Alternative light and anti-tank guns, 1935-45 (1 Viewer)

[bf109xxl]

Quirk with this system is that one still uses the off-the-shelf ammo.
RT-20 was supposedly doing 850 m/s, despite the short barrel and the divertion of small % of the gasses.

I understand why it was necessary to complicate the design in this particular case (for use of standard large caliber ammunition), but with AT guns, why? Artillerymen will have to either jump into a trench or run a decent distance away from the gun every time it is fired.
If the percentage of gases used is low, there will be no large effect of recoil reduction. Conservation of momentum law. The Soviets played around with recoilless guns before the war, realizing that they require a lot more powder. And I'm not sure these tricks are even possible with caliber above 30mm.

 

[marathag]

But the Germans used heterogeneous armor with a medium hardness backside, and the Soviets used medium hardness armor (42SM, 52S) after the war.

British weren't able to examine newer armor from the USSR before the choice was made to deply all the various *BAT HESH tossing recoilless guns.
And turned out to be effective all the same, until the new Composite Armor designs were introduced

2nd, HESH could be fired thru rifled tubes, without effecting the warheads effectiveness, unlike HEAT.

 

[ThomasP]

Also, HESH did double duty as a HE round and was used as such - eliminating the need to carry an additional type of ammunition.

The countries that adopted HEAT rounds either carried dedicated HE rounds in addition to the APDS and HEAT - or developed HEAT/MP rounds to be used as a bit sub-par HEAT and HE.

 

[yosimitesam]

I'm still studying armor penetration - trying to understand how much the caliber of the projectile mattered, and how much the design of the projectile mattered for different types of armor and different thickness. Soviets used homogeneous armor of high (or very) hardness, even late cast Soviet armor was high hardness, Germans used heterogeneous armor (with rare exceptions at the end of the war), Americans used medium to low hardness armor with a high proportion of cast parts, etc. In some cases APCR was optimal, somewhere only a high hardness cap was sufficient. In addition to armor properties, the ratio of core size and armor thickness mattered. All this is time-consuming, but I still want to get some kind of overview for myself.
Some of the things that came across during my research: scans of Soviet reports (terrible quality, unfortunately) on tests in early 1942 of 45mm APCR with different core materials and different projectile design, but the same geometry for each core material (tungsten carbide or high-hardness steel). It turned out that I was wrong: steel cores demonstrated much worse armor penetration and were never mass-produced - they were even banned from further testing.
A projectile with a more massive core had higher armor penetration but worse accuracy and was rejected.
When German shells were fired from a Soviet 37mm anti-tank gun in 1941, the armor penetration was superior not only to the original Soviet shells but also to that of Soviet 45mm shells.

Armor penetration is a subject so complex that even different modern computer models can't always agree on results. A projectile moving at 2500f/s and penetrating 4-in of armor all happens in 13 MICRO-seconds (.00013 sec, or thereabouts.) Macroscopic (Newtonian) things happening in this short amount of time can give results that are almost impossible to predict with certainty. There's shock waves bouncing around, melting of both the projectile and target due to kinetic energy transforming into to thermal engergy, unequal forces on the projectile and target, etc. There are numerous "formulas" for amor penetration that can be modeled (PRODAS, Thompson, Lambert-Zukas, etc.) and all their outputs will vary with different materials on both the target and projectile. The best you can do is predicting "roughly" what will happen, or should happen. Google a copy of AD1045347 (PDF, 2018) for information on the WWII 76mm Sherman tank gun vs Tiger/Panther using modern "computer models" to get an idea for how complex this subject is. Hat's off to you, though. Your studying this subject is highly admirable, and "you will never have to prove your courage to me in any other way." Post anything interesting you find (or calculate.)