in the M26 and M46 had been developed from anti-aircraft guns and thus had recoil systems mounted externally around the breech of the gun, the T42 mounted the TI19 gun in a much neater concentric recoil mechanism, reducing the intrusion into the gunner's working space in the turret. Tank rangefinders were not new in 1950, but had only just reached the point of sufficient refinement when they could be considered for inclusion in an integrated fire contro.! system. The T41 Stereoscopic Rangefinder of the T42 tank used a base of 60in and had a magnification of x7.5. The accuracy of a rangefinder is directly related to its optical base\ength but it was felt that the relatively short base of the T41 rangefinder would be adequate. It also allowed the turret to be fairly narrow, which was attractive ballistically . Although the first M47s were issued without rangefinders, by March 1952 it was possible to conduct firing trials of 1\1475 fitted with rangefinders. These tests and others were carried out at Camp Irwin and Aberdeen

13

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Proving Ground and were in general quite successful, although deficiencies were revealed in the hydraulic traversing mechanism. On 16 April 1952 the Department of the Army announced its acceptance of the M47. The gamble taken 20 months previously had paid off, and it was estimated that a year had been taken off the normal development cycle. There had also been a saving in costs and it was widely felt that the common component concept had passed the crucial test.

14

Production of the M47 The invasion of South Korea on 25 June 1950 and the subsequent involvement of the United Nations against the Chinese and North Korean armies had revealed the alarming extent to which American tank production had declined. Tanks were not being produced; they were being rebuilt , and this did not justify the retention of large foundries and heavy industry solely for military use. A factory had been built in 1940 on a hundred acres of

farm land outside Detroit and from these humble beginnings arose the immense Detroit Tank Arsenal, ope rated by the Chrysler Corporation on behalf of the Government. During World War 2 this Govemment­ wned , Contractor-operated (GOCO) plant grew to over ihree million square feet of covered working area and orod uced over 22,000 new tanks. This valuable asset was al lowed to decline at the end of the war as requirements diminished and although the need to reactivate the ..:vsenal was recognised at the outset of the Korean War, it ·.\'as nearly two years before the Ordnance Corps reached Left: The M47 under lesl al Aberdeen Proving Ground in Augusl 19S1. US Anny via R. P. Hunnicutt Below lefl: This early M47 has the rangelinder openings blanked olT. The muzzle of the coaxial .SOin machine gun is jusl visible above the 9Qrnm gun barrel. US Anny Below: M47 during durability testing at Aberdeen Proving Ground in September 1952. US Anny via R. P. Hunnicutt

agreement with the Chrysler Corporation on the reactivation of Detroit Arsenal. Other production facilities had suffered in a like manner. The Cast Armor Plant at East Chicago, Indiana had been a major producer of castings (mainly turrets) in World War 2 and had then been placed in suspended animation. A new GOCO agreement was reached with American Steel Foundries of Chicago to operate the plant with an eventual workforce of some 6,000 men. The rehabilitation of casting facilities at Pittsburgh, Califor­ nia, to be operated by the Columbia-Geneva Steel Division of the US Steel Company cost $9.5 million. In New Orleans a Chrysler-operated Ordnance Plant was built for the production of engines , and first deliveries were due less than a year after work began on the factory. Detroit Arsenal was not the only producer of the M47. On 22 November 1950 a contract was let to the American Locomotive Company for the production of M47s in a moderni sed plant at Schenectady, NY. It took five months to convert this factory for the production of tanks,

' :'0 and the the - ::-;;\';;aled the

'7 :

~;-,s ~f ai nst

- ::"D acres of

15

udldli

I

Ii

,.

-'­

-­

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--­ --­

The :'\14­

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;.: . ~ ~ : ~-::- - :Lengtb:

.....

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-­

-

:;. ­

- -- -~ -

Above: A brand new M47 at the Alco plant at Schenectady, New York. A/co

but the plant eventually comprised a 300,000sq ft assembly facility with a 100,000sq ft secondary modification and test centre and a test track of 1.125 miles. Despite the obvious need for new tank production, there were al ways other demands on defence expenditure. It is the normal practice in the USA for the Department of Defense to submit requests for appropriations in the year or years ahead of the fiscal year in which the expenditure is planned. Production of the M47 was to be financed in Fiscal Year CFY) 1951 and 1952 but as the fighting in Korea became more static , with a United Nations victory seeming imminent , pressure grew for defence expendi­ ture to be cut in Fiscal Year 1963. This was somewhat

16

short-sighted, for the Army stood to lose production of 3,000 tanks, resulting in a shortfall of almost 80% in post-World War 2 tanks. Even during 1951, when the North Koreans used armour very little, American tank losses amounted to 400 tanks and although most of these were Shermans the Army could ill afford to lose production while at the same time sustaining losses in Korea. Of course, a di scussion of the strategic priorities of the United States would be out of place in thi s account, but there may have been other, more pressing calls on strategic materials. The availabi lity of production materials was governed by the Controlled Materials Plan, with the National Production Authority allocating those resources in particularly short supply such as nickel. A total of 8,576 M47s was made of which Detroit Arsenal produced 3,440 and the American Locomotive Company another 5 , 136 before production was completed in November 1953. The M47 was too late for Korea, so first deliveries to combat troops went to the US 7th Army in Germany.

~- -

-

Right: A top view of the M47 showing the elongated form of the turret. The rangefinder ports are blanked ofT and there is also a blanking plate over the bow machine gun port. US Army. via R. P. HunnicuCl

x :...~ lose production of -"°1 of almost 80% in :~_-: ~ 1951, when the ~ ~ :: !e ..-\merican tank

=

ai ning losses in srrate gic priorities - :c -- ; :_:e in this account, - ='~:: pressing calls on - _Ey of production : . . - ,,::= \-Iaterials Plan , - -':":':1._' al locating those ~:::. ;; u h as nickel. ;;'J5

:::K

-= ::~Xl

s went to the US

The M47 described Crew: S Weight: 101 ,77Slb (4S2.7kN) combat loaded 92,8831b (413.2kN) less crew , ammo , fuel and equipment Length: 27ft 11.19in (S.S2m) overall, gun forward 23ft 3.7Sin (7 .09m) gun in travelling lock 20ft 10.31in (6.36m) hull only Width: 11ft 6.2Sin (3.Slm) overall 11ft lin (3.38m) over tracks Height: 11 ft (3.3Sm) to top of commander's MG Ground contact length: 12ft lOin (3.91 m) Track centre distance: 9ft 2in (2. 79m) G/c1earance: 1ft 6.Sin (0.47m) Turret ring diameter: Sft 9in (I. 7Sm) Armament: Main - 90mm M36 (T 119) gun in M78 mount with 360° traverse and -So to + 19° elevation Secondary-One .30in MI919A40r .SOin M2HB MG (coaxial) One .SOin M2H8 MG (commander's) One.30inM1919A4EI MG(bow) Ammunition carried: 90mm - 71 rounds .SOin - 3,440 rounds .30in-4, 12S rounds Armour: Hull- From 4in (102mm) at 60° front to 2in (SI mm) at 10° rear Turret- 4in (l02mm) at 40° front to 3in (76mm) at 3° rear Engine: Continental A V -1790-S8 , -7 or -78, 810hp (at 2,SOOrev/min) air-cooled, four-stroke, 12-cylinder petrol engine (bore and stroke S. 7Sin) compression ratio 6.S: I Transmission:Allison CD-8S0-4, -4A or-48 Suspension: Torsion bar type (six pairs of road wheels and five dual return rollers per side) Power/weight ratio: IS. 9hp/ton (I . 33kW/kN) gross Max tractive effort: 66,800lb (297 . 1kN) Tractive effort/weight ratio: 0.66 Max speed: 30mph (4SkmJh) Max gradient: 60% (31°) Trench crossing: Sft 6in (3 .S9m) Vertical obstacle: 3ft (0.9 I m) Fording depth: 4ft (I.22m) Turning radius: Pivot to infinity Fuel capacity: 233gal (882Iitre) Fuel consumption: 0.34mile/gal (0. 14Skmllitre) Ground pressure: 14. 361b/sq in (99kPa) Cruising range: 80 miles (12Skm)

The cast turret of the M47, inherited from the T42, is perhaps its most characteristic feature. The long turret bustle, housing the radios, has a stowage box mounted on the outside. Curiously, these boxes are perhaps the feature of the M47 which has survived longest in the US Army, for some units in Germany have salvaged these boxes and have mounted them on their M60Als. The pointed gun shield, or mantlet, was 4.Sin thick and was much narrower than that of earlier tanks. Inside the turret the gun was mounted with a coaxial machine gun in the Combination Gun Mount M7S. Initially the .SOin Browning M2E I was used as the coaxial weapon but this was later replaced by the .30in machine gun Ml9l9A4EI. The90mmGunTI 19, inan improved form as the T 119El, was standardised as the M36 and had a vertically sliding, semi-automatic breech block . It was provided with a cylindrical blast deflector, although later production guns were fitted with a T-head blast deflector. The commander's cupola had a single hatch and five

17

vision blocks, and another .SOin machine gun was pedestal-mounted on the turret roof as a dual-purpose weapon for the commander's use against air or ground targets. Also in the turret roof were an armoured cover over the ventilating fan, and a small hatch through which the loader entered the tank. The hull was constructed from welded flat armour plate and castings and was derived directly from the M46. The hull of the T42 had been of welded plate construction but offered less ballistic protection. Belly escape hatches were provided below the driver's and co-driver's positions and the design had been improved to overcome the defects noted with the M46 in Korea. The engi ne compartment was separated from the crew compartment by an amloured bulkhead and there were separate fire extinguisher installations for each compartmen t. As well as the main engine , an auxiliary engine was provided for charging the four 12V batteries. The engine of the M47 was the Continental A V -1790-SB , later production also using the - 7 or -78 models. As mentioned earlier, the Ordnance Corps had achieved a commendable degree of standardisation among engine components , and of these components the A V -1790 series engines were V-12 air- cool ed engines with the larger 149cu in (2 .4Slitre) cylinders giving a total displacement of I , 791.7cu in (29.36Iitre). The A V-1790­ S series produced 81 Obhp net (604kW) at 2, 800rev/mi n but to avo id running the main engine merely to charge batteries or to traverse the turret, a small auxiliary engine was also fitted. The engine, located at the forward right

corner of the e ngine compartment, drove a generator which charged the vehicle's four 12V batteries, and was popularly known as 'Little Joe ' . Power was transmitted to the tracks by means of a crossdrive transmission with two forward and one reverse ranges . The driver used two main controls ; a foot throttle and a hand range selector, or ' wobble-stick ' and could thus drive the vehicle with only one hand. Even though this type of transmission was not new there were initial reliability problems due to the production changes made to speed up the initial deployment of the M47. A doubling of the life of the transmission was later obtained by tightening control of materials and tolerances in production. Access to the brakes and transmission for adjustment could be gained throu gh three circular hatches at the rear of the engine compartment, and these three hatches are one of the characteristic features of the rear view of the M47. The suspension was of the torsion bar type typical of American tanks since World War 2. On each side the re were six pairs of 26in rubber-tyred road wheels and there was a characteristic gap between the first and second roadwheels, due to the fact that the first pair on each side were mounted on leading arms, the remainder being on trailing arms. The running gear also incorporated a small idler wheel between the last roadwheel on each side and th e rear sprocket, and this idler was positioned to maintain track tension. Hydraulic shock absorbers were provided at the first, second, fifth and sixth wheel stations.

" l Or!! 11"', .. : .II,r".

18

IlA PD .

'I '

a generator : :,,-ccries. and was

=-~ '. ' ;:

_....: :-:.-;x:

typical of - -:.,- e::.: side there . ~ :-.rr.S and there ::"-0: and second ---. ; ..:.:.~ o n each side

• _ .. . _ control system, in those tanks which were ~~d ti ned with the rangefinder, allowed targets to be .- ;. ; :eJ at battle ranges of up to about 2,OOOyd, although _-e -.!..~ :;~ti nder was actually calibrated to 5 ,OOOyd. The - . ~ . nge fi nder had been standardised as the M 12 and .~ _ -:ng produced by the Airtemp Division of the ::-~ " e~ Corporation in Dayton, Ohio. It was of the -=::c-O-e o pic type , and required the operator to have a ; - : cegree of stereoscopic vision. A ballistics drive _ - ·:=~:ed the integral computer in the rangefinder to the _-- _-:-.2..1de(s periscope, while a superelevation transmit­ -:.. : :-nnec ted the rangefinder to the gun. Thus the =- ~ ·e ~· 5 ac tion of reading the range automatically _;-.ec th e commander's periscope and the gun on the ~ ; ;: : ociec ted. This was the first production integrated -' .~ : l'. trol sys tem and as such had its problems. The "-::>:- ~ " k " ati on transmitter required its own power supply, . _: ~ I inverter had to be provided. More seriously, it _, ':'::·icul t to train gunners to the required accuracy with :.- ~ -:ereoscopic type of rangefinder and troops quickly : ,' ntidence in the instrument. Tank commanders -:--~:'e :-:-e instead to use the time-honoured methods of -:; ~ es timation, with the commander 's periscope as the -:-- - .1.1"\' sight. To allow the gun to be fired indirectly ­ ::::..-..: .' . as artillery outside the range of the rangefinder­ : ':"':::ilut h indicator and range quadrants were provided. - ~~ditio n to this fire control equipment, the driver was :---, .i!e with a periscope to enable him to drive _ - :~ c - d ow n , and both the loader and the co-driver also _...: :'o:-ward-facing periscopes.

Variants of the M47 M47EI The US agreed in 1951 to conduct troop trials of the United Kingdom Fighting Vehicle Gun Control Equipment (FVGCE) Mk 4, as fitted to the Centurion. This system, made by Metropolitan Vickers, was not suitable for acceptance for US production and so could not be produced in the quantities required for a troop trial. Instead two M47s were fitted with the FVGCE Mk 4 and were made available to Army Field Forces for test, these tanks being designated M47El . The outcome of these tests is not known , but the significant difference from the gun control system of the M47 was that the British sys tem used electric traverse and a form of stabilisation. From this point Minneapolis-Honeywell went on to develop a similar system.

M47E2 When product improvement was being considered for the M48, similar improvements were also proposed for the M47. The de signation M47E2 was given to the proposed vehicle which was to incorporate a modernised fire control system, a fuel injection engine and modified transmission , an increase in protected fuel capacity and a rear engine deck modified to reduce infra-red radiation. As far as can be determined, the M47E2 was not built.

MJ02 Combat Engineer Vehicle A project for an armoured engineer vehicle based on the M26 chassis was initiated in 1947 as the Tank, Pioneer,

Th e .-\.\' -1790-5 series engine of the - =d "1~8. The engine mounts were - "-311,' locked , as opposed to the -iOCking mounts of the diesel engine

_. ~ 1 -l8 .-\.3. The two oil bath air

, - ~ seen on top of the engine were

..,... >~ on the AV05-1790 engine by --, .~ poe ai r cleaners, US Af71JY ~_

- - :: The T39E2 combat engineer ~ , standardised as the M102, In ~ture the boom at the front is erected. When not required it ...: ::i.sassembled and the components - ~ on both sides of the hull on the ~ d5 provided. US Af71JY via Col R.

-=-

19

T39. Many concepts were proposed and rejected before there was agreement that the vehicle should at least have a bulldozer blade , a winch. some mineclearing capability and the ability to launch assault bridges. There was less agreement about the armament, and suggestions even included the 8in rocket launcher T114. Eventually the British 6.5in A VRE gun was selected and adopted as the T156. As the overall concept hardened, the requirement for mineclearing and bridgelaying was dropped and the T39E I vehicle was built on the basis of the M46. Finally the M47 was used as the basis of the T39E2, which was standardised as the M 102. It would seem that the efforts to develop the M 102 were unrecognised, for although Tables of Entitlement were produced in which the M I 02 was available to engineer units in infantry and armoured divisions as well as to combat engineer battalions , by the time it could be produced the M47 chassis was becoming obsolete and other vehicles such as the T I 18 were on the way.

T66 Flamethrower Vehicle In discussing the T42 medium tank earlier, mention was made of a turret having been made available to the Chemical Corps for flamethrower development. The T66 used this turret which was fitted with the E30 flame gun and the E25 fuel system. (The 'E' designation is Chemical Corps practice, 'E' and 'R' being used in a manner analogous to the Ordnance Corps use of ' T' and 'E'. It is normal to refer to flamethrowers by combining the flame gun and its fuel system in a single designation.

20

Thus the T66 mounted the E25-30 flamethrower.) A previous model, the E24-29, was fitted to the glacis of the M46 tank which also towed a fuel trailer, but the E25-30 actually replaced the main armament of the M47 and its fuel supply was contained within the hull. Like the M 102, the T66 never saw service, for by the time the T66 design was fully developed, its chassis, the M47 , was approaching obsolescence. A.ssociated components

Bulldozer, Earthmoving, Tank Mounting, M6 To assist in route clearance and digging-in, an add-on dozer kit was developed for the M47. It was only a slight modification of the M3 dozer for the M46, and the operating mechanism was fitted in armoured pods below the glacis plate. The controls were placed between the driver and co-driver. Nearly 500 kits were ordered but only 31 were delivered by the time the M47 was designated Limited Standard in 1958. The bulldozer for the M 102 combat engineer vehicle was designated the M7.

Flotation Device Tl5 It was originally planned to adapt the M20E I swimming device, developed for the M241ight tank, to the M47, but in 1953 the T 1.5 flotation device was tested. It consisted of four pontoon sections carried on large brackets bolted to the glacis and engine decks, in addition to which long exhaust stacks were fitted. The pontoons were jettisoned on the tank's exit from the water obstacle, but the TI5

-: -::.:: .\ \-+ ­ and its

=-_''' th ~ \1102,

--"' :~ =--- ~

T66 des ign

.. .17.

\vas

-:- Gp left: The MI02. The hull of the M47 is obvious but the turret is e"cns;Yely modified. US Army

-:- op: The TIS notation device takes to the water. US Army ::z, : ~n a te d

the

- , ':i mming - c :.'" :-'1·+7 . but

.-: ... h.ich long ::::-0: : ~ !1 isoned - ~_ :"~ : th e TlS

,oo'-e: The TIS notation device on dry land. Immensely c-..m bersome on land, and not much better in the water, the TIS was : a practical solution to the problem of crossing inland waterways ~

takes.

consisted of nylon bladders which were inflated with a quick-setting resin foam , mixed at the crossing site. The bladders were supported in an aluminium platform on each side of the tank. At the same time as these attempts to float the M47 across water obstacles , a deep fording kit was developed to enable the tank to drive through rivers and lakes.

US Army

J;:\ ice was clumsy and unwieldy. It marked the end of -,::-empts by the US Army to float the M47, but the US . IMine Corps developed the Device, MC-l, apparently :' 2 ~ the same purpose. This is the only record of any .":-'IC involvement with the M47. The MC-l device

Other modifications M47M The firm of Bowen-McLaughlin- York announced a complete rework of the M47 in 1969. This version, which they designated the M47M, has the A VDS-1790-2A engine in an engine compartment similar to that of the M60, although the M47M's engine compartment actually

21

ul:l l l l l~1 1 ~

i I

II

Above: The M47 modernised by Bowen-McLaughlin-York, known as the M47M. Bowen-McLaughlin- York

has about 20% more louvred grilles on the top deck, giv ing eve n better engine cooling. The track tension idler is removed and the sixth wheel station moved nearly 4in to the rear to provide clearance between the engine oil pan and the torsion bars. The opening for the hull machine gun is sealed, and the exhaust for the hull personnel heater is led out through the now-defunct co-driver's hatch. The fuel capacity is greatly increased , and the performance of the M47M is very close to that of the M60. Commonality with the M4RA3 and M60 is further enhanced by the installation of the Cadillac-Gage Constant Pressure tun'et control system, which is of the electro-hydraulic type. The 90mm gun is retained. BMY undertook conversion of Iranian M47s to M47M standard and also organised the modification of Spanish M47s to the nearly-identical M47S. The M47 was also used by the US Army as a testbed for various components of succeeding vehicles - not all of which were adopted. The flat track suspensions of the T95

22

and T96 tanks were first tested on the M47, as was also the GEC Orion gas turbine engine. The UK 20pdr tank gun was installed in an M47 in another test, and the Rheem Manufacturing Company also carried out work on a rigid mounting of the Tl19 gun in the M47 turret. In common with most other combat vehicles a winterisation kit was produced for the M47, and there was also a gunnery training aid, the M 18 turret trainer.

The M47 in service US Service The M47 never saw action with the US Army and was never given a familiar name or nickname. Man y thousands were produced but the M47 was replaced fairly quickl y in service by the M48. It also appeared when several thousands of M46s were still around, and so the M47 found its way into the hands of reserve components and allies fairly soon. First issues to the National Guard were announced in November 1953 and in the following April the 40th (Grizzly) Southern California Armored Division in Southern California received its first battalion's-worth of M47s. Although the M47 and M48 served side by side for some time , the M47 was actually preferred for training, as the five-man crew allowed for 20% more men to be trained per training cycle and it was

Left: This photograph shows men of the Jordanian Army mounting their M47 COl Below: M47s of the Austrian Army on exercise. The 90mm gun of the nearer tank has the T-head blast deflector. Ausrrian Army

.­ - :.s '... as also the

easier to train drivers. Since there were plenty of M47s, and the differences between the M47 and M48 (for training purposes) were slight, the M47 remained in use for training for a considerable period after its replacement by the M48, Because of the appearance on the scene of the M48, theM47 was classified Limited Standard in October 1955, just 5 '12 years after its acceptance into service - a fairly short active life for a tanle

Foreign service -

nd was _~-:-:O' , :vtany , -~ : l':cd fairly ~xrcd when ::. 3.od so the

-=~' n2.1 Guard - - ::-:: :'o!lowing :_ .: .:-:-_: ~ :\rrnored =--= .. -:- .: ' :t5 first - _. _ .~ - J.nd M48 .!. - " 2.S ac tually ':':'Iowed for - : : :.e 2.n it was

Belgium was the first foreign country to receive M47s and its first 10 tanks arrived in Antwerp docks on board the vessel Steenstraete on 28 June 1952, in what must have been a most reassuring gesture under the Mutual Security Agency programme , for by this time the US Army was only about 25% re-equipped . 62 M47s remain in service. Pakistan received 380 M47s under the Military Aid Program, and these tanks saw action in the 1965 Indo-Pakistan War. Since then the M47 has also been involved in operations by the Jordanian Army during the 1967 Middle East War and against Palestinian guerrillas , and it was also used by the Turkish Army in the 1974 invasion of Cyprus . M47s were also supplied to Brazil , Greece (reported to have c350 in service), Jordan, Pakistan, Portugal (c30

obtained in late 1970s), Saudi Arabia, South Vietnam, Taiwan and Turkey. Belgium's M47s are now believed to be in reserve, and South Vietnam's tanks are assumed to have been absorbed into the Vietnamese Army after the communist victory. There are unconfirmed reports that South Africa has obtained a quantity of M47s . When Yugoslavia demonstrated her neutrality in the late 19505 , several items of US equipment were supplied including M47s. In 1978 50 of these M47s found their way to Ethiopia.

Foreign variants Austria In the early 1970s it was reported that Austria was considering re-engining its 120 M47s with a diesel engine. Little more was heard of this suggestion, but in view of Austria's order for an additional 60 M60Als in November 1978 it may be assumed that plans to re-engine the M47 have been dropped.

France Many M47s were received and these saw service for many years in the French Army, including active service during the 1956 Anglo-French operations at Suez. In 1967 the government armament agency DTAT reported

23

the development of a 105mm gun for the M47 which could fire the same ammunition as the AMX-30, and in particular the notorious 'Obus G' , a hollow charge mounted on ball bearings inside the projectile casing. Little more was heard of this development of the M47.

