Certainly there is some testing that goes into propeller selection, but I'm not sure I would categorize it as "a lot." That would imply that most combinations are bad, there is no science that allows a correct selection, and therefore it is just luck. Sure, there is testing that confirms performance optimization, but that's not what we are talking about here. If my memory serves correctly, to certify a propeller installation in a given airframe the FAA requires a torsional study be
performed, which involves internal sensor be installed to measure the torsional vibration of the crankshaft. This costs money, so STC's for new propellers come slowly. Frankly, I don't understand at all the requirement for the prop/engine/airframe combination to be verified. The engine is stiffly connected to the prop (big bolts, metal/metal joints, etc) and softly connected to the airframe (rubber), so how could the torsional vibrations involve the airframe? In any event, I recall that the number of operational hours required is small, something like 50. And then to confuse and obscure the issue further, the only FAA requirement for experimental aircraft is that if the engine/prop combination (not airframe) has been certified the fly-off requires only 25 hours - otherwise 40. So they sort of admit that the airframe has nothing to do with it. Finally, I don't know of any prop failures related to the engine to
which they were attached. So with great trepidation I might slightly disagree with Brent in that I doubt that attaching an otherwise-successful prop to a V8 engine will almost certainly result in a prop failure. In the end, we have to decide on the odds with which we are willing to play. Is being "pretty sure" something will work good enough? For some it seems so, but for others not.
Gary Casey
Ted,
A lot of testing goes into propeller selection for engines.
Jeff Edwards