AmmoSgt
Posts: 1002
Joined: 10/21/2000
From: Redstone Arsenal Al
Status: offline
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Actually the spin affects HEAT rounds much more than APDS. The centrifical forces messed with the jet formation in any monroe effect (technical term for principle behind HEAT round) weapon , this is why bazookas worked so well . Also velocity has an adverse effect on HEAT in so far as the initiation time in early HEAT was more or less fixed and faster or slower impacts could affect jet formation . APDS works more along the line of weight per square inch of impact area long thin heavy penetrators applying more energy per sq inch than short fat rounds the fins are for stabilization more than anything else and affect accuracy more than anything else . Since the math is Energy = mass times velocity squared speed affect energy in APDS in a positive way and rifling in a rifled tube bleeds off energy thru increased friction and loss of linear energy into spin slowing the round ..you gain energy thru velocity by using a smooth bored weapon and stabilizing thru fins, perferably not canted fins that spin the round due to the drag increase. the heavier and denser the base material for the penetrator the more mass per square inch at inpact: hence depeleted uranium works better for a couple of reasons (the other main reasons being it is about the right hardness that it does not shatter on impact..to hard can be bad, things do shatter ya know .. and that uranium tends to ignite like magnesium when you get your kenetic energy impact conversion to heat effect).
There are other factors that go more into art than science while barrel length (the longer the better ) is a norm matching the burn rate and time of the propelant to the barrel as well as the burn characteristics can make a shorter barrel in those sweet coincidences that rarely happen out perform a longer barrel and the pitch of the rifleing can over or underspin a round usually due to manfacturing defects(lack of uniformity of weight distribution of explosive filler usually) can cause shells to spin out of kilter .
The French CN series cannon have a Boruele ( that part of the shell the rides the Rifleing) that spins seperate from the round allowing their HEAT to operate more efficently while providing a gyroscopic effect for stabilization that is pretty much uneffected by filler density . The shell still spins somewhat but not as much as a fixed Boruele round like a NATO 105 .
Speaking of ammo how come we don't have any HEP ammo thats some preety good stuff especially when you consider it is pretty predictable in behavior over a wide variety of ranges . HEP is basically a big wad of plastic expolsive behind a windscreen that smashes onto the target with an impact fuse at the rear causing tremendous spalling in conventional homegenious armor plate say pre 1990 and it works on a variety of armor thicknesses like from thin APC armor thru thick Main battle tanks ... any way hope this helps
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"For Americans war is almost all of the time a nuisance, and military skill is a luxury like Mah-jongg. But when the issue is brought home to them, war becomes as important, for the necessary periods, as business or sport. And it is hard to decide which
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