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 RB.50 Trent Rolls-Royce RB.50 Trent The Rolls-Royce RB.50 Trent was the first Rolls-Royce turboprop engine. The Trent was based on a concept by Sir Frank Whittle. It was a Derwent Mark II turbojet engine with a cropped impeller (turbine unchanged) and a reduction gearbox (designed by A A Rubbra) connected to a five-bladed Rotol propeller. The Trent ran for 633 hours on test before being installed in a Gloster Meteor jet fighter which flew for the first time on 20 September 1945 at the start of a 298-hour flight test programme. A preserved Rolls-Royce Trent turboprop engine is on display at the