Germany (Federal Republic of) The Bundeswehr made little effort to improve the M47 for its own benefit. One chassis was used as a testbed for the engine for Leopard l, but apart from this, other modifications have been commercial proposals. Among these is Rheinmetall' s proposal to fit their 105mm smoothbore gun in place of the M47's 90mm gun, but this new gun has yet to attract any customers. Iran A tank manufacturing facility was constructed in Iran by the American firm of Bowen-McLaughlin-York between 1970 and 1972. M47s were rebuilt to M47M standard in this plant and two were fitted with a Hughes laser rangefinder for test purposes. Italy The firm of OTO Me lara of La Spezia undertook the installation of the UK 10Smm L7AI tank gun in the M47 after a study which bega n in 1964. Trials of the up-gunned M47 showed it to be more stable when firing than with the 90mm gun. Since the 105mm gun actually has a smaller outside diameter than the 90mm gun , it was a relatively simple matter to fit it into the 90mm mounting with a threaded adapter, and barrel changing in the field was also simplified. At the same time inner sup­ plementary fuel tanks were added to increase the range by

24

~~~~~.------------------

-

­

about 60%. OTO-Melara estimated that the cost of regunning the M47 would be between If12th and Ifl,th of the cost of a new tank fitted with the IOSmm gun. As OTO-Melara had produced the M60AI under licence for the Italian Army, the firm was familiar with the engine and transmission, so it was not surprising that attention was given to installing the diesel engine of the M60 in the M47. The vehicle which was fitted with the A VDS-1790-2A engine was also fitted with the I05mm gun and was probably a very potent tank, although it is not thought that either of the OTO-Melara conversions was adopted by the Italian Army. Another Italian firm, Astra SpA of Piacenza, made a study of the retrofit of the M47 and M48A I , and one M47 was actually re-engined. The engine used was the Detroit Diesel (General Motors) 12V71T, which is the engine used in the MI07 and MlO9 series of self-propelled artillery. The same firm also produced a bridgelayer based on the M47, although it was claimed that the M48, M60 and Centurion chassis could also be employed. This

Below: The M47 re-engined by Astra SpA. The turret and suspension are unchanged but the engine deck has been modified to cope with the ditTerent air intake and exhaust arrangements of the General Motors 12V71 diesel and its associated cooling. Astra via C. F. Foss RighI: The M47 AVLB developed by the Italian firm of Astra SpA. Astra via C. F. Foss

Below right : OTO Melara upgunning of M48 with installation of a British IOSmm gun.

cost of Ijlsth of

'x it h

the

\ehicle, known as the ' Veicolo corazzato lancia-porte ;:lasse 60 , Modello A26' was interesting in that the ends of the bridge could form adjustable piers to allow mUltiple bridging of gaps of up to 38m (124ft). It was reported in 1979 that 600 M47s had been sold to the FRG from surplus Italian Anny stocks. Korea An expedient armoured recovery vehicle (ARY) was produced by the removal of the annament from some of its M47s. A winch was installed in the fighting compartment and the cable fed out through the gun opening in the mantlet.

Spain The Spanish Army received a total of 400 M47s under the MAP. In 1976 work began on the modernisation of some of these M47s. Bowen-McLaughlin-York Co, of York, Pennsylvania , supervised the modification and assembly of the first M47S, which was similar to the M47M modified for Iran. Production of the M47S , known in Spain as the M47E , was supervised by Chrysler Espana at their Villaverde plant. In the M47E the German MG42/59 machine gun is fitted as the coaxial machine gun. Of the 400 M47s in Spanish service, it is believed that Chrysler modified between 100 and 200 tanks - sufficient to equip two to four battalions.

_.:.;-,jone M47 ~ :h.: Detroit - _- ...s :.he engine -­ :~: :-- ~ro pelled . :idgelayer - : :...- ~ : the M48, This

no n or a

- .'

....

.;:

.....

:

-.

..

~-

..

25

Above: The British Aerospace Corporation's installation of Swingfire ATGWs on an M47, shown at Farnborough in 1967. C. F.

Foss

Right: A rear view of the Swingfire installation on the M47. The tank still bears a Belgian Army number. BAe

UK Although not a user of the M47, various British component manufacturers put forward schemes for the improvement of the M47. The British Aircraft Corporation proposed mounting four of its Swingfire anti-tank missiles on the M47 and a tank so fitted was shown at Famborough in 1967. A proposal to re-engine the M47 with a GM diesel engine involved the Weybridge firm of Airscrew Howden, with their considerable experience of cooling tank engines. The diesel engine left

less space for the cooling system but the Airscrew Howden design took less space and less engine power. A new gun control system was suggested by Marconi for those countries using the M47, but none of these three improvements met with any commercial success.

26

--~--~

3. TheM48

Development of the M48 Deficiencies in the M47 were apparent even before production began. The Ordnance Corps was confident that its amalgamation of the hull of the 46ton M46 with the turret of the 36ton T42 would not pose any engineering problems , and its confidence was largely justified as the previous chapter discussed . However, a 36-ton tank must inevitably be designed to a lower level of protection than a tank IO ton heavier, and the earliest assessments of the M47 all agreed that its turret protection was generally lower than that of the hull . The fuel carried by the M47 was poorly protected and was insufficient to carry the tank through its battlefield day. For some time brand new M47s were stored in Ordnance depots until Anny Field Forces were satisfied that the defects were at least recognised. Work had begun on the new medium tank even while the M47 was being accepted as the US Almy' s standard medium tank. The AGF Equipment Review Board's recommendations have been quoted earlier in the book , but in 1950 revised characteristics were stated in the Army Equipment Development Guide (the Hodge Report) . These characteristics were agreed in 1951 by the United States, Great Britain and Canada at the Tripartite Conference on Armour. The main features of these revised military characteristics were: • the combat loaded weight should not exceed 90,000lb • the height over the highest fixed feature should not exceed 9ft 8in • the ground clearance should be a minimum of Ift 5in • the gun should defeat 4in armour angled at 60° at 2 ,OOOyd with an 80% chance of a first round hit , using kinetic energy ammunition and a rangefinder • the speed should not be less than 28mph • fuel consumption should be better than 0.72 miles/gal at 22mph. Army Field Forces later concurred in these characteristics, adding that: • any tank considered for production before 1958 should not weigh more than 50ton; • the tank must have built-in fuel (protected) to enable the vehicle to drive for 120 miles, at a rate of 25 miles in each 2h . Jettison tanks would be acceptable

• the frontal armour should be a minimum of 4in angled at 60° and elsewhere a maximum within the weight limitation but not less than proof against SAA and a near airburst of light artillery • it was desirable that the crew be protected against the disabling effects of a 20lb mine, and • there should be provision in the design for protection against flame attack as long as th e normal fighting efficiency remained unimpaired It was accepted that certain of these characteristics could not be incorporated into what was to become the M48 , but in order to kee p abreast of technology and to incorporate improvements when they were feasible, other models of medium tank were considered. These are covered later. A significant change in nomenclature was made at this point. Before 1950, tanks were designated as light, medium and heavy, but thereafter it was the tank gun which determined the role of the tank. Tanks were referred to in general terms as, for example , ' medium gun tanks', or ' heavy gun tanks ' . In specific terms , each model was now designated by the calibre of its gun . In November 1950 the nomenclature of the M47 was changed from 'Tank, Medium, M47' to 'Tank , 90mm Gun , M47' and this form of nomenclature applied to the M48 series from the very beginning. The design study for the M48 began in October 1950 when Detroit Arsenal first began to study improvements to the M47 design. As well as improving the distribution of armour protection, the study aimed to produce a tank with lower ground pressure, greater range, a more durable fire control system and improved ammunition for the 90mm gun . It was highly desirable that the excellent manoeuvrability and overall mobility of the M47 be retained . Detroit's design study was accepted by the Army and on 8 December 1950 an order for the design and manufacture of the Tank , 90mm Gun, T48 was given to the Chrysler Corporation. Chrysler began work on 22 December 1950 and were to produce six vehicles as engineering pilots - the first to be completed by the end of 1951. One of these prototypes was earmarked for the Marine Corps. An immense factory had ~een built in under 12 months

27

Right: The second pilot T48 at Aberdeen Proving Ground in April 1952. The 90mm gun is at its maximum elevation of 20'. US Army Below: The T48 is displayed to the press at Aberdeen Proving Ground in October 1952. The T1l9 gun and the massive mantlet are clearly shown. US Army

by the Chrysler Corporation outside the small town of Newark, Delaware. Here the first T48 was completed on 14 December 1951 - with just two weeks to spare. The Delaware Tank Plant covered 240 acres and consisted of five principal buildings, the largest of which itself covered 900 ,000sq ft (20.7 acres) , and there was also a one-mile test track within the Plant. The T48 was first publicly shown on 1 July 1952 at the Delaware Tank Plant, although service trials had begun a month earlier. The Chrysler Corporation was represented by the chairman of the board, Mr K. T. Keller, and the President of the Chrysler Corporation , Mr L. L. Colbert. Mr Keller had been the driving force behind the rapid initial construction and rapid growth of Detroit Tank

Arsenal in 1940. The Hon Frank Pace Jr, Secretary for the Army, performed the unveiling ceremony before 1,000 guests and the T48 obligingly burst through paper screens and snapped telegraph poles in similar fashion to the unveiling of the M3 Medium in 1940. Later, Mrs Beatrice Ayer Patton, widow of the flamboyant General George S. Patton, named the tank the 'Patton 48' in honour of her late husband. General Patton was kiJled in 1945 but his widow lived until 1953 having christened a tank her husband would have been proud of. The Chrysler Corporation rightly took most of the credits at the unveiling ceremony, but behind the scenes other large automotive concerns were becoming involved with the T48. On 2 March 1951 the Ford Motor Company

28

---

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/

Right: As part of the festivities at the roll-out ceremony, this T48 went though the smashing of telegraph poles which was traditional since the days of the M3 Medium. US Army Below: An exuberant performance by one of the pilot T48s at the unveiling ceremony at Newark on 1 July 1952. The gun at the commander's hatch is a .30in machine gun. US Army Bottom: Mrs Beatrice Ayer Patton and her daughter-in-law, Mrs George S. Patton 111, sample the ride in a T48 after the naming ceremony at Newark. US Army

- =-:-: :::-":;I ~ involved

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Left: The T48 under test at Army Field Forces Board No 2 at Fort Knox. The 90mm gun is fully depressed (_9°). RAe Tank Museum Below: The requirement for the T48 called for the ability to cross an eight foot trench. The test on the bridging device at Aberdeen showed that it could cross a trench of 8ft 6in, although the towing pintle had to be removed to negotiate any trench ormore than 7ft . USAnny

was awarded a contract for production of 400 T48s, and five days later the Fisher Body Division of General Motors received a similar letter contract. Chrysler's contract was for 548 tanks. Meanwhile , much of the production capacity of the Detroit Arsenal was standing idle, but in May of 1952 Chrysler and the Department of the Army reached agreement that Chrysler should once more take over Detroit Arsenal on a GOCO basis. A T48

30

Design Coordinating Committee met monthly to oversee the project. Now that the T48 had been revealed to the public it was a suitable time to assess the new tank against the M47 . There were many improvements, such as the wider tracks , the 'quick-change' gun barrel, the longer-base optical rangefinder and the armour protection. The T48 was in fact the first American tank to have a one-piece cast

hull - even the Sherman and M47 had consisted of cast sections welded together. But there was a price to pay for some of these improvements. The combination of an air-cooled petrol engine and the crossdrive transmission of the M47 was known to result in a high consumption of fuel and the M47's range of 85 miles was very poor. The same combination in the T48, with more weight and less fuel, gave an unacceptably low range of 70 miles. The maximum speed was also slightly reduced. Crew: 4 Weight: c90,000lb (400.3kN) combat loaded c83 ,4001b (371kN) less crew , ammo, fuel and equipment Length: 28ft 2.25in (8.59m) overall , gun forward 24ft 1.5in (7. 35m) gun in travelling lock 22ft 0.063in (6.71 m) hull only Width: 12ft 2in (3.71 m) overall 11ft 9in (3.63m) over tracks Height: 10ft7.62Sin (3.24m) to top of commander's MG Ground contact length: 13ft 1.5in (4.00m) Track centre distance: 9ft 7in (2. 92m) G/clearance: 1ft 6in (0.46m) Turret ring diameter: 7ft I in (2.16m) Armament: Main - 90mm T139 gun in T 148 mount with 360° traverse and _9° to + 20° elevation Secondary - Either one .SOin M2El (left) and one .30in M 1919A4EI (right) or two TI53 MGs (coaxial) One .SOin M2HB MG (commander's) Ammunition carried: 90mm - 60 rounds .SOin - 2,500 rounds . . d dependlfig on coaXIal weapons ' 2 500 . 301 0 - , roun s Armour: Hull - From 4. 75in (120mm) at 60° front to I. 37Sin (3Smm) at 30° rear Turret- 7in (l76mm) at 0° front (inc!uding4.Sin (l14mm) ofTI48 mount) to 2in (5 I mm) at 0° rear Engine: A Y-1790-SB details as for M47 Transmission: Allison CD-8S0-4

Above: A top view of the T48 with all hatches open. US Anny via R . P. Hunnicutt

Suspension: As M47

Power/weight ratio: 18hp/ton (1.5 IkW/kN) gross

Max tractive effort: 78,OOOlb (347kN)

Tractive effort/weight ratio: 0.86

Max speed: 31 .8mph (SJkm/h)

Max gradient: 60% (31°)

Trench crossing: 8ft 6in (2.S9m)

Vertical obstacle: 3ft (0 . 91m)

Fording depth: 4ft (1.22m) unprepared

Turning radius: Pivot to infinity

Fuel capacity: 21Sgal (813Iitre)

Fuel consumption: 0.3mile/gal (0.13km1litre)

Ground pressure: 10.2lb/sq in (70.3kPa)

Cruising range: c I 00 miles (160km)

The significant details of the T48 lie largely in those areas in which it surpassed the M47, and these fall into three groups: armament and fire control, armour protection and suspension. The 90mm Gun M36 (TI19EI) of the M47 was replaced by the TI39 Gun developed by Watervliet Arsenal. Both guns were identical ballistically and in their ammunition and chamber dimensions . The difference lay in the way in which the barrel was locked into the breech ring. The barrel of the T 139 gun could be unscrewed, after the removal of a locking key , and replaced within ISmin by a trained tank crew whereas it was a task for a workshop to change the barrel of the M36 gun of the M47. The T46 rangefinder of the T48 had a baselength of 6ft 7in , compared to the Sft baselength of the MI2 rangefinder in the M47. It also gave x 10 magnification as opposed to x7.S of the MI2 and thus offered greater

31

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Above: The Chrysler mount for the .500n MG is well shown on this

T48. US Army

accuracy in ranging. In fact it was claimed to make ranging 43% more accurate but this figure may be optimistic. The cast hull and turret of the T48 were better shaped than the M47. The one-piece hull was simpler to produce while the elliptical turret was better ballistically and also allowed the longer rangefinder to be operated by the tank commander. The new design also made possible an increase in the turret ring diameter from the 69in of the M47 which had been a feature of American medium tanks since the Sherman. The turret ring of the T48 was 85in in diameter. The effect of this was to allow for the installation of a larger gun at a later date, the longer recoil being accommodated inside the increased diameter. Changes to the suspension included the use of wider tracks and the elimination of the track te nsion idler of the M47. A new type of shock absorber or 'snubber' was used in which energy was absorbed in concentric tubes lined with the material used for brake linings. These friction type shock absorbers were estimated to last five to six times as long as the normal hydraulic type.

Production of the M48 In May 1953 the T48 was adopted as standard with the nomenclature 'Tank, 90mm Gun, M48'. By this time production was well under way at Ford and Fisher Body as well as at Chrysler, and deliveries ofT48s had begun in April 1952. Chrysler produced a total of 2,538 T48s and M48s up to July 1953, after which the Newark plant turned to manufacture of the T43 Heavy Tank. Ford produced 900 M48s in their $50million factory in Livonia, Detroit, while Fisher Body turned out M48s in

32

Detroit until June 1955 in a $200million contract which started in August 1952. Their bid for this contract was reputedly 12% lower than the Chrysler bid, although in earlier bidding Chrysler had secured a similar $160million contract by a margin of $7.6million. 120 M48s from early production had non-ballistic hulls , probably of mild steel, and were assigned for training only. The designation M48C was given, and the letter 'C' was embossed at the front of the right hand side of the hull. The production of the M48 presents a complex picture. There were at times three production lines, each working at different rates, and in 1953 production had to be slowed in order to keep all the lines going, although construction of a new Tank Modification Plant adjacent to the Delaware Tank Plant was still under way. It was decided that after April 1954 Chrysler would cease manufacture at the Delaware Tank Plant but would preserve the tooling for future use. The Tank Modification Plant was to be completed and used to store these machine tools. It was planned to use the additional facility to process, outfit and modify tanks but these tasks could now be accomplished by the Tank Plant, and the Modification Plant became known as the Delaware Tank Depot. Throughout the production the Chrysler Corporation retained the design parentage of the M48. Several estimates of the unit cost of the M48 have been made, ranging from $110,000 to over $250,000. Of course, inflation later made these prices less meaningful, for by 1978 it was estimated that the M48A5 represented capital investment of almost $500,000. The inventory price quoted in 1967 for an M48 was $130,80 I per copy, and this seems a fairly reasonable figure . It represents the cost of some of the production resources which went into producing a tank: 90 ,000lb steel; 6,5121b bauxite, from which aluminium is extracted (65% had to be imported); 1,800lb rubber; 950lb manganese, of which 92% was

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- -:::.= ~!-+ 8 have been ~~ ) .50.000. Of _ .-~ .7"" meaningful, . ~ -~.", 5 represented :: The inventory _ :. -' : 0 I per copy, - ;-_.~ 1: :c presents the .~ .... hi ch went into -.: . : .: ~aux. ite, from - -:0 De imported); ~ ~.: "':-.,-h 92% was

imported ; 1,4841b copper , of which 29% was imported ; TUiTet- From 7in (176mm) at40° (including4.25in 5201b nickel, of which 92 % was imported; 60lb cotton; (110mm) ofM87 mount) front to 2.5in (54mm) at 30° rear 1 ,9151b chromium, of which 99% was imported ; 100lb Engine: Continental A V-1790-5 series details as for M47 tin, of which 78% was imported; and 75,000 man-hours Transmission: Allison CD-850-4 of labour. Suspension: As T48 The costs of production overheads such as energy and Power/weight ratio: 16 Ahp/ton (l . 37k WIkN) gross transportation are not included , but the figures give an Max tractive effort: 78,OOOlb (347kN) Tractive effort/weight ratio: 0.79 idea of the raw materials and labour involved . Although the manufacture of tanks would not normally Max speed: 26mph (42km1h) be considered a commercially competitive business, there Max gradient, Trench crOSSing, Vertical obstacle, are nonetheless other pressures on the tank designer, and Fording depth, Turning radius: As T48 these are stronger than market forces. He must seek Fuel capacity: 215gal (813Iitre) constant improvements to his own design, and the Fuel consumption: 0.3mile/gal (0. 13km/litre) simultaneous improvements to enemy tanks provide an Ground pressure: 11.2Ib/sq in (77 AkPa) additional stimulus . While the standardised M48 was Cruising range: 70 miles (I 12km) being manufactured, work on the T48 continued and in the M48El the fuel-injection A VI-1790-8 engine and The hard lines of the M47 were somewhat softened in the austere XT -1400 transmission were tested. The Report of M48 , and tank recognition caricatures soon reflected this. the 1951 Tripartite Conference on Armour included a Both the M47 and the contemporary Centurion were of a comparison of the T48 with the Centurion Mark 3, then distinctly angular appearance but the M48 was the UK's medium tank. The T48's armour was thicker, characterised by rather more graceful curves. The floor of but cast, and overall the M48 was some 8-1 Oton (short the hull was rounded to minimise the effect of mine blast . tons) lighter. The extra coaxial machine gun met with The upper hull was also rounded and the pointed edge of approval, and the ease of control and simplicity of driver the glacis had a distinctive boat-shaped rounding as a training in the crossdrive transmission compared well result of the bevelling of two curved surfaces. Similarly with the Centurion's crash gearbox. Against these credits the turret was ellipsoidal in shape, rather like the 'frying the debit side was equally long. The power train was pan' turret of the Josef Stalin tank (although this complicated to maintain, expensive and time-consuming comparison was not drawn in .contemporary press to manufacture and costly to operate. The T48 carried less stories'). ammunition for its (unproven) gun, and the fire control The hull was an armour casting with a floor of armour system was also an unknown quantity. plate. Since any opening weakens the structure, an effort was made to reduce the number of holes required in the hull casting. "levertheless there were 13 different access The M48 Described holes, hatches and drain holes in the armour floor - and Crew: 4 this figure does not include the holes for the torsion bar Weight: 99,0001b (440AkN) combat loaded suspension housings. A bulkhead separated the hull space 93, 125lb (414.2kN) less crew, ammo, fuel and into two parts. In the fighting compartment the driver's equipment controls were grouped in the centre of the bow of the tank. Length: 27ft 8.5in (8A5m) overall, gun forward Behind the driver came the turret. The rear portion of the 24ft 5in (7 A4m) gun in travelling lock hull was the engine compartment, which housed the main 22ft (6.71m) hull only engine, auxiliary engine, transmission and fuel tanks. A Width: 12ft4in (3.76m) overall patchwork of armoured grille covers allowed access to 12ft 3in (3 .74m) over tracks each component and to the fuel and oil filler spouts . The Height, Ground contact length, Track centre engine covers were louvred to allow the forced circuJation distance: as T48 of cooling air , and the engine exhaust silencer (muffler) G/c1earance: 1ft 3.5in (0.39m) was mounted centrally and forw ard of the louvres. The Turret ring diameter: As T48 fuel tanks were mounted on each side of the engine, and Armament: Main - 90mm M41 gun in M87 mount with refuelling was therefore made hazardous by the proximity 360° traverse and from _9° to + 19° elevation of the hot exhaust and slow by the fact that the right tank Secondary-One .30in Ml919A4El MG (coaxial) could only accept fuel (highly inflammable petrol) at the One .50in M2HB MG (commander's) rate of 25gal/min. Ammunition carried: 90mm - 60 rounds The turret was more spacious than previous American .50in-180rounds tanks. There was more elbow room for the turret crew and . 30in - 5 ,900 round s the longer rangefinder was accommodated in a position Armour: Hull- From 4.03in (ll Om) at 60° front to 2in convenient to the commander. At the front of the turret (51 mm) at 30° rear there was a Jarge rectangular ape11ure for the gun and this

33

Above: Side view of the 1\148.

opening was covered by the 4.Sin armour mantlet of the T 148 mount. A cover of ballistic nylon material served to seal the opening against the elements . The :'v1inneapolis­ Honeywell gun control system was used . Standardisation of the T139 gun as the M41 was approved at the same time as the T48 became the M48. The .30in Browning machine gun M1919A4EI was mounted in a cradle on the left side of the T 148 mount and the same cradle would also accommodate the T1S3 machine gun (later adopted as the M37), The Browning could only be fed from the left hand side while the T 153 could accept left or right hand feed, Both the coaxial and main armament could be fired electrically by the commander and gunner; additionally the gunner could fire both guns manually in the event of a power failure. A .SOin machine gun was mounted on the commander's cupola and could be loaded , aimed and fired from within the turret. The tank commander could also operate the gun while standing in the cupola. To load the gun from within the tank the gun was traversed to a position from which the loader could perform the loading from his hatch . Ammunition for the 90mm gun was stowed in tubular racks in the hull and around the turret ring, Two racks occupied the space beside the driver and another rack was fitted on the turret floor. Ready racks were provided on the left side of the turret. Radios, in the required combination, were mounted in the turret bulge, The appropriate power, intercom and antenna connecting boxes were situated on the turret wall as part of the wiring harness, Two antenna bases were mounted on each side of the rear of the turret.

34

By contemporary standards, crew comfort was at least acceptable. The commander's seat was adjustable and could be folded to allow him to stand, or to sit with his head either inside or outside the cupola, Four plastic M17 periscopes gave him all-round vision , and the inside of the cupola ring was padded to prevent injury when the vehicle pitched on rough ground. Having acquired a target the commander then had to determine the range using the T46EI rangefinder mounted in the turret roof in front of him, The gunner's seat was also adjustable. His primary vision device was the M20 periscope sight. The loader did not fare quite so well. His seat was smaller and folded out of the way when he stood up to load the gun, and he had no means of seeing outside the tank when closed down, When not actually loading the gun, most loaders preferred to sit or stand in the open loader's escape hatch, The driver's seat had a 'dumping' feature, A lever on the floor released his escape hatch , after which by pulling a red-painted lever at his left he could swing his seat aside and then drop through the hatch , This was very much an emergency exit to be used when his normal exit was blocked. The driver's normal entry to the vehicle was through the hatch in front of the turret and in early models of the M48 this had a rather small opening which caused a certain amount of difficulty - particularly when a large driver wanted to leave the tank in a hurry, For driving when closed down he was provided with three T2S periscopes which gave him vision over a forward arc of 180°, and in tanks with the small hatch these dropped down when the hatch was opened . Later production tanks had a larger, heavier hatch which was raised before being swung into the open position and in these tanks three T36 periscopes were permanently installed, In these later

