Re: Rail Guns don't recoil

Glen Herrmannsfeldt wrote:

Assuming the comparison is to an ordinary rifle or handgun,
it is certainly possible to design a system where the explosive
material burns at the appropriate speed to keep a constant pressure
in the barrel through the travel time of the bullet, but I don't
know that is usually done.

I've never known of such a weapon. There are devices that carry a propellant inside the bullet so that the bullet is propelled outside the barrel IOW, the bullet is a rocket and the barrel an alignment device.

For larger guns it would seem more important and more likely
that it is done that way.

http://community.seattletimes.nwsource.com/archive/?date=19900412&slug=1066024

No such cannon exists that has constant pressure.

Is a story from some years ago about Iraq trying to build the
worlds longest gun. It seems 131 feet and 40 inch bore.
To make that work, it would seem you would want the pressure
somewhat constant during the time the payload is in the
barrel.

Very large cannons use a low-velocity, high expansion fuel (charge) similar to black powder and 'Pyrodex' fuels. And they recoil, of course.

Otherwise, it seems that traditional cannon barrels have
varying wall thickness, presumably because the pressure isn't
constant.

Conventional cannon barrels have not had significantly varying wall thickness since the old iron days, and in that case it was done because casting processes and the making of iron was crude, not well known, and the iron barrels were fragile. The cannons one sees from, for example, the 1600s are those that did not explode, or were never used.

Back to the rail gun - speaking of the device where the magnetically susceptible projectile is FAPP suspended above a rail in which electrical pulses along the rail are used to forward the projectile - the force is efficiently moved from the rail's emission to the projectile so that the projectile behaves more like a rocket in an open-ended tube - whereas a conventional rifle acts like the rocket itself with the projectile being part of the overall charge - it is expelled by the rifle.

See recoil-less weapons - they are open at each end. The projectile is a rocket.

.

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