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 Kestrel the Kestrel VIII, was configured as a 'pusher engine' for the Short Singapore flying boat. Apart from supercharging, the variant differences centred on varying compression ratios and propeller reduction gearing. "From Lumsden, the Kestrel may not be the main powerplant for these types." Several Rolls-Royce Kestrel engines remain in service, powering restored Hawker biplane types: Preserved examples of the Rolls-Royce Kestrel engine are on public display at the: Rolls-Royce Kestrel The Kestrel or type F is a 22-litre (1,342 Cu In) 700-horsepower (520 kW) class V-12 aircraft engine from Rolls-Royce, their first cast-block engine and the pattern for most of