SABRE was a concept under development by Reaction Engines Limited for a hypersonic precooled hybrid air-breathing rocket engine. The engine was designed to achieve single-stage-to-orbit capability, pr

LAPCAT was a 36-month European FP6 study to examine ways to produce engines for a Mach number 4-8 hypersonic flight aircraft. The project ended in April 2008. It was funded by the European Commission