[Graham Boak]

To my understanding, the sole reason for moving to a 4-blade propellor for the Merlin 60-series Spitfires was to retain ground clearance. had it been to gain more speed I think it would have been mentioned somewhere. The preference would have been for a larger diameter propellor, but this was not possible on the Spitfire. The same can be seen in the progress to a 5-blade propellor on the 2-stage Griffon Spitfires, and the later Sea Fury.

One advantage of a multi-blade propellor is that it reduces vibration, as on the Typhoon.

I have not seen any suggestion that the British companies even considered wider blades rather than multiple ones, but my year's intake was the one that missed out propellor theory.