Rolls-Royce Merlin prey, Rolls-Royce named the engine the "Merlin" after a small, Northern Hemisphere falcon ("Falco columbarius"). Two more Rolls-Royce engines developed just prior to the war were added to the company's range. The Rolls-Royce Peregrine was an updated, supercharged development of their V-12 Kestrel design, while the 42-litre (2,560 cu in) Rolls-Royce Vulture used four Kestrel-sized cylinder blocks fitted to a single crankcase and driving a common crankshaft, forming an X-24 layout. This was to be used in larger aircraft such as the Avro Manchester. Although the Peregrine appeared to be a satisfactory design, it was never allowed to mature since
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.