Hypergolic hybrid motors are advantageous for rocket propulsion due to their simplicity, reliability, low weight, and safety. Many hypergolic hybrid fuels with promising theoretical performance are not practical due to their sensitivity to temperature or moisture. Ammonia borane (AB) has been proposed and studied as a potential hypergolic hybrid fuel that provides both excellent performance and storability. This study investigates the effect of droplet impact velocity, pellet composition, and storage humidity on ignition delay of AB with white fuming nitric acid as the oxidizer. Most ignition delays measured were under 50 ms with many under 10 ms and some even under 2 ms, which is extremely short for hybrid systems. Higher droplet velocities led to slightly shorter ignition delays, and exposing samples to humidity slightly increased ignition delay. An AB pellet composition of at least 20% epoxy binder was found to minimize ignition delay. The epoxy facilitates ignition by absorbing or adhering the oxidizer and slowing the reaction with the fuel, preventing oxidizer expulsion and holding it close to the fuel. These results emphasize the importance of binder properties in hypergolic hybrids. Pellets varying in composition and storage method were extinguished and reignited with the oxidizer to demonstrate reignition capability.

超混合动力马达由于其简单，可靠，重量轻和安全性而对火箭推进有利。由于其对温度或湿度的敏感性，许多具有理想理论性能的高混合动力燃料不实用。已经提出并研究了硼烷氨（AB），它是一种潜在的高混合动力燃料，可提供出色的性能和可存储性。本研究研究了以白色发烟硝酸为氧化剂的液滴撞击速度，颗粒组成和储存湿度对AB点火延迟的影响。测得的大多数点火延迟在50 ms以下，许多在10 ms以下，甚至在2 ms以下，这对于混合动力系统而言非常短。较高的液滴速度会导致点火延迟稍短，而将样品暴露在湿气中会稍微增加点火延迟。发现至少20％环氧粘合剂的AB粒料组合物使点火延迟最小。环氧树脂通过吸收或粘附氧化剂并减慢与燃料的反应，防止氧化剂排出并将其保持在燃料附近，从而促进点火。这些结果强调了结合剂在超高果杂交种中的重要性。熄灭组成和储存方法各异的药丸，并用氧化剂再点燃，以证明其再点燃能力。