LAPCAT

The Low Atmospheric Pressure Combined‑cycle Aircraft Technology (LAPCAT) is a hypersonic passenger‑aircraft concept developed under a European collaborative programme (ESA, DLR, and industry partners) that ran from 2006 to 2009. The project was led by Reaction Engines Limited, which supplied the Scimitar combined‑cycle engine – a precursor to the company’s later SABRE system. Scimitar uses a high‑efficiency precooler to chill incoming air to roughly ‑150 °C before compression, allowing a turbine to operate at very high pressure ratios without overheating and to transition seamlessly from a conventional turbo‑ram mode to a ram‑jet mode at Mach 5.

LAPCAT’s airframe was designed as a slender waverider with a low‑drag forebody and high‑temperature carbon‑carbon skin, optimized for cruise at 30 km altitude. The concept called for a 70‑ to 100‑passenger cabin, a range of about 9 500 km, and a transit time of under two hours between London and Tokyo. Though never built, the study demonstrated that a single‑stage, air‑breathing vehicle could sustain Mach 5 flight while carrying commercial payloads. Its significance lies in proving the viability of combined‑cycle propulsion for ultra‑fast air travel, influencing subsequent research into hypersonic transport, reusable space launchers, and the broader vision of near‑space aviation.