Tuesday, 30 April 2019

SU-76M Successor Requirements



"Tactical-technical requirements for the design of experimental light SPGs with a rear fighting compartment

A. Main requirements
  1. Type of SPG: tracked, rear fighting compartment
  2. Weight: no more than 25 tons
  3. Crew: 4
  4. Dimensions:
    1. Width: 3000 mm
    2. Height: 2300 mm
    3. Clearance: minimum 450 mm
  5. Protection:
    1. Front armour of the hull, front armour of the casemate, sides of the casemate, and sides of the fighting compartment must be impenetrable to 88 mm guns with a muzzle velocity of 1000 m/s.
    2. Lower side armour of the hull, rear armour of the hull, and rear armour of the fighting compartment must be impenetrable to shells of this gun from ranges over 1000 m.
    3. Roof of the hull and fighting compartment: 30 mm
    4. Floor in the front: 30 mm
    5. Floor in the rear: 20 mm
    6. Protect the SPG from HEAT rounds and grenades
  6. Armament:
    1. Cannon: 85 mm with a muzzle velocity of 900 m/s
    2. 2 coaxial belt-fed machineguns
    3. 2 intermediate machineguns, stowed
    4. 1 flare gun, stowed"
Via Yuri Pasholok.

4 comments:


  1. 1) Front armour of the hull, front armour of the casemate, sides of the casemate, and sides of the fighting compartment must be impenetrable to 88 mm guns with a muzzle velocity of 1000 m/s.

    2) Lower side armour of the hull, rear armour of the hull, and rear armour of the fighting compartment must be impenetrable to shells of this gun from ranges over 1000 m.


    Yikes!! On a vehicle with a 25-tonne weight limit? A bit ambitious, wouldn't you think?

    I suppose from the "85 mm gun, 900 m/s" stipulation this was supposed to be a very well-protected Soviet Nashorn-equivalent? But that's really not a SU-76 successor, the SU-76 was a versatile infantry support vehicle that could be pressed into an anti-tank role when pressed, rather than a dedicated tank killer. Or am I getting something wrong?

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    Replies
    1. Perhaps these specifications are for a tank never produced. Seeing that during the war, the Soviet Union received plenty of good lend lease light tanks better than what Germany used. And after the war their priorities changed and the PT-76 came out which was more flexile. But you are correct. The SU-76 like the M-8 Motor Carriage worked fine as infantry support vehicles.

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    2. True, this SPG was never produced, and I doubt it would be possible to produce a vehicle matching these specifications at all. There were similarly ridiculous requirements for a light tank, and as we see with the PT-76 and ASU-85, the GBTU settled for a more realistic approach.

      The 85 mm D-5 and S-53 were better for infantry support than 76 mm guns due to better HE ammunition, if this high power gun went into production it would be possible to get a good HE round in there as well.

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    3. Agree with the 85 mm vs 76 mm guns on HE performance, but wouldn't the experimental high-velocity 85 mm have a bit worse than the D-5 or S-53? There's no reason to go with the long 85 mm unless you want a tank killer.

      As an infantry support tank, I really liked the SU-122. Larger caliber gun, with much superior HE performance against soft targets, and if called upon for anti-tank service its HE round could take out a Panther or a Tiger at 500 meters (and thus, presumably, less-well protected things like Stugs, Marders, Hetzers, etc). If it would be possible to have made a 'SU-122M' with 75 mm of hull armor similar to the SU-85M and SU-100, then you also have a vehicle that's very well-protected frontally against the ubiquitous 75 mm Pak 40 (again think Stugs, Marders, and Hetzers and similar vehicles it is likely to face).

      Only downside I can think of is the slow rate of fire (I would think more important in an anti-tank role than infantry support, given as a turretless vehicle it would hold back to provide overwatching fire, not right up at the very front) and limited ammo. But the latter is compensated that one hit with a 122 mm round could likely destroy something that it would take several hits with 76 mm rounds.

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