ORIGINAL: tsmithh
===========================
Concerning the methanol/nitro burning engines your statement, ''Compare that to the glow engine guys and the alky burner boys have basically one mfg of 3 blade props and that company advises matchups from the 70s ....'', is not altogether accurate
;
Personal observation seldom is altogether accurate for the whole country.
I've seen those you mention being for sale, but only on Tower. They don't ever seem to be stocked in any LHS ever. MAS and Graupners are often in LHSs I've been in. A Tower search shows 2 and looking up both for the engine size recommendations gets just diameter, pitch, hub thickness and hole diameter.
What is kewl is that searching through the props it turns out that Tower has four 4-bladers for sale. Same deal, no engine size mentioned. But the size could match up with my engines and they are cheap enough to be worth testing on a chance they'll work.
What is more surprising is that the APC website only lists 2 three bladers and they're not the size Tower has. And quite disappointing is they do have a section that is titled
"Propeller Size Recomendations[sic]" but it tells you they aren't going to do it. Have you seen them make specific recomendations somewhere? As for MAS's recommendations, they are the ones I mention being basically from the 70s. and my observations made earlier give the reasons I think they are pretty much out of date:
Master Airscrew first offered their line of 3-blade props and wrote up their recommendations. Back then, the recommendations on the back of the packaging suggested a 12x6 for a .90-1.08. No mention of 4strokes ('cause there were none) and the power output back then must have been a lot less than nowadays. Because what you see on most OS91FXs today will be a 14x7(3)