Shaped charge ammo

[Pirate-Drakk]

Originally Posted by The Land

If the question is "Why weren't HEAT tank rounds used in World War 2?", then I think the answer lies in the balance between calibre and muzzle velocity.

HEAT was the AT round used for the 105 mm armed American Shermans and the 105 mm armed German StG's.

The thin Schurzen plates and wire meshes used on German tanks later in WWII was effective at causing predetonation of HEAT rounds from all sources.

In the German attack on Eben Emael in 1940, very large shape charge explosives were used to destroy case mates and and other gun enclosures on the fort.

[The Land]

Originally Posted by Pirate-Drakk

HEAT was the AT round used for the 105 mm armed American Shermans and the 105 mm armed German StG's.

Great. This also fits with my hypothesis that the reason it wasn't used for 75mm rounds was that the rounds were too small for it to be effective.

[17thfabn]

The U.S. Army in World War II issued HE.A.T. projectiles (shaped charges) in:
75mm pack howitzer
M2 105mm howitzer (standard howitzer)
M3 105mm infantry howitzers (short barreled howitzer used by regimental cannon companies).

Of course the howitzers fired at a lower velocity than the tank guns. The H.E.A.T. projectiles seem to have been a last ditch defensive weapon against tanks.

I don't know how effective these H.E.A.T. projectiles were. I vaguely remember that there is a rule of thumb that shaped charges would penetrate 1.5 to 2 X the diameter of the war head. These numbers are much better in modern shaped charge weapons.

[17thfabn]

The German and American 120mm tank guns have H.E.A.T. projectiles. This gun developed by the Germans is smooth bore.

The British with there rifled 120mm tank gun don't seem to have a H.E.A.T. projectile, but use a "squash head" projectile instead.

One big advantage of H.E.A.T. projectiles is they are not effected by range. And the newer rounds with multiple settings have some anti-personnel use.

[17thfabn]

The German and American 120mm tank guns have H.E.A.T. projectiles. This gun developed by the Germans is smooth bore.

The British with there rifled 120mm tank gun don't seem to have a H.E.A.T. projectile, but use a "squash head" projectile instead.

One big advantage of H.E.A.T. projectiles is they are not effected by range. And the newer rounds with multiple settings have some anti-personnel use.

[nikolas93TS]

Take in consideration that those early rounds were quite primitive.Effects of rotation on HEAT,due to rifled barrels at elevated speeds,was indeed a major problem,probably more than caliber itself.Germans had HEAT rounds for 75mm guns,in particular short L24 used them.However sacrificing better and more economical AP rounds was not justified when barrels got longer.

In those early rounds,even with then available fastest reacting explosives,rotation dispersed the "jet stream" of HEAT round.In rifled guns,faster velocity (positive for AP rounds,and giving greater ranges due to better round stability) meant HEAT was useless.That is why HEAT rounds were fired at such low velocities. If they were fired faster, they would spin faster, annulling their effect.Germans tried to remedy later in war,with modification to HEAT rounds, trying to make the jet thicker ,or implementing bearings,something French tried as well after the war.

The thin Schurzen plates and wire meshes used on German tanks later in WWII was effective at causing predetonation of HEAT rounds from all sources.

Ironically,what was side effect.Schurzen was implemented as additional protection against Soviet AT rifles.

[llkinak]

Originally Posted by The Land

Great. This also fits with my hypothesis that the reason it wasn't used for 75mm rounds was that the rounds were too small for it to be effective.

If I remember right, and I may not, the German 75mm HEAT round for the L24 armed Panzer IVs could penetrate somthing like 90-95mm of armor. It was much harder to hit something with it, however, due to the low velocity and high trajectory.

[Bwaha]

The latest in the development of the shaped charge...

http://en.wikipedia.org/wiki/Explosi...sion_generator

[GCoyote]

I've seen a version that uses a plate charge to compress a high-current coil but not one that uses a shaped charge. It wasn't clear from the article but if you look at the fusing in the last diagram, the explosive isn't laid out to form a jet, but rather to compress the hollow copper shells into a series of flat disks. Still really interesting though and very cool.