::1odels an infra-red periscope was mounted in the hatch for night driving. The T41 periscope was a binocular :n strument and incorporated a headrest to protect the .:r, \er's brow when traversing rough terrain. Illumination .::une from the infra-red head lamps beside the normal , ~ [\ 'ice headlights. Controls for the driver were grouped around his driving ='O sition. An aircraft-type steering wheel controlled the steering which was conventional enough in the forward ..jirection , but in reverse the steering wheel acted in the v pposite direction. The transmission W:>.S controlled by me transmission shift level at the right hand side of the steering wheel, and this had five positions; park , neutral, :ow . high and reverse. Selection of the range was simple al though novice drivers sometimes made a mistake in s"lifting from the low range into high, selecting reverse :ostead - once! It was a somewhat drastic way to learn not to squeeze the grip which located the lever in reverse. Piacing the transmission in neutral effected a neutral steer al though care was needed to avoid throwing tracks. Just as in a car, the accelerator pedal controlled the speed and :..ne brake pedal controlled braking. The brake pedal also acted as a parking brake when locked in position by selecting the ' park' position of the transmission. On instrument panels beside the driver were displayed fuel m d oil pressure gauges, the speedometer, and various '.::arning lights. The crossdrive transmission made a tachometer unnecessary. Switch panels held light sw itches and controls for the heaters and auxiliary engine. The main engine was the standard Continental .-\ \ '-1790-5B, designed on the modular concept of Ordnance engines described earlier. The same engine was also installed in the M47. A GM A41-1 auxiliary engine

:: C=.:=. ..-.. le ver on _~ .:;., :'1 y pulling - ~ \': 5 seat aside

was mounted in the left front corner of the engine compartment and drove a 28V , 240A DC generator. This served four purposes: battery charging, operation of electrical equipment when the main engine was not running, supplementing the main engine generator output as required, and heating the engine compartment to assist in starting the main engine in cold weather. There was no direct mechanical connection between the two engines although the auxiliary engine could be started by using the series winding of the generator as a starter, powered by the vehicle batteries . The four 12V , 100Alhr batteries were located on the floor of the crew compartment. All the mechanically dri ven engine accessories and the starter motor were fitted around the forward end of the engine with the exception of the two cooling fans which were on the top. An oil cooler and fan were mounted on each side of the engine, serving to cool both engine and transmission oil. These fans were driven from the transmission. At the rear of the engine the transmission was coupled directly to the flywheel. Power was transmitted to the final drives from the transmission by two universal joints and underwent a reduction of 5: I, terminating in the two sprockets. Four fuel tanks were fitted , two on each side of the engine. The total capacity was 215gal , of which about 200gal could be used. The hull was supported on 12 pairs of rubber-tyred roadwheels suspended on torsion bars. Each wheel

Below: The M48 on exhibit at the RAe Tank Museum, Bovington, is shown arriving on a Dyson SOtonne tank transporter trailer. The gun has the early cylindrical blast deflector, covered in preservative tape. RAe Tank Museum

Left: The business end of a 90mm gun barrel during final inspection at Watervliet Arsenal. US Army

station acted as the anchor for the torsion bar of the opposite wheel station, so there were six pairs of torsion bars spaced along the floor of the hull where the high tensile steel bars were later found to be rather vulnerable to mine damage. Each pair of road wheels was mounted on trailing arms and those on the left hand side of the tank were some 3-4in ahead of the other side, since the torsion bars were arranged side by side. Shock absorbe rs were installed on the firs t, second and si xth wheel stations (n umbered from the front) . As mentioned earlier, friction 'snubbers' were also fitted to some vehicles but their use was not yet universal. At the front of the tank the compens ating idler had the functi on of regulating the tension in the track . This idler was connected to the arms of the first road wheel on eac h side. When the roadwheel rode over a bump the compensating idler was pushed forward , absorbing any slack in the track. The adjustable link between the idler and road wheel was the means of setting th e correct track tension. Five pairs of trac k support rollers guided the track on its return run to the sprocket and another roller of the same size, suspended on a torsion bar between the sprocket and the sixth roadwheel, served to take up the slack in that particular section of trac k when the tank was turning or pivoting. The track was th e T97 rubber-backed steel type. This was a 'live ' track ; that is, a track in which the individual links are held together by end connectors which give the track an inherent tendency to roll up. Although thi s feature reduces rolling resi sta nce it also leads to the buildup of heat and results in a heavier track which is complicated to maintain. The links of the T97 track were fac ed with rubber chev ron pads for quieter, smoother running on roads. Each track of the M48 consisted of 78

links , although an older , worn track might require shorte ning by one link at times. An alternative to the T97 was the T96 steel track. This was noisier but gave a better performance in dry, rocky terrain. Very little use was made of the T96 track in later mode ls of the M48. The top run of the track was covered by trackguards and those on the M48 were rounded at the front. Later models were distinguished by angular trac kguards . To complete the description of the M48, the various hull fittings should be mentioned. Three large carbon dioxide bottles were carried as a fixed fire extinguisher system which was operated by the driver to smother any fire which might start in the engine compartment. The system could also be activated from outside the vehicle by pulling the exterior control handle to the left of the driver's hatch. A portable fire extinguisher was carried on a bracket on the turret wall next to the gunner. Two petrol-fired perso nnel heaters , controlled by the driver, were fitt ed in the hull. A blower in the rear of the turret provided a degree of ventilation in the vehicle when closed dow n, at least removing any fumes which might arise from battery charging or firin g the coaxial or main armament. No nuclear, bio logical or chemical (NBC) protection was fitted. As part of the radio installation an intercom set was fitted in order that the tank co mmander mi ght pass orders to crew members. An ex tension kit to thi s intercom terminated in a tel ephone in an arm oured bo x on the rear of the tank by which infantry could speak to the tank commander. Also on the rear of the hull were fitted towi ng hooks for the attachment of towbars or cables and a pintle for towing trailers, while a gun travelling lock was fitted on top of the e ngine compartment. Fire control equipment in the M48 vari ed and was bas ically whichever items were available when the tank was issued. Earl y tanks appeared with a similar arrangem ent to that of the M47 and were known as Phase III tanks. The Phase IV, or Ultimate , Fire Control System (FCS) differed mainl y in the addition of a ballistic computer. Despite the advanced-sounding connotation of computerised fire control, the T30 ballistic computer was only a mech anical analogue device which removed from the gunner the task of operating the T25 range drive. Th is device added elevation to the line of sight of the gunner's M20 periscope to allow for the trajectory of the gun , while ballistic information on the ammunition selected was added by means of the T24E2 ballistic drive . In the Phase IV FCS the computer automaticall y indicated the required elevation of the gun by combining the superelevation and ballistic information , and the T24E2 balli stic d,ive aligned both the commander's sight picture in the rangefinder and also the gunner' s periscope.

36

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Perhaps the one aspect of the M47 and M48 which aroused the most controversy and generated the most discussion was the rangefinder. There are two types of rangefinder: stereoscopic and coincidence. In optical terms the stereoscopic type (,stereo') is superior but not everyone has stereoscopic vision, even those with otherwise perfect eyesight. Training soldiers to make use of a phenomenon they cannot always perceive clearly presents problems , but both the M12 and T46 rangefinders of the M47 and M48 respectively were of the stereo type. Another problem arose over the division of crew duties. Before the advent of rangefinders, it was the tank commander who had traditionally estimated the range, but the configuration of the M 12 rangefinder had decreed that the gunner should perform this task. The longer rangefinder and better shaped turret of the M48 allowed the task of reading the range to pass once more to the tank commander, but some users advanced the view that with the gunner doing this , the commander could give more attention to operating his cupola, and acquiring other targets. There were also users who just objected to the rangefinder, preferring instead the World War 2 methods of range estimation. The debate centred on five main issues: • was the instrument too complex for the average GJ? • did the additional training involved lead to improved accuracy? • did the rangefinder actually improve ranging accuracy? • if the rangefi nder was the answer, where should it be mounted for the most effective results? • should a stereo or coincidence instrument be chosen?

Above: A vivid paint scheme on an M48 at Fort Ord, California in 1958. US A/my

The results of comparative trials showed that at least 2,000 practice readings were required to produce a consistently accurate reading, and during basic training this could be achieved if trainees took about 300 readings per day. Accuracy was improved at ranges between 800 and 2,200. As for the instrument itself, although it was complex, the crew were only required to perform minor adjustments , such as boresighting, and to change bulbs. In other cases the company turret mechanic would simply change the complete item. The argument for the centralisation of responsibility for fire control with the gunner lost the day, more for technical than tactical reasons. The integration of the primary sight, rangefinder and laying of the gun into the one instrument operated by the gunner caused many engineering difficulties, was unreliable and led to lack of confidence in the rangefinder. For this reason the sight and rangefinder were separated in the M48. As for the choice of instrument, the superior accuracy of the stereo rangefinder decided the issue, even though operators would have to be hand-picked. Laying the gun accurately is of little value if the fall of shot cannot be see n. This has always been a problem with armour-piercing ammunition which has no effect if it does not hit so mething hard , such as a tank. With high explosive ammunition it is possible to see the shell land to make corrections so that the next round hits the target. However , the high velocity tank gun creates such a pressure at the mu zzle that even with smokeless powders a doud of dust is thrown up, completely obscuring the

37

tank's vision in that direction. In an attempt to overcome this problem the M48 was fitted with a so-called blast deflector, or mu zzle brake. In theory, such a device should clear the smoke and dust away from the muzzle as well as reduce the recoil on the gun by reversing the direction of some of the propell ant gases. The blast deflector of the M36 gun on the M47 was a simple cylinder with two holes at right angles, a simple design hav ing no effect on recoil. Early models of the M48 retained this pattern on the M36 guns fitted but when the M41 gun became available in quantity a single-baffle muzzle brake similar to that of the 90mm Gun M3Al of the M46 was fitted . Both of these , and the later T-shaped blast deflector, were described as ' . . uniformly unsuccessful as anti-obscuration devices'. There has always been doubt as to the value of such devices , and in fact the successor to the M48 series, the M60, does not use a muzzle brake . Types of ammunition ava ilable to the M48 were divided into two mai n types: armour-defeating and other natures. Armour-defeating ammunition falls into two categories; those employing kinetic energy , and those using chemical energy. In simpler terms the two approaches may be resolved into blUte force and high explosive . The term ' armour-piercing' (A P) is specifical­ ly applied to the form of kinetic energy ammunition which uses a solid shot of the same calibre as the gun. ' Hyper- velocity armour-piercing' (HV AP) referred to a core of a high density material such as tungsten carbide in

a jacket of a lighter material such as aluminium alloy. Overall the projectile weighs less than the AP shot and can therefore be fired at a higher velocity and deliver its energy over a smaller area of the target. This type of projectile is known in British service as APCR, for ' composite rigid'. Developments in kinetic energy attack are described later. Chemical energy antitank ammuni­ tion likewise divides into two approaches. ' High explosive anti-tank' (HEAT), is the term reserved for ammunition using the shaped charge principle to defeat a target. Unlike the kinetic energy attack, where muzzle velocity is all-important, the effect of the shaped (or hollow) charge is independent of the velocity with which it strikes the target. Indeed, its effect is degraded by spin ,

Below: The high explosive anti-tank (HEAT) round for the M48. This is the M348 which was the first to be fielded . US Army Bottom: The later M431 HEAT round, showing the nose spike which contains the impact fuze. The shaped charge is initiated at its base to produce the jet which penetrates the target. US AmlY Right: Loading HE into a tank of Company D, 11th Armored Cavalry Regiment at Hung Nghia in January 1971. Smoking during replenishment was normally discouraged! US Anny

CARTRIDGE, gO-MILLIMETER: HEAT, M348Al (T108E46) AND M348 (T108E40)

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so most HEAT projectives fired from tank guns are fin-stabilised. The other fonn of chemical energy ammunition is the 'high explosive squash head' or HESH projectile. Originally developed by the UK during World War 2 as a means of attacking concrete structures, and known as 'Wallbuster', HESH uses a projectile with a filling of plastic explosive to cause a scabbing effect inside the tank, hence its name in US nomenclature of HEP, for 'high explosive, plastic'. In tank ammunition, the conventional high explosive (HE) projectile is not considered to be chemical energy ammunition - that is, it has no primary armour-defeating role. It is grouped with other natures as secondary ammunition, and is used for the destruction of non-annoured targets, where its fragmentation and blast action are most effective. Other secondary natures include smoke ammunition, both for obscuration and for marking targets, and canister for anti-personnel use. Training ammunition is used to simulate primary natures of ammunition and consists of inert projectiles designed to be ballistically similar to the service item but without the destructive effects. A later fonn of armour-piercing ammunition is the annour-piercing discarding sabot (APDS) round. Developed in Britain during World War 2, APDS employs a subcalibre core, or penetrator, of dense

material which is supported in the gun by a sabot in three or four sections. On leaving the muzzle the sabot separates and falls away , leaving the core to travel to the target at a much higher velocity. For a long time the US were quite satisfied with HV AP , and no effort was made to produce APDS. Although some APDS rounds were developed in 90mm, none were standardised. The 105mm gun of the M48A5, described later, fires APDS. HV AP and HEAT were the armour-defeating rounds for the M48, although development HEP rounds existed and some sight graticules were marked for HEP.

The M48 enters service In the first few years of the service life of a new weapon system there may be literally thousands of modifications. The majority may appear to be of minor significance, such as the moving of an internal stowage bracket, or the addition of protective padding to sharp objects and fittings which might otherwise cause injury to the crew . Only hard usage can reveal these slight failings, and this 'burning-in' period is the heyday of the 'why ever didn't they ... ?' question. While the M48 was being ' de-bugged' of these irritations, there remained some more serious shortcom­ ings. In the spring of 1955 Exercise 'Desert Rock VI' was held in the Nevada desert . Task Force Razor, consisting

39

Above: Father and son. Chief Thomas K. Yallup examines the M48 with the assistance of his son, Cpl Bill Yallup during training at Yakima Firing Center by armoured units of 44th Division in May 1954. US Army Below: The Chrysler mount for the .50in machine gun is clearly shown on this M48 of 32nd Infantry Division at Yakima Firing Center, Washington in May 1962. US Army

of 55 M48s and supporting vehicles, mounted a counter-attack after a nuclear strike. An atomic weapon of 35-40 kiloton yield was detonated at the Atomic Energy Commissions's test site in the desert at 5. lOam on Tuesday, 3 May. Task Force Razor was in hull down positions at 3,OOOyds from ground zero of the strike and motored through the fallout zone in order to arrive on its

objective by 6am. As a related exercise, three unmanned M48s were exposed to the blast at 500yds and remained basically sound. The tank at a three-quarter oblique angle to the bJast was rolJed over 1112 times, stripping both tracks and one idler. The gunner's periscope was destroyed, the battery cracked and fueJ and oil lines fractured, but the engine was serviceable . The tank facing the blast head-on was blown back 10ft but only superficially damaged and was driven away. The third tank was positioned with its right side facing ground zero. The track on that side was tom off, and light metal (such as mudguards and stowage boxes) was wrapped around the gun. With the track replaced the tank drove away. Of the jeep and Y4 ton truck at 525yd there remained'. . . no identifiable pieces'. The three M48s eventually survived six nuclear strikes. Of course, the fact that two tanks out 6f three could be driven away does not mean that they were combat-worthy by any stretch of the imagination. External optics were scoured by sand; delicate fire control

equipment such as the rangefinders hopelessly jarred, and in a manned tank the crew would certainl y have been killed by immediate radiation . At this time the M48 had no collective protection against contamination although the slight overpressure provided by the turret blower would tend to keep out radioactive dust. Pe rhaps the major lesson from Exercise ' Desert Rock VI' was completely unconnected with the nuclear strike. Part of the build-up to the simulated counter-attack had been a long approach march across some 200 miles of desert, and this operation highlighted the extremely high fuel consumption of the M48. As a result of this and other experiences, psychologists at the Army Human Resources Research Office (HumRRO) were tasked to instil the virtues of fuel conservation into tank drivers, thus anticipating the energy crisis by 20 years. At the same time efforts were begun toward s the conversion of the Army from the use of petrol (gasoline) to diesel fuel. The nuclear survivability tests had also shown that petrol was especially vulnerable on the nuclear battlefield. Complaints from other users both in Germany and in the continental United States had concerned the size of the

driver 'S hatch and the commander's difficulty in aiming and loadi ng this machine gun. Another major deficiency reported was the high level of infra-red (IR) radiation emitted by the e ngine exhausts. With 1954 state of the art technology the M48 could be detected and identified at 1,200yd. An earlier comparison with Centurion Mk 3 has already been mentioned. Detailed comparisons with the T-34 and T-54 , as well as with the M47, were now available and showed that the M48 was basically evenly matched with the T-34, but that the 100mm gun of the T-54 would probably be superior at ranges greater than I,OOOyd. This disadvantage might have been redressed

Below: A dead M48A I is loaded on to a tank transporter at Yakima Firing Center during Exercise ' Lava Plains' in 1961 . US Anny Bottom: The recovered M48AI aboard an MI23iM15A2 tank transporter of704th Ordnance Company. US Anny

Above: This photograph shows the M I cupola. The vision block, gM!riscope guard and the pivot for the hatch are well illustrated. US Anny

Left: In this photograph of an M48A2 the hatch on the commander's cupola can be seen to swing horizontally. The .50in machine gun is at full elevation. US Anny

by the higher first round hit probability afforded by the M48's Phase IV fire control system. The M48 could defeat the armour of the T-34 with ease at up to 2,OOOyd, but even the T-34 presented a serious threat to the frontal armour of the M48 at up to 500yd . Against the M47 the M48 's range of75 miles was difficult to accept, and it was not easy to persuade seasoned tankers that the new tank with about 10 rounds of 90mm ammunition and one machine gun less was really an improvement. Pound for pound, the M48 was baHisticaHy better than the M47, particul arly in the turret, but the hull sides were still a weak point. While undoubtedly better than that of the M47, the M48 's fire control system was still seen as insufficiently rugged or ·soldierproof'. The mechanical reliability of the M48 had also given

cause for concern. Design faults had led to costly modification problems, but even so the overall availability of the M48 and M48A 1 was unacceptably low. A General Accounting Office report of 1960 was strongly critical and drew attention to the average of one breakdown every 37 miles. Some production models of the T48 were fitted with a larger driver's hatch, and the Model 30 cupola developed by Aircraft Armaments Inc , was installed on some of these. The Model 30 cupola , orT6 mount, was to become one of the hallmarks of the M48 series. Interest in remotely controlled secondary armament had remained high since preliminary work on the Tl21 and T 122 cupolas on light, medium and heavy tanks in World War2 and both the TI8 armoured infantry vehicle and the T37 and T 41 Iight tanks had also featured remotely aimed and fired .50in machine guns. Military Characteristics for a commander's dual purpose machine gun mount were published in 1950, but the design of such a mount was

42

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insufficiently advanced in May 1953 to be included in the standardised tank and the awkward, fragile 'Chrysler mount' was adopted instead. The new mount replaced the entire vision ring and was in effect a small turret, adding over a foot to the height of the tank. The commander was given a periscope sight to aim the machine gun, and vision blocks for an all-round view. The T6 mount was adopted as the M I machine gun mount but was always referred to as the cupola - and indeed this later became its official nomenclature (,Cupola, Tank Commander's: .50in machine gun, M I '). It used a slightly modified form of the .50in used on the M48, adapted for electric firing and fitted with the :\IUO manual charger, but the heavy-barrelled M2 was not the ideal choice as the receiver and working parts protruded so far inside the cupola. It was not until the M85 machine gun was available that this problem was solved in the M60 tank. The extremely short radius of action of the basic M48 has been mentioned. In the T48E 1 Detroit Arsenal attempted to double the range by carrying more internal fuel and this was shown to be feasible. However, it did require a rebuild of the rear of the tank hull, and since major changes were underway in the concurrent T48E2 project, the T48El was dropped. Another way to increase range was to carry fuel externally. The Universal Jettison Fuel Tank Kit was developed as a means of carrying four extra 45gal drums on a crib at the rear of the tank. (These drums actually held 55 US gallons!) These jettison tanks were widely used in peacetime training but when used in action by the Jordanian Army they proved to be extremely hazardous and were abandoned with unseemly haste. Later models of the M48 M48Al Crew: 4 Weight: 104,000lb (462.6kN) combat loaded 97 ,000lb (431.5kN) less crew, ammo, fuel and equipment Length: 28ft 7. 75in (8. 73m) overall gun forward 24ft 2in (7 .36m) gun in travelling lock 22ft 5.5in (6.87m) hull only

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Width: 11ft llin (3.63m) overall Height: 10ft 3.375in (3 .13m) to top of cupola Ground contact length, Track centre distance: As M48 G/clearance: 1ft 3.25in (0.38m) Turret ring diameter: As M48 Armament: As M48 except commander's .50in M2HB is in cupola in M I mount Ammunition carried: As M48 except .50in 500 rounds Armour: As M48 Engine: Continental A V-1790-7C details as M47 Transmission: Allison CD-850-4B Suspension: As M48 Power/weight ratio: 15. 6hp/ton (131 k W/kN) Max tractive effort: 83 ,0OOlb (369kN) Tractive effort/weight ratio: 0.8 Max speed, Max gradient, Trench crossing, Vertical obstacle, Fording depth, Turning radius: As M48 Fuel capacity: 200gal (757litre) 410gal (1 ,550Iitre) with jettison tanks Fuel consumption: 0.3mile/gal (0. 13km1litre) Ground pressure: 11.8Ib/sq in (81.3kPa) Cruising range: 70 mi les (112km) 135 miles (216km) with jettison tanks

On standardisation of the T48 in May 1953 there were three different versions of the T48 : (1) with a small driver's hatch and Chrysler cupola; (2) with a large driver's hatch and Chrysler cupola; (3) with a large driver's hatch and the Model 30 cupola. Version (I) was adopted as standard as the M48 and the designation M48Al given to version (3) and version (2) with the Model 30 cupola substituted , although the M48AI was not yet formally adopted. 20 months later the M48A 1 was

Below: M48Als on the firing point on Range 4 at Grafenwohr in

July 1959. These tanks from 4th Armoured Division have the cribs

for the Universal Jettison Fuel Tank Kit. US Army

44

