Design and Validation Testing of the SolBrid Rocket Motor

Abstract

Hybrid rocket motors o er several distinct advantages over more conventional solid and liquid propulsion systems. A hybrid rocket motor typically consists of an inert solid fuel which is combined with a liquid or gaseous oxidizer. This concept yields better performance than a solid rocket motor while maintaining a lower level of overall complexity than a liquid rocket engine. In addition, the oxidizer and fuel are stored in separate forms providing an inert propulsion system until ignition. This property makes hybrid rocket motors ideal for the emerging insensitive munitions (IM) drive in the defense industry. A conventional missile or vehicle is a liability when it is in storage on a ship or aircraft due the inherent explosive nature of solid rocket motors. Unfortunately current hybrid rocket motor technologies su er from several technical hurdles preventing wide-scale adoption by the major propulsion companies, tactical or otherwise, with only a few exceptions. Of these their inherently low grain regression rate and a subsequent historically low initial thrust to weight ratio are their largest shortcoming. Other drawbacks include lack of heritage and low volumetric e ciency. One possible solution to address several of these design issues is by way of a straightforward addition to the standard hybrid rocket motor. This solution implements a concentric grain of solid Ammonium Perchlorate Composite Propellant (APCP) inside of the standard hybrid grain. This concentric grain is expected to provide the high initial thrust necessary to achieve an adequate initial thrust to weight ratio for vehicle takeo while still allowing for a high e ciency and controllable sustained burn prole. The proposed system will be referred to as a SolBrid motor because of this dual-mode, solid followed by a hybrid, burn pro le.