December 1942. The Rolls-Royce Merlin engine

Last week we accepted the invitation of Rolls-Royce Ltd to inspect an example of the firm’s new ‘Merlin 61’ supercharged aero-engine, which is being fitted by the Royal Air Force to the improved Spitfire now operating with Fighter Command.

The Rolls-Royce ‘Merlin 61’ Supercharged Fighter Engine

Last week we accepted the invitation of Rolls-Royce Ltd to inspect an example of the firm’s new ‘Merlin 61’ supercharged aero-engine, which is being fitted by the Royal Air Force to the improved Spitfire now operating with Fighter Command.

By using a double-stage supercharger with a water-cooled passage between the first and second stages of the supercharger and a cooler between the supercharger outlet and the induction pipe to the rear cylinder, it is found possible with the new engine to develop double the power output as compared to that of the Merlin III…

…It may be recalled that at the beginning of the war and during the battle of Britain, every RAF first-line fighter was fitted with a Merlin III engine, and the complete defeat of the Luftwaffe in August and September 1940 definitely established the technical superiority of British machines.

The superiority was not obtained by chance, but every move of the enemy had been anticipated and a definite counter-move worked out.

Early in the war, German aircraft resorted to low-flying tactics, and in order to counter this, Rolls-Royce immediately increased the sea-level power of the Merlin engine by 40 per cent by raising the supercharger pressure.

This move so improved the performance of the Spitfire at low altitude that German aircraft were forced to fly higher…

1942 The Merlin Engine