Barry's Coilguns |
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Coilgun Mark 2 |
Barry's Coilgun Mark IIWhat if I made a single-stage coilgun, with capacitive discharge timing? How well can it work? A coilgun is a great teaching device. As such, it illustrates principles of magnetism and stored energy. Rotary motors are highly refined creatures with a hundred years of development. It is difficult to understand how rotary motors work because they have several things happening at once: multiple poles and multiple windings are all doing their thing together. As the rotor turns, the contacts transfer electrical energy, and the rotary load interacts with the rotational inertia and magnetic fields that come and go. Through some massive oversight, the engineers pretty much ignore all the transients and study the motor as if it were steady-state! In a coilgun there is no such thing as steady-state. Everything that happens is a transient. I find this a very interesting puzzle to analyze. GoalsMy second model, the Mark II, will launch small projectiles at a better speed with simpler construction. It will be much easier to build, because there are no timer/counter circuits. On the other hand. it will take more fiddling to tune it up. The main goal: minimum part count. Java AppletsThese Java applets help analyze coils and RLC circuits:
Here's how to build the Mark II:
ResultsNow here's the results of my measurements and comparisons. I started at low voltage to tune the coilgun, then worked up to higher voltages and different projectiles.
In summary, here is the Mark II coilgun:
By the way, 9 m/s is equivalent to a flight of eleven feet out and two feet down. Not much danger... except maybe some nearby feet and ankles. |
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Last Update 2008-06-14
©1998-2024 Barry Hansen |