Theoretically a 3 bladed prop that is pitched the same as a 2 bladed (same manufacturer is best) and is the same disc area of length, the 3 bladed should make approximately 17% more thrust than the 2 bladed, or behave like the same 2 bladed prop but 17% longer. I cannot recall the author's name right off, but if interested I will look up the book and post it here. The author's formula in my specific case said that my 3 bladed prop at 54 inches would perform just like a 2 bladed of the same pitch that was 58 inches long (.93 times the 2 blade length). As has been stated here many times, there are several factors that go into prop selection, number of blades and pitch only two of them.
However, I will make some generic observations for the group that apply to those that are beginning to push towards higher horsepower and torque engines: 1) Multi-bladed props climb better than 2 bladed props, as a rule. 2) Multi-bladed props are known to be easier to balance, and inherently more balanced (two sources confirm this). 3) Multi-bladed props tend to be a little to much quieter than 2 blades in operation. 4) Higher HP aircraft almost always use multi-bladed props; I am deducing because they cannot swing a 2 bladed prop long enough to handle all the torque they have, and convert it to thrust (this may be of interest to 3100cc Corvair guys etc...). We happen to be small aircraft that some people are beginning to experiment with higher HP engines, but still have the problem of ground clearance, so the answer? Multi-blades... I too will be running a 3 blade Warp Drive once I settle on which engine I will install (already have the prop). Colin Rainey brokerpi...@bellsouth.net