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Above left: Side view of the M48A1. Left: Driver training in the M48Al. The point of balance is just behind the third wheel station. US Army Above: Army Reservists of 103d Infantry Division refuelling their M48A I from an M49 tank truck during summer camp at Camp McCoy, Wisconsin in 1961. US Army Right: Rebuilt M48A Is at Red River Army Depot, Texarkana, Texas. The 90mm gun has no blast diffuser and the track tension idler has been eliminated in the rebuild. These tanks, photographed in 1978, are probably destined for a foreign country rather than US Army reserves. US Army Below right: Nightliring of the M48A l's .50in machine gun. The tank's exhaust is torching as brightly as the tracer in this picture taken at Fort Benning in January 1964. US Army

adopted as Standard and the M48 reclassified as Substitute Standard. One point worthy of note is that like the M47 , the M48A I never had a development designation. Production of the M48A 1 was undertaken by the Chrysler Corporation in 1955 and 1956, a total of 1,800 being supplied to the US Army . The last in Regular Army service were in the 4/69th Armor at Fort Benning, Georgia in support of the Infantry School. They were replaced in mid-1970 by M48A3s.

45

Above right: M48Als firing at Hohne in 1956. The tank telephone is shown connected 10 Range Safely. US Anny Centre right: M/Sgt Charles E. Taylor of Company D, 13th Cavalry adjusts the fire of his M48Al during an exercise at Grafenwohr in September 1960. US Anny Below: Maintenance, while not very glamorous, is an essential part of the tank's life and also ofits crew. The powerpack is about to be lifted back into the engine compartment of the M48 on the left. Capt Jerome E. Rolle and CWO C. M. Osborn are examining the CD-850 transmission . Behind it the oil coolers and fans can be seen. US Anny Above right: A top view of the M48Al. US Anny via R. P. Hunnicutt Right: An M48A I moves on to Ihe firing JMlint on Range 4 at Grafenwohr during a 4th Armored Division field training exercise in July 1959. US Army

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Above: M48A Is and M59 APes of the 709th Tank Battalion on training in Germany. US Anny Right : The gunner's position in the M48A I. The rubber-covered forehead protectors of the periscope mount are obscuring the eyepieces of the M20 Periscope Sight. The gunner's left hand is on the turret traverse control and the handle to the right is the gun elevation control. US Anny

.\/-+ .4..:' Crew: -+ Weight: : : : 9S.000lb ..::­ Length: '::: 5:':: ­ 24ft4.7" in --: 22ftS .75i Width: I I f: : _~ _ Height: 10:': : : ~ Groundco n~-~~~

M4SAI G/clearance: _-'- ­ Turret ring di­ Armament: ..;:, MS7Al mouc = Ammunition .SOin -1,365: _ ­ .30in - 5,950:-c

Armour: Det'· , Engine: Conti- _ 2,SOO rev/mi petro) engine I L ~ ': (l46mm)) com:-:­

48

Above: Side view of the M48A2

M48A2 Crew: 4 Weight: 105 ,0001b (467kN) combat loaded 98,0001b (434kN) less crew, ammo, fuel and equipment Length: 28ft 6in (8.69m) overall, gun forward 24ft4.75in (7 A3m) gun in travelling lock 22ft5. 75in (6.85m) hull only Width: II ft II in (3 ,63m) Overall Height: 10ft 1.625in (3.09m) on top ofcupola Ground contact length, Track centre distance: As M48AI G/clearance: 1ft 4,5in (OA2m) Turret ring diameter: As M48A I Armament: As M48A I except M41 90mm gun could use M87AI mount and coaxial.30inofM37 (TI53) type Ammunition carried: 90mm - 64 rounds .50in- I ,365 rounds . 30in - 5,950 rounds Armour: Details as M48A I Engine: Continental A VI-1790-8, 825hp «615kW) at 2,800 rev/min) air-cooled, four-stroke, 12-cylinder, petrol engine (bore 5. 75in (I 46mm) stroke 5.75in (l46mm» compression ratio 6.35: 1

Transmission: Allison CD-850-5 Suspension: As for M48A I except three return rollers each side Power/weight ratio: 15 Ahp/ton (I, 29kWI kN) gross Max tractive effort: 84,000Ib (373, 6kN) Tractive effort/weight ratio: 0,8 Max speed: 30mph (48kmlh) Max gradient, Trench crossing, Verticle obstacle, Fording depth, Turning radius: As M48A 1 Fuel capacity: 325gal (I ,230Iitre) 535gaJ (2,025Iitre) with jettison tanks Fuel consumption: cO,5mile/gal (0,3kmllitre) Ground pressure: II ,9lb/sq in (82.0kPa) Cruising range: 160 miles (256km) 250 miles (400km) with jettison tanks One serious fault in the M48AI which was not rectified was the IR signature - the characteristic pattern of infra-red radiation by which the tank could be detected and even identified. The problem was addressed in the T48E2, also known as the Product Improved M48 , which had a completely redesigned engine compartment. From the inside this allowed a 50% increase in the fuel carried under armour, as well as the installation of the A VI-1790-8 fuel injection engine, mated to the CD-850 series transmission, An experimental model. the M48EI, was fitted with the AUI-1790-8 engine and XT-1400 transmission, From the outside the engine compartment was more box-like and the exhaust in the centre of the M48 's engine deck was replaced by a twin system beneath the armoured decking which vented through the two large doors at the back of the engine compartment. The exhaust heat was dissipated over a larger area and thus gave a much lower

49

Above: Refuelling an M48A2 of 7th Infantry Division on exercise in Korea in 1962. The crewman holding the fire extinguisher is a reminder of the .ver-present fire risk with petrol (or gasoline). US Army Right: A rear view of the M48A 1 at Aberdeen Proving Ground in July 1955. US Army via R. P. Hunnicutt

50

This page: Three views of the M48A2 undergoing Engineering Test at Aberdeen Proving Ground in January 1957. US Army via R. P Hunnicutt

I.

signature . The tank telephone had to be relocated on the right trackguard. The revised engine compartment arrangement was in fact carried over into the M60 series and also features in most other armies' rebuilds of the M48 series and also in the Spanish Army's rebuilt M47s. The improvements to the T48E2 were completed by an up-dating of the fire control and gun control systems. The M13 stereoscopic rangefinder was replaced by the M13A 1, supposedly to allow engagements at greater ranges, and the mountings of the sight and telescope were modified to better withstand the shock of firing. Tests had shown that the Cadillac Gage constant pressure gun control system operated more smoothly and predictably and was quieter, although the recharging cycle was still alarmingly noisy. The Cadillac Gage system was installed in the T48E2, and this tank became known as the T48E3 although the designation was unofficial. After tests at APG, Fort Knox and Yuma Proving Ground it was this version of the T48E2 which was adopted as standard as the M48A2 in September 1955, At the same time the M48A 1 was reclassified substitute standard and the M48

51

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Above: An M578 wrecker lifts the 13ton turret of an M48A2. The lugs on the front of the tank hull may have been for an experimental mine exploder. US Army

declared limited standard. The designation M48E2 appears to have been used for a time to describe the M48A2. The fuel injection in the AVI-1790-8 engine was originally an English design. The firm of Simmonds Accessories in Tan)'town, New York had negotiated the world rights (less the UK) for the SU Carburettors system similar to that fitted to the Conqueror. Based in Coventry, SU Carburettors now forms part of the British Leyland group. Simmonds approached the Continental Aviation and Engineering Corporation (as it then was) and offered the SU system. It was adapted to the Ordnance­ Continental engine in the hope of improving its fuel economy. An improvement of 27% was claimed , and even without the larger fuel tanks the M48EI gave an increase in range of about 45 miles. In the fire control system of the M48A2 the superelevation actuating shaft was connected to the M20A3 primary sight , with the M 13A I rangefinder somewhat optimistically graduated from 500 to 4,800yd. The constant pressure electro-hydraulic gun control

52

system was also introduced, allowing control by both gunner and commander, but there was still no stabilisation. In the M48A2C the fire control equipment was graduated in metres, and the Ml7 (MI3AIEI) rangefinder was of the coincidence type. Apart from the prominent cupola and distinctive engine decks, the M48A2 could be recognised by its three return rollers , compared with the five of the M48 and M48A I. The two rollers were removed to save weight , and in the M48A2C of 1959 production the track tension idler was also eliminated. A lOin 2kW tungsten searchlight could be installed and used with an IR filter - however, viewing devices were limited to the driver' s periscope and the commander's binoculars. Production of the M48A2 began in June 1956 at Aleo's plant in Schenectady. Some M48s were converted to M48A2C standard by Chrysler at their Delaware Defense Plant, known by then as the Lenape Ordnance Modification Center. Production of the M48A2 ended in 1959 to allow the M60 programme to begin. A total of 11,703 M48-series tanks was produced, but to account for all of them now is impossible. Many went to foreign armies and have since been sold , with or without the approval of the US Government. Many have been captured from their former owners, and even today the Vietnamese Army has a considerable force of M48 series tanks.

M48A3

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Crew: 4 Weight: I04 ,0001b (462k.N) combat loaded 98 ,0001b (435.9k.N) less crew , ammo, fuel and equipment Length: 28ft 6in (8.69m) overall gun forward 24ft 5in (7 A4m) gun in travelling lock 22ft 7in (6.88m) hull only Width: Ilftllin(3.63m)overall Height: lOft 3in (3. 12m) overall Ground contact length, Track centre distance: As M48A2 G/clearance: lft4in (OA1 m) Turret ring diameter: As M48A2 Armament: Main - As M48A2 Secondary - One 7 .62mm M73 MG (coaxial) One .50inM2HB MG in MI cupola withMIOmanual charger (com mander's) Ammunition carried: 90mm - 62 rounds .50in- 630 rounds 7 .62mm- 6,000 rounds Armour: Details as M48 Engine: Continental A YDS-1790-2A, 750bhp «559kN) at 2,400rev/min) air-cooled , 12-cylinder, diesel engine (bore and stroke 5. 75in) compression ratio 16: I Transmission: Allison CD-850-6 Suspension: As for M48A I Power/weight ratio: 14Ahp/ton (1.2IkW/kN) gross Max speed, Max gradient, Trench crossing, Vertical obstacle, Fording depth and Turning radius: As M48A2 Fuel capacity: 375gal (I ,420Iitre) early version 385gal (I ,457Iitre) late version Fuel consumption: cO.7mile/gal (0. 42krnilitre) Ground pressure: I 1.81b/sq in (81 AkPa) Cruising range: 290-310 miles (464-496km)

By late 1958 plans for the M48 's successor were going ahead. The T95 project was bogged down in its over-sophistication, so the next alternative was a complete revamping of the M48 series. This concept was provisionally known as the XM60, the prefix XM- having by now replaced the old T-numbers . Following the line which began with the M26, the XM60 was an evolutionary design but was to be vastly improved in two major areas. Firstly, the 90mm gun was to be replaced by the British 105mm gun and secondly, the thirsty petrol engine was to disappear in favour of a diesel. This latter decision had been taken once before in the US Army, in 1941 - only to be reversed after a few months. This time minds were somewhat clearer and the diesel was here to stay . An early diesel engine, the A YDS-1790-P, had been installed in an M48 in 1957, mainly to test the engine. Now , to investigate the installation, work began in mid-1959 on the M48AIEI, which was the M48AI modified to accept the new A YDS-1790-2 diesel and also the 105mm gun. Six pilots were built but in the M48AIEI the diesel engine was fitted in an ad hoc fashion into the cramped engine compartment of the M48A I hull. One of the requirements for the diesel engine had been that it should fit into exactly the same envelope as the fuel injected engine, so in the M48A I E2 the rear of the hull was altered to the configuration of the M48A2. This time the 90mm gun was retained but a 7.62mm coaxial machine gun was substituted for the .30in. The M48AIE2 was a simple conversion and after production

Below: A late model M48A3 in ' factory-fresh' condition after rebuild by Bowen-McLaughlin-York. BMY remanufactured and modified a total of 578 M48A Is to the M48A3 standard. Bowen-McLaughlin- York

Left: The first task at the halt is to dig defences, in this case on the edge of the airstrip at Plei Djereng. The suitcase carried on the engine deck of this M48A3 of troop C, 1st Cavalry (Mechanized) is not standard vehicle equipment. US Anny Below: M48A3 top view showing salient details

U'..d..---------- Muzzle brake

(bore eva cuator)

1-----------9Clmm gun

j.

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M27 periscope (one of three)

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Fire extinguisher h.

>;:-~~~r--C!""",-I-+---.mr---Gunnet's M1 05C telescope ;:~~;;=!~f---Personnel heater exhaust

Searchlight ---1IT~ff"ff/7"'~~~~lJ

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Tool 80'< ----iftHo-

Rangefinder 'ear'_--fH+--+H+ (one each side ) Loader 'S hat,'h----+lI++-+-I-1!--++<~

machine gun

LJIj-_"...,f-¥--HlI---Gu"n.' · s M31 sight ~tIt---Stowage

box

([t:::I;;i:~~t.1~UI!__ Commander'S

M28C periscope

--->,t>IL-+W+I!I---Cup(,la hatch

Antenna base (one of th",eJ.---+~w.,.,~~oij:Jl'\

I

Water can ---l+t--'t:...<

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stowage basket

Searchlight stowage Ii':<1UI'o----+++_---I

Hinged .n~line 10'OV",.---.,Iii'F~ Stowage bo,'---Htt-­

Gun travelling

10CI'---tt==~~~~~~k:J~~r:Jr--Tank telephone

of the M60 was under way the conversion of 2,000 M48Als to the new model began in July 1963. The M48AIE2 was standardised as the M48A3 and replaced earlier M48 series tanks in units which were not scheduled to receive the M60. A similar conversion based

54

1I+---'++1r---Enoinedeck cover

on the M48A2, designated M48A2El, was absorbed into the M48A3 programme. Both Army depots and contractors worked on the conversions which continued for many years . Contrary to popular belief, the diesel is not intrinsically

Left: Fire control equipment in the M48A3 (A I) M28C periscope in cupola; (A2) M28C periscope in stowed position ; (B) M44C infinity sight (for coaxial machine gun) ; (C) MIOSC telescope; (0) M27 periscope; (EI) M24IR periscope, installed; (E2) M241R periscope, in stowed position; (F) MilS periscope mount; (G) M31 periscope; (H ) Filters for MIOSC telescope; (I) Ball mounts for searchlight when stowed; (J) Loader's hatch; (K) MI7B1C rangefinder; (L) MI3BI quadrant; (M) MIOBI Ballistic Drive; (N) M28Al Azimuth Indicator; (0) Ml3BIC ballistic computer; (P) Breech of I05mm gun; (Q) Turret ventilator. US Army

~-{) wing

salient

Centre left: Layout of the armament in the M48A3 (A) M2 machine gun in commander's cupola; (B) M737.62mm coaxial machine gun; (C) Radios in turret bustle; (0) Spent case container for coaxial machine gun; (E) Interphone and control boxes; (F) Antennas; (G) M28C periscope in commander's cupola ; (H) Turret portable fire extinguisher; (I) Elevating mechanism; (J) Turret basket90mm ammunition stowage rack ; (K) Driver's periscope (M2?) in front M24 IR periscope behind; (L) Fume extractor; (M) Muzzle brake (blast deflector); (N) Gunner's periscope sight M31; (0) Rangefinder MI7BIC. US Army Bottom left : Marine LlCpl Gene Maire, of 1st Tank Battalion, 1st Marine Division , cleans his .50in MG in a combat base south of Oa Nang. The improvised machine gWl mount and vision riser blocks for the cupola are clearly seen . USMC

-

--oS .0~orbed

into -::::pots and _ "_ continued trins ically

better than the spark ignition engine. For a given power a diesel will probably be heavier, bulkier, noisier, more expensive and will produce more smoke. Its redeeming feature is its fuel economy and in the M48A3 this was combined with larger aluminium fuel tanks which gave a range of over 300 miles. Diesel fuel is also less flammable than petrol; it is in fact quite difficult to ignite under ordinary conditions. Even under battle conditions it makes the tank less prone to ' brewing up ' and of course refuelling is made safer. Because more power is needed to crank a diesel engine, the number of batteries was increased to four. At the same time the auxiliary generator was eliminated. Although the 105mm gun was not included in the package, experience with the M60's fire control equipment was applied to the M48A3 , and lR equipment was provided for the gunner. The two track return rollers which had been removed from the M48A2 to save weight reappeared on the M48A3. The Chemical, Biological and Radiological (CBR) protective system of the M60 had been tested first in an M48A2. Now in the M48A3 a collective protection system was installed. Two filters were fitted; one for the driver and one for the turret crew. The driver's unit was mounted at the rear of the ammunition rack to his right, and the turret unit was fixed on the turret wall beside the fire extinguisher, providing clean, filtered air to a face mask for each crew member.

55

Above: The M48AIE3 combined the M48AI chassis, a diesel engine and the M60 turret, This vehicle also has the T142 track of the M60 and only the rounded nose of the glacis distinguishes this from the M60, US AmlY

I I

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!I I

After experience with battle damage in Vietnam, M48A3s were further improved by the re-routeing of some of the driver ' s control linkage to minimise the effects of mine damage. An adapter ring of eight vision blocks was added between the tunet and the cupola to increase the commander's view when operating closed down. Since M48s were invariably operated with every possible hatch open, this modification was rather a wasted effort. The Xenon searchlight was less of a waste of effort, although 'pink ' searchlights, such as that of the Sheridan tank , were generally prefened in V ietnam where the enemy only rarely took any action to counter lR illumination. Specially designed mountings (based on a caravan-type ball hitch) were fitted to the gun mantlet, with an annoured power socket to the rear and left of the gun. A similar mounting was provided at the left of the turret rear stowage basket for stowing the searchlight, but it was if anything even more vulnerable to damage from trees in this position, and the stowage bracket was rarely used. The first Army unit to deploy in the tank role in Vietnam was the I st Battalion, 69th Armor (the ' Black Panthers'). The 1169's supporting vehicles - its APCs, recovery vehicles and A VLBs - were all shipped from Hawaii, but its M48A2s were left behind and newly rebuilt M48A3s were drawn from depot storage in Okinawa. The M48A3 was the workhorse of Armor units throughout the war in Vietnam and a new fonn of tank-APC combined anns tactics evolved, with the M 113A I APC itself becoming a small tank-like fighting vehicle when the going could not support the M48A3.

56

M48A4 The M48AIEI had mounted the M60 's 105mm gun; the M48A3 had the M60's diesel engine installation. By bringing these two features together in the M48A I E3 the result was a pseudo-M60. In fact, since the M 19 cupola was also fitted , the only ways to tell the M48AIE3 apart from the M60 were by the rounded edge to the glacis plate, the 5 return rollers and the plain steel roadwheels as distinct from the ribbed aluminium wheels of the M60. The careful observer might also notice that the gap between the 5th and 6th wheel stations was still there . Several M48AIE3s were built in 1964 and the programme reached the stage of Engineering and Service Tests. It was planned to install M60 tanks tunets which were made surplus by the conversion of the M60 into the Shillelagh-armed M60A I E2, and in April 1964 it was proposed that the designation M48A4 be assigned to the two standardised M48A I E3s produced in this way. However, the M48A4 did not enter production as a yet more ambitious programme was foreseen for the modernisation of M48-series tanks. M48A5 Crew: 4 Weight: As forM48A3, except 108,000lb(480.4kN) combat loaded Length: 30ft 6in (9.47m) overall gun forward 27ft lin (8.25m) gun in travelling lock 22ft 7in (6.88m) hull only Width: 11ft J I in (3.63m) overall Height: 10ft lOin (3. 29m) with M 1 cupola overall Ground contact length, Track centre distance, G /clearance and Turret ring diameter: As for M48A3 Armament: Main - J05mm M68 gun in M87 mount details as M48 Secondary- Three 7.62 mm M60D (one coaxial; one commander's in reserve service, M2HB .50in used in early conversions one loader' s)

Left: The M48AS, seen under test at Fort Knox. Both the commander's and the loader's stations have the 7.62mm M60D machine gun. US Army via G. Binder

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Below: One of the biggest parts of the jI,'J48AS conversion programme was the welding required. Additional steel was added to the chassis to accommodate the larger diesel engine; new fittings also had to be attached. US Army

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Ammunition: 1OSmm S4 rounds 7 .62mm- S,400 rounds .SO- 600 rounds Armour: As for M48 Engine: Teledyne Co'ntinental A VDS-1790-2A RISE (M48ASs converted from M48A3s) Teledyne Continental A VDS-1790-2D (M48ASs converted from M48A Is) Transmission: Allison CD-8S0-6A Suspension: As M48A3 Power/weight ratio: 13, 9hp/ton (1, 16kW/kN) gross Max speed, Max gradient, Trench crossing, Vertical obstacle, Fording depth and Turning radius: As M48A3 Fuel capacity: 38Sgal (1 ,4S7Iitre) Fuel consumption: 0.8mile/gal /0.34kmllitre) Ground pressure: 12,2Slb/sq in (84.4kPa) Cruising range: 3 10 miles (496km) Around the time that the first M48A3s appeared, Secretary of Defense Robert McNamara and his West German counterpart were putting the final touches to the Main Battle Tank loint Development Agreement. Signed on 1 August 1963, the agreement provided for the joint development of the prestigious MBT-70, Construction of the US FRG tank first required the construction of loint Project Management Structures as complicated as the new tank, MBT-70 was to be the answer to everyone's prayer, but sadly did not happen that way, Failure to agree on characteristics, and excessive costs caused the cancellation of the project in 1969, Attempts to salvage something of value from the project also failed, and it was clear that the United States had to start from the beginning to develop a successor to the M60, The outcome was the XM I, which is due to enter service in 1982, but meanwhile there was an enormous disparity in Europe between the numbers of tanks available to NATO and those of the Warsaw Pact. Worse still, the quality of the

Soviet product was steadily improving, so that it was no longer possible to trade quality against quantity. Countering this threat took the form of three programmes. The first, and major part, was the fielding of the XMI in the largest possible quantities as quickly as possible. The second part was a major product improvement of the M60 series, linked with continued production, and the third part called for the M48 series to be brought up to the standard of the M60A I, As mentioned previously, the diesel engine and lOSmm gun could be installed in the M48A2. Earlier conversions such as these had taken second place to the M60, but the new rework programme used the latest moden components, identical to those going into the M60 production line, and with equal priority. Clearly it would be simpler to convert M48A3s, since half the work had already been done. Initially 360 M48A3s were converted

57

Left: The finished product of the M48AS conversions programme at Annistion Army Depot has the same engine main gun, firing and operating controls as the current M60-series tanks. The completed M48AS has a lower profile than the M48A I because of the new Israeli cupola. This M48AS, with searchlight, machine guns and communication equipment installed, is ready for issue. US Army Below: M48ASs of2/72d Armor, 2d Infantry Division at Camp Casey in Korea. These tanks have .SOin machine gun mountings on the Israeli-style cupolas and have no US Army markings. R. P. Vaughan

1,

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at Anniston Army Depot, Alabama, at a cost of $130,000 each. These almost-new tanks were designated the M48A5, and there are indications that the pilot modification was designated M48A3EI. In the hull, the top-loading air cleaner recently adopted for the M60 was installed, and a solid state voltage regulator was fitted. 90mm ammunition racks were modified to accept the larger 105mm rounds; a turret basket was added, and the track was changed to the later T142 type . The 105mm gun was a straightforward fit in the original gun mount, and most of the M48A3' s fire control equipment was easily modified. New cams in the ballistic computer and reticle changes in sights and telescopes were similarly straightforward. The advantage of the 105mm gun was in the wider range of ammunition available. The first APDS round was the British L28, manufactured in the United States. Later rounds were developed by Picatinny Arsenal. More recently the fin-stabilised APDS (APFSDS) round has been developed. The so-called 'long rod penetrator' is much longer than a normal APDS core and requires fins for stability in Hight. Its penetration is claimed to be far superior to that of conventional spin-stabilised APDS. HEAT and HEP are also authorised for the 105mm gun, as is the usual range of secondary ammunition. Converting the M48A I and M48A2C to the M48A5 was a more involved operation. Nearly 30 hull modifications were called for, and almost 20 turret modifications required. The opportunity was taken to install the A VDS-1790-2D RISE (Reliability Improved Selected Equipment) engine. Conversion of an M48A I or M48A2C to M48A5 standard took four months, a month longer than the M48A3, and cost $240 ,000. This work followed the M48A3 at Anniston. The XM I Project Office was established to oversee all

58

aspects of that programme. To supervise the accelerated conversion and production of the M48 and M60 a programme was set up within the office of the Army Chief of Staff in January 1975. Maj-Gen Chester M. McKeen Jr was given the task of ensuring that the tota! of just over 5,000 combat-ready tanks (M48 and M60) was increased to the required 10,381 tanks within the shortest possible time. By marshalling all the available stocks of M48A Is, M48A2Cs and M48A3s, including those of the Marine Corps, and beginning conversions without delay, M48A5s were in the hands of troops early in 1976. With one exception , the M48A5 was destined for Reserve Army and National Guard units, and the first units to be re-equipped were the 2/263d Armor and Troop E, 196th Armored Cavalry of the South Carolina National Guard at Fort Jackson, South Carolina. The exception was the mid-1979 report that the M60Als of two battalions of the US 8th Army in Korea were to be replaced by M48A5s. These would be the only M48A5s in Regular Army use, and would differ slightly from those in National Guard use. Apart from the M48A5 programme, there are also several commercial improvement programmes within the United

-

r. 2ci

St l e S. Hughes have advertised their Laser Tank Fire Cont rol System , and Napco Ordnance offer a re-engining se rvice in conjunction with Airscrew Howden in the UK and Detroit Diesel Allison in the US. Bowen­ :vlcLaughlin-York also offer a rebuild service . In 1977 the CS Ariny made one M48Al available for a trial installation of the Avco Lycoming Six-Fifty gas turbine engine . The installation was carried out by Joanell Laboratories. The low weight and reduced volume of the turbine engine (claimed to be only 4901b and 29cu ft) supposedly allow an extra 300gal of fuel to be carried , giving a range of 300 miles. Fuel consumption is improved by 40% . A diesel auxiliary power unit is also accommodated within the engi ne compartment.

The M60 Because the T95 series was intended to produce the successor to the M48 series the possibility of evolving a new MBT from the M48 was not considered for a long time. As the T95 programme foundered , so the Armor Board looked to the growth poten tial of the M48. The

