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 Holdings 2007 that production of the Trent 900 had been restarted after a twelve-month suspension caused by delays to the A380. On the military side, Rolls-Royce, in co-operation with other European manufacturers, has been a major contractor for the RB199 which in several variants powers the Panavia Tornado, and also for the EJ200 engine for the Eurofighter Typhoon. Two modified RB199 engines also powered the EAP demonstrator which evolved into the Typhoon. Rolls-Royce has matured the Rolls-Royce LiftSystem invented by Lockheed Martin for the Joint Strike Fighter (JSF) F-35 Lightning II to production level, planned to be produced in significant numbers.