From: john122333@hotmail.com (John P)
Newsgroups: sci.physics.plasma
Subject: question about a gun/rocket projectile
Organization: ?


Hi,

I'd be grateful to anyone who could help me with the following:

I'm wishing to describe the dynamics of a projectile that is propelled
by a combination of rocket action and gun action.

At t0 a cylindrical projectile is stationary in a barrel, with a 'high
pressure gas layer ' adjacent to its rear surface. This gas layer may
be considerred as being infinitely deep. In front of the projectile
there is a vaccuum.

At t>t0 the rear surface of the projectile starts to 'burn' producing
an exhaust which, at the rear surface of the unburnt projectile, has a
pressure roughly five times greater than that of the 'high pressure
gas layer'. Initially at least, this exhaust pushes back into the high
pressure gas layer.

As the projectile accelerates, the burning of the projectile becomes
increasingly less efficient. The exhaust pressure at the rear surface
of the unburnt projectile goes roughly as t^(-0.6).

At some late time, t, the projectile is made to collide with a target.
At which point only about 20% of the original projectile mass is left
un-burnt. The projectile reaches a final velocity greater than the
sound speed in the 'high pressure gas layer'.

I need to describe the dynamics of this projectile. I am having great
difficulty in finding literature that describes such combined
gun/rocket situations- and would be most grateful for either a pointer
towards some suitable literature, or alternatively some ideas as to
how to deal with the problem.

Thankyou,
John

PS. This is posted in sci.physics.plasma since I know you guys
sometimes deal with hypervelocity launchers and so may be able to lend
a hand.