Above right: Napco's installation orthe Detroit Diesel12V71TA engine in the M48A 1. Napeo Indusrries. Inc

~ : .·ust over :;.; :ncreased - : -:._:: possible , : :- :-'1 -i8Als, _: :: e Ylarine - -- ~ delay, - : -;6. With

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Centre right: An early production model of the M60. Because of a shortage of the M85 machine gun, an improvised mounting has been welded to the right side of the cupola for the M2 machine gun. The longer I05mm gun and the straight edge of the glacis are shown well in this photograph. US Army Below: The M60Al, the last major descendant of the M48 series. Chrysler

hemispherical-shaped turret could be improved, and the 90mm gun was inadequate. The disadvantages of using petrol engines had become apparent, so a diesel engine was called for. The M 1 cupola of the M48 was lacking in some respects, and there were ways in which the hull casting could be simplified. Nearly all these shortcomings were examined in various experimental models in the M48 series, and in 1958 the XM60 105mm Gun Tank was announced. Because the new turret was not yet available the old hemispherical M48-style turret was used. Production of the M60 began immediately and it soon became the US Army's standard MBT. However, the M60 has a story of its own.

4. M48 Variants

M48 Bridgelayer Crew: 2 Weight: I22,OOOlb (S42.6kN) complete with bridge

II !,

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91,OOOlb (404.8kN) launcher only Length: 36ft 3in (II .OSm) overall, with bridge 28ft4.Sin (8.6Sm) launcher only Width: l3ft2in (4.0Im) bridge on launcher 12ft (3.66m) launcher only Height: 13ft 3in (4.04m) bridge on launcher (folded) IOft4 .Sin (3.16m) launcher only

Ground contact length, Track centre distance, G/cIearance: As for M48A2 Ground pressure: 13 .8Ib/sq in (9S.4kPa) Other details are similar to M48A2

BRIDGE Length: 63ft (19. 2m) emplaced 31ft 6in (9.6m) folded Width: l3ft2in(4.0Im) Treadway width: Sft 3in (I.6m) (each) Height at centre: 3ft (0.91m) Weight: 31 ,000lb (137. 9kN) Construction: aluminium alloy in 3ft panels, tapering to Sin at the ends Military Load Classifications: 60 (equates to approximately 60 US tons) Time to lay: 2-3min (average) Time to recover: Min I Omin on good ground Max difference between banks: 20% gradient (II.SO), or 12ft (3.66m) 12% (6.9°)

Above right: The pilot model M46 bridgelayer, built at Fort Belvoir in 1952. The scissors bridge was made of aluminium and was virtually identical to that used with the M48 bridgelayer. US Army Right: The T2 assault bridge was pushed into position by the M47 but unlike hYdraulically-actuated bridges it could not be recovered by the vehicle which had laid it . Here troops of 16th Armored Engineer Battalion use a 20ton bridging crane to recover a T2 bridge during Exercise 'Sage Brush' in Louisiana in 1955. US Army

60

Below: An M48 AVi,B of 7th Engineer :3attalion, 5th Infantry Division (Mechanized) is demonstrated at Fort Carson , Colorado in 1962. The bridge operating cylinder can be seen in the half of the bridge attached to the launcher, and the quick-disconnect couplings are visible on the end which is about to touch down. US Anny. Above: A folding assault bridge, believed to be either the T3 or ".'4, at a demonstration at Fort Belvoir in 1955. The mechanical 'push-along' geared actuating mechanism is clearly in evidence. Problems of the driver's vision, his ability to steer the bridge, and the difficulty of deciding on the exact point at which to engage the actuating gears probably led to the rejection of this type of bridge. The M48 is marked with its inventory price - $135,597 - which makes an interesting comparison with the quoted price of $130,801 in 1967. US Anny

Nearly all families of main battle tanks now include, along with an armoured recovery vehicle, a bridgelayer. The Armoured Vehicle Launched Bridge (AVLB), to use the correct term, is an assault bridge. It is intended to span short gaps under fire. These gaps may be unexpected, such as shell craters or demolitions, or previously known obstacles such as streams or ditches. Tank-mounted assault bridges were used in World War 2 but were cumbersome items, generally with complicated cable­ operated mechanisms and slow and conspicuous in use. By the end of the war, assault bridging ('combat bridging') in the US Army consisted of fixed length bridges which were carried on or towed behind other vehicles. The next development was a hydraulic scissors bridge, the M I, which was built on and launched from a semi-trailer. In 1950 the Engineer Research and Development Laboratory (ERDL) at Fort Belvoir, Virginia, began work on a tank-mounted hydraulically operated scissors bridge. Tested on the M46 chassis , the concept worked. At the same time other concepts were also under consideration, including towed bridges both rigid and folding. The designations Tl to T4 were assigned to a series of rigid and folding bridges built by the LeTourneau Company , and the bridge illustrated is believed to be the T2 . One of these pusher-type scissors bridges was in fact tested with the M48 but was not proceeded with. Tests on the M46 bridgelayer were conducted at the Armor Board at Fort Knox and at Fort Belvoir. The vulnerability of the hydraulic system to small arms fire and to artillery shell splinters, and the vehicle's overall mobility were tested at Fort Knox while

the development of tactical doctrine continued at Fort Belvoir. This refinement of the concept took long enough for the M47 to be bypassed , and in September 1958 the Armored Vehicle Launched Bridge and Launcher were standardised using the M48 chassis. Initial issues were made on a scale of six launchers and nine bridges to the divisional combat engineer battalion, forming a separate assault bridging platoon in the bridge company. After standardisation minor corrections were later made to the hydraulics and communications. In the M48 hull the driver's hatch was now obscured by the overhead hydraulic cylinder so for better visibility and communications the driver and commander were seated side by side in the space below the plated-over turret ring. Each had a hatch, and unconfirmed reports suggested that some early models gave both the driver and the commander a .50in machine gun in a small cupola, but no photographs of such mounts have been located.

61

II II I,

I,

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Bridges came in two lengths: 63ft (19 .2m) and 43ft (13.1 m), the 63ft bridge being the more commonly used. Operational research had shown that the 63ft bridge could satisfactorily span S8.S% of the gaps likely to be encountered on a Western European battlefield, and this 40% chance of not being able to cross a gap was accepted. Nowadays a somewhat more favourable probability might be expected! The bridge consisted of two symmetrical halves hinged together. Wedge-shaped ramps of low alloy steel and aluminium plate panels were used to keep the weight low and the strength high , but even so the bridge weighted 14ton. A hydraulic cylinder in one hal f controlled the opening of the bridge through a quadrant linkage , and it was this opening which gave the familiar name of ' scissors bridge'. When carried on the launcher, the bridge was supported in two places. At the rear of the tank a heavy girder structure surmounted the engine deck . The bridge rested on this support and for travelling was secured by a chain . A hydraulic cylinder released this chain prior to launching the bridge. At the front of the hull the launching mechanism held the bridge. A massive triangular structure, which functioned essentially as a bell crank, could be rotated forward through 90° thus tipping the folded bridge into the vertical position. At the same time the substantial sole plate transferred the weight of the bridge to a point 6ft (1.83m) in front of the vehicle. With the bridge vertical another cylinder, the swing cylinder, lowered the bridge forward over the gap. Simultaneously the bridge actuating cylinder began to open the bridge, so that by the time the swing cylinder had fully lowered the bridge it was also completely extended. There was a smaller tongue cylinder below the swing cylinder and this compensated for differences in height between the sale plate and the launcher. When the bridge was laid an ejection cylinder in the launching arm pushed the bridge forward some 7-8in (18-20cm) to disengage it from its cross-pin sockets, or keyways. At the same time two quick-disconnect couplings (which took the hydraulic power to the bridge opening cylinder) were released. Both ends of the bridge were identical , so the bridge could be recovered from either side, although the half containing the bridge actuating cylinder was of course heavier. The complete laying operation was stated to take two minutes , but to this very optimistic figure must be added the time to line up the launcher accurately. To provide the launcher with hydraulic power , a pump was mechanically clutched to the main engine. The hydraulic cylinders, to 1O-12in diameter (2S-30cm) were operated at 3,SOOIb/sq in (24MPa), and the system, including the reservoir, held a total of 13Sgal (Slllitre) of fluid. Properly used, the A YLB is a tremendous aid to battlefield mobility - but its use should be carefully

62

planned in advance, rather than using it as an emergency measure when other form s of bridging may have been more suitable. The launcher itself has mobility equal to that of the tank, but the bridge adds 3ft (0.9m) to the width and 2ft (0.6m) to the height of the tank , and even the bridge alone is an outsize load . It was found that the 43ft bridge, consisting of just the four end ramps joined by braces and pins, could be carried disassembled on the standard engineer stake truck, the Stan M328. The 63ft bridge, in two halves , needed two M328s, although the 2Ston semi-trailer M 172 was suitable for the carriage of assembled bridges. The folded bridge could also be carried on a special 10ton tilt-bed trailer. Carrying the 14ton bridge in one piece gave quite an advantage, for assembly required seven men and a crane and took two hours. Even putting the shorter 43ft bridge together took the same team an hour. Early production A YLBs used both M48 and M48A I hulis , usually without the track tension idler. Later the M48A2 hull was used as this became the standard item. No attempt was made to fit the diesel engine of the M48A3 until 1976 when plans were laid for the conversion of 142 M48 and M48A 1 bridgelayers to diesel operation. More recently funds were requested in the Fiscal Year 1979 appropriations for the conversion of 61 M48 chassis to the M48AS standard. This request was justified by the fact that the estimated cost of $8 .6million would be considerably less than the cost of procuring new M60Al hulls. With the arrival of the M60 in 1960, this had become the preferred item for production of tank variants (although neither the bridgelayer nor the recovery vehicle was brought up to standard for IS years). The M60A 1 launcher chassis, using the same bridge as the M48 series, was type-classified in 1963 with the intention at the time that all M48 series A YLBs in the active army and reserves should be replaced. Bridgelayers of the M48 series were also supplied to many countries receiving M48 tanks . These include Israel and West Germany. The Netherlands, while not a user of the M48, adapted the M48 scissors bridge to the Centurion hull. It will be recalled that the Centurion Mk S bridgelayer laid its 40ft No 6 tank bridge in one piece , presenting a much higher silhouette at the bridging site. Judicious use of smoke could normally conceal this type of signature, although the rigid bridge may also be more cumbersome in close cover near to the obstacle. It is perhaps worth noting that many Netherlands Centurions were in fact provided by the US under the Mutual Defense Aid Program.

Right: The M67 A2 flamethrower tank. The fatter gun tube,

modified mantlet and flattened head lamp brush guards distinguish

the M67 A2 from the standard gun tank. US Anny

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--= - emergency :::2: ha\-e been ::;)_ : :~: :y equal to ~-::: :0 the width - • ::2.:1 eyen the : :.:, t the 43ft - --'- ;CO' joined by :"::.) k d on the _ ~: : ~ _ The 63ft ~ : ~;. ';; rhough the : 7 ::-;:: : arriage of ~ - :~ :, _id also be ~ Carrying the ..:;. ~\-an tage, for IT. took two -r- ~;~ ~ ~ ge t her took ~

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Y148Al - . .:~;:: : _ Later the - - - ;:.;ndard item. iC :-:J ~ i n e of the ~ : ~ ' d for the ~ -:7.3::ers to diesel . =-~ : st e d in the . - ::: - -. ersion of 61

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M67 Flamethrower Tanl, Crew: 3 (commander, driver & gunner) Weight: lOS,790lb (470.74kN) combat loaded IOO,79S1b (449. 16kN) less fuel, crew and equipment Length: 26ft 8.37Sin (8. 14m) overall , flame gun forward 22ft 7 .12Sin (6.89m) flame gun to rear 22ft 6.Sin (6.87m) hull only Width: II ft II in (3 .63m) overall Height: 10ft 1.62Sin (3 .09m) to highest fixture Sft4.Sin (1.64m) hull only GroundcontactIength: 13ft l.Sin(4.00m) Track centre distance: 9ft 7in (2. 92m) G/clearance: lft4.2Sin(0.4lm) Turret ring diameter: 7ft I in (2. 16m) Armament: Main - Flamethrower, Mechanised, Main Armament: Turret Mounted, M7 A 1-6 consisting of Flame Gun, M6 and Fuel and Pressure Assembly , M7 Al with traverse of 360° and elevation from-12° to +4So Secondary- .30in MG MI919A4 (coaxial) .SOin MG M2HB in Mount M 1 (commander's) Ammunition carried: flamethrower fuel- 36Sgal .SOin - 700 rounds . 30in - 3 ,500 rounds Mobility: as for M48A2 Armour, Engine, Transmission, Suspension: As M48A2

Above: This M67 A2 namethrower of lst Tank Battalion, 1st Marine Division is in action during a sweep against Viet Cong 10 miles south ofDa Nang in mid-1967. USMC

Power/weight ratio: 15. 7hp/ton (1.31 kWIkN)

Max tractive effort: 80,000lb (3S6kN)

Tractive effort/weight ratio: 0.80

Maxspeed: 31.8mph (Slkm/h)

Max gradient, Trench crossing ability, Vertical

obstacle, fording depth, Turning radius: As M48A2

Fuel capacity: 21Sgal (813Iitre)

Fuel consumption: O. 7Smile/gal (0. 32km!1 itre)

Ground pressure: 10.21b/sq in (70 .3kPa)

Cruising range: 160 miles (2S6km)

2S0 miles (400km) with jettison tanks

During the war in the Pacific from 1943 until VJ-Day on

14 August 1945, the US Army and US Marine Corps

came to appreciate the value of the flame-thrower ­ particularly as a tank-mounted weapon. Various official

and unofficial models were developed and saw service,

but by the end of the war there was no single standardised

type. In its Preliminary Report of April 1945 the Army

Ground Forces Post War Equipment Review Board had

merely commented that ' . . . development of flame

I':I II "

I:

Ii I"

throwers. .. for mounting on (tanks) should be continued. Use of the flamethrower both as a primary and an auxiliary weapon should be considered.' Development did continue at a fairly low priority until the Korean War showed that there was a real requirement for flamethrower tanks. Work was focused on specialist vehicles using the M4 and M26 chassis but as these vehicles became obsolete, so the projects were dropped. The first thoughts of using the new tanks came in 1949 when the previous projects were cancelled and the T66 was conceived in 1951 as the flamethrower variant of the M47. The development of the M48 overtook the T66, and a version of the M48 was initiated with the designation T67. From the outset the T67 was designed to resemble the M48 as closely as possible and this was simple to achieve. The weapon was the E30R 1 flame gun, supplied with fuel by the E28 fuel system, only slightly modified from that of the T66. On 28 July 1955 the T67 was standardised as the Tank, Combat, Full Tracked: Flame-Thrower, M67 on the basis of the M48A I. To avoid being singled out as a target , the M67 was indistinguishable from the M48A 1 from more than 50yd distance. In fact the flame gun was considerably shorter than the 90mm gun, so a shield was provided to simulate the tank gun. Because this shield also served for access to the igniter and as a combined air sleeve and drip guard , it too was shorter and fatter than the 90mm gun. In addition, the end of the tube differed slightly from the T-shaped blast deflector of the M48A I. The top arcs of the headlamp brush guards were also slightly flattened to aJIow greater depression of the flame gun. The E28-30R I flamethrower of the T67 was now designated the Flame Thrower, Mechanised, Main Armament: Turret Mounted, M7-6 and in the M7 fuel and pressure assembly were held 378gal of fuel together with the necessary thickener and 10cu ft of compressed air at 3,000lb/sq in. This allowed the M67 to project flame to a range of about IS0-200yd with a total duration of 60sec. Under average conditions of weather and visibility a maximum range of 100yd would be more realistic. The range and duration of the flame could be altered by nozzle settings and elevation

64

Above: A platoon or M67 AI Hamethrowers was held at Fort Knox for demonstration purposes. This M67 Al is part or a display ror cadets in June 1961. US Army

Cn; w. ­ ­ \\' -'

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control, and a rudimentary form of fire control was provided by the gunner's M21 periscopic sight and by corrections from the commander's observations . The absence of90mm ammunition meant that the loader could be dispensed with, leaving a crew of three men. The M67AI was equipped with the M7AI-6 flamethrower and used the hull of the M48A2. These were built by Chrysler at Newark between 1956 and 1959 and were the only M67 model to see service with the US Army; both the M67 and the later M67 A2 were for US Marine Corps use only. An improved fire control capability was added in the M67 A I in the form of the XM30 periscopic sight, but this made no attempt to correct for the effects of wind - still the greatest single source of inaccuracy, as the bulky, slow-moving jet of fuel was easily deflected. The M67 A2 , for USMC use, mounted the same M7 A I -6 flamethrower on the hull of the M48A3. Flamethrowers were issued to the Flame Platoon in the Headquarter and Service Company of the USMC Tank Battalion and deployed in sections of two tanks. The flamethrower has its advantages and disadvantages. It has a good shock effect, yet is inaccurate and lacks the capability to sustain a good rate of flaming. Refuelling takes time (as indeed does replenishment with 90mm ammunition!) and requires specialised vehicles - and flame fuel is obviously more dangerous than diesel fuel. It was stated that any gun tank could be converted to flame operation in the field in six-eight hours , but this facility does not appear to have been used. It does after all suppose that crews trained in flamethrower operations are available in the same time. Mainly because the smaller M I 13-based M 132A 1 flamethrower had become avail­ able, the M67 A I was deleted from the Army inventory in March 1970, but at the time of writing it remains in service with the Marine Corps.

G

Boom :

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M88 Recovery Vehicle Crew: 4-6 (commander, driver, 2-4 riggers) Weight: 117 ,0001b (S20kN) combat loaded Length: 27ft 3.Sin (8.32m) overall ~ 0 :1tro l

~

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was and by 21ions. The : 0 3 er could

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~ !.~.~2. These :':':;6 and 1959 - : ~ ". ilh the US - - -.: ,:" ~ re for US -=-.: :'.re control - :':.7 form of the -7 :. ~ attempt to :.:.e ~~ test single ~:::o\' ing jet of

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- - ...:.:ed the same ::- :.ne M4SA3.

33ft 7 .Sin (I 0.2Sm) boom at max forward extension Width: 13ft 3in (4.04m) overall Height: 9ft 7in (2 .92m) to highest fixture 25ft 1.Sin (7 .66m) boom at max elevation Ground contact length: 15ft (4.S7m) Track centre distance: 8ft II in (2. nm) G/clearance: 1ft 6in (O.4Sm) Armament: One .SOin M2HB MG in commander's M2 cupola Armour: No details available Engine: Continental A VSI-1790-6A, 980hp «730 .8kW) at 2,800rev/min) air-cooled four-stroke, mechanically supercharged 12-cylinder petrol engine (bore S. 7Sin (146mm) stroke S.7Sin (146mm». Compression ratio 5.5: 1 Transmission: Allison XT-141O-2 Suspension: Torsion bar (six pairs of road wheels and three du al return rollers on each side)

Above: The M88 Recovery Vehicle. Detroit Arsenal

RECOVERY CAPACITY Boom: Capacity 4 part line - 12,000lb (S3AkN spade up SO,OOOlb (2 22AkN) spade down 19ft (5. 8m) at 8ft reach 25ft (7 .6m) at 4ft reach

Winches:

:: re:nains in

Top: The T88 Armored Recovery Vehicle is shown to the Press at

Aberdeen in 1959. Just visible is the commander's cupola and the

protective guard of the periscope sight mount. US Army

Main winch-Cable: 200ft (61m) 6 x 31 IWRC, 1. 2Sin (3cm) diameter Capacity: Line pull, bare drum: 90,0001b (400AkN) at 27ft/min (8.23m/sec) or 108ft/min (32.9m /sec) Line pull full drum: 5 I ,400lb (228.6kN) at

42ft/min (l2.8m/sec) or 170ft/min (5 1.8m/sec) 400ft

(122m) 6 x 19 fibrecore, .62Sin diameter (l.6cm)

Line pull, bare drum, 4 part line: SO ,OOOlb

(222AkN) at 8.Sft/min (2.6m/sec) or 35ft/min

(10.7m/sec)

Line pull, full drum, 4 part line: 30,0001b

(133.SkN) at 16ft/min (4.Sm/sec) or6Sft/ min

(19.8m1sec)

Towing:

Max drawbar pull: 81 ,0001b (360.3kN)

. Max tractive effort: IS2,000lb (676 . I kN) Power/weight ratio: 16.7Shp/ton (IAKW/kN) gross

Tractive effort/weight ratio: \.357 Max speed: 30mph (4Skmlh) Max gradient: 60% (31°) Trench crossing: Sft 6in (2.6m) Verticle obstacle: 3ft 6in (1 .07m) Fording depth: Sft 4in (l.62m) unprepared Fuel capacity: 44Sgal (1 ,648 litre) Fuel consumption: 0.5 mile/gal (0.3kmllitre) Ground pressure: I O.Slb/sq in (nAkPa) Cruising range: 220 miles (3S0km)

65

Compared with motorcars, tanks are indestructible. A car may have a calculated life of say 5-10 years (reduced even more by built-in obsolescence) and a tank may be designed for an operational life of 15-20 years. The M48 will probably have an operational life of at least 30 years, to quote a now-familiar example. But the tank is not destroyed by rust, or engine wear. Apart from being physically rent asunder by enemy action, tanks do not die; they become obsolete. Even then they are normally disposed of to another army, or relegated to other duties such as training , or converted for other purposes. Economic considerations may affect this, but another factor is the sheer size of the problem of disposing of a tank. It is just not worthwhile spending time, money and labour on cutting up armoured hulls and turrets. Because tank engines wear rapidly, and guns may require to be changed, many maintenance operations are comparative­ ly simple and relatively economical.. It is cheaper to change a power pack than to buy a new tank. For these reasons there exist in most armies extensive base repair facilities where tanks can be periodically rebuilt. For most purposes the rebuilt tank is a new tank, and this is certainly the case with the M48A5. Base overhaul facilities can also repair most battle damage provided the damaged tank can be transported to the workshop, and at this point the value of an armoured recovery vehicle becomes apparent. Tanks which are for any reason immobilised on the battlefield must be quickly recovered to the appropriate facility capable of repairing the damage. In many cases this can be done within the unit­ such as the replacement of torsion bars and wheel stations, or repairs to fire control equipment, or even power pack changes. More severe damage, such as the damage caused by an ammunition fire , may nevertheless still leave the hull and turret structure intact as the basis for a rebuild. Cannibalisation allows serviceable components to be pooled. Since reserves of new tanks are likely to be at a premium, it is vitally important that tanks are not abandoned on the battlefield when they can be

repaired and returned to service -leaving aside the danger of their capture by the enemy. Tank recovery vehicles first appeared in the US Army in 1942 with the T2, a modified M3 medium tank. Standardised as the M31 it saw wide service and for a long time served alongside its successor, the Sherman-based M32 . Around 1,600 of the eight variants of the M32 were built and, although it was found to be unsatisfactory in Korea when the M26 and M46 were beyond its capabilities, its design was a strong influence on the M74 which was based on the final model Sherman chassis. However, the M74 was only intended to be an interim solution and it was proposed that recovery vehicles should be developed in the light and heavy tank classes; that is, based on the T41 and T43 respectively.

Above: The M88 Recovery Vehicle with A-frame in the raised position. Detroit Arsenal via T. L. Mayer Left: The M88 Recovery Vehicle with A-frame raised and spade lowered and complete stowage. US Army

_- Yehicle with

The heavy recovery vehicle, designated TS I, was needed to handle battle casualties in the 60-70ton class and several projected vehicles fell within this category, but it was over-matched to casualties in the medium tank class of up to SOton. For this reason a project for a medium recovery vehicle was initiated in April 1954. Proposals were received from Pacific Car & Foundry (PCF) and Bowen-McLaughlin (B-M). PCF's concept was for rear operation and was not favoured by Continental Army Command (CONARC) , the user, but B-M's proposal for front recovery wa, endorsed. The characteristics of what was now the Recovery Vehicle, Medium, T88 included maximum utilisation of components from the medium tank, then the M48 , but by 1954 Ordnance were warming to the virtues of the T9S and saw this as the next medium tank. Ordnance therefore proposed that the new recovery vehicle be based on the T95. CONARC insisted on the T88 concept as it stood, based on the M48, to which Ordnance replied with a plan to combine the functions of both recovery vehicle and combat engineer vehicle in a single vehicle, the T 118 ­ but still based on the T95 chassis. The user's view prevailed, at least in the case of the recovery vehicle, and B-M were authorised to produce pilots of the T88. In their design, the hull was shaped for good angles of approach and departure, good visibility for all recovery operations, and for adequate space for winches and other recovery equipment. Ballistic protection came lower down the list! The volume of the crew compartment was in excess of 300cu ft (8.Scu m) and housed two winches under removable floor plates. The requirement specified that the main winch should have a capacity of 90,0001b (400kn) and the auxiliary winch, 12,500lb (55.6kn). The auxiliary winch was intended for use with a folding A-frame and in the pilot T88 a SO,OOOlb (22.4kn) winch was installed instead of the specified 12 ,SOOlb. The T88 was specifically designed for good balance in both axes to give a high degree of stability when using the A-frame and for good traction when towing, dozing or winching. To this end the ground contact length was considerably greater than that of the M48, by some 23in or 13% , but the width was in fact reduced, the track centre distance of 107in comparing with the M48 's value of IISin. The quantity LlC, often referred to as the steering ratio, is the ratio of ground contact length (L) to track centre distance (C) and for good manoeuvrability LlC should lie between 1.2 and 1.4, while 1.8 is considered the upper limit. The M48 , at 1.35, had good control over steering but the T88 's LlC ratio of nearly 1.7 meant that manoeuvrability on soft ground was somewhat impaired. The front-mounted dozer blade was provided primarily to stabilise the vehicle when lifting or winching, but it could also be used to clear obstacles or even to help climb over them. It was originally planned that the dozer would be detachable to allow the use of a fascine carrier or fork lift,

