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 RZ.2 about . Rolls-Royce RZ.2 The RZ.2 was a British design for a liquid oxygen (LOX) / kerosene-fuelled rocket engine to power the Blue Streak (missile). The design was a development of the Rolls-Royce RZ.1 rocket engine, which had in turn been a development by Rolls-Royce of the Rocketdyne S-3D.. Rolls-Royce, Ansty was the design authority. Two variants of this engine were developed: the first provided a static thrust of and the second (intended for the three stage satellite launch vehicle) . The engines were unique at that time in that they could be vectored by seven degrees in flight for