[mfitz]

Originally Posted by kuma

The US knew the benefits of shaped charge warheads in benefiting tank armor early on nd the bazooka was born. I'm not aware of any shaped charge ammo being developed for use by tank cannon though. If true, it makes,me,wonder why as this wouod appear to be a significant oversight as they would have helped Allied tanks take out their more heavily armored German tanks,like the Tiger.

The fundamental problem was that firing a HEAT round from a rifled barrel significantly reduced its performance and the technology to fin stabilize rounds from a rifled barrel wasn't there yet.

The German's of course developed a HEAT round for the French Mle 1897 when they converted them to PAK 97/38's and 97/40's. This gun fired fundamentally the same 75x350 ammunition as the 75mm gun on the American M3 and M4 medium tanks, M3 half-track GMC and M24 light tank. The Germans developed HEAT rounds though not so much because they were better than AP but to overcome the problems the light carriage had firing the higher velocity AP ammo.

So yes, the American's could have developed a HEAT round for this series of guns and presumably it should have had similar performance to the German weapon. In fact the 75mm M1 pack howitzer, which fired the same projectiles as the M3 tank gun but from a shorter 272mm case did have a HEAT round, the M66 and this could easily have been fitted to the 350mm tank gun case. However, the only mention of its performance I have ever seen was in an army manual which listed a penetration of 3 inches (76mm). Hardly an improvement over the existing M72 AP ammo which could do about the same at 500 yards which would probably have been about the effective range of a HEAT round.

The German's when they fielded the 8H63 anti-tank gun in 1945 designed specifically to fire HEAT ammunition made it a smoothbore precisely because fin-stabilization offered much improved penetration performance. This is also why the Bazooka was so much more effective against armor than the M18 57mm recoilless rifle. With the recoilless rifles M18 and M20 I think the American's made a mistake. They should have been smoothbore weapons in 60 and 81.4mm calibers respectively instead of rifled 57mm and 75mm. They would have had much longer post-war careers as anti-armor weapons that way. The 75mm M20 firing HEAT was credited with about 4 inches of armor penetration where the Soviet post-war 82mm smoothbore recoilless gun firing fin-stablized HEAT was credited with 250mm or almost 10 inches.

For the 75mm M3 tank gun I think HESH rather than HEAT offers more attractive possibilities but then HESH doesn't really catch on until just after the war is over.

Hindsight is always 20/20.

[dutched]

Originally Posted by Pirate-Drakk

HEAT was the AT round used for the 105 mm armed American Shermans and the 105 mm armed German StG's.

The thin Schurzen plates and wire meshes used on German tanks later in WWII was effective at causing predetonation of HEAT rounds from all sources.

In the German attack on Eben Emael in 1940, very large shape charge explosives were used to destroy case mates and and other gun enclosures on the fort.

True, but Zuenderanspechung (Pre-detonation)did not stop Durchschlag (penetration) of the main armour.
The Schuerzen themselves were ineffective

Stand off armour is only effective if the gap between the stand off sheet and the main armour is large enough.
This safe distance depends on the diametre of the mirror of the projectile. The Germans tested shaped charged rpg Panzerfaust, against a variety of stand off materials such as mild steel sheet, wood, steel wire mesh and even burlap.
De facto: it did not make a blind bit of a difference. Durchschlag (penetration) was achieved.

The shaped charges used at Eben had legs on them to create a stand off distance making the charge more effective!!!!!!!!!
However because of the domed shape of the gun cupolas of the fortress
the legs made the charges slide off. Thus the charges were placed on the gun cupolas without extending the stand off legs.

Ed.

[NagaSadow]

I am currently reading Rainer Karlsch's book about the various German atomic bomb programs and therein is a chapter about the development of shaped charge weapons.
He mentions some interesting things.
The first anti-tank weapon for the Wehrmacht using HEAT rounds was proposed in 1935 by Franz Rudolf Thomanek, the "7-cm-Tankgewehr".
Perhaps the single most important breakthrough was achieved during the war, when Hubert Schardin and Max Steenbeck developed X-ray flash tubes that were capable of taking more than 45.000 pictures per second, thereby making it possible for the first time to fully study and understand what happens if a shaped charge hits an armor plate.