Rolls-Royce Merlin exhaust flow and waste-gates, meant that this option was rejected in favour of the two-stage supercharger. Fitted with the two-stage two-speed supercharger, the Merlin 60 series gained 300 horsepower (224 kW) at over the Merlin 45 series, at which altitude a Spitfire IX was nearly faster than a Spitfire V. The two-stage Merlin family was extended in 1943 with the Merlin 66 which had its supercharger geared for increased power ratings at low altitudes, and the Merlin 70 series that were designed to deliver increased power at high altitudes. While the design of the two-stage supercharger forged ahead, Rolls-Royce also
Rolls-Royce Eagle XVI aircraft industry where it was felt that the unusual layout would block the pilot's forward view in a typical fighter aircraft installation. The project was dropped and development efforts then concentrated on the Kestrel. Like the Crecy the Eagle XVI was one of the few Rolls-Royce projects that did not fly, it is of note that the 'X' engine layout was reused in the later Vulture and Exe designs. Rolls-Royce Eagle XVI The Rolls-Royce Eagle XVI was a British experimental 16 cylinder aero engine designed and developed by Rolls-Royce Limited in 1925. The engine was test run but did not