but this feature fell into abeyance when the separate T 118 began development. The main role of the T88 was specified as: 'to provide a medium recovery vehicle to perform the functions of battlefield rescue and recovery of disabled light and medium tanks and other comparable equipment.' Recovery, with the use of the winch and possibly the A-frame, requires mechanics and riggers to leave the armour protection of the vehicle and attach towbars or cables to the disabled tank and is clearly a hazardous occupation on the battlefield. To perfonn the other function s of battlefield resc ue it was proposed that automatic coupling devices be used remotely to attach the dead tank in order that the recovery vehicle could drag it to a place of relative safety where the crew could do the work with less hindrance and at less risk. Two devices were tested , both with two arms 7-IOft long; one electrically actuated and the other hydraulically. These anns could be moved through 90° horizontally , 55° vertically and rotated through a total of 110°. Along with thi s development went an attempt within the UK , US and Canada to standardise on tank towing eyes, of obvious advantage when remote coupling was being considered. However, neither the electric nor the hydraulic system was accepted. Provision was made for some of the 470ga l of fuel on board to be pumped to a stranded vehicle if the need arose. The winches were hydraulically operated and power came from a pump driven by the main engine although in an emergency the auxiliary engine could also provide limited hydraulic power. The T88 proved acceptable and on 19 February 1959 was type classified as Standard A under the designation Recovery Vehicle, Full Tracked: Medium, M88. In anticipation of this, three pre-production pilots had been ordered from the renamed firm of Bowen-McLaughlin­ York and quantity production began in their plant at Bair, Pennsylvania on 28th February 1961. On average, two vehicles per day were produced until the contract ended in February 1964 , and at this time the cost to the government was quoted at $169,410. The large hull of the M88, a single casting weighing 17ton, provided space for the commander and driver to sit side by side at the front , and for roomy crew and engine compartments at the rear. The turret-type cupola of the T88 was replaced early in production by the Commander's Cupola :\12, an open mount for the .SOin. The boom , or A-frame, was operated by two internal hydraulic cylinders and controlled by a single lever. It was normally stowed lying flat on the engine deck but fully rigged. A certain amount of fore-and-aft movement was possible by adjusting the stayline crank arms. In addition to the emergency operation of the boom , the spade and the hydraulic fuel pump, the auxiliary engine also provided power for a hydraulic impact wrench required to handle the bolts of up to I. 25in diameter used

67

in some suspension components. The engine used was an uprated version of the engine of the M48A2 designated the A VSI-1790-6A and developing 980hp gross at its maximum speed. A new crossdrive transmission was also fitted to cope with the loads imposed by dragging dead tanks and to provide the necessary power to steer the long vehicle. One criticism of the M88 was its lower level of ballistic protection compared to the M48. This is only to be expected, and vehicles such as recovery vehicles should not be exposed to direct fire if at all possible. The armour was designed to give protection against small arms fire, light automatic weapons and shell splinters , and that was sufficient. Over 1,000 M88s were made and many were supplied to other armies where they remain in service , and in 1970 the production line at Bair was re-opened to overcome shortages in the US Army. In 1972 plans were announced to modernise the M88 by the use of M60 automotive components and in March 1975 the new M88A I was type classified. Once again, Bowen-McLaughlin- York were awarded contracts both for new M88A 1 production and also for conversion of existing M88s.

Self Propelled Artillery Variants of the M48 It was only towards the end of World War 2 that self-propelled artillery was recognised as a consideration in the planning of future vehicles. The first generation of equipments had used obsolete or obsolescent tank chassis and thus suffered from inferior mobility and reliability as well as logi stic problems with spare parts. The weapons mounted on these chassis had been standard field pieces, complete in their top carriages , in limited traverse pedestal-type mounted in whatever working space the tank hull could provide. Armour protection and ammunition stowage received only secondary considera­ tion and were far from ideal. With the Common Chassis Concept of 1944, some of this changed. No longer were obsolete chassis to be 'wasted-out ' as self-propelled mounts, but each new class of tank chassis was to be capable of adaptation to various other roles - including self-propelled anti-aircraft, anti-tank and field artillery. The medium tank chassis was expected to be capable of accepting the 155mm gun and the 8in howitzer. This concept was altered somewhat by General Cook's Post War Equipment Review Board, which stated that 'The present policy of expediency of adopting complete tank chassis fo r self-propelled mounts should be abandoned as this results in heavier carriages than are required. However, development should provide for interchangeability of components of gun motor carriages and tanks whenever practicable without sacrifice of the characteristics deemed essential in each type .' It was expected that the 155mm gun and 8in howitzer motor carriages could be kept down to 40ton by this relaxation , and this was included in the Military

68

Characteristics agreed by the various development agencies on 4 December 1946. Detroit Arsenal prepared a design study and the Pacific Car & Foundry Company was awarded a modest contract in April 1948 to design the l55mm Gun Motor Carriage T97, to be capable of accepting the 155mm gun and 8in howitzer interchange­ ably, and to build a wooden mockup. Funds were short in the period between World War 2 and the Korean War, but on 13 April 1950 the procurement of one prototype was authorised. New ordnance was also to be developed for self-propelled artillery, and in February work had begun on the 155mm gun T80 and the 8in howitzer T89. These were referred to as 'lightweight' because the weight of the vehicle to absorb recoil would allow the ordnance itself to be lighter. The T97 was designed to use medium tank components and so began life with the A V -1790-3 engine of the M46. The suspension also utilised M46 components with a variation - a larger trailing idler was used to increase the ground contact length and thus the stability as a firing platform. This trailing idler was also needed to support the massive box-like turret of i/2in armour mounted at the rear of the hull. The driver sat on the left hand side of the turret. By the time the first pilot came to be built the T48 was set to become the standard medium tank , so the AV-1790-5B engine was installed. T48 running gear components were largely the same as the M46 , but the narrow (23in) track was retained, and the larger trailing idler was replaced by a standard 26in road-wheel. Pacific Car and Foundry delivered the first T97 (now the Gun , Self Propelled, I55mm, T97) in April 1952. A contract had been let for the manufacture of the Howitzer, 8in, Self Propelled , TlO8 and the first pilot TlO8 was delivered three months behind the T97. Although modifications were needed, production of both vehicles began at PCF's Renton plant in August 1952 and continued until April 1955. Classification of the T97 as the M53 came in February 1956 and the Tl 08 followed suit in May, becoming the M55, while the extensive modification programme continued . If that were not surprising enough , the Army decided in early 1956 that it no longer had a role for the M53 with its 155mm gun, and so all its M53s were converted to the M55 configuration. The US Marine Corps had received the M53 and these were retained in service. There are only four known variants of the \153-M55 series. PCF built an experimental modification, the M55EI, in which the turret was lengthened and the engine decking altered - presumably to accommodate another engine . PCF also built three pilots of the 175mm self-propelled gun Tl62. Although externally similar to the M53 this ambitious project was virtually a completely new vehicle. The hull was wider and the suspension was changed to accept the wider 28in tracks of the M48 . The supercharged engine and hydraulic torque converter of the T88 recovery vehicle were used, and one of the major

L

~

::-2..._::1f idler was -!fld rhus the -: _~: ~ was also := :'!ITer of 1f2in ~- :' Jri \'er sat on

- ~-...::.

- , -. SO the _-~ :-~n nmg gear :: - \, 1-+6. but the

_- ­ :: ~ '.':i rzer, 8in, n08 was Although h vehicles 1952 and (1-: rhe T97 as - - - -:­ 0 followed :..~.: ex tensive : ::.3t were not - :-_-::. 1956 that it __ :' :" :mn gun, and _~:" : onfi guration. -- ­ .' ~ :' 3 and these

-=

-

--­ :..":.: \153 -M55 -_:'. : ation, the and the

sim ilar to 'ompletely

,-~~.

:

l

Above: A Marine Corps M55 self-propelled howitzer fires during an exercise in Sardinia. USMC Right: The T97 155mm Gun Motor Carriage. The chassis used many components of the T48. US Army

problems encountered during testing of the TI62 was ' torching ' of the exhausts due to their configuration and position relative to the engine. The gun also had its problems, but it was the difficulty in manoeuvring such a bulky vehicle which led to its cancellation in the mid-J950s. Projects were also initiated in the late 1940s for self-propelled versions of the 240mm howitzer and the 8in gun , designated T146 and TI47 respec ti vely. These were to be similar in concept to the T97 but the weight was to be kept below 60ton. The sheer impracticality of such a weight limit, and the limited usefulness of such weapons (the 8in howitzer now had a nuclear capability) meant that these two projects were abandoned even before concept drawings were completed. M53 series vehicles were also supplied to other countries and saw service in Vietnam with the USMC, but most have been replaced in frontline service by the later M107 series. The lighter weight of these vehicles is largely made possi ble by a relaxation of the requirement for an armoured cab around the gun.

DIVAD Organic air defence of armoured units is a subject which has for a long time received scant attention. Despite efforts by all the major combatants in World War 2, no satisfactory air defence weapon with the desired characteristics of mobility , firepower and protection was fielded. Mobility was required to enable the weapon to accompany armoured units, while firepower was required to be able to detect, track and destroy attacking aircraft.

Since the weapon had to accompany armour it had to be protected from at least th e secondary hazards of the armoured battlefield , such as small arms fire and overhead shell bursts, and some form of all-round protection was therefore called for. The attributes of mobility, firepower and protection are those of the tank , and early designs were attempts to produce anti- aircraft tanks. American efforts to develop armoured turrets, although numerous , were unsuccessful, so their self- propelled air defence at the end of World War 2 consisted of the M 19, a light tank chassis with twin 40mm guns in an open turret , and various halftracked vehicles­ once again with open turrets. The M 19 and the halftracks were very popular in Korea where a large vo lume of fire against ground targets was greatly appreciated. Similarly the successor to the M19 , the M42 'Duster' found wide employment in Vietnam for perimeter defence and similar functions. Nei ther in Korea nor in Vietnam had there been a significant enemy air threat, so the air defence capabilities of these two weapons were not really tested. Attempts to provide better armour protection had continued , but nothing materialised . Other arm ies had adopted similar solutions to the United States, although the British Army was notable in

69

Both the General Dynamics prototype (the XM246 seen above during US Army trials) and the Ford contender (the XM247 seen below) used the XM988 chassis, an M48AS hull modified by the addition ofa primary power unit to suit the turret installed. The vehicles were subjected to intensive contractor and service testing, but the Army delayed making a final decision until May 1981 when it announced that the Ford XM247 was to go into continued engineering development. It was considered that both systems had met the specification; however, it is possi ble that the etTectiveness and growth potential of the Bofors proximity-fuzed ammunition swayed the choice in favour of the Ford system.

The US army designate the Ford D1VAD the 'Gun, Air Defense Artillery, Self-propelled: 4Omm, XM247', but Ford have chosen to promote it simply as 'Gunfighter'. In tests, Gunfighter successfully engaged 900 fixed-wing, helicopter and ground targets, including engagements while the vehicle was manoeuvring at over 2Smph. The US Army invested over S79million in two of each of the XM246 and XM247, and originally expected to spend up to $3billion on production and support of the required 618 weapon systems. More recent estimates put the cost of these systems at $S.lbillion, with an Initial Operational Capability of 1985. In times of rapid inflation and increasing pressure on defence budgets, these figures are still subject to change. One thing is certain: this most costly vehicle will ensure that the M48 will form part of a frontline weapon system well into the 21st century. Ford Aerospace. General Dynamics.

f­

70

-

not adopting any solution at all. The Soviet ZSU-57-2 and later ZSU-23-4 and the West German Gepard reawakened US AmlY interest in armoured air defence. A series of programmes under exotic acronyms such as GLAADS, ARGADS and SHORADS examined the fe as ibility of many different gun and missile solutions, mounted on a variety of chassis both tracked and wheeled, armoured and unarmoured. The most recent and most definite programme is known as DIVAD (Division Air Defense Gun System) , and evolved from the ARGADS programme. Under the Defense Department's competitive development con­ cept, firms were invited to make proposals for the development of DIV AD. The US Army issued a specification in April 1977 which called for , in essence, the following characteristics: • The weapon to be an automatic gun linked to a search and fire control radar incorporating Identifica­ tion Friend or Foe (IFF) and an optical auxiliary fire control system • The weapon and its fire control to have a range of not less than 4,500m , and the requirements of standardisa­ tion within NATO would be a major factor in selection of the gun calibre and its ammunition • The whole equipment to be turret-mounted on the hull of the M48A3 The use of the M48 hull was expedient, but as plans for the M48A5 were finalised it became clear that this would be the better choice . Five fimls submitted proposals , and these are briefly summarised here:

Ford Gun: Improved Bofors 40mm L-70 gun in twin mount, firing proximity fused ammunition. Radar: Modified acquisition and fire control radar from the F -16 aircraft.

General Dynamics Gun: Originally the triple mounting of the Mauser F-30 30mm cannon was proposed. Later twin Oerlikon 35mm cannon were substituted. Radar: An adaptation of the US Navy's Phalanx Close-In Weapon System (CIWS) radar.

General Electric Company Gun: The seven-barrelled 30mm gun GAU-8fA of the A-IO aircraft. Radar: Originally a Rockwell proposal but this was replaced by a Westinghouse design.

Raytheon Gun: Twin Oerlikon 35mm GOA cannon. Radar: Hollandse Signaalapparat-Contraves in 5PZF-C turret of the CA-l weapon system in Dutch service.

-----------------------------------------------

Sperry Gyroscope Gun: An adaptation of the 37mm Gun T250 developed for the earlier Vigilante project. Maremont had redesigned the gun to 35mm calibre. Radar: A Sperry design incorporating low light level TV (LLLTV) , a laser rangefinder and a Teledyne computer. Raytheon's proposal was based on the most satisfactory performance of one of the 12 pre-production prototypes of the Leopard Flakpanzer, the Gepard, in firing trials at Fort Bliss in 1974. The vehicle itself was too heavy, but Raytheon had been sufficiently impressed to take out the provisional US selling rights for the turret with Siemens radar, and to embark on studies to mate this turret to the M48 or M60. As the DIVAD requirement evolved, the CA-l turret with the HSA digital fire control system was substituted. However, Raytheon's enthusiasm was in vain, for only Ford and General Dynamics were se lected to take their concepts forward to the prototype stage.

T44 Flotation Device Just as flotation equipment was developed for the M47, so the T44 device was designed for the M48. Initial tests were scheduled for October 1955 and it was hoped that the device would allow a water speed of about 4kts, possibly improving to 6kts. Little is known of what became of this device, but even by 1953 the user was no longer really interested in cumbersome, bulky and vulnerable flotation equipment and a deep fording kit was under development in 1954. Later models of the M48, from the M48A2 onwards, could be equipped for deep fording , normally to a depth of 8ft (2.44m). In this mode the engine compartment was flooded and a single exhaust extension was fitted. Engine air was drawn through this extension. This flooding of the engine compaItment not only avoided the tedious process of sealing the engine compartment but also reduced the buoyancy, giving the tank a better exit performance in strong currents. Studies of water crossing were carried out and these showed that bottom crawling was the best solution. An inflatable seal was permanently fitted around the turret ring and other seals and covers could be installed by the crew.

M8 Dozer Blade Introduced as the Bulldozer, Tank Mounting, Tl8, the M8 (T 18E I) was standardised in 1957. A hydraulic pump driven by the main engine supplied hydraulic pressure to double-acting cylinders. Valves in the driver's compart­ ment controlled the raising and lowering of the blade which was mounted on a parallelogram linkage . 'B lade tanks' were normally so equipped on a scale of one per company, although dozer blades were much more widely used in Vietnam. The M8AI (M8El) bulldozer was standardised in September 1959 and was an adaptation of the M8 to fit the M48A2 . The control valves and hydraulic reservoir of the M8AI are mounted on the right

71

Left: The Tl8Et Bulldozer under test at Aberdeen Proving Ground. US Army via R. P. Hunnicutt ".

trackguard of the tank whereas those of the M8 are mounted on the hull wall at the rear of the tank. Later the M8A2 and M8A3 bulldozers were standardised. A snow interceptor kit was also available for most M48 series tanks.

Mineclearing with the M48 In the early 1950s much work was done on tank-mounted mineclearing devices and a series of vehicles was built. Generally the name suggests the method of operation and in many cases the name was more impressive than the

72

Below: A view of the M8 Bulldozer on an M48AI. RAe Tank Museum

device itself. 'High Hennan' and 'Larruping Lou' described the heavy and light tank-mounted rollers respectively. The latter, 'Larruping Lou', consisted of two sets of heavy rollers weighing 21 ton and able to survive a 20lb mine detonation. It was developed in the mid-1950s but although it was never adopted, neither was it ever rejected. The pilot was stored until the mid-1960s when it served as a model for the design of a mine roller for the M60. 'Peter Pan' was a light mine excavator pushed by a tank , while a rotary mine excavator was known as ' Fargo Express'. This used five M46 tanks as its

1_

Left: An early M48 minedearing device , ' Larruping Lou'. The large cast iron rollers were intended to detonate single impulse fuzed anti· tank mines. The announcement of this equipment states that the attachment 'does not hinder the fighting capabilities of tank weapons' but the mobility is obviously hampered. US Army

- = der test at :... ~-5Army

Below: Another view of the rollers, showing the way in which each roller is frce to move up and down and to castor. US Army Bottom: The rollers of this ' Larruping Lou' mine roller have swung forward as the M48 propelling tank reversed. The exhausts for the personnel compartment heaters are visible in front of the turret. US Army

:1

-= :-::, ;ltor was -: :2JTh S as its

motive power and for obvious reasons was not pursued . A jet-type mine clearing device was known as 'Dust Storm'. An expendable roller was developed by the Corps of Engineers but no nickname was given. This roller was reactivated by the US Army Engineer Research and Development Laboratories for the ENSURE 202 equipment, its two rollers being replaced by two sets of six M48 roadwheels. The ENSURE 202 project is mentioned in Chapter 5.

The Shillelagh Missile System The Shillelagh 152mm gun-launched missile system was first tested in a heavily-modified M48. The system, as the 152mm Gun-Launcher M81 or M162 , was later fielded in the M551 and M60A2 tanks, but the modified M48 tank ended its days as a target. One last, non-military, variation of the M48 deserves mention. An enterprising contractor building power pylons in remote areas along the Arizona-New Mexico border modified a surplus M48 hull to carry a concrete mixer. This vehicle had sufficient mobility to reach isolated sites where it could pour concrete for footings. The pylons were then positioned by helicopter.

Above left: 'Larruping Lou', seen here on an M48AI, detonates a mine. The blast has lifted the cupola hatch and may well have damaged the gun barrel. US Anny Left: A more radical approach to the problem of mine clearance was the mounting of a solid fuel rocket engine at the front of the tank. Seen here on an M26, the device (nicknamed 'Dust Storm') was intended to use a turbojet engine to clear the soil away from buried mines so that other equipments could then dispose of them. US Army Below: Smoke has always been useful both for blinding the enemy and for covering one's own movements. This Marine Corps M48AI has been fitled with an experimental smoke generator for close-in screening. Although this device was being tested at the Marine Corps Landing Force Development Center in 1959, it was 20 years before this type of smoke generator entered service on the M60. USMC

5.

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s. M48 in US Service The M48 first entered service in the US Army in the 2d Armored Division (,Hell on Wheels') in 1954. The 'Hell on Wheels' Division was stationed in Germany as part of the US 7th Army, and when they had received theirs , the next M48s went to the I st Armored Division (,Old Ironsides') in the Continental United States. The first operational deployment involving the M48 was ill 1958 when three Marine Battalion Landing Teams CBLTs) were sent to the Lebanon on 15 July at the request of President Chamoun. Sabre-rattling by Syria, and encouragement by that country to revolutionary elements within the Lebanon, had followed the overthrow of the

Iraqi government, making this intervention necessary. At the same time British paratroops landed in Jordan at the request of King Hussein. Later , units of the 7th Armored Division arrived in the Lebanon complete with their M48A Is . These were employed mainly in the protection of Beirut Airport and in peace-keeping in the surrounding area. By 4 October all US troops had withdrawn, and the M48 was not used in action. To the US Marine Corps must go the credit for deploying the first armoured unit in the Vietnam war. On 8 July 1965 the 3d Marine Tank Battalion disembarked at Da Nang, its task the support of Marine Infantry of the 3d

a

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Left: The 1st Armored Division ('Old Ironsides') were the friendly forces in Exercise 'Spearhead' at Ford Hood in May 1954. The road wheels of this M48 show that the tank is almost factory-new. Details of the Chrysler mount for the commander's machine gun can be seen and the small driver's hatch is also shown. The 90mm gun has the smaller T-head blast deflector. US Anny Below: When the United States intervened in the Lebanon in October 1958, tanks of the 3/35th Armor were among the force. Here an M48A I with the M8 dozer blade clears the remains of a rebel roadblock. The trunking on the glacis is the armour protecting the hydraulic lines to the dozer blade cylinders. US Anny

Above: M48A3s of the 3d Marine Division in support of a BLT near Da Nang in May 1965. USMC

Left: An M48A3 moving into action during Operation 'Sitting Duck' near Da Nang in April 1966. The shock absorber is missing from the first wheel station. USMC

Below: The Marine Corps caption to this photograph is titled 'Looking for Viet Cong'. The Marine on the left of the tank is taking a less warlike approach than his comrades. USMC

II

Marine Division . The Marines' original task was the defence of the important airfield at Da Nang , but in drafting the request for Marine involvement the staff of the US Military Assistance Command, Vietnam (MACOV) had overlooked the fact that the establishment of a Marine BLT included tanks . The Marines for their part saw no reason to operate without tanks and so their M48A3s also lumbered across the beach at Da Nang. This embarrassed the US Ambassador to Vietnam, who took the view that tanks were an over-reaction. Nevertheless, tanks were now in-country and when the Army's 1st Infantry Division was sent to Vietnam in the autumn of 1965 the divisional cavalry sq uadron kept its tanks although the two tank battalions were left behind. MACOV's justification for this was that the 1st Squadron, 4th Cavalry would test the effectiveness of

76

-"= "Iarine _ E ~T r.earDa

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annour in Vietnamese operations. The l!4th's M48A3s were soon withdrawn and held at the squadron's base at Phu Loi. So far, informed Army opinion had taken the view that there was no role for armour in Vietnam. Later General Westmoreland changed this position and in late 1965 he asked for more troops, this time to include armour. The 25th Infantry Division anived in March 1966 and the 1st Battalion, 69th Armor (,Black Panthers') became the first Army tank battalion in Vietnam. Their area of operations was centred on Pleiku in the Central Highlands. New tactics had to be evolved to deal with an elusive enemy in a new type of lenain, and it \-"as three years before tank engaged tank. M48A3s were used for 'jungle-busting' - clearing trails through primary jungle­ and many were fitted with the cutting edges from dozer

Above: Mines were not the only problem in Vietnam. This M48A3 has become bogged-down in the edge of a rice paddy during a patrol with Ist Squadron, 1st Cavalry north-west of Tam Ky in December 1967. The M88 is just visible behind the bogged tank. US Army

blades to make them efficient at this. A fresh look at maintenance was called for in a climate and tenain where dust clogged oil coolers and air cleaners during the dry season, and mud caused tracks to throw in the monsoon. Sights developed condensation and mould, and lubricants quickly became contaminated by the all-pervading damp. The Viet Cong's wide use of mines was perhaps the greatest obstacle to armoured operations in Vietnam and

