RISE & SLEP Upgrades for M103A1/A2?

[Christopher Wang]

Had the M103A1/A2 remained in service until Operation Desert Storm (1991), could it have been modernized with upgrades similar to those featured in the USMC's M60A1 RISE?

The Reliability Improved Selected Equipment or RISE featured the following upgrades:

• Uprated Continental AVDS-1790 engine and transmission;
• Redesigned hull electrical system;
• Top Loading Air Cleaner (TLAC) and Add-On Stabilization (AOS);
• Passive night vision for the gunner and commander;
• Kevlar turret spall liners; and
• Ability to mount explosive reactive armor (ERA).

In addition, perhaps the M103A1/A2 could have also been rearmed with the 120mm M256 smoothbore cannon featured in Raytheon’s M60A3 Service Life Extension Program or SLEP. Unlike the M103A1/A2’s M58 rifled cannon which fired two-piece ammunition and thus required two loaders, the M256 smoothbore cannon fires one-piece ammunition which requires only one loader. By eliminating the need for a second loader, perhaps the upgraded M103A1/A2 could have its crew reduced from five to four and thus free up space for more ammunition or equipment.

SLEP also featured the following upgrades:

• Raytheon Integrated Fire Control System (IFCS) integrating an eye safe laser rangefinder, second generation gunner's night sight, digital ballistic computer, cant sensors, a fully electrical superelevation resolver and a MIL-STD 1553 data bus;
• Curtis-Wright Gun Turret Drive;
• Upgraded AVCR-1790-2C engine producing 950 hp and improved hydropneumatic suspension;
• Automatic Fire and Explosion Sensing and Suppressing system (AFSS); and
• Upgraded armor protection with STANAG 4569 Level 6 protection plates to the frontal arc and side skirts and slat armor added to the bustle.

Another possibility is replacing the M103A1/A2’s turret with that of the M60 or M1 Abrams. As detailed in the American Fighting Vehicle Database ( http://afvdb.50megs.com/ ), the M103, M60, and M1 shared the same turret ring diameter of 85.0 inches / 215.9 centimeters. Perhaps with some modifications, it could have been technically feasible to outfit the M103A1/A2 hull with the M60 or M1 Abrams turret.

Thus, could it have been technically feasible to upgrade the M103A1/A2 with RISE and SLEP as was done with the M60?

 

[Kat Tsun]

M103 was literally just a worse M60A1 so I don't see why not?

 

[Christopher Wang]

Since the M103 shares the same turret ring diameter (85.0 inches / 215.9 centimeter) as the M60 and M1 as shown in the American Fighting Vehicle Database ( http://afvdb.50megs.com/ ), is it possible to replace the M103's four-man turret (Commander, Gunner, & 2 Loaders) with the M60 SLEP's or M1 Abrams' three-man turret (Commander, Gunner, & Loader) carrying the 120-mm M256 smoothbore cannon?

 

[isayyo2]

You're proposing putting an Abrams turret on essentially a lengthened M48 chassis, the turret alone of an M1A1HA is north of 25 tons...

If you want to give the M103 a chance to live anywhere close to 1990, I would dump them all on Israel during Operation Nickel Grass and bring up to a M60A1 RISE equivalency. The Israelis can go further by adding a laser range finder and slapping Blazer ERA over its thing armor.

 

[Elan Vital]

You're proposing putting an Abrams turret on essentially a lengthened M48 chassis, the turret alone of an M1A1HA is north of 25 tons...

It worked just fine on M60 chassis and M103 turret is already superheavy, so no issue with such conversions, though pretty pointless when you can get entire M60A1s or M1s that were produced in huge numbers.

M103 and to a certain extent Conqueror both proved fairly pointless/underwhelming/dead-ended. Their very low production numbers and high weight made them expensive and problematic from a maintenance and logistics standpoint. Their conservative gun design meant they became outdated almost as soon as they entered service from a firepower standpoint (with a successor to the 20pdr even being considered for the 1954 medium tank before Korea on the British side). HEAT and APDS both were more efficient ammo designs than AP (US side only) and allower smaller and lighter guns equivalent to the 120s.

By the time M103A1 was even ready (the true service version), the US had the option to build better successors or sidegrades like the T54E2 medium tank. The US in particular would have been better off ramping up R&D work on 105 guns and APDS and producing more M48s instead of M103. Luckily the Army itself only adopted a few for a few years before giving them to the Marines.

 

[isayyo2]

It worked just fine on M60 chassis and M103 turret is already superheavy, so no issue with such conversions, though pretty pointless when you can get entire M60A1s or M1s that were produced in huge numbers.

From an age prospective, I would worry about 30+ year old hulls cracking from the weight of the new turret. Asides from that we seem to agree on everything

 

[T. A. Gardner]

The M103A2 got the Continental AVDS 1790-2A engine and new rear deck like the M60 did. It also got fire controls about equivalent to those on the M60A1 along with improved turret controls. As for the 120mm that it mounted, that fired HEAT and HE almost exclusively. There was an AP shot round, the M385, but it was rarely carried or used.

Given that it would be a bigger, heavier, and somewhat slower tank that numbered less than 200 vehicles in service, I'd say it isn't worth the effort and the resulting differences in parts and maintenance required to keep it in service.

 

[isayyo2]

Given that it would be a bigger, heavier, and somewhat slower tank that numbered less than 200 vehicles in service, I'd say it isn't worth the effort and the resulting differences in parts and maintenance required to keep it in service.

