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 WR-21 Rolls-Royce WR-21 The Rolls-Royce WR-21 is an advanced gas turbine marine engine, designed with a view to powering the latest naval surface combatants of the partner nations, and currently fitted to the Type 45 destroyer of the Royal Navy. Developed with government funding input from the UK, France and the United States, the WR-21 was designed and manufactured by an international consortium led by Northrop Grumman as prime contractor. The turbine itself was designed primarily by Rolls-Royce with significant marine engineering and test facility input from DCN, with Northrop Grumman responsible for the intercooler, the recuperator and system integration. WR-21