Re: [Phys-l] techshop opportunity

[Stefan Jeglinski <jeglin@4pi.com>]

> I twin apposed piston air-rifle.....  Two pistons and springs 
> travelling in opposite directions cancelling out and producing no 
> recoil.  I have read of one obsolete gun, the Park91 (Gafac 
> Engineering company in England) even taking into account the mass of 
> the pellet in one of the pistons so that the gun is completely dead.

Was having hard time picturing rifle that doesn't fire at targets 
fore and aft at same time :-)

Almost nothing via google on the Park91/Gafac (found reference to 
Kenard Engineering; virtually no information on topic available), and 
that all historical. I assume the principle is same/similar to that 
described in the 3rd paragraph under "design" in this wiki article, 
wherein literally, one is indeed "firing forward and backward" at the 
same time (the principle behind all recoilless projectile launchers I 
suppose?):
http://en.wikipedia.org/wiki/Recoilless_rifle



Stefan Jeglinski