Small, low-thrust, long-burn-time solid propellant rocket motors could provide propulsion for a new class of kilogram-scale, transonic, uncrewed aerial vehicles (UAVs). This paper investigates technological challenges of small, low-thrust solid rocket motors: slow-burn solid propellants, motors that have low thrust relative to their size (and thus have low chamber pressure), thermal protection for the motor case, and small nozzles that can withstand long burn times. Slow-burn propellants were developed using ammonium perchlorate and 0–20% oxamide (burn-rate suppressant), with burn rates of $1–4\mathrm{mm}\cdot {\mathrm{s}}^{-1}$ at 1 MPa. Using these propellants, a low-thrust motor successfully operated at a thrust/burn area ratio 10 times less than that of typical solid rocket motors. This kilogram-scale motor can provide 5–10 N of thrust for 1–3 min. An ablative thermal protection liner was tested in these firings, and a new ceramic-insulated nozzle was demonstrated. This paper shows that small, low-thrust solid motors are feasible and presents a baseline design for the integration of such a motor into a small UAV.

小型、低推力、长燃烧时间的固体推进剂火箭发动机可以为新型公斤级、跨音速、无人驾驶飞行器 (UAV) 提供推进力。本文研究了小型低推力固体火箭发动机的技术挑战：缓慢燃烧的固体推进剂、相对于其尺寸具有低推力的发动机（因此具有低腔室压力）、发动机外壳的热保护和小喷嘴可以承受长时间的燃烧。使用高氯酸铵和 0-20% 草酰胺（燃烧速率抑制剂）开发了缓燃推进剂，燃烧速率为$1——4\mathrm{毫米}\cdot {\mathrm{秒}}^{-1}$在 1 兆帕。使用这些推进剂，低推力发动机成功地以比典型固体火箭发动机小 10 倍的推力/燃烧面积比运行。这种公斤级电机可以提供 5-10 N 的推力，持续 1-3 分钟。在这些烧制中测试了烧蚀热保护衬里，并展示了一种新的陶瓷绝缘喷嘴。本文表明小型、低推力的固体马达是可行的，并提出了将这种马达集成到小型无人机中的基线设计。