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I have no idea if this would work....but i was basically thinking, could the projectile be used to turn on each coil as it moves through the barrel? The barrel itself would be at 0v, and one end of the coil would be linked to +v, and the other would go to a contact of some sort inside the barrel. Then as the projectile moves through, it would link the contact to the barrel, turning the coil on and pulling it forward. This powerpoint might explain it better (sorry i dont have flash installed) http://rapidshare.com/files/158070159/coil_gun_idea.pptx.html
If this could work, then it would be like a multistage coil gun, but it would only need one capacitor bank. Also, it could be possible to make the seperate coils very small, maybes just a few turns each.
Registered Member #1062
Joined: Tue Oct 16 2007, 02:01AM
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Posts: 1529
this idea is used to trigger SCR's in multistage designs, but connect a capacitor directly would be bad, there would be sarking and arcing. Also, save the power point as a earlier version, i ahve that one, but alot of ppl dont.
Registered Member #1062
Joined: Tue Oct 16 2007, 02:01AM
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Posts: 1529
now whats the point in that? the only reason to use that many stages if you have a very small caliber projectile, so you cant dump alot of powr into one coil, it would saturate. Multiple stages allow you to add energy slowly, do 100stages would be impractical unless it was somekind of micro caliber.
i mean you could make it so that multiple coils are linked at once so that the active coils are always a certain distance infront of the projectile....pretty hard to explain
basically the active coils could be at the ideal distance from the projectile all the time as it moves through the barrel. or is it still just a bad idea?
Registered Member #1062
Joined: Tue Oct 16 2007, 02:01AM
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Posts: 1529
i understand what you mean. What i said earlier still stands. It is pointless to add stages when one stage is suffiecent without saturation. Its a great idea for a low voltage coilgun, i think it would be worth trying with like a 50v high capacitance bank, i say give it a try, starting with a couple stages to 10, then go higher if it actually helps. Your original small coil idea, i think, would be a bad idea, as the bank would discharge fast into the first coil with the little resistance and inductance. I think a coil about half the size of a normal coil would be good. Also, since there are so many stages, the coils could be built up rather then to the side. This means there are less turns per layer, but more layers.
Registered Member #968
Joined: Fri Aug 24 2007, 04:54PM
Location: Norman, Oklahoma
Posts: 104
A similar concept has been implemented. It instead used voltage spikes in "sensor coils" to trip following coils. I believe it was Evgeny Vasiljev, but don't quote me. You still face di/dt and d^2i/dt^2 limits due to the RLC equation, as well as inductive suckback.
Having two coils on at the right time should minimize suckback, though I doubt this will help efficiency considerably. Such a condition would be comparable to dynamic braking of an h-bridge, as opposed to the preferred static braking(friction&drag) between coils in our CG.
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possible idea for different switching of coils
