Do I remember that at max rpm the blade tips were just supersonic, which accounted for the noise
As someone who had a lot to do with Harvards at 5 FTS (RAF Thornhill, S. Rhodesia) in the early 1950's ISTR that this turned out to be an urban myth. The diameter of the prop x the 2,600 rpm round the circumference wouldn't have led to the prop tips travelling faster than sound (760 mph). However, mathematics have improved since them and I'm willing to be corrected!
RAF Thornhill (5 FTS) 'F' Flight, line-up c. 1952 below.
