Thursday 23 May 2019

Great Minds Think Alike

The British were questioning the value of a hull machinegun by 1943. The gun was hard to operate and seemed to offer little actual benefit in combat. It did, however, significantly weaken the tank's armour. By 1944 the Soviets had relegated their hull MGs to fixed mounts operated by the driver, but the main drawback still remained.



"To: Deputy People's Commissar of Tank Production of the USSR, comrade Zernov
CC: GBTU TU Chief, Major General comrade Afonin

RE: hull machinegun on the IS-2 tank

Orders ##158ss and 244ss request the improvement of the front hull armour. This was done by straightening the hull front, increasing the thickness and slope of the front of the turret platform.

However, with the increase of the angle of the turret platform, the opening for the hull machinegun is stretched out. As a result, the right side armour is split (see attachment). Instead of being reinforced, this wall can be considered weakened.

Considering that the design of the machinegun does not allow for aimed fire, we are of the opinion that the presence of this machinegun does not justify the weakening of the hull that it creates.

We consider it necessary to get rid of the machinegun.

Chief Engineer of Factory #200, Nitsenko."

16 comments:

  1. No question. The Soviets were at least 10 years ahead of America on the hull machine gun dogma . To be fair American bow gunners tended to have superior optics which enabled bow guns to have at least a little effect in close in battles. In battles in Korea this helped a little.

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    1. To be fair the US military (or rather the Army I guess) had nothing short of a massive irrational fetish for tank MGs that lasted well into the early Cold War era. It's rather telling that they were still cheerfully designing Old Skool bow MG blisters - with due demerits on glacis geometry as WoT players also noted long ago - at a time when pretty much everybody else had abandoned the entire concept outright or reduced it to the bare minimum of fixed mounts either fully external or with only small openings for the muzzle (and even that didn't last long, looking at the successive T-54/55 models).

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    2. Not a lot of infantry attacking tanks in WoTs is there?
      Sure in tank on tank combat you don't want the weak point of a MG blister.

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    3. Indeed I'm a little surprised that it took so long to reach the obvious solution. Two machine guns mounted on top of the turret with ergonomic mounts and good shields. This way the bow and turret front are well armored, and the vehicle can engage infantry from all directions simultaneously. By the way. I drove one of those T-54s with the little hole for a bow machine gun. The machine gun wasn't there, but I couldn't help but notice that the hole was very small, and I would be worried that all the rounds fired, went cleanly through the little hole.

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    4. Mobius is correct about WoT and War Thunder and how tank gaming distorts ideas on how tanks actually are used in combat; WWII tanks historically actually shot more rounds at things-not-tanks than they do other AFV.

      However, the decision was correct as William Sager notes. With the IS-series, as I've posted, their offensive role usually consisted of them providing overwatch fire from long range behind the advancing attacking units--so no use for a machine there. However, some IS tanks could be selected to also follow the T-34s and infantry into the penetration, so there a MG makes more sense--but as a turret-topped MG can fire in all directions. Besides infantry trying to take out the tank will try to do so from the sides/rear, not the front anyways, so the hull MG won't stop that. All the IS tanks lost in the Berlin operation that Peter posted an article about were taken out by side or rear shots, there were no frontal takeouts at all. The unfortunate crews probably never saw the enemy that hit them.

      Short summary is--the best solution for everyone is to have friendly infantry accompanying the tanks when facing enemy infantry. Even a turret-top MG like William Sager describes is not an ideal substitute. However, in war, you while you try to devise an 'ideal' doctrine/solution you also try to design your weapon systems to at least survive or make do when conditions are far less ideal.

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    5. Generally, in my opinion T-34 tank show what (un)important is bow MG which was operated by bow gunner- T-34-85 tanks in postwar Poland was used with... 4 man crews. 3 tankers inside turret, driver in hull, bow MG as fixed MG and additional ammo rack on former bow gunner position. I found information that also Yugo M47 tanks was used with 4 man crews (additional ammo instead bow gunner).

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    6. The point about the WoT reference is how players figured out real quick that the MG blisters compromise armour slope something fierce, even when they're sufficiently massive that they're not straight up weakpoints. And last I played to my knowledge the game didn't even model edge effects which are a further strike against bow MGs (or any holes whatsoever in the main armour belt for that matter) IRL.

      As for infantry, well, it was kind of the point that bow MGs proved to be rather useless against those in practice and *certainly* not worth either the protection penalty from the unavoidable compromises in frontal plate geometry and edge effects or the volume ergo mass penalty of a crew position to actually operate the damn thing, especially as technical progress rendered both assistant driver and dedicated radio operator roles unnecessary dead weight.
      Fixed-mount MGs operated by the driver probably had more or less the same practical combat effect (ie. inaccurate suppressive fire) for altogether fewer penalties and even those were soon enough ditched as pointless. The sum of practical experience worldwide pretty much seems to boil down to vehicular MGs only being actually worthwhile in main-gun co-ax and flexible roof mountings.

