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
General Electric/Rolls-Royce F136 General Electric/Rolls-Royce F136 The General Electric/Rolls-Royce F136 was an advanced turbofan engine being developed by General Electric and Rolls-Royce plc for the Lockheed Martin F-35 Lightning II. The two companies stopped work on the project in December 2011 after failing to gather Pentagon support for further development. All early F-35s were to be powered by the Pratt & Whitney F135 but it was planned that engine contracts would be competitively tendered from Lot 6 onward. The engines selected would be either the F135 or an engine produced by the GE/RR Fighter Engine Team and designated the F136. The GE/RR Fighter