Napier Oryx

The Napier Oryx was a British gas-turbine engine designed and built by Napier in the early 1950s to power the Percival P.74 tip-jet helicopter. It was a small bypass-style design: a 12-stage axial compressor under nine inches across fed five tubular combustors and a two-stage turbine, and an auxiliary compressor mounted behind the turbine blew cool air so the stainless steel rotor ducts stayed below 400 degrees Celsius. Development began in 1951, the first prototype ran in November 1953, and about 1,400 hours of testing had been achieved by July 1955. The P.74 was unsuccessful, so the helicopter and the Oryx were cancelled.