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 Eagle XVI aircraft industry where it was felt that the unusual layout would block the pilot's forward view in a typical fighter aircraft installation. The project was dropped and development efforts then concentrated on the Kestrel. Like the Crecy the Eagle XVI was one of the few Rolls-Royce projects that did not fly, it is of note that the 'X' engine layout was reused in the later Vulture and Exe designs. Rolls-Royce Eagle XVI The Rolls-Royce Eagle XVI was a British experimental 16 cylinder aero engine designed and developed by Rolls-Royce Limited in 1925. The engine was test run but did not