Asides from the hull itself, were the road wheels and track also unique to the M103?

I've always viewed it as a larger, slower M48 that still had a great deal on commonality with the Patton series.

 

[Christopher Wang]

You're proposing putting an Abrams turret on essentially a lengthened M48 chassis, the turret alone of an M1A1HA is north of 25 tons...

It worked just fine on M60 chassis and M103 turret is already superheavy, so no issue with such conversions, though pretty pointless when you can get entire M60A1s or M1s that were produced in huge numbers.

M103 and to a certain extent Conqueror both proved fairly pointless/underwhelming/dead-ended. Their very low production numbers and high weight made them expensive and problematic from a maintenance and logistics standpoint. Their conservative gun design meant they became outdated almost as soon as they entered service from a firepower standpoint (with a successor to the 20pdr even being considered for the 1954 medium tank before Korea on the British side). HEAT and APDS both were more efficient ammo designs than AP (US side only) and allower smaller and lighter guns equivalent to the 120s.

By the time M103A1 was even ready (the true service version), the US had the option to build better successors or sidegrades like the T54E2 medium tank. The US in particular would have been better off ramping up R&D work on 105 guns and APDS and producing more M48s instead of M103. Luckily the Army itself only adopted a few for a few years before giving them to the Marines.

The M103A2 got the Continental AVDS 1790-2A engine and new rear deck like the M60 did. It also got fire controls about equivalent to those on the M60A1 along with improved turret controls. As for the 120mm that it mounted, that fired HEAT and HE almost exclusively. There was an AP shot round, the M385, but it was rarely carried or used.

Given that it would be a bigger, heavier, and somewhat slower tank that numbered less than 200 vehicles in service, I'd say it isn't worth the effort and the resulting differences in parts and maintenance required to keep it in service.

The question is not whether it is practical or necessary to keep the M103 in service.

Since the M103 shares the same turret ring diameter (85.0-in / 215.9-cm) as the M60 and M1, is it possible to put the turret of the M60 SLEP or M1 Abrams onto the M103's hull?

 

[Scott Kenny]

The question is not whether it is practical or necessary to keep the M103 in service.

Since the M103 shares the same turret ring diameter (85.0-in / 215.9-cm) as the M60 and M1, is it possible to put the turret of the M60 SLEP or M1 Abrams onto the M103's hull?

Theoretically.

I'd sooner put all the SLEP, RISE and TTS parts into the M103 turret, maybe along with the M256 smoothbore. Give the Marines a 120mm instead of the 105s they were stuck with.

 

[KonTim]

M103 was a Heavy Tank (comparable of Soviet T-10) armed with 120mm smoothbore gun, the moment that MBT of its era (M47-M48) were armed with 90 guns. A modernized M103 should be armed with a 152/155 mm gun in order to maintain its "heavy tank" designation.

 

[Scott Kenny]

M103 was a Heavy Tank (comparable of Soviet T-10) armed with 120mm smoothbore gun, the moment that MBT of its era (M47-M48) were armed with 90 guns. A modernized M103 should be armed with a 152/155 mm gun in order to maintain its "heavy tank" designation.

120mm Rifled gun, but yes.

Problem with going to bigger bore guns is a lack of AT rounds unless you tried using the MGM-51 gun/launcher from the M60A2 and MBT70. And the MGM-51 system did NOT work well at all.

So the best bet would be to stick an M256 smoothbore into the existing turret. Still a step up from the 105mm the USMC had in their M60s.

 

[KonTim]

120mm Rifled gun, but yes.

Problem with going to bigger bore guns is a lack of AT rounds unless you tried using the MGM-51 gun/launcher from the M60A2 and MBT70. And the MGM-51 system did NOT work well at all.

So the best bet would be to stick an M256 smoothbore into the existing turret. Still a step up from the 105mm the USMC had in their M60s.

You are right, 120mm rifled gun, my fault. Is there any technical difficulty in developing 155mm AT rounds???

 

[Scott Kenny]

You are right, 120mm rifled gun, my fault. Is there any technical difficulty in developing 155mm AT rounds???

A 155mm smoothbore gun wouldn't be particularly difficult to machine (easier than a rifled gun tube), the challenge is figuring out the ammunition.

155mm artillery guns are completely different from most tank guns. Only the British use separate loading projectile and propellant for their 120mm rifled gun, everyone else uses a single combustible-cased projectile.

155mm tank guns would very likely require an autoloader, even for separate loading ammunition, just due to the weight. Separate loading ammunition places a limit on the length of the projectile as well as complicating the propellant setup. Usually a sabot penetrator goes very deep into the case so that there is propellant wrapped around the outside of the penetrator, and the fin end of the penetrator is more or less right at the end of the primer tube that ignites the center of the propellant charge instead of just the end of the charge. On the 120mm NATO, the part of the propellant that could be loaded separately is only about 10"/255mm long!

Getting the combustible case figured out took a long time. The MGM-51 had a terrible reputation for incomplete combustion, swelling due to humidity, and even having the case rupture. It took at least another decade after the MGM-51 to get the Rhinemetall 120mm combustible case working better, and even it is still rather fragile.

Also, the 120mm M256 was capable of defeating any tank of the time frontally, so there just wasn't much demand for a bigger gun at the time (late 1970s).