A basic component of any electromagnetic coil-based launcher will be described here - the coil itself. The section will be formed by short publications placed on separate pages - they will discuss the features of the windings concerning electromagnetic launching issues, such as driving force on a ferromagnetic, acceleration efficiency etc.

An equation for output projectile velocity in an accumulator-driven reluctance launcher is derived. Influence of an internal accu resistance is investigated. Comparison with experimental results is given.

Limitations for the speed achievable in a reluctance coilgun commutated by thyristors are investigated based on geometrical properties of the accelerating coils. Thermal, and  also capacitor weight and ESR issues are taken into account.

A process of capacitor charging through a resistor from a consstant voltage source is investigated. A strong dependence on relation of initial voltage on the cap to the source voltage is demonstrated.

Limitations for velocity of projectile are investigated for a multistage reluctance accelerator having identical coils. Geometrical parameters of winding are used as basis, assuming an overdamped system fed from large common capacitance.

The paper is prepared as continuation of the previous publication and investigates the efficiecny of half-bridge coilgun basing on real examples. FEMM simulation is used to predict efficiency of both half-bridge and simpler competitive circuit with varistor at high initial velocity of projectile.

Simple equations are presented to assess so called "characteristic speed" of projectile in a coilgun, which specifies the moment when kinetic power equals to ohmic losses of the acceleration process. 

There is often need to assess some parameters of coilgun (e.g. peak current to choose an appropriate power switch) quickly. Exact formulae (given here) may be used, but it is more convenient to establish few simple relations. 

This section collects such relactions for different cases.

Variation of the parameters such as capacitance, initial projectile velocity etc and its influence on acceleration efficiency  is analyzed for two base configurtions of the accelerator - with and without feedback.

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.