Alternative light and anti-tank guns, 1935-45 (2 Viewers)

[peceed]

Penetration goes up with the square of the speed. 10% more veleocity means 21% more penetration in theory.

According to the de Marre formula, it is more like V^1.4283, or Ek^0.714.

The HEAT round at 4.54kg was fired at 450m/s.
The Pak 40 fired a very similar projectile at 450m/s also.
The 8cm PAW fired a 2.70kg HEAT projectile at 520m/s.

The muzzle velocity of 450 m/s was a limitation caused by rotation.
The PAW600 was limited by the muzzle energy resulting from the gun's mass.

US had tested the T45, a HVAP for the M3 75mm gun.
8.4 lbs/3.8kg projectile at 2870fps/870m/s
116mm penetration at 500 yard with 30 degree plate

Interesting - 1.4MJ of muzzle energy. The cartridge probably had a very shallow bullet seating, therefore a larger amount of powder.

A few posts ago in this thread, I've suggested that the small gas divert tube is added to the small AT gun so the recoil is lowered, since part of the high-speed gasses is pushed backwards. That again means that the whole gun can be lighter due to the lower stress exerted on the weapon. Sorta 10% recoiless gun.

A very stupid idea - introducing the main utility disadvantage of a recoilless weapon (backblast) without tactical advantages (weapon with minimal mass). In addition, it causes a rather significant loss of muzzle energy.

RT-20 was supposedly doing 850 m/s, despite the short barrel and the divertion of small % of the gasses.

Do you believe in fairy tales?
Using the same cartridges as the M55, the rifle achieves the same muzzle velocity with a barrel that is half as long with a gas bleed?
2/3 of the length of the Polsten barrel...

 

[tomo pauk]

A very stupid idea

I wish you all the best.

 

[peceed]

I wish you all the best.

It's nothing personal. Stupid ideas deserve an honest assessment. The lack of feedback deprives you of information when you should have thought twice, making it impossible to improve.
Crazy ideas might work, stupid ones don't.

BTW, flooding the forum with ill-considered ideas is a form of trolling. If you like the game, fine, but expect direct criticism.

 

[peceed]

HESH bypasses the 1st step and goes to the 2nd step, several pounds of metal flying around inside the tank.

But this does not work with any form of composite or space armor. Actual penetration is no greater than ~1.25x caliber.

The higher values mentioned, such as 400mm for 125mm guns, are the equivalent for heavily sloped monolithic steel armor - slope has minimal effect on hesh penetration in absolute terms.

How low might one go and still have a satisfying light AT gun that uses HEAT?

The best candidate is the 37mm SA 18 for obvious reasons, highly developed (by WWII standards) variants could achieve penetration of up to 50mm.
Earlier development of HEAT ammunition would be an excellent alternative to the SA 38, radically improving French AT capabilities.

The pre-war development of shaped charges fired from low-velocity guns would have hampered the development of tank armour, favouring more light and fast machines.

 

[Shortround6]

Are we looking at history sort of how it actually happened or are we getting into the "what if" if they knew in 1938 what they knew in 1943-44 or a 1938-1948 time shift?

Military shaped charges in several countries came about, at least according to most popular history's, when different military's were offered "NEW, Powerful Secret Explosives"
by inventor XX. There seem to have been at least 2 teams running around at about the same time offering pretty much the same spiel, including test demonstrations.
In the stories an astute observer (or more than one) recognized the effect they were witnessing as the old Munro effect from 1888, although the idea was used earlier but trying to use the idea with black powder meant it wasn't very effective.
At any rate the general narrative is that the astute observers either declined the offer or recommended their governments either decline the offered "secret explosive" or offer much less than the asking price. Armies started working on reproducing the observed effects from the demonstrations at their own testing facilities and thus the shaped charge entered service.
Sort of.
British No. 68 Rifle Grenade which entered service in Nov 1940 (?)

When the picture was taken (Home Guard in 1942) the British army was recommending best distance was 50-70 yds and best use was at the rear of a tank after it had passed by.
The 2.5 in diameter bomb was supposed to go through 2in of armor if it hit at a good angle.
There were several reasons for this

Like not enough stand off, a less than optimum cavity diameter to projectile diameter and a less than optimal distribution of the explosive.
The Explosive in the rear corner of the 'cup' doesn't do much for the shaped charge.

The Germans are reported to have used shaped charges by the assault engineers attacking the Belgian fortress but these were large demolition charges and while effective, they may have been skipped over by the anti-tank crowd. Germans later (?) used large shaped charges held by magnets to attack tanks.

This came in different sizes but the 3kg version is considered to have been good for penetrating 140mm of armor (?).
Not a good result for the size of the cone and explosive weight to be copied by a gun designer.
Some the other early German tries did not give great results. First German 75mm shaped charge projectile was good for around 40mm of penetration ?
More in next post.