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 program. This marked the first complete engine assembled following US Government validation of the F136 design in 2008. The milestone was achieved one month ahead of schedule. Citing the Weapon Systems Acquisition Reform Act of 2009, the GE Rolls-Royce Fighter Engine Team submitted an unsolicited fixed-price offer for the F136 to the Pentagon on 28 September 2009. The fixed-price approach would cover initial F136 engine production, beginning with the F136 second production lot. According to the GE Rolls-Royce Fighter Engine Team, the proposal would shift significant cost risk from taxpayers to the Fighter Engine Team until head-to-head competition begins between