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 Medway Rolls-Royce Medway The Rolls-Royce RB.141 Medway was a large low-bypass turbofan engine designed, manufactured and tested in prototype form by Rolls-Royce in the early-1960s. The project was cancelled due to changes in market requirements that also led to the development and production of the smaller but similar Rolls-Royce Spey, and the cancellation of the Armstrong Whitworth AW.681 military transport aircraft project. Designed by a team led by Alan Arnold Griffith, the RB.141 was originally designed to meet a new propulsion requirement for the de Havilland DH.121 airliner project which later became the Hawker Siddeley Trident. The engine was later named