A Hybrid of Coil and Rail gun
This is some ideas and observations that have to do with coil guns (mostly). I'm in the process of finishing up several projects, so my resources are kinda spread out. I should have a prototyped coil gun finished in 2-3 weeks though, so if this doesn't clear things up, hopefully that video will. I should point out, I am a chemist with expertise in biochemistry, not electrical engineering.
Basically my idea is to combine a railgun and a coil gun for the expressed purpose of avoiding the pitfalls that a pure coilgun or a pure rail gun have. At present, none of the designs out there would be capable of competing with an actual gun. By mixing the two, i'm hoping to get something that might eventually be capable of doing so.
So.. I've included a very poor drawing (I'm not an artist). The barebones circuit is sketched in the lower right hand corner. The gun barrel, which is a piece of aluminum tubing split into two pieces to sever as a rail system, is sketched in the upper left, and again in the middle figure to show how to integrate the coil and rail system.
Looking at the circuit design, you can see that this starts off as a very basic capacitor-inductor circuit. The charge is purposefully allowed to trickle through the circuit until the coil reaches saturation and the capacitor(s) are charged.
When the trigger is pushed, the inductor side of the circuit has to dump into the rail system to complete the full closed loop.
Because of the ferromagnetic material (the brown stuff), the magnetic force persists for a while (that is to say, it has high reluctance). The ferromagnetic material does one other thing that is important here. It forces the middle of the coil to be far off center. The coil is pulling the projectile into the middle of the magnetic field, but that is not necessarily in the center of the winding. Adding ferrite, or other high reluctance material, towards the end of the barrel biases the field towards that end.
At the same time that the coil stops getting current, the rail system become active. This allows a charge to pass through the bullet/projectile, and, even though the majority of the force is going to be caused by the inductive coil, the rail system allows an eddy current to setup in the bullet. This does several things.
First the bullet doesn't have to be iron, nickel, or cobalt. With a stray eddy current in the projectile, any conductive material will work. The advantage here is that once the current stops, the non-magnetic material stops being to the magnetic field, preventing backwards acceleration of the projectile as it exits the barrel.
Second, Rail systems and coil systems are not often used because they are perpendicular to one another, but, this can be used to put spin on the projectile, in a similar manner to rifling in a barrel.
After the projectile is fired, the circuit is open, preventing excessive electrical discharge.
My circuit design is really badly drawn... =T
if it needs more explanation please post up questions.