Overall Thrust, Thrust Grading, and Torque Measurements on a Two-blade, 61/2 per cent thick, NACAi6 Section Propeller in the High-Speed Tunnel

摘要

(i) The corrections employed in the determination of propulsive thrust from the overall measurements are uncertain and of large magnitude ;consequenth the propulsive thrust and efficiency at forward Mach numbers greater than 0-74 are rather doubtful.n(ii) The basic cause of the uncertainty is the drag characteristic of the motor installation, the critical Mach number occurring too early and the ensuing rise being very steep. Delay of the critical Mach number by at least 0-05M is neces¬sary before satisfactory results can be expected ;this can be achieved only by drastic re-design of the installation.n(iii) Satisfactory thrust grading and hence overall free air thrust measurements can be obtained at all forward speeds and operating conditions of the propeller, but the time and labour involved in the experimental work and subsequent analysis is very great.