mandead said:
I was just thinking that in theory it could work.
Focussing just on the technical aspects of the weapon, and not on its purpose...
In theory, a multi-chambered gun is a great idea. In practice, it sucks.
The theory is this:
In a normal gun, a propelling charge is fired inside the breach of the gun, sending the shell zooming down the barrel and out the gun-muzzle. The impulse given to the shell is greatest just at the instant of firing... but as soon as the shell starts to travel down the barrel, the "space" behind the shell starts getting larger and larger, and the propelling gasses have to expand to fill that space, which steadily lowers the pressure behind the shell. Every inch (or cm) that it travels down the barrel means leaving a larger space behind it, which further lowers the pressure in the breech, which in turn means that it accelerates more and more weakly.
A multi-chambered gun seeks to remedy this problem, by firing off additional propelling charges from secondary "breeches"... clearly visible in the photograph above... as the shell passes them on its path down the gun-barrel.
There are at least three problems with the idea, however, which (taken together) make it almost unworkable... especially with WW-II technology.
1) The ignition of the secondary charges must be very carefully timed... right to the micro-second... since if one of them ignites BEFORE the shell passes instead of immediately afterwards, it will drastically slow the shell instead of speeding it up. This can (and often did) cause the entire gun to explode. If they ignite too late, they are both worthless for speeding up the shell, and a parasitic drag on the operation of the gun as a whole.
2) The geometry of the gun ensures that the secondary breeches must fire off-center... they could not be placed along the center-of-mass without obstructing the path of the shell itself... and this compromises the aerodynamics of the shell even before it has left the gun-barrel.
3) In order for the shell to move rapidly down the gun-barrel, it must fit the barrel loosely enough to slide easily, without excessive friction. This requires at least a small air-gap between the shell and the internal walls of the gun-barrel. Unfortunately, with the high pressures generated inside the breech of the gun, this small air-gap allows burning gasses to blow past the shell as it begins to move... often igniting the charges in the secondary breeches BEFORE the shell has moved far enough to pass them. This was another common cause of catastrophic failure during the early German tests on multi-chambered guns.
A good idea in principle... but a nightmare to actually impliment.
