Rolls-Royce Limited increase its own production rates. By the late 1920s, aero engines made up most of Rolls-Royce's business. Henry Royce's last design was the Merlin aero engine, which was first flown in prototype form in 1935, although he had died in 1933. This was developed from the R engine, which had powered a record-breaking Supermarine S.6B seaplane to almost in the 1931 Schneider Trophy. The Merlin was a powerful supercharged V12 engine and was fitted into many World War II aircraft: the British Hawker Hurricane, Supermarine Spitfire, de Havilland Mosquito (twin-engine), Avro Lancaster (four-engine) (a development of the Avro Manchester with
Rolls-Royce–Bentley L-series V8 engine Flying Spur and Continental models. The first engine of V8 configuration was developed in 1904 by the Marmon Motor Car Company in the United States. It was experimental, however, and did not find its way into a passenger vehicle. Rolls-Royce premiered the world's second V8 engine in 1905 for their Rolls-Royce V-8 Legalimit – governed not to exceed the legal speed limit in Britain at the time of . It was not a success, with only three made and just one sold, which was soon returned to the factory to be scrapped. It was another decade before Cadillac pioneered a