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 Holdings however, obliged to set up a proxy board to manage Allison and had also to set up a separate company, Allison Advanced Development Company, Inc., to manage classified programmes ""that involve leading-edge technologies"" such as the Joint Strike Fighter program. In 2000, this restriction was replaced by a more flexible Special Security Arrangement. In 2001, Rolls-Royce and its LiftSystem was among the group that won the JSF contract for the F-35. The Allison acquisition, at $525 million (equivalent to £328 million), brought four new engine types into the Rolls-Royce civil engine portfolio on seven platforms and several light aircraft applications.