RE: prop conversion 2 blade to 3
Frenchie:
Have you ever seen a 3 bladed prop on a national Q-500 or 40? No. On WW11 war birds, yes, 3 and 4 bladed. That was a no choice option. The large engines required big props, much biger than the airframe design would allow, hence the multiple blades. The 2 blade design is simply more efficient. Same general principals in boat props. At one time, the U control speed guys were running 1 bladed props. In boat drag racing, we used 2 blade hydroplane props if you wanted to go fast top end and live on the edge, used 3 blades to get out of the hole faster, but lost out on the high end side. The more efficient hydroplane 2 blade props had a interesting effect of pushing the bottom rear of the boat out of the water, ok for a true hydroplane boat with the front sponsons in the water. With a flat bottom boat, sort of got squirley over 100 mph. Fun to watch, not so fun to drive. Suspect the multi bladed sub props are for noise reduction design, but don't know. Hope this helps. ENJOY