HCR Repulsor

The HCR Repulsor is what I'm calling my attempt to build a hybrid coil rail gun.

HCR - Hybrid Coil Rail

Repulsor - Because the magnetic field is repelling the projectile, rather than pulling it.


Because traditional coil gun design is an open-air coil / sliding core, it is highly inefficient. If one could utilize a iron-core electromagnet in the generation of the magnetic field, efficiency could be drastically improved. My hypothesis is using an iron-core electromagnet paired with a non-ferromagnetic slug which has a magnetic field around it due to a large current passing through it will be more efficient than an open air coil pulling on ferromagnetic slug.

This repulsion-based design side steps several issues with tradition coil gun design:

  • Where to position the projectile relative to the coil (this ties into the below problem)
  • Timing issues with the capacitors being fully drained before the slug gets to the middle of the coil
  • No drag due to the (now magnetized) slug passing through the coil

Note: being the uneducated plebeian that I am, I have not actually done the physics/engineering calculations on this and could be very very wrong. I'm still trying to learn how to translate magnetic field strength (gauss/tesla) into force (newtons).


I have evidence showing that a magnetic field around the rail gun absolutely improves efficiency. This can be from permanent magnets or from coils. This changes my design a tad, but increases the likelihood of functioning.

See Also