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    7. Kellomies and others,

      The point about the WoT reference is how players figured out real quick that the MG blisters compromise armour slope something fierce, even when they're sufficiently massive that they're not straight up weakpoints.

      I have been playing around trying to figure out how Livingston and Bird calculated the hit probabilities they cite for the angle of impact on the Panther's rounded mantlet, for I can't reason how they (or someone else) arrived at them--for a hemicircle, the median angle would be 45 degrees, and if you throw out all hits > ́80 degrees as skim-offs then it becomes 40 degrees, for instance. They cite both long-range and short-range probabilities, and I can't fathom them, they almost seem reversed (the median impact angle drops for longer range hits, when I would think for short-ranges that would be the case because the flatter areas could be targeted).

      Anyways, this drove me to look up accuracy data on guns that Peter has posted here. What I conclude is that at 1000 meters, the test firing range accuracy of most guns is about on par with the size of the Panther's mantlet, at least height-wise, which means, "nope, it's a fools errand to believe you can target the flatter central area at 1000 meters". Mind you, these are *test range* accuracy results; the accuracy in actual combat would be worse.

      Given the fact that the Panther's mantlet is far bigger than any MG blister--does WoT and War Thunder really drive players to believe they can accurately target such dinky little things? Seems to be that it's a matter of dumb good luck or bad luck if they are hit.

      (I have never played either game).

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    8. Millan Kellomies In real world conditions you can not target any specific part of a tank at a 1000 yards, so you aim center mass hoping your laser got the right range and the wind speed is the same all the way to the target. And at closer range one generally panics and is more concerned with just getting off the first shot, because at close range, any hit will penetrate in most modern tanks. And yes bow guns are of little use. But when you sit down front in the driver seat, there is a frustrating sense of being by yourself. Practical or not, just being able to spray bullets directly in front of you feels comforting.

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    9. The point being that you're creating a weak point in what's just about the most important part of the vehicle to protect to the max for, essentially, no purpose given the highly dubious practical utility of bow MGs. Real tank combat ranges are something very different from WoT obviously but it's a given that already by random dispersion an enemy shell WILL sooner or later end up in a place where the protection compromises from the bow MG blister and opening matter.

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    10. I'm not talking about a real bow machine gun. Just something mounted on top near the drivers hatch which sprays almost any type of bullets directly in front of the tank. Something to give the driver comfort. It's not easy driving all night in the dark across country.

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    11. If you want a tank with fixed machineguns take a look at the Chieftain's video of the IS-7. https://www.youtube.com/watch?v=Hoecf7ovrRM
      This is festooned with them.

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    12. As already mentioned even those minimum-profile fixed-forward MGs operated by the driver were abandoned quickly enough as pointless. And, not to put too fine a point on it, the driver's peace of mind is a *terribly* irrelevant design concern and should it hinge on the presence of such functionally useless gadgets that in practice do little but waste ammunition it's probably a high time to review your training curriculum.
      Particularly the parts that deal with mentally preparing troops for the stresses of combat.

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  2. I have a question about tank MGs. Do HMG mount on Sherman tank turret can be used by commander without exiting from turret? I think that usage of HMG mount on Sherman tank turret can be problematic without exiting, especially if we discuss about M4s with "commander vision cupola". In earlier tank, with "commander cupola" (rotating hatch system) maybe usage of HMG can be less problematic (in this system HMG mount can be rotated in relative to commander station).

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    1. I suspect different groups were fighting over priorities in regards to the pintle mount for the HMG on Sherman tanks. No doubt we were just learning the importance of good vision blocks. But America also had a fascination with mounting a lot of machine guns on our tanks, which combined with early fears of enemy aircraft drove us to put a HMG on our tanks. Except it's hard to build a proper ring strong enough to mount a .50 cal. that that doesn't block the commanders vision blocks and doesn't sit up so high that one can easily get in and out of the hatch. So most likely they just put a pintle mount behind the hatch which could only basically be used by standing behind the turret.

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  3. Killomics You are correct. Even during regular training we tended to just break up our Armored Battalion into Company sized units and train against each other. When Gen Abrams was first shown the tank which bore his name the crew proudly tore around a gunnery course and blasting away the targets and getting back in about 15 minutes. So Abrams took the tank out again with him in charge and showed the men how to survive. Abrams showed them things like getting out and looking around corners first, or spraying machine guns into nearby tree lines as they drive by. It took around two hours, but he gave them a great instruction of why we lost so few men in WW 2.

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