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 Dart airliner, it powered a number of other European and Japanese designs of the 1950s and 60s and was also used to convert American-manufactured piston aircraft to turboprop power. The list includes: Power output was around 1,500 hp (1,120 kW) in early versions, and close to twice that in later versions, such as those that powered the NAMC YS-11 airliner. Some versions of the engine were fitted with water methanol injection, which acted as a power restorative in hot and high conditions. Rolls-Royce Dart The Rolls-Royce RB.53 Dart is a long-lived British turboprop engine designed, built and manufactured by Rolls-Royce Limited.