A 10g projectile moving at 100m/s has a kinetic energy given by 1/2 m (v^2), ie 50J.

Assume 10% efficiency, so you need to supply 500J from the capacitor bank. Assume we're using your 16milifard suggested number. Rearrange F = J/V^2 to V = sqrt(J/F). That yields a comparatively modest 176V. Of course, that's the energy in fully charging them, and you can't use all of it due to the voltage drop.

Assume a 50cm rail and a stationary projectile to start (in practice they're launched in mechanically). By s = (v1 + v2) t/2 that gives us 1/100s time of acceleration. That yields an instantaneous power of 50kW and current of ~280A. Delivering that kind of current requires extremely low resistance wiring and busbars and will be quite hard to achieve in a portable design. I suspect that a practical design will use a higher voltage to offset this problem and offset the voltage drop as the capacitors discharge. Perhaps only the top 10-20% of charge can be used effectively.

Putting switches in the power path is to be avoided as the current will tend to weld them shut.

Heat issues: one shot will dump a few hundred J of heat into the rails and air around them. Air cooling will do for low rates of fire.

Safety: is a relative term. You're never going to get this thing CE approved. Shrouding the whole thing in ABS (or PVC piping) to keep fingers away from high voltage, temperature, and moving parts is a good start. I'd apply an insulating varnish or conformal coating to all exposed metal on the internals (except rail active surfaces) as well, as an attempt at double-insulation and to keep out moisture.

Charge indicator: this is really the least of your problems. Start with a voltmeter.

Cap discharge: they will stay charged to lethal voltages! "Bleeder resistors" are usually used to drain them off. Note that discharging a 500J pack through a 1W resistor will have to take at least 500 seconds. Voltmeter comes in handy here for watching the discharge.

Sabot: I don't think this is normally done, and it complicates the whole thing hugely.

Construction: you have a bit of a mechanical engineering problem in ensuring that the rails are securely fixed but at the same time electrically isolated from each other and the chassis. You can get insulators to fit around screws and bolts, but the clearance required to do this at kV levels may be a problem.

Getting the rails parallel enough and contacting the projectile without too much friction or arcing is also going to be a problem.

I want to build a portable railgun and I'm a complete rookie
While opening a DLL in ILDASM, I am getting an error msg telling the dll has no valid clr header and cannot be disassembled.None of the dll's are getting opened. I am using vs2010 ultimate version. Can any1 help me in this?
