Hybrid Rocket Motor Ground Testing Results to Enable the Vision of Rapid Flight Testing for System Development

Abstract

The Johns Hopkins University Applied Physics Laboratory (APL) explored a reusable hybrid rocket design to enable low-cost, rapid flight testing. Rocket motor reusability requires addressing the unique thermal challenges of the combustion chamber. Specifically, APL focused on addressing an unexpected thermal load on the forward bulkhead that resulted in melted aluminum near the injector. Thermal management design concepts included changes to the forward bulkhead by adding insulation, lengthening the precombustion chamber, and adjusting the spray angle of the injector. The design study showed that both lengthening the precombustion chamber and using an axial injector with contoured ports resulted in adequate thermal management, confirming that aluminum is suitable for the hybrid rocket combustion chamber forward bulkhead in APL’s design.