A Compressible Fluid Power Dynamic Model of a Liquid Propellant Powered Rifle

This paper presents a dynamic model of the interior ballistics of an experimental liquid propellant-powered rifle. The liquid propellant-powered rifle described utilizes a misture of Hydroxyl Ammonium Nitrate (HAN) and hydrocarbon fuel to replace gunpowder typically used in such firearms. The motivation for such a development is to discard the need for a shell casing whereby carrying only propellant and bullets will reduce both the mass and volume per shot carried by the soldier. A first-principles dynamic model of the interior ballistics is derived as a compressible fluid power problem with the chemical liberation of heat within the chamber modeled via a condensed-phase reaction rate law. The model is used to predict the overall performance in terms of ballistic kinetic energy as well as draw design insight regarding the role of friction, chamber geometry, and the profile of chamber pressure with respect to time. Simulation results are presented as well as preliminary experimental results from a proof-of concept device.