Investigation of Throttleable Hybrid Rocket Engines with application to Attitude Control

The growing number of companies entering the private space sector has reignited the search for innovative propulsion techniques in an attempt to secure a position in the competitive launch vehicle industry. Hybrid Rocket Propulsion has been turned to as a cheaper and safer alternative to complex bi-propellant liquid rocket engines, appealing primarily to start-up companies in the private space sector. Previous research into Hybrid Rocket Propulsion has put focus primarily on combustion behavior and regression rate characteristics, with little literature regarding the ability to throttle such a Hybrid Rocket Engine. For Hybrid Rocket Propulsion to be more widely adopted, examination of the throttleability of Hybrid Rocket Engines must be undertaken. This research intends to examine the feasibility of throttling a Hybrid Rocket Engine through variation of oxidizer mass flow rate. The research will be focused on decreasing the engine response time (transient throttling region) through the modification of various engine components. These components primarily include injector design, fuel grain geometry, and metallic fuel grain additives. Through multiple ground test fires with varying engine component designs, an investigation into the prominent factors that dictate the transient throttling region of Hybrid Rocket Engines can be undertaken