Project INFRA #4: GPN14

bronsen and I went to GPN14 a week ago and learned a few very valuable design-lessons.

1) The coils using ~10 loops of 2.5 mm² NYM wire don’t cut it. We can’t feed enough current through them to produce any serious magnetic field.

2) Thinner wire but also more loops results in way better magnetic performance.

3) Using pieces of threaded rod as ammo we did science (a bunch of measurements and some math) and determined there’s an optimum distance between coil-center and projectile-center paired with an optimal trigger-pulse duration to fire a single stage coilgun. It doesn’t seem to matter much how long the coil and/or projectile is.

4) Record muzzle velocity was 3.8 m/s (not really much)

5) We need better coils (more loops, way more loops)

We did some preliminary trials with a double-stage coilgun. Results weren’t really what you could call a break through, we’ve only gained around 0.4 m/s in muzzle velocity. Probably the hand-tuned timing is off.

Timing will be replaced by proper real-time calculations in the next iteration. As a preparation for better speed measurements, we’ve already soldered simple light barrier breakouts that come with the required resistors and can be simply hooked up to the Arduino board which we’re using currently for prototyping.

In other news, we’ve decided to name the project INFRA. Short for infuanfu rapid accelerator. There’s also some code on Github which is almost certainly no use to anyone at this point.

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