2012年5月8日,美国、澳大利亚联合开展的HIFiRE-2超燃冲压发动机研究性飞行试验取得成功。试验中,飞行器从位于夏威夷的太平洋导弹靶场发射,装有碳氢燃料超燃冲压发动机的试验飞行器依靠助推火箭爬升到大约30 km的高度,在Ma=6~8的加速飞行条件下,大约工作了12 s。试验团队对结果表示满意,并称此次试验有助于推动高超声速技 May 8, 2012, the United States, Australia jointly conducted HIFiRE-2 scramjet research flight test success. In the test, the aircraft was launched from the Pacific missile range at Hawaii. The pilot aircraft equipped with a hydro-scramjet engine relied on a booster rocket to climb to a height of about 30 km. Under accelerated flight conditions of Ma = 6 to 8, Worked for 12 seconds. The team was satisfied with the results, saying the trial helped to promote hypersonic technology