Barry's Coilgun Mark IV

This is my ongoing engineering notes for the Coilgun Mark IV, a 150-joule medium energy coilgun demonstrator.

This notebook describes the design and construction along with choices and trade-offs. It is a reasonably impressive coilgun built to see if a critically-damped design has any advantages over under-damped models.

How successful was it? To find out, read my conclusions at the end.

Outline

1. Objectives
2. Schematic
3. High Power Design
   1. Projectiles
   2. Capacitor
   3. Estimating Kinetic Energy
   4. Estimating Timing
   5. Coil Design
   6. Silicon Controlled Rectifier
   7. Protective Diode
   8. Damping Resistor
   9. Bleeder Resistor
   10. Type of External Iron
   11. Shape of External Iron
   12. Size of External Iron
4. Low Power Design
   1. High Voltage Power Supply
   2. Isolation Transformer
   3. Low Voltage Power Supply
   4. Charging Resistor
5. Construction
   1. Firing Tube
   2. Retention Bolt
   3. SCR Wiring
   4. Transformer
   5. External Iron
   6. Purchases
   7. Speed Measurement
6. Results
   1. Coil of 97 Turns
   2. Coil of 84 Turns
   3. Damping Resistor Construction
   4. Burned Coil #1 of 56 Turns
   5. Coil #2 of 56 Turns
   6. Eddy Currents
   7. Sensitivity to Starting Position
   8. Conclusions