December 1942: Merlin powers Spitfire fighter to new heights

There are few aircraft that are as iconic as the Spitfire. Often contrasted to the more workmanlike qualities of its RAF partner, the Hurricane, the fighter plane played an important role in RAF Fighter Command during all theatres of the Second World War. However, the Spitfire wasn’t a fixed entity, being subject to a number of key improvements throughout the conflict.

It was under this aegis that The Engineer was invited by Rolls-Royce Ltd in December 1942 to inspect an example of the firm’s new Merlin 61 supercharged aero-engine, which was being fitted by the RAF to an improved Spitfire then operating with Fighter Command.

The Engineer reconnaissance team explained: “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, the first engine to be fitted to the Spitfire fighters.”