Henry Royce had been asked to deliver an engine able to produce 200hp and when first run in February 1915 the Rolls Royce Eagle exceeded this by 25hp at 1,600 rpm, it was soon realised that the engine would produce more power if run at higher RPM so production engines were rated at 255 hp at 1,800 rpm although an emergency use of 1,900 rpm was authorised for short periods producing about 270hp. The Royal Aircraft Factory's need for the engine was greater than Rolls Royce could produce, so they tried to get Henry Royce to allow the engine to be produced elsewhere under licence, but he strongly resisted, claiming the engines performance and reliability would be adversely affected. By the end of WW1 the latest versions of the Rolls Royce Eagle were producing 360 hp, development of a non military Eagle, the Rolls Royce Eagle IX continued after WW1 and at the end of the Rolls Royce Eagle engine's production run, a total of 4,681 had been produced.
Rolls Royce Cars had a reputation for unequalled reliability, quality and performance, the Rolls Royce Eagle extended that reputation in to the field of aero-engines, it was of little surprise that when the first non-stop Trans-Atlantic crossing was achieved by Atlock and Brown, Rolls Royce Eagle's powered their Vickers Vimy faultlessly the whole way.
Rolls Royce Eagle IX Specifications: