Rolls-Royce Crecy - Design and Development

Design and Development

Sir Henry Tizard, Chairman of the Aeronautical Research Committee (ARC), was a proponent of a high-powered "sprint" engine for fighter aircraft and had foreseen the need for such a powerplant as early as 1935 with the threat of German air power looming. It has been suggested that Tizard influenced his personal friend Harry Ricardo to develop what eventually became known as the Rolls-Royce Crecy. The idea was officially discussed for the first time at an engine sub-committee meeting in December 1935.

"The Chairman remarked that if it was the desire of the Air Ministry to develop a type of sprint engine for home defence....there was the question as to how far fuel consumption could be disregarded. Mr Ricardo had raised this point in a recent conversation by enquiring whether a high fuel consumption might not be permissible under certain circumstances, for if so, an investigation of the possibilities of the two-stroke petrol engine appeared to be attractive." —Henry Tizard, The Rolls-Royce Crecy

Previous experience gained between 1927 and 1930 using two converted Rolls-Royce Kestrel engines through an Air Ministry contract had proven the worth of further research into a two-stroke sleeve-valved design. Both these engines had initially been converted to diesel sleeve-valved operation with a lower power output than the original design being noted along with increased mechanical failures, although one converted Kestrel was subsequently used successfully by Captain George Eyston in a land-speed record car named Speed of the Wind. The second engine was further converted to petrol injection which then gave a marked power increase over the standard Kestrel.

Single-cylinder development began in 1937 under project engineer Harry Wood using a test unit designed by Ricardo. Although originally conceived as a compression ignition engine, by the time Rolls-Royce started serious development, in conjunction with the Ricardo company, the decision had been taken by the Air Ministry to revert to a more conventional spark-ignition layout, although still retaining petrol-injection.