Low-thrust long-burn-time solid rocket motors may be useful as propulsion for small, fast, uncrewed aerial vehicles. These motors require a slow-burning propellant that can operate at unusually low chamber pressures (0.3–2 MPa). Slow-burn propellants were developed using ammonium perchlorate oxidizer and the burn rate suppressant oxamide. By varying the amount of oxamide (from 0 to 20%), burn rates from 4 to $1\mathrm{mm}\cdot {\mathrm{s}}^{-1}$ (at 1 MPa) were achieved. The adjustable burn rate allows a set of similar propellants to serve many aircraft and mission concepts. This work presents burn rate measurements (from both a strand burner and a research motor), minimum burn pressure measurements, and combustion chemical equilibrium simulations. A novel model of oxamide’s effect on burn rate is also presented, and it fits well to the experimental data. Finally, these propellant data and models are applied to select the propellant and chamber pressure for an example low-thrust solid rocket motor.

低推力长燃时固体火箭发动机可用作小型、快速、无人驾驶飞行器的推进器。这些发动机需要一种缓慢燃烧的推进剂，可以在异常低的腔室压力 (0.3-2 MPa) 下运行。使用高氯酸铵氧化剂和燃烧速率抑制剂草酰胺开发了缓燃推进剂。通过改变草酰胺的量（从 0% 到 20%），燃烧率从 4 到$1\mathrm{毫米}\cdot {\mathrm{秒}}^{-1}$(在 1 兆帕) 达到。可调节的燃烧率允许一组类似的推进剂为许多飞机和任务概念服务。这项工作提供了燃烧率测量（来自线束燃烧器和研究电机）、最小燃烧压力测量和燃烧化学平衡模拟。还提出了草酰胺对燃烧速率影响的新模型，它与实验数据非常吻合。最后，应用这些推进剂数据和模型为示例低推力固体火箭发动机选择推进剂和腔室压力。