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 RB401 Rolls-Royce RB401 The Rolls-Royce RB.401 was a two-spool business jet engine which Rolls-Royce started to develop in the mid-1970s as a replacement for the Viper. RB.401-06 prototype engines were already being manufactured when a decision to develop the higher thrust RB.401-07 was taken. Although ground testing of both the -06 and -07 continued into the early 1980s, a lack of funds caused the project to be cancelled. Although the basic configuration of both engines was almost identical, the -07 variant had a larger fan diameter. The -06 version HP compressor was based on the eight-stage version of the RC34B research