77

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Above: Mine damage was a constant threat to armoured operations in Vietnam. This early model M48A3 was involved in Operation 'Cedar Falls' against the 'Iron Triangle' in the III Corps Tactical Zone in January 1967. Apart from damage to shock absorbers the tank appears undamaged and would soon have been back in action. US Army Right: An M48A3 of Company C, 1177th Armor after hitting a mine about eight miles north-east of Cam Lo on 9 July 1970. The 90mm gun has the earlier blast deflector. US Army

78

on average 70% of all tank losses were due to mines , although only 20% of personnel casualties were caused this way. Conventional Chinese or even US anti-tank mines were sometimes used but far more often the mine was an aircraft bomb or an artillery shell which had failed to explode - the biggest which could be conveniently dug into a hole in the road. Such improvised mines could be as large as a 500lb (250kg) aircraft bomb, detonated remotely by command wire . There was little chance of the tank or crew surviving an attack on this scale, but smaller mines often left the M48A3 drivable , if not unscathed , and the crew were usuaJly unharmed. If the hull floor took the blast then the torsion bars would probably be distorted, making repair a difficult and lengthy task. Harking back to the Korean War, Ordnance mechanics used the field expedient of one or two ounces of C-4 plastic explosive to dislodge the fractured ends of torsion bars . In an attempt to reduce losses to mines, the Engineer Research and Development Laboratories at Fort Belvoir

Right: One set of rollers of this ENSURE 202 mine roller has been badly damaged and is secured in the raised position. The effect on the tank's suspension is obvious. US Anny Below: this ENSURE 202 mineclearing tank is preparing to go into action along Highway 19 in Vietnam in August 1970. The tank is a late model M48A3 and is comparatively uncluttered. US AmlY

were asked to produce a mine roller. This equipment was known as ENSURE 202, being the 202nd item developed under the Expedited, Non-Standard, Urgent Requirement for Equipment, and the first was delivered to the II th Cavalry in late 1969. Its 20ton (l78kN) weight made it unpopular , and it was found to be unsuitable for jungle-busting (for which purpose it was never intended). The mine rollers then went into abeyance for a while until

1

Left: Yie\< . ' ­ painted on 'C"'o Handel

Below left: T..-__ ......

combat W:.. Canister :'...~ perimete~ .:-:­ jungle. \\ -:-r.-­ HE fired ::-." similar e;':':--:­ The · H ~ . .-_ 11 th Ca\'a::-: in V ierna.:: pulled off l:::' 45° to the L--:, of fire for :'... One of ::-.:' _ that of rou:,: ~ mobile P L: ~ sandbags a:: : M48 tuITe: :

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the 4th Infantry Division had more success with the equipment mounted on a combat engineer vehicle. Eventually 27 were in use, including one loaned for a while to 1st Field Squadron, Royal Australian Engineers. Jungle-busting was an operation which taxed engines and transmissions to the limit. Extended slow speed driving in heavy going made engine cooling vitally important and oil coolers needed constant attention. The close country made short work of track guards and other less substantial external fittings , and if a track lasted for more than about 750 miles it had done very well. With monthly track mileages of the order of700 miles thi s was clearly a sizeable logistic problem , although old track could always be used to reinforce gun pits and bunkers. The first real jungle-busting took place at the end of March 1966 when Lt-Col Robert M. Shoemaker , the squadron commander of }/9th Cavalry, led Task Force SPUR into virgin jungle near the Chu Pong mountain in

80

the II Corps Tactical Zone. His nine M48A3s blazed 20km of trail in seven hours , proving that tanks could operate in terrain without roads or tracks. In all, Task Force Spur completed 108km of jungle-busting during Operation ' Lincoln' . A facet of the jungle-busting capability of the M48A3 was that six tanks could crush out a helicopter landing zone in about l5min. Tanks also excelled at bunker-busting. Firing HE, if necessary with concrete-piercing (CP) fuses, they quickly proved their worth. Viet Cong prisoners revealed that tanks were greatly feared because of the damage they could inflict on bunker systems and tunnel entrances, and because of the canister round. Gen Hay, in the Vietnam Study entitled 'Tactical and Material Innovations', said: "Captured documents and intelTogation reports disclose that the enemy is afraid of tanks . We feel what he really fears is the cannister (sic) round and its effect. This (feeling) has been justified, to a degree, by the absence of

Left: View of the M48A3 mine roller 011 loan to 1st Field Squadron, Royal Australian Engineers in Vietnam. A kangaroo has been painted on the turret and ' US' deleted from the vehicle number. Paul Handel

Below left: Tanks of 1st Squadron, 11th Armored Cavalry Regiment in herringbone formation astride a road at Ben Dong, November 1966. US Army

combat when tank and infantry units move together." Canister ammunition was also useful in ambushes, for perimeter defence at night and on occasions, for clearing jungle. When supplies of canister ran out, impact-fused HE fired into the ground in front of the enemy had a similar effect. The 'Herringbone' formation was developed by the 11 th Cavalry , whose tanks had been the first Army tanks in Vietnam. When ambushed or just halted, vehicles pulled off the road or axis in alternate directions, angled at 45° to the line of march. This fonnalion gave the best arcs of fire for all weapons. One of the less glamorous chores for armour units was that of route security. In this role , tanks were in effect mobile pillboxes , and were heavily festooned with sandbags and other added protection. Penetration of the M48 turret by a HEAT round was likely to start an ammunition fire, with dire results, and any stand-off protection was worth having. (The Royal Australian Armoured Corps had cause to be thankful for the design of Centurion. Since the early days of World War 2, it had been British policy that no explosive be stored above the turret ring, and despite being petrol-engined, no Centurion is known to have been destroyed by a HEAT round in Vietnam). M48A3 crew members rode outside the vehicle and it was nonnal to mount the cupola machine gun on a cut-down tripod mount on top of the

_ - "' lil al l, Task _ -:: ~, : in g during ,-_::Jgle -busting ~ ( - :: uld crush 5 ;::in . : ? :..--:ng HE, if -_: ~, :.,o.' =Y quickly --; :-c\'ea led that ; ' - _ 2l-nage they ::-;:::rances , and - :he Vietnam :::!ons' , said: __ :xJ :1S disclose ~ -~ ~:u he really - :s =ifect. This :::::- a bsence of

cupola. Convoy escort was one aspect of route security; another was the task of actually keeping route s open and free from mines and ambushes. To prevent the Viet Cong from laying mines and ambushes at night the technique of 'Thunder Runs' or 'Roadrunning' was developed. Tanks would move along roads at night firing canister and machine gun fire into likely ambush sites, and while this speculative fire may not have killed many Viet Cong, it certainly discouraged many more from taking the risk. There were very few occasions in the Vietnam War when M48 gunners actually saw enemy armour in their sights. During the 1969 Tet offensive several tank engagements took place and in each case the result was a clear victory for the M48. The only clash between American and North Vietnamese armour took place at Ben Het in the Central Highlands , in March 1969. During the night of 3/4 March two PT-76s were destroyed by tanks of the 1I69th Armor firing HEAT ammunition. When the tanks' complement of HEAT rounds had been fired, gunners fired HE with concrete-piercing fuses. In April 1972 the 20th Tank Regiment of the Republic of Vietnam fought a series of engagements with North Vietnamese T-54s and PT-76s. On several occasions, enemy tanks were destroyed at ranges up to 3.200yd (2,925m), and no M48A3s were lost to enemy tank fire. Almost all the tanks in American service in Vietnam were the M48A3 model. However, after the 1968 Tet offensive it was necessary to issue M48Al s to unit s to make good their battle losses. The reduced range and greater vulnerability to fire and HEAT attack made this an unpopular action , and rebuilt M48A3s replaced the M48A I s as quickly as depots could carry out the necessary refurbishment. Below: An M48A I of 1167th Armor on training with 3d Battalion, 4th Marines in Hawaii in January 1964. The searchlight is the earlier lkW white light. US Army

Above: One M48A3 tows another to an equipment collecting point at t(eystone Robin in Vietnam in February 1971. Both tanks from the 11th Armored Cavalry Regiment show the signs of heavy jungle-busting. US Ann)' Left: Until the mid-1960s units from the US 7th Army, stationed in the south of Germany, used the ranges at Hohne for annual weapon qualification. Here troops load a round of HVAP into an M48AJ of Company B, 67th Tank Battalion, 2d Armored Division (' Hell on Wheels') . US Army

Perhaps the one feature of armoured warfare illustrated by the American use of tanks in Vietnam was the value of shock action against an enemy without tanks. General Hay commented: 'The NV A and VC have shown a reluctance to engage tanks where they ca n be avoided . ' This statement might appear to be self-evident , but indicates that the enemy did not go in for tank-hunting in the way that might be expected in a European conflict.

82

Above: Tanks cannot be expected to drive for long distances without showing signs of wear , and this is unacceptable in peacetime or when deploying over long distances when out of contact with the enemy_ The MI23 tractor and MISA2 semi-trailer were the US Army's standard tank transporter for almost the entire life of the M48 series. This photograph taken in April 1960 shows an almost new M48. US Anny

:.-rc illustrated

::.:: o.e avoided.' xc <~''- id ent , but .:­ :..::...t:, · hunting in - =--c xln conflict.

Below: An M48A3 of Company B, 1177th Armor moving into aellOh near Cam Lo in July 1970. The stowage is fairly typical. In front of the driver and below the 90mm gun the handles for the external operation of the fire extinguishers can be seen . US Army

Left: This photograph of an M48A3 with dozer blade gives an idea of the problems of visibility and maintenance which arise in close country and jungle, such as this banana grove. The 900101 gun would almost certainly have canister 'up the spout' although here the gunner is riding outside the turret. US Anny Below: Two M88 recovery vehicles lift a battle-damaged M48A3 on to an M 15A2 trailer for evacuation for base repair. Despite its forlorn state this tank is almost certainly repairable . The nearer M88 has twin .50in machine guns at the commander's position and another mounting on the rear deck. US AmlY Right: Three M48A 1 'blade' tanks in the motor pool in Hessen-Homburg Kaserne, Hanau, Germany in October 1959. US Anny

Below right: An M48Al of the 3/35th Armor in a leaguer near Beirut Airport during the United States intervention in the Lebanon in August 1958. US Anny

84

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Left: An M48A3 of C Company, 3rd Battalion, 3rd Marine Division is loaded into a Navy LSD en route for the battalion area at Quang Tri. USMC Below left: A convoy of Marine Corps M48A3s moves along a dirt road south of the dcmilitarised zone in September 1967. USMC

Right : Hearts and minds. This blade tank from 1st Tank Battalion, 1st Marine Division is clearing a firebreak to protect a V ietnamese village from the fire hazard of dry trees. USMC Below: A bulldozer from 11 th Engineer Battalion is called on to assist a Marine Corps M48A3 during Operation 'Pegasus' in the area of Khe Sanh and Ca Lu in April 1968. USMC

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6. TheM48

in Foreign Service

Of the 11,703 M48 series tanks produced, approximately 6,000 ended up in other armies. Some were provided under the Military Assistance Program; others were sold as Foreign Military Sales, and some were sold by their initial recipients. These latter transactions require the approval of the US Government, but several deals in recent years appear to have igno red this condition and of course there have been occasions when tanks have been captured , or when a change of government result s in a change of political alignment. Many countries have instituted their own improvement programmes. Fitting a diesel engine tends to be the highest priority , followed by upgunning (in variabl y with the British JOSmm g un ) and at the same time there is usually a case for improving the fire control system . In this section user countries are listed with details of any known improvement schemes.

Austria Although not a user of the :\148 , the Austrian Army received some M88s as part of its fleet of M60A Is. There are no current plans to modernise their M88s.

Belgium The M48A2 A VLB remains in Belgian service and for a long time the M55 SP howitzer was also used although th is has now been replaced by the MIlO.

Bolivia

120 M48s were supplied .

-

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Below: Belgian M48A2 AVLBs of the 3rd Engineer Battalion crossing the Rhine on a causeway of UniOotes at Hersel, north of Bonn, in spring 1979. Belgian Army

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Top: Conversion of the M48A2 into the M48A2GA2 for the Bundeswehr. The mantlet is much more conspicuous than that of the M48AS, and the new cupola is not much lower than the M I cupola it replaces. Wegmann

Abo"e: An M48A2 AVLB of the Bundeswehr about to touch down on the opposite bank of the obstacle. Bundesministerium der Veneidigung

Chile The Chilean Army is reported to have 270 M48 series tanks of which it is planned to convert 40 to the Y148A5 standard.

France The French Army has not received the M48 or any of the variants. However, the strongly competitive French armament industry has offered two updated fire control systems for the M48 from the firms of Sopelem and GIAT.

Germany (Federal Republic of) Beginning in 1958, the Bundeswehr was supplied with a total of 1,400 M48-series vehicles including the M88 recovery vehicle, the M55 SP howitzer and the M48 AVLB. In a major improvement programme costing DM180million, 650 of the Bundeswehr's remaining 1,045 M48A2s have been converted to the M48A2GA2. The conversion centres on improvements to firepower, and the rifted I 05mm gun L7 A3 is being installed in a new mantlet , with a much improved fire control system. The petrol engine is retained. Wegmann of Kassel are responsible for the conversion work, which began in February 1979. Rheinmetall have offered both their 105mm and 120mm smoothbore guns as retrofits for the M48A2, but so far there have been no customers for either. A very sophisticated fire control system called LEMSTAR (Laser Entfernungsmesser und Stabilisiertes Richtschutzenzielgerat) was developed by AEG· Telefunken. It included a low light level TV camera with a stabilised sight, as well as a laser rangefinder. A similar system, without the TV system, is used in the

89

-

----- -

-

Above: A proposed installation of Rheinmetall's lOSmm smoothbore gun in the M48A2. Despite the claimed superiority of the smoothbore gun, NATO standardisation of ammunition won the day and the British L 7 gun was selected for the up-armed M48A2GA2 of the Bundeswehr. Rheinmetall GmbH

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Left: An M48A2 of the Bundeswehr on the firing point at the range at Castlemartin in South Wales. These tanks have no track tension idlers, but German smoke dischargers and a searchlight stowage box have been fitted to the turret. Soldier Magazine

I:

Below left: A troop returns to the rangehead for a midday meal during firing at Castlemartin. Soldier Magazine

90

Above: Rheinmetall's study for mounting their 120mm smoo~hbore gun selected for Leopard 2, In the k M48A2. This suggestion was not ta ~n up by the Bundeswehr nor, as far as IS known, by any other country. Rheinmela/l GmbH

bl d Left: An M48A2C of the Bundeswehr, . d with the l\18A 1 dozer a e, eqUlppe bridge which has been laid by crosses Biber abridgelayer. Bundesminisler;um ader Verteldlgung ,

VI

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B low left: A commercial up-armouring of\he turret of the M48A 1 by the 'German consortium ofGLS. The gun appears to be the 90mm, modified to represent a IOSmm gun. GLS

91

--

M48A2GA2. The German firms of GLS and MTU are also active in M48 rebuild programmes in other countries such as Greece and Turkey . Finally, the Franco-German mineclearing project called LSM (Landmineschnell­ raiimmittels) is to use M48 hulls as motive power for a flail equipment. The same device might also be mounted on the AMX-30 hull. Greece The Greek Army received 500 M48s and a number of M88 Recovery Vehicles. It was reported that MTU, the makers of the diesel engine of the Leopard tank, were examining the re-engining of the Greek Army's M48 fleet. However, Greece later bought 600 kits to convert its M48A 1s to M48A3 standard and this package would include the A VDS-1790 diesel engine. Discussions are in progress with other firms on improvements to the fire control system associated with the fitting of the rifled 105mm gun.

Iran The United States supplied Iran with 240 M48s in the early 19605. Re-engining of M48s in the plant built by Bowen-McLaughlin-York (see the M47 entry) is reported to have continued even after the revolution in early 1979. Several Iranian M47s and M48s have been captured by Iraq in the fighting which began in 1980 .

Israel The Israeli Armoured Corps (,Hel Shirion ' ) received its first M48A2s from Germany in 1965. In the Six-Day War of June 1967 these Pattons fought well and earned the respect of their crews. The 7th Armoured Brigade, which oven'an the 20th Palestinian Division during the advance on EI Arish, included a battalion of M48s, and M48s were also included in the composition of 'R' Force, which occupied the Gaza Strip and Kantara. On the Jordanian front there was often confusion because both sides had M48s. Exploiting this type of confusion , a predominantly Shelman-equipped brigade entered Nablus on 7 June without firing a shot. A strong counter-attack by the Jordanian 40th Armoured Brigade (with 50 M48s) was only beaten off with the aid of Israeli close air support. After this, many Jordanian M48s were captured. On the Syrian front a battalion of M48s took part in the advance on Keneitra, while on the Jordanian side two brigades equipped with M48s were deployed in the Jerusalem sector along the Jordan River. When the first M48A2s were received from Germany, plans were made to convert them to the diesel engine and 105mm gun , but by the time war broke out in June 1967 only enough for one company had been completed. During the Six-Day War over 100 M48s and M48Als were captured from the Jordanian Army and soon

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=

The OC ((l~",,: ­ danger p0~": :: (ATGW ). a;-- -=­ ATGWs on :.:c ­ tended to ne ;~-:-_­ ' Saggers'

-=-:= ...-ed its - :_'\-:JJy \\-ar

- - e::"'-::'= the .:. -=: - ;::--== _'.'. hich -; - r" 2iha nce - - _!.!. ' s \'.-ere -: :- ::: _ whi ch

_::':>:-:linantly - --.: : ~_ - June

~ -:r:,

Gennany, _~ ==_gi ne and - G Ju ne 1967 : 0:npleted . - ,: '- I-l8Als l:1d soon

=

Left: An Israeli M48 modified by the substitution of lOSmm gun, diesel engine and low profile cupola. This tank, of the 2nd Company of the 1st Battalion of its Brigade, has a .SOin machine gun installed on the searchlight mountings as a subcalibre training weapon. Israeli Defence Forces Above: An M48 ofthe Israeli Army in a revetment. Irvine Cohen Right: A welder at work inside the engine compartment of an Israeli M48 during its refurbishment. Irvine Cohen

afterwards 'large numbers' of M48s and M48A 1s were purchased as US surplus, or in various roundabout ways. Conversion of the varied selection of models to the same standard, with the British lOSmm gun which then equipped Israeli Centurions , and the diesel engine which was later fitted to the Centurion as well, was given a high priority and by the beginning of the Yom Kippur War around 800 M48s were in service with the Israeli Army. The designation M48A4 was given to upgraded Israeli M48s but is not a US designation. The October 1973 war brought home to the Israe lis the danger posed by infantry anti-tank guided weapons (ATGW) , although two M48s had been lost to 'Snapper' ATGWs on the Suez Canal in 1967 _ Initial tank actions tended to neglect infantry support but after heavy losses to 'Saggers ' (the Soviet 'suitcase' ATGW), intimate

infantry support with massive machine gun firepower became the nonnal tactical grouping. One of the lessons of the Six-Day War had been the vulnerability of the M48A2's controlled pressure hydraulic gun control system. A leak could send hot, hi gh pressure , flamm able hydraulic fluid all round the turret, and this point was well taken by the US Army_ Non-flammable fluid was introduced, but the M48 series was still very vulnerable to HEAT attack. It was this which caused the majority of losses in the 1973 war.

93

series ~. suppl ie.: : . Neve n:1...~. :­ tank U5~': : s ign ific ~ ·

pro vide': :-­ first in

Italy Like Fr.::< ~

Above: A squadron of M48s of the Royal Norwegian Army lined up for inspection . Royal Norwegian AmlY Left: An M48 of the Royal Norwegian Army 'somewhere in North Norway' . Royal Norwegian Army Above right: An M48 of the Royal Norwegian Army reversing in the snow during exercises in the north of Norway. Soldier Magazine Righi: An M48 oflhe Norwegian Army outside a garage at Trandum. Royal Norwegian AmlY

94

After the Six-Day War, Israel took delivery of M60 series tanks from the United States, and many more were supplied by air from the US during the Yom Kippur War. Nevertheless the M48 remains the principal American tank used by the Israeli Army, and has been not only a significant factor in its effectiveness, but has also provided much of the experience e mbodied into Israel 's first indigenous tank, the Merkava .

Italy Like France, Italy is not a user of the M48 although a quantity of the M55 SP Howitzer was supplied. The firm of Selenia has proposed another fire control system based on its VAQ-3 laser range finder.

-

.--.c

~

Jordan Saudi Arabia has financed the construction of a tank conversion workshop in Jordan where 160 M48s will be brought up to the \148A5 standard.

Morocco There are plans to moderni se one battal ion of the 107 M48s supplied to the Moroccan Army. Detai Is of the conversion are not known.

Norway The Royal Norwegian Army operates 38 M48s, organised in independent sq uadrons. Although the Leopard I is now in service, there do not seem to be any plans to modernise the M48s .

Pakistan Mention has been made of the use of the M47 by the Pakistani Army. The M48 was also supplied to Pakistan , and in this extract from Military Review, Leo Heiman analysed the differences between the Indian Centurions and the Pakistani M48s , and their tactical handling in the Kashmir in September 1965 . 'The tanks themselves were better handled by the Indians than the Pakistanis , mainly because the Indian tanks were older, simpler and less complicated than the American-made Patton tanks used by the Pakistani forces . This may sound like a paradox, but there is no doubt that the sheer modernity of the Patton was its undoing vis-a-vis the older, slower, weaker and simpler Centurions and Shermans used by the Indians. 'As an armoured fighting vehicle, the Patton is so vastly superior to Centurions and Shermans that under

_' me Royal

95

normal conditions no comparisons could be made. But the US tanks proved too complicated for the soldiers who operated them. The Patton weapon system relies on computers which control the main gun. For effective firing the crew must feed correct information into the computer which then does the rest. ' During manoeuvres and field exercises, the Pakistani tank brigades proved to be quite efficient, but real war is vastly different from war games. In the zone of military operations, computers went wrong, Pakistani tank crews fed misleading information into the electronic brains, the heavy guns had to be operated by hand, and the crews were so occupied with modem gadgetry that they had little time left for fighting. To many armies, ultramodern hardware is not an asset. 'Apart from having trouble with the Patton's automated fire control equipment, the Pakistanis were handicapped by their battle deployment. They applied proper deployment procedure by sending an armoured brigade of 70 Pattons streamrolling across the Indian defences in the Kashmir sector without bothering about the open flanks. But lack of armoured infantry precluded tactical exploitation of the initial gains. When fuel and ammunition supplies were exhausted, the Pakistani brigade ground to a halt. Lacking infantry protection, the Pakistani tanks became easy prey for Indian hunter-killer teams which stalked the Pattons with jeep-mounted 106mm recoilless rifles, bazookas and flamethrowers . 'In the Punjab sector, the Pakistanis also sent a 70-tank brigade steam-rolling forward, but failed to screen its advance with jeeps and motorised patrols. The heavier Pattons could not manoeuvre on the rain-soaked muddy ground as easily as the Indian Centurions and Shermans, and the few dry tracks across the battle zone were heavily mined by the Indians. Combat engineers were not sent ahead to clear the mines and prepare attack lanes across the muddy fields. 'Moreover, at this time of the year, Punjab fields are covered with sugar cane and grass 2-3m (6ft 6in-9ft lOin) high. The low silhouette of the Patton is intended to guarantee extra protection against enemy anti-tank fire and provides better conditions for hull-down deployment in major armoured battles. But in the grass and sugar cane of the Punjab, the Pakistani tanks had to operate blindly. To direct their fire, tank commanders would climb up on to the turrets and scan the fields through binoculars, shouting down orders to the crews who then fed them into computers. 'The exposed tank commanders became easy prey for Indian snipers and were mowed down by machine guns,

Right: Soldiers or the Indian Army beside a Pakistani M48 destroyed in the fighting in late 1965. Indian Anny

96

shrapnel and mOl1ar bursts. If the armoured infantry had accompanied the Pakistani tanks into battle, they and their vehicles would have cleared lanes of fire in the grass, making ultimate victory certain. But lack of specially trained infantry and carriers turned success into failure. 'On the Indian side, orthodoxy and lack of imagination paid off.

Soutb ~ :.

There are one or two factual errors in the account - the ballistic computer is not an electronic computer, and the 90mm gun has always relied on mechanical control, and a certain amount of imagination is required to regard the M48's silhouette as low - and many would not agree that the Patton is so vastly superior to the Centurion as Mr Heiman would suggest. However, the article does illustrate the extent to which sophisticated equipment can be made worthless by lack of attention to training. Indian losses in the Kashmir War were 114 tanks and 57 armoured cars, while Pakistani losses amounted to 471 tanks and armoured cars. Again in 1971, Pakistan found herself at war with India. This time there was less scope for armoured warfare , and the composition and equipment of the Pakistani Army had changed. M48s were still in service, and still are today, but their particular contribution to the 197 1 war has not been recorded. In addition to the M48 MBTs , Pakistan has also received the M88 recovery vehicle. It was reported in 1976 that a further 100 M48s had been received , and it was suggested that these tanks had been originally supplied to Turkey and later refurbished in Iran.

