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 Griffon Rolls-Royce Griffon The Rolls-Royce Griffon is a British 37-litre (2,240 cu in) capacity, 60-degree V-12, liquid-cooled aero engine designed and built by Rolls-Royce Limited. In keeping with company convention, the Griffon was named after a bird of prey, in this case the griffon vulture. Design work on the Griffon started in 1938 at the request of the Fleet Air Arm, for use in new aircraft designs such as the Fairey Firefly. In 1939 it was also decided that the engine could be adapted for use in the Spitfire. However, development was temporarily put on hold to concentrate efforts on the