Daily Shot of Homemade Coil Guns!

Ok, this video is amazing!  If you thought the mini cannons were cool - check this out!  Technical specs and links after the jump!

By the way - if you like investing information, check out my other blog! 



After 2 long years of on-and-off work my coilgun project is finally completed. For anyone who doesn't know what a coilgun is, it's a gun that fires a projectile with magnetic force instead of gunpowder. The projectile from this gun won't kill a person, but the electrical energy stored in the capacitors is 78 times the lethal amount for human beings so this is no toy.

Some technical data:

- Action: single stage, bolt
- Power supply: 12V NiMH battery (fires about 15 times/charge)
- Charging: 40 watt regulated ZVS flyback driver (charge time ~30s)
- Capacitor bank: 4x 3900uF @ 400VDC
- Stored electrical energy: ~1.25kJ
- Switch: SCR
- Efficiency: unknown, probably 1-3%
- Body: lightweight ABS plastic pipe and sheets

Pictures: http://www.youtube.com/watch?v=ovSVYK...
Discuss: http://4hv.org/e107_plugins/forum/for...

***Answers to commonly asked questions***

Q: What is the projectile speed/energy?
A: I don't know yet. I'll post what it is once I have the equipment to measure it (speed trap, scale).

Q: Will a smaller projectile result in better efficiency?
A: No, a smaller projectile won't be able to absorb as much magnetic flux as a larger projectile, due to a phenomenon known as magnetic saturation (Wikipedia it!)

Q: Will multiple coil stages improve power/efficiency?
A: Yes! I only have one stage on this design for the sake of simplicity.

Q: Will rifling in the barrel improve accuracy?
A: No- not at these projectile speeds. A projectile has to be moving at a certain speed before rifling is effective.

Q: How do you claim 1.25kJ of energy?
A: 1.25kJ is the electrical energy stored in the capacitors, according to the equation E = 0.5*C*V^2. For this gun, C=15600uF and V=400V, thus E = 1248J. One of the main drawbacks for coilguns is EFFICIENCY, which, for single-stage hobbyist designs (like mine) is limited to about 3%. So if we assume a 3% efficiency, the kinetic energy (delivered to target by projectile) is in the area of 37J, which is much more than a bb gun but much less than a real gun. I don't have the equipment to measure the exact kinetic energy, but as soon as I do I will report it. Thanks!

Via