During the work on EM-2 and EM-3 projects, the author of this paper has performed some experiments and calculations, which resulted in creation of unfinned arrow for electromagnetic accelerator.  Nonetheless, I became interested in this question and (after EM-3 projected was finished) decided to conduct more detailed investigation, which is described in this paper.

This short article considers mathematical estimation of the projectile spread during reluctance accelerator shooting. Using simple formulae, conservative assessments are conducted for cylindrical and sphere-shaped projectiles.

The sequential electromagnetic feeding system for coilgun is described, operating on the "travelling wave" principle. The system is tuned for standard 4.5 mm steel balls and has capacity of 17 charges.

Analytical solution describing recuperation of the energy for the diagonal halfbridge scheme is performed. Efficiency is analyzed for variety of conditions inherent to the real coilgun implementations.

The theory of inductive sensor using the current shape in coil to detect a projectile is presented. Experimental setup which realizes this principle is also described.

Basic equations for current and voltage in RLC-circuit of one-stage coilgun are presented in this article. Using them, some interesting specific cases of practical importance are analyzed (for example, current decay in a half-bridge recuperative coilgun).

IR proximity sensor for safe loading of the coilgun is described.

This article bases on results of experiments conducted when EM-2 and EM-3 coilguns were being constructed. Their purpose was to  obtain accelerated body (projectile), optimal for portative electromagentic accelerators. Besides, I had to do some caluclations and Web data retrieval. The findings of those investigations are presented.

Opical sensor used in "Electric bow" EM-3 is described.