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 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.