This p~e: l<",,~~~ part in tbe skirts and ......'

Portugal In 1978 Portugal received 18 M48s under the NATO Aid Programme. It was reported in late 1979 that a further 12 M48s were shipped to Portugal from West Germany and that these tanks were fitted with 105mm guns.

640 \1..: ' ,,_ to ivl-k .'_: _ been u :: ~:.2.._ fitted v.::..- _

Tank Maf ' - ·

South Korea 640 M48 series tanks were supplied to South Korea. In early 1977 the South Korean Army ordered 416 M48A 1 to M48A3 conversion kits. Many M48A3s have now been upgraded locally to M48A5 standards and are also fitted with track skirts.

This page: Locally-modified M48·series tanks of the ROK A taking part in the October 1978 parade in Seoul. The \oSmm gun, track skirts and ANIVSS·3 searchlight can be clearly seen. The smoke grenade dischargers on the turret sides are of the German pattern. Tank Magazine

.' ..: war with

-, -. has also

-

:y- \' .-\ TO Aid - ~ "' iurther 12 =:;;: 2 :-:nany and

97

---

-

---------

---

7.

Above: An M48A3 of the ROKA (Republic of Korea Army) photographed at Munsan, Korea in the spring of 1979. The thin wire bracket on the 90mm gun barrel may be an aid to the commander in aligning the gun, but would be vulnerable to damage by undergrowth and other obstacles and even muzzle blast. R. P. Vaughan Below right: Oerlikon suggested the installation of the twin 35mm gun turret of the Cepard on the hull of the M48A3, shown here in model form. Raytheon proposed the virtually identical CA-I turret for the D1VAD requirement, and the Spanish Army set aside some M48 hulls for a similar project. Oerlikon·Contraves

Thailand 50 M48A3s are in service. More recently a quantity of M48A5s has been supplied to the Thai Army. Turkey 160 M48s .were reponed to have been supplied to the Turkish Army. The German firm of GLS, in association with MTU , is examining the re-engining of Turkey ' s M48s. As mentioned earlier, some Turkish M48s may have found their way to Pakistan .

UK

Spain Both the M48 and the M48A I were supplied to Spain, and the M48A I was used in operations in the Spanish Sahara against Polisario guerrillas. Many M48s have been converted to the M48E by Chrysler Espana SA by the installation of the A VDS-1790-2A engine, and some M48E's have now been fitted with a 105mm gun of the British L7 type. These guns are reported to have been obtained from Israel 'at an advantageous price ' . Some surplus M48s were offered for sale in late 1979 and others have been earmarked for use as anti-aircraft tanks by the eventual installation of the Gepard turret. Taiwan 350 M48A3s have been supplied. It is believed that there are now plans to update some of these. In late 1977 Taiwan bought a further quantity of M48A I s.

98

The UK has not used any of the M48 series, although one M48Al was received on Standardization Loan and given the British Army number 02B833. The M55 SP howitzer was also tested. Vickers offer a re-engining service for the M48 and both Ferranti and Marconi have developed upgraded fire control systems. Vietnam The Vietnamese Army now possess one of the largest fteets of M48A3s, estimated at 940 tanks. This includes 340 tanks abandoned during the closing stages of the Vietnam War.

7. Parallel Developments

The Light and Heavy Tank Families The development and use of the M48 should not be viewed in isolation, and this account would be incomplete without a short mention of the two companion vehicle families. A requirement for both light and heavy tanks was confirmed at the same time as that for the medium tank , and the T41 light tank and the T43 heavy tank were developed alongside the T42. The T41 entered service as the 76mm gun tank'M41 and was widely deployed as a reconnaissance vehicle. Its chassis was used in much the same way as the medium tank chassis, resulting in a family of lighter vehicles. This included the following: Twin 40mm Self-Propelled Gun, M42 - using the modified chassis. 105mm Self-Propelled Howitzer, M52 - using some suspension components and engine.

l55mm Self-Propelled Howitzer, M44 - the same basic chassis as the M52. Carrier, Personnel, Full Tracked, Armored, M75 ­ engine and chassis. Carrier, Personnel , Full Tracked, Armored, M59 ­ suspension. Carrier, Mortar, l07mm , Full Tracked, Armored, M84­ based on M59. Recovery Vehicle , Light, T50 - using the modified chassis, but not proceeded with. Tractor, Cargo, M85 - using the basic chassis but with front sprocket. Standardised but not produced. Bulldozer, Tl6 and Swimming Device, Tl4 were also produced experimentally. Tank, 90mm Gun , T49 - a different gun. The T43El heavy tank was standardised as the M 103 120mm gun tank but saw little service with the US Army. Left: The M41light tank, the parent vehicle of the contemporary light vehicle family.

[he largest -:;U s includes s - ~ g es of the

0 --

99

I

Above left: The name 'Walker Bulldog' was given to the M41 light tank in US Army service. This M41 of the 759th Tank Battalion is preparing for a fire mission at Grafenwohr in July 1955. US Army

artillery formed another class of its own. So US armoured vehicles once more fell into three fairly distinct categories , only one of which included tanks.

Left: The MI03 was the heavy tank developed alongside the M48. This T43EI pilot model is undergoing wading tests at Aberdeen Proving Ground in September 1953. The picture gives an idea of the size of the massive 120mm gun turret. US Army

T54 l05mm Gun Tank

Above: The long gun and huge turret of the M 103 heavy tank are well shown in this photograph. US Army

The US Marine Corps took 158 of the 225 produced into service in heavy tank companies in Marine tank battalions. Only one variant, the M51 tank recovery vehicle, was standardised although other wrecker-type vehicles and cargo tractors were developed. The Ordnance Committee's move to redesignate tanks by gun calibre was an indication of the trend which was to replace the classical three-way split. The heavy class subsequently disappeared as the medium gun tank became the main battle tank , and the M 113 APC formed the basis of the lighter vehicles, while self-propelled

Not to be confused with the Soviet medium tank T-54 , the American T54 was an early attempt to upgun the M48. The United States had agreed at the 1951 Tripartite Conference that the medium gun tank should be capable of defeating 4in of armour angled at 600 at 2,000yd using kinetic energy ammunition, and the 90mm gun M41 could not achieve this performance. The Ordnance Committee initiated development of the T54 and its gun in August 1951 and Army Field Forces endorsed this in January 1952. The T54 used the hull of the T48 unchanged, but had a different turret mounting the new 105mm gun T 140. The turret was a conventional design , with the gun in a hydromechanical recoil mechanism , and was 3.5ton heavier than the T48 turret. The 105mm gun fired fixed ammunition and about 45 rounds weighing 681b each were stowed in the tank. Two pilots of the T54 were built. The United Shoe Machinery Corporation might appear to be an odd choice for tank manufacture, but in fact their experti se in this field went back to 1942 when they designed an automatic loader for the T22El medium

101

--

~

--

-- --

--

­

Top: This view of the T54El tank shows the hinge for the massive hatch in the turret roof through which the automatic loader was replenished. The problems of sealing an oscillating turret are indicated by the canvas cover. Both the designation and the date on the notice beside this tank at Aberdeen Proving Ground are incorrect. C. F. Foss Above: The ' torpedo' turret orthe TS4EI is well shown in this photograph taken at Aberdeen. The long TI40 gun in its oscillating turret makes the tank nose-heavy and the effect on the suspension of the basic M48 hull can be seen. C. F. Foss

102

tank. Automatic loading was to be a feature of the T54E I, made possible by the adoption of an oscillating turret design. The Tl40El gun was mounted in a conventional multi-cylinder hydrospring recoil mechanism and the automatic loader was located behind the gun , its position remaining fixed relative to the gun , since the entire turret moved in elevation. Problems with protecting the gap between the moving parts of the turret,and the fact that the turret weighed 20.8ton (185kN) , lead to the abandoning of the T54E I. Detroit Arsenal later designed the T54E2 which returned to a conventional pattern of turret. In this model

the fi re C 0 ~. __ subframc " ::: kinet ic t r.e:;:. tw o d iffe:=~ :53.5to n ": - . nearly

Q

'"' ,' ,

:"'- c ::.J: je turret -' -ll ~

_' =

~;:j

the gap fact that to the

- :'- ::=:~

whic h - ::-ti s model

the fire control equipment was mounted on a shockproof subframe within the turret to increase its survivability in a kinetic energy attack. Four pilots were authorised, to test two different turret power sys tems. At a combat weight of 53.5ton (476kN) the T54E2 was 100 heavy , and it was nearly 20 years before the M48 was effectively upgunned. The Rheem Manufacturing Company of Philadelphia, PA had been responsible for the T54 . In the T77 120mm gun tank , they had their chance to develop an oscillating turret with an automatic loader when two pilots were ordered in April 1953. As with the T54 series, the M48

Top and above: The lOSmm Gun Tank TS4E2. Although the turret was quite a good ballistic shape, the long overhang of the gun and the excessive weight of the vehicle meant that it would not be a satisfactory replacement for the M48 series. US Army. via Col R. I leks

hull was used without modi fica tion. The vehicle's weight of 56ton (498kN) exceeded the design target by Iton (8.9kN) and excessive weight probably killed the T77 project in the same way as the T54 had perished. A II0mm gun was developed at about the same time and may have been considered for the T77.

103

-

-

'-

----

, - - - -­

Crui.,-->-­ :c

Left: Tho T : hatch .

T95 Series of Tanks Crew: 4 Weight: 83 ,600lb (371.8kN) combat loaded 77 ,3001b (343. 8kN) less crew, ammunition, fuel and equipment Length: 33ftO.625in (10.075m) overall , gun forward 32ft 9in (9. 98m) gun in travelling lock 22ft 7. 75in (6.9m) hull only Width: 10ft 4in (3. 15m) over tracks 6ft 7i n (2.0m) hull only Height: 9ft 5in (2. S7m) to highest fixture Ground contactlength: 13ft 9.5in (4.2m) Track centre dista:1ce: Sft 7in (2. 62m) G/c1earance: 1ft 5in (OA3m) but less under driver's seat Turret ring diameter: 7ft 1in (2.16m) Armament: Main - 90mm T208 gun in T 191 rigid mount with traverse of 360° and elevation of _10° to + 20° Secondary - one or two .30in MGs (coaxial)

104

Ammunition carried: 90mm - 50 rounds (17 ready rOunds in turret basket) . 50in - 1 ,500 rounds .30in -4,500 rounds Armour: Glacis, noseplate, turret ring and sides of hull forward of turret centre Iine - cast, one piece Hull-4Ain ( 112mm) at 60° front to Iin (25mm) at 20° rear Turret - 7in (l78mm) at 60° front to 2in (3Smm) rear Engine: Continental AOI-1195-5 Transmission: XTG-41 0 series (Allison) Suspension: Torsion bar (hydropneumatic on some later models) five pairs of dual roadwheels Power/weight ratio: II hp/ton (0. 92kW/kN) gross Max tractive effort: 92,300Ib (41OAkN) Tractive effort/weight ratio: 1.10 (41O.5kN) Max speed: 37mph (59kmlh) Max gradient: 60% (31 °)

.\', ::.~

Trench crossing ability: 8ft 6i n (2. 39m I

Verticle obstacle ability: 3ft (0 .9: m I

Fuel capacity: 235gal (889Iitre)

Fuel consumption: O.64mile/gal (O.27km/ litre )

Ground pressure: l2.02lb/sq in (82. 9kPa)

Cruising range: 150 miles (240km) at 17mph (27kmih)

A conference on future equipment policy at Fort Knox in

April 1954 gave support to proposals to broaden the scope

of tank development within the 'medium ' class - even

though this class no longer officially existed. It was

accepted that the use of a conventional gun and power

plant made a weight of about 40ton the lower limit, but

the use of a smoothbore gun and a power plant then in

development might allow a reduction in weight.

The concept known as TLI was developed into the 90mm Gun Tank, T95. The tank was not conceived as an immediate replacement for the M48 , but more as an exploration of technology and concepts. Models from the T95 to the T95E8 are known, but they may have gone as far as the T95E 13. These models varied in the combinations of armament, fire control equipment and

Top left: The T95E3 had the turret of the T54E2 I05mm gun tank. By the time this photograph was taken, development of the l05mm gun T140EI shown here had ended, so the vehicle was used mainly for automotive trials . US Army, via Co} R . 1. leks Left: The T95. The armoured cover over the OPT Ax rangefinder is in the closed position. The cupola has the horizontally swinging hatch. Narhan N. Shio virz Below: This T95 has the T57 coincidence rangefinder and the design of roadwheel is slightly ditTerent. US Anny

:-

the 15: ITln1 f U:1 - :.l~:--_ ': :-.;;:- \.."'l :- ::1;: S:-_: ~~t ~ :: {: ..~ =.:. ~~ ~. system \\ 3 5 also mounted o n the T95 -:ha, sis at 0 e ; ta ~ e . Rigid mounting of the 90mm smoothbore gun T208 was investigated , as was installation of the LK 120mm bag-charge gun then under development for Centurion' s replacement. Other innovations in firepower included the testing of different methods of fire control and gun control. An advanced type of rangefinder, the T53 , was fitted to the first three pilots. This rangefinder, better known as OPTAR (Optical Tracing Acquisition and Ranging) was the forerunner of today' s laser rangefinders, but instead of a laser it used a non-coherent pulsed beam of light which tended to scatter and thus gave too many false readings , and was only accurate to 2,000yd. It looked like a small searchlight on the right side of the turret. A more conventional rangefinder featured in later pilots . Other T95 models used turrets from other tanks , such as the M48 , T54E2 and T96. The developmental engine for the T95 was cryptically known as the 'X-engine', possibly because the cylinders were arranged in a cross. An engine designated AX-880 was under development at that time. Whatever the history of the X-engine, early pilots of the T95 were built with the AOI-1195 engine installed . Another model tested the 1,I00hp Solar Saturn gas turbine , and in the T95E8 a commercial diesel engine was installed. The T95 was also used as a testbed for different running gear components. Five large (32in (81 cm) diameter) wheels were fitted, suspended on torsion bars . The suspension was referred to as . flat-track' , me aning that return rollers were not fitted. !\'lany different de signs of road wheels and trac k we re tried . includ ing a trac k manufactured in titani um . Yet another farsighted

~eady

(-T

- : ­ - ,:':<::5 o f hull ':: ~:n I at 20

0

) rear

: ,' :1

so me later

gross

H

if

t

Above: A Solar Saturn gas turbine was ins.lalled in a T9S tank and here is shown on display at the Pentagon in March 1961. US Army Left and below left: These two photographs show the T9S's hydropneumatic suspension ' kneeling' . The hull will not go any lower because the driver's seat is in a bulge in the hull noor in order to achieve a lower silhouette when closed down, yet still retaining the driver's seated position. The semi-supine position of Chieftain was tried and rejected. US Army Above right: This T9S lank has been heavily modified to accept a sophisticated hydropneumatic suspension system and relains the single pin track of the T9S. The turret is a developmenlal model from the M60A2 programme, but the tank shown here does not have a model number. National Warer Life Company Right: Another view of the T9S, this time with different roadwheels. US AmlY

innovation hydropneu nc ::....= the tank ' 5 a:-.::­ The T96 [ 0 - , is , it would ~ _ _ within a \\ c:::-­ generated b~ ::-<7 T96 , and i fabricated ...\ :.:

· the T95, this '.. beels.

innovation was the experimental installation of a hydropneumatic suspension, which allowed control of the tank's attitude. The T96 tank was seen as an interim 'heavy' tank - that is, it would be able to mount a larger gun than the T95 within a weight limit of 45ton. The intense interest generated by the T95 programme somewhat eclipsed the T96, and it was abandoned before a pilot could be fabricated. A few turrets were built and used to explore

the mounting of the 120mm gun on the T95.In a way, the fate of the T96 had depended on the success of its I05mm smoothbore gun and its 'arrow shot'. This round, which would today be known as a ' long rod penetrator' , was fired from the T210 gu n at a very high velocity , but in 1958 the required performance was beyond the state of the art. The T95 programme is widely regarded as a failure . It ran from 1954 until 1961 and consumed $26.6million in

107

the process. However, gas turbine engines, hydrogas suspensions, smoothbore guns and laser rangefinders are now commonplace features of main battle tanks. The T235 series of self propelled artillery which led to the M107 and MilO was based on a chassis which drew heavily on experience with the T95 , and the T95 was also used as the basis of the TI18 combat engineer vehicle, leading directly into the M728 based on the M60Al. So although no tank entered service as a result of the T95 programme , nearly every aspect of current main battle tanks owes something to the T95 . Right: T95 showing OPT AR rangefinder in open position. US Army

'1

Below right and bottom right: Two views ofthe T118 Combat Engineer Vehicle, taken at Fort Benning in April 1960. The Tll8 was hased on the T95 tank but its equipment was derived from the MI02 combat engineer vehicle. US Army

THO 120mm Gun T ank Crew: 5 Weight: c90,OOOlb (400kN) combat loaded Length: c32ft 6in (9. 9m) overall c22ft 6in (6.86m) hull only Width: II ft 3in (3 .43m) Height: estimates vary between 8ft 2 .5in (2.5m) and 9ft 7in(2.92m) G/clearance: 1ft 5in (O.43m) but 1ft 2 .5in (O.37 m) under driver's bulge

Armameo: with 15: : ~ :=­ elevation Seconda:-:. - :'> (commaL ':: ;"': Ammu ni ' Armour : r:_ (2.5-4:' ~ ::-.

Engine: C : -~

Ordnanct .~. = - (537k\\' ;:-:

Transrni.s.5 :

Suspensio

side

Gross po "' .:-­

Fuel capa :"

battlefiek -:--=-­

Ground pr~

In an a

~ = ::­

firepo \\"c~

: .: 120mm G_ ­ -=­ that the C_-: Although ;-_

almost missile wao _ for the kir:;"' :.:

--

108

~

-

, - and 9ft : :: - :-l

un der

Armament: Main- 120mm TI23 gun in a rigid mount with ISo (left and right) Ira verse and -I 0' to -= 20 c elevation Secondary- .50in M2HB in cupola similarto \148AI (commander's) Ammunition carrled: 120mm - 30 rounds Armour: Hull- cSin (12. 7cm) at 70° front to I-I. 7Sin (2.S-4.Scm) rear Engine: Continental A VI -1790-8, later amended to Ordnance AOI-1490; Gross Power (AOI-1490) nOhp (537kW) gross , S60hp (410kW) net Transmission: 'XTG-SOO Suspension: Torsion bar with six pairs of roadwheels per side Gross power/weigM ratio: 16hp/ton ( I. 34k WIkN) Fuel capacity: 3S0gal (1.324litres) allowing 22.S hours battlefield running Ground pressure: clO.37lb/sq in (71.SkPa) In an attempt to field a vehicle with greater anti-tank firepower but weighing less than the \148 , the TllO 120mm Gun Tank was designed in 19S5 . It was intended that the Chrysler Corporation would be the design parent. Although guided missiles were at this time capable of destroying tanks of any size (the 60lb HESH warhead of the UK Ma.lkara missile could inftict terrifying damage on almost any target , and the HEAT warhead of the Dart missile was a similar proposition), there was still a need for the kinetic energy attack of enemy armour. The most

potent weapon available at the time was the 120mm gun of the MI03 heavy tank . This TI23 gun was to be mounted in a limited traverse and elevation mounting on a modified M48 hull. Nowadays the turretless tank concept makes much of a low silhouette, but the design for the TllO shown in the drawing is only 7in (l7.8cm) lower than the basic M48. The running gear was the same as the M48, but the volume of the hull was enormous because of the five-man crew and the volume swept out by the gun breech inside the hull. The TI23 gun used separated ammunition, requiring two loaders - one for the projectile (typically SOlb (22.7kg» and one for the propelling charge (typically 581b (26.3kg». The overall height was accentuated by the configuration of the power pack at the rear of the tank. The commander's position, and his cupola over the engine added still more to the height. Because the weight was expected to be less than the M48, the 1790 series engine was considered larger than necessary and so the AO 1-1490 engine, mated to the new XTG-SOO transmission, became the intended power pack. The TII0 was shrouded in secrecy as a project in 1955 and abandoned in October 1956 without a piLot being built. Twenty-five years later it remains an enigma. Perhaps the Armor Board realised just how inftexible such a vehicle would be, in time to forestall the prototype. Below: The TlIO with 120mm main gun.

:------------­ ----- OO~~u~-=-= \~~u

i I I I I IL ___ _ _

~-_.~"'--:....•

2. No

Appendices

The sYS[C'= a particu:.;.: .. time the ::C'­ nomenc l2. ~~ nomen c i,,:--~

II

I I: I

J

1. Imperial and SI Units Modern technical usage requires that dimensions and capacities be quoted in the SI (Systeme Internationale d ' Unites) system of units. However, in this book the emphasis has been placed on the original units used, which may also be more familiar. Most dimensions were

originaJly quoted in the fps, or Imperial system, but calibres of guns are now nearly all given in millimetres. The one exception to have continued in use is the cal.50 machine gun (0.5in, or l2.7mm). A comparison of

Imperial and SI units is given below.

Quantity

US unit

Imperial unit

SI unit

Familiar unit ('Metric')

Weight (in SI; Mass)

ton (2,000lb) (8.9kN)

ton (2,240Ib) (9.96kN)

kiloNewton (kJ'\!) (224. 8Ibf) (0. II US ton) (0 . I imp ton)

tonne (T)

(I ,OOOkg)

(2 ,204Ib)

cu in (O.OOOOI64cu m) (0 .0164 litre) Volume

(eg fuel capacity)

gallon (0.00378 m 3) (3.78 I)

gallon (0.00455m 3) (4.55 I)

m (6I ,349in 3) (1,000 I) (I,OOO,000cm 3)

litre (1) (I,OOOcm 3 ) (61.35in 3 (O.OOlmJ)

m3 (220 imp gal) (264 US gal)

litre

(0.22 imp gal)

(0.264 US gal)

Power

horsepower (hp) (0.745kW)

kiloWatt (kW)

(1.34hp)

ft Ib (1.36Nm)

Newton-metre (Nm)

(0 74ft Ib)

Torque

Pressure

pound per square inch (psi) (6.89kPa) (0.07kg/cm2)

110

kiloPascal (kPa) (0.145psi ) (0.3kg/cm2)

=.

obvious c: :. _ more tha c- · intense de·, = _ standardis::-.:: develop m e ~.: -=­

Volume (eg engine capacity) J

The pre ,::;:.· .. letter!\! fc : Modi fi c2.:::::" _ approp ri 2:~ ­ first mo .: :' : ­ design a[:( ~ develop n::: -­ indicate :.::: modific a:::-_ elevent h

kg/cm2

(3.217kPa)

(l4.2psi)

After the ". .;.: ­ T num bc:--; . : ~

2. The US Army Ordnance Nomenclature System

s

The system is officially described thus: '. . To identify a particular design, a model designation is assigned at the time the item is classified as an adopted type. This model nomenclature becomes an essential part of the standard nomenclature and is included in the marking on the item. The present system of model designation consists of the letter M followed by an Arabic numeral , for example MI. Modifications are indicated by adding the letter A and an appropriate Arabic numeral. Thus, M I A I indicates the first modification of an item for which the original model designation was MI. Similarly, a system applied to development items involves the use of a T designation to indicate the basic design and an E to indicate modifications thereof. Thus, T I 08E II would indicate the eleventh modification of a development item originally designated n08.' This system evolved in about 1927 from an earlier convention under which equipment was designated by the letter M , followed by the year of its inception . There were obvious drawbacks , such as the problem of dealing with more than one design per year. The M and T system wa s in use throughout World War 2. During this period of intense development activity it was common for the standardised M numbers to bear no resemblance to the development T number, and this could cause co nfu sion. After the war an attempt was made to relate .\1 numbers to T numbers, but there were stili many discrepan cies.

Finally in the late 1950s yet another change was made . T designations were replaced by XM, and on eventual standardisation of an item the X was simply dropped. Thus the XM60 became the M60. A different method existed for designating engines, since the adoption of standard components in 1946, A series of letters and numerals were used , signifying the type of engine and its capacity. These letters are:

A D II I L M

o

S V X

air cooled diesel possibly a cylinder configuration fuel injection liquid cooled multi-fuel opposed cylinder arrangement supercharged vee cylinder arrangement (but VCR refers to Variable Compression Ratio ) possibly a cylinder co nfig uration

The nu merals indicate the tl al e n f in ~ ': 5=, !:: c ~::-. e .. : :.n cubic inches. This \\ ill nO:o:·.:11: y:-e.'. :-:: ._ ::::o : ~ ~ :' :.:..: C ~ 298. as thest aJl ard : y !j :1':e~5::O: ; ': ~ ~ c::: - .:..:' : .: ~ ~ _: . :

inches. The :1 f S[ e g : ~. o:: ~ ~: ': -: '.::: :-e ~ _-. :0': :.:_: ,:.• was the .-\\'-:-9':1-: . ..::.: .:.. _._ .

.-\ \'DS - : -91: ·: ; ~~ : ' :-= ': .- ::-: \~ : .

-=­

: :7:1: ,

-:-'. gal) : -- .. ~ gal)

-

:. : : -:J'a) - =;si) l ' .

3. 90mm Ammunition

Ammunition for the earlier M3 gun of the M26 and M46 used the M 19 and M27 series cartridge cases. The later 90mm guns had larger chambers and thus ammunition Nature

Model

AP-T

M318AI (T33E7) M82

APC-T I:

HYAP-T

,I

TP-T

:1

HE-T HEAT-T

I:

SMK,WP CNSTR

f

I

APERS-T

M332AI (T67 series) M353 (T225EI) M71Al M431A2 (T300 series) M313 M377 (T22EI5) M580

Length

Weight

in (em) 37.1 (94.2)

Ib (kg) 43.9 (19.9)

38.2 (97.1)

42.75 (19.4)

35.9 (91.2)

developed for the T 119 and Tl39 would not chamber in the M3 gun. The standard rounds for the 90mm M41 gun are shown in this table: Muzzle Ve!oci:y ft/sec (m/sec) 3,000 (912)

Maximum Range yd (m) 21,030 (23,000)

Case

21,400 (19 ,570)

MI9

32 .3 (14.6)

2,600-2,800 (790-850) 3,875 (1 , 180)

15,700 (14 ,350)

M19

36.9 (938)

43.9 (19.9)

2,730 (830)

23,000 (21 ,030)

MI08

37.5 (95.1) 36 (91.4)

39.5 (17.9) 33 (14.9)

2,400 (730) 3,950 (1 ,200)

16,800 (15,360) 8,900 (8,140)

MI9 M1l4

37.4 (95) 34 (86.5)

42 (19.1) 39 .5 (1 7.9)

2,700 (820) 2,800 (850)

18,170 (5 ,540) 402 (366)

MI9 MI08

38 (96 .7)

41 .2 (18.7)

3,000 (914)

4,400 (4 ,810)

M200

MI08

Other rounds included: HYAP, M304 (T30EI6); HEP , TI42 series; HYAPDS, T65, Tl37 series ; HEAT, M348 series (TI08 series); Canister, M336 (T22EI) Dummy, M12.

4. l05mm Ammunition

Nature

Model

APDS-T TPDS-T APFSDS-T TPFSDS-T HEAT-T TP-T* TP-T** HEP-T

M728 M737 :Yl774 XM797 M456 M467 M490 M393 (T383) M494 M416 M457

APERS-T SMK, WP Dummy

Length

Weight

in (em) 33 (83 .8)

Ib (kg) 42.2(19.1)

39 (99) 37 (94) 39 (99)

48 (21.7) 45 (20.4) 45 (20.4) 45 (20.4)

3,850 (1170) 2,400 (730) 3,850 (1170) 2,400 (730)

8,975 (8,200) 10,400 (9,500) 8,975 (8,200) 10,400 (9 ,500)

M148AIBI MI50BI MI48AIBI MI50

39 .2(99.6) 37 (94) 37 (94)

47 .5 (21.5) 45.5 (20 .6) 44 (20)

2,700(820) 2,400(730)

4,810(4,400) 10,400 (9,500)

M150 MI50BI M148

Muzzle Velocity ftlsec (rn/sec)

Maximum Range ft(m)

Case

M115BI

Other rounds include: APDS, M392 series (T382), XM563 , M726; TPDS, M724; HEAT, XM604, XM815; APERS (Beehive) , M380; APFSDS, M735 , XM814, XM833. * TP-T M467 simulates the HEP round ** TP-T M490 simulates the HEAT round

112