Which Rolls-Royce aero engine set a world speed record in 1931?

The Rolls-Royce R was the aero engine behind a world speed record in 1931. On 29 September 1931, a Rolls-Royce R-powered Supermarine S.6B reached an average 407.5 mph, setting a new world airspeed record.

The R was a highly developed V-12 racing engine created for Britain’s Schneider Trophy campaign. It evolved from the Rolls-Royce Buzzard and was designed for enormous power at relatively low weight. Intensive testing led to stronger components and improved reliability, allowing the engine to produce more than 2,500 horsepower in its ultimate forms.

Flight Lieutenant George Stainforth made the record flight in aircraft S1595, shortly after Britain won the Schneider Trophy outright. The engine’s success was not limited to aviation: R engines later powered land-speed cars and record-setting boats associated with Sir Malcolm Campbell, Donald Campbell and Sir Henry Segrave. The R also influenced the later Merlin, so confusing it with the Merlin reverses the historical relationship—the R came first.