Light fighter in 1938 and remained in production throughout the war. The empty weight of the Battle of Britain-era Spitfire IIA was 2,142 kg (4,723 lb), increasing to 2,984 kg (6,578 lb) in a later variant. It was highly maneuverable and was generally a match for its German opponents. Most Spitfires had a Rolls Royce Merlin engine, but later variants used one of the most powerful engines of the war – the Rolls Royce Griffon. The Spitfire was produced and improved throughout the war but was complex to build and had limited range. In other respects it was considered an outstanding fighter.
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.