24-ft. tunnel tests on a Rotol wooden Spitfire propeller. Test results, and data for single radius calculations

Abstract

This note contains the results of tests made in the Royal Aircraft Establishment 24-ft. tunnel on the Rotol hydulignum propeller RA.10046 designed for the Spitfire IX aircraft. The overall thrust and torque measurements have been analysed to give mean lift-drag data, and these have been compared with those for other propellers. When account is taken of the comparative root thickness and pitch distributions, it is shown that in general, the present results confirm conclusions from earlier analyses particularly as to the large influence of root thickness on the start of the stall. The blade has however a higher CDmin at low Mach number than was expected. For the take off condition on the Spitfire IX, the propeller gives almost 25 per cent. more thrust than does the corresponding Rotol metal design. Part of this increase results from the 15 per cent. greater solidity of the wooden propeller.