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 V8 engine the L410I, denoting fuel injection, the L410IT (for Injection Turbo) and the L410ITI (for Injection Turbo Intercooler). 94MY (model year) saw the introduction of a serpentine drive belt front-end, revised combustion system and an integrated engine cover. Developments of the L410 continued in production to power Rolls-Royces and Bentleys until the adoption of BMW V12 power by Rolls-Royce in the Silver Seraph and, subsequently, after BMW was granted a license to use the Rolls-Royce brand (for automobiles) in the Goodwood-produced Phantom. The L410 engine is still used by Bentley well into the 21st century, having been brought back into production