Monday, 31 January 2022

Patton's Growing Pains

The US Army received the M48A5 tank in the early 1970s. This index represented earlier tanks, chiefly the M48A3, upgraded to match the characteristics of the M60. The modernization consisted of installing a 105 mm gun, new fire control systems, new engine, improved cruising range, etc. Large scale modernization began in 1975 and touched about 2100 tanks. However, there were earlier attempts to modernize the M48 to the M60 standard, attempts that will be covered in this article.

M48A2 with the T254/X15E8 gun

This tank was never going to go into mass production. It was only used for trials, in this case trials of the new T254 (M68) 105 mm gun. For comparison purposes, the T254 was later replaced with the analogous British X15E8 gun. These trials took place in 1958-1959 during trials of the X15 and T256 guns for the new XM60 tank at the Aberdeen Proving Grounds. The gun barrels were interchangeable.

M48A2 tank with the T254 gun. This gun made 35 shots before it was replaced with the X15E8. Aberdeen Proving Grounds, 1969.
X15E8 (left) and T256 (right).

90 and 120 mm guns mounted in specialized turrets also took place in the trials. The T256 proved to be the best choice. It was sufficiently powerful and comparatively light.

M48A1E1

Artillery Command asked the Ordnance Tank-Automotive Center to develop a project to modernize the M48A1 to the level of the M60 on June 10th, 1959. The new tenk received the designation M48A1E1 on April 21st, 1960.

The tank received the AVDS-1790-2 engine and CD-850-6 transmission, aluminium fuel tanks, and engine deck components from the M60. The gun was replaced with the 105 mm M68. The new tank carried 57 rounds of ammunition for it. The fire control system from the M60 was also installed.

The suspension was also changed. Most components from the M48A1 remained, but it had to be reinforced to make up for the extra weight. Only three return rollers were used instead of five. The tank with ammunition loaded weighed about 48 tons.

Six vehicles were converted in total. #1 was sent to the Aberdeen Proving Grounds in March of 1960. #2 arrived in Fort Knox on April 6th. #3 was used to evaluate the complexity of repairs and maintenance. #4 was sent to the Detroit Tank Arsenal. #5 and #6 were used in 1960-61 for extreme weather trials in Yuma (Arizona), Aberdeen Proving Grounds, and the Arctic.

Trials reports indicated that the M48A1E1 was identical to the M60 in everything except armour and surpassed all production M48 variants in mobility, cruising range, and armament. The report also noted that the M1 commander's cupola needs to be replaced since it was too cramped for installation of new equipment.

The OTAC decided to cut costs in November of 1960 and get rid of the 105 mm gun. The reason was that there was still a large amount of unused 90 mm ammunition in storage and production of 105 mm rounds was limited by the budget. Two M48A1E1 prototypes that were re-armed with 90 mm guns were indexed M48A1E2. After a few minor changes, these tanks were indexed M48A3 (Type A). The tanks converted from the M48A1 to M48A3 still had five return rollers per side.

A new modernization program was enacted on December 7th, 1965. This was essentially a revival of the M48A1E1 program, consisting of installing the M68 gun on the M48A3. Unfortunately, while the financial and bureaucratic aspects of the program were ironed out, all the tanks were either sent to Vietnam or already earmarked for use in that theatre.


Since the war moved into an active phase, all the money allocated for modernization went with it. The $16,772,847  contract with the Bowen-McLaughlin-York company in Pennsylvania was only signed on April 14th, 1967, but by then the 105 mm gun was dropped from the modernization program once more. The M48A1 tanks were only modernized to the M48A3 standard. These tanks were called M48A3 (Type B).

M48A1E3

The M60A1E1/E2 (M60 with a new turret and Shillelagh ATGMs) program began to take off in mid-1965. The Americans expected many turrets with 105 mm guns to free up, and so Chrysler received a contract to develop a project to install the M60 turret on the M48 tank. The project was indexed XM735 in December of 1965. It was decided that both M48A3 and M48A1 chassis would be used. In case of the latter, they were modernized to the M48A3 standard.




The height of the turret ring was increased so that the turret bustle didn't foul the engine deck. New 105 mm ammunition racks were also installed. Two tanks indexed M48A1E3 were built in 1966. The prototypes went through trials in Fort Knox from the fall of 1966 to the fall of 1967.

Initial plans called for conversion of 243 tanks. The new tanks would be called M48A4. However, the amount of M60 tanks converted to use the Shillelagh missiles was drastically reduced, and so the M48A4 program was cancelled in late 1967.

M48A2C with the M68 gun

In early 1966, Israel decided to modernize their M48A1/A2C to the level of the M48A3, as well as add a 105 mm L7/M68 family gun. Chrysler took up this project and presented the modernized M48A2C. The biggest changes involved installation of the M68 gun and new ammunition racks for the 105 mm rounds. It's possible that the M60's fire control system was used as well. The fighting compartment heater was removed, as it was not necessary in hot climates.



Israel liked these changes, and a widespread modernization program began later that year. These tanks were indexed Magach-3. 

It is not known whether or not this vehicle had a new engine or transmission, but Magach tanks had engines and transmissions from the M60: the same AVDS-1790-2 and CDS-850-6 used on the M48A1E1.

M48A5

After analyzing main battle tanks of its potential enemies in the early 1970s, they finally saw that their 90 mm gun was hopelessly obsolete. It was finally decided to re-arm the M48A1, M48A2, and M48A3 with 105 mm guns.


The project was indexed XM736 and later M48A3E1. After standardization in May of 1975, the tank was indexed M48A5. The final vehicle consisted of an M48A1, A2, or A3 tank with a 105 mm M68 gun. A maximum amount of M60A1 components was used to make repairs easier. A later version of the M1 commander's cupola was also installed, among other small changes.

Fve pre-production tanks were delivered in June-July 1975. A contract with the Anniston depot was then signed and the first 500 production tanks were modernized to the M48A5 standard from October 1975 to September 1976.

Results

There were several projects to modernize the M48 tank:
  • M48A2 with the T256 (M68) and X15E8 (L7) 105 mm guns, 1958-1959
  • M48A1E1 with the M68 gun, fire control system, engine, and transmission from the M60, 1960
  • M48A3 (Type B) with the M68 gun, fire control system, engine, and transmission from the M60, 1965
  • M48A1E3 with the turret, engine, and transmission from the M60, 1965-1967
  • M48A2C with the M68 or L7 gun, engine, transmission, and potentially the fire control system from the M60, 1966-1967
  • M48A5 with the M68 gun, fire control system, engine, and transmission from the M60, 1975
It took 15 years between the experimental installation of the M68 gun in the M48 turret and the army receiving these tanks. The M48A1E1 was an M48A5 available in the fall of 1960, but bureaucracy and reduced budgets killed one attempt at the same project after another over the course of 15 years. The military ended up returning to almost the same thing they gave up on 15 years prior.

It's strange that despite the constant threat of war with the USSR the American government was unwilling to pony up for a modernized M48 to obtain a quick and cost effective alternative to the new M60. Interestingly enough, Israel used the American development seven years earlier. The first Magach-3 were essentially the same M48A1E1. Israel continued to modernize these tanks until the end of the 1970s.


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