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 RB211 Rolls-Royce RB211 The Rolls-Royce RB211 is a British family of high-bypass turbofan engines made by Rolls-Royce plc. Mismanagement of the initial development and consequent cost issues led to the effective nationalisation of Rolls-Royce Limited, in order to save the workforce and the engine businesses important to the nation and many other aerospace and aircraft operating companies. The engines are capable of generating of thrust. Originally developed for the Lockheed L-1011 TriStar, it entered service in 1972 and was the only engine to power this type of aircraft. The RB211 engine was the first production three-spool engine, and it was to