Fin Stabilised

[motto (RIP)]

I seem to remember hearing/reading somewhere that shaped charge projectiles have limitations on them as regards maximum velocity. They depend on the blast being focused due to the distance from the armour when detonated and if travelling too fast may even be knocked out of shape at the time of detonation. Maybe how squash heads were invented.
As I understand it, delivery systems for shaped charge projectiles tend to be relatively low velocity.

David

[Mike Cecil]

Dave,

MV of rounds fired from an L7A3 105mm tank main armament (eg Leopard AS1):

L52A2 APDS/T = 1,478 m/s
L35A2 HESH/T = 732 m/s
M456A1 HEAT/T = 1,174 m/s

I'm certainly no expert on the physics of shaped charges, but it seems to me the 'stand off' distance of the PIBD (Point Intitiating Base Detonating) initiator ie the distance from the initiator to the shaped charge, would be the critical factor. The higher the velocity at impact, the greater that distance would need to be to allow development of the slug by the shaped charge?

The M456A1 was fitted with a rotating Nylon band - the band rotated in the rifling, but did not impart appreciable spin to the projectile (which I think answers your query, Ed). The projectile included a set of tail fins for flight stability.

Mike

[Tony Smith]

I was always surprised that the M456 didn't have some sort of ballistic cover; it was counter-intuitive that that shape should fly right. But it seems that is exactly what the shape does:

http://sturgeonshouse.ipbhost.com/to...jectiles-work/

[Mike Cecil]

Hi Tony,

I agree - the spigot sticking out the front of a cylindrical, flat-faced projectile just seems all wrong, but it works, as the linked you provided shows.

In contrast to the M456A1's protruding spigot ,the 106mm HEAT rounds for the M40A1/M40A2 Recoillesss Rifle have a conical, hollow nose cap (as do the various Soviet Bloc RPG rounds). In the case of the 106mm HEAT round, the spin imparted by the rifling is only about 12 clock-wise revolutions per 100 metres, with flight stability provided by six fins protruding from the base of the projectile. These are housed within the cart case, and spring out after the round leaves the barrel. In this case, the MV of both the HEAT and High Explosive Plastic (HEP) rounds are about the same: about 503 m/sec for the HEAT and 498 m/sec for HEP. (HEP is the US equivalent to the Brit HESH).

Mike