Rolls-Royce R engine was invaluable in the subsequent development of the Rolls-Royce Merlin engine and the Spitfire. A de-rated R engine, known as the Griffon, was tested in 1933, but it was not directly related to the production Rolls-Royce Griffon of 1939, of the same exact bore/stroke and resultant displacement figures as the "R" design. Three examples of the R engine are on public display in British museums as of 2014. Rolls-Royce realised that the Napier Lion engine used in the 1927 Supermarine S.5 Schneider Trophy winner had reached the peak of its development, and that for Britain's entrant in the next
Rolls-Royce Condor aircraft: Rolls-Royce Condor The Rolls-Royce Condor aircraft piston engine was a larger version of the Rolls-Royce Eagle developing up to 675 horsepower (500 kW). The engine first ran in 1918 and a total of 327 engines were recorded as being built. "Note:" In 1932 the Air Ministry initiated a conversion of the Condor petrol engine to the compression ignition system. The conversion was developed at the Royal Aircraft Establishment, Farnborough, with the co-operation of Rolls-Royce Ltd. Engine layout, bore, and stroke remained the same as for the petrol version; the compression ratio increased to 12.5:1. The more robust construction required