Demonstration of ammonia borane-based hypergolic ignitor for hybrid rocket

The low toxicity hypergolic solid fuels (HSFs) and hydrogen peroxide (H2O2) oxidizer have been demonstrated as environment-friendly hybrid propellants. In the present study, a new HSF containing ammonia borane (AB), Pd–C, and paraffin wax, was fabricated in the form of the hypergolic ignitor for the hybrid rocket. Furthermore, the atmospheric combustion test (ACT) and hot-fire test (HFT) with HSF ignitor, PMMA or PE fuel, and 95% H2O2 oxidizer were performed using fuel-exposed-hybrid-combustor; studied the ignition reliability and combustion characteristics of HSF. The hypergolic ignition of HSF initiated through Pd–C followed by AB combustion with H2O2 was observed by using the high-speed camera images of ACT. A HFT with a ground thrust of 120 N exhibited the rising time and pressure instability of 137 ms and ±4.00%, respectively. Moreover, smooth combustion transition from HSF to PE was achieved with stable chamber pressure and no hard-start. The results suggest that the HSF ignitor containing AB may be the suitable preference for the hypergolic hybrid rocket.