ORIGINAL: da Rock
....Try a couple of different 2bladed props that are recommended by people who have experience enough to trust. Pick which performs the best. Then see if there is a 3blade available that is one step shorter in diameter and one step greater in pitch. If there is another of the same diameter and two steps greater in pitch, get that one as well. Try them both....
Useful thread because 3 blades are a bit of a mystery to many of us less experienced barn stormers.
Years ago, I was recommended a 10x6 3-blade by a RC shop guy (which I bought; good prop). It was
either for my 70 4-stroke (12x6 2-blade) OR for my 46 2-stroke (10x7 2-blade)... don't remember which. I never ended up using it before I side tracked from the hobby.
So that's either two steps down in diameter and same pitch
OR one step down in pitch and same diameter. As this recommendation clearly deviates from the advise here, could it be that it was a compromise recommendation for
both the 46 and the 70?
I'll need a 3-blade at some point for my 4 stroke for clearance... 2 steps down in diameter would certainly do the trick for clearance, but after reading this not sure if that's right. Any opinions welcome. But no biggy to get a new one...
edit: Oh but it's not like my 2-blade sizes are the only sizes for those engines, so... depends what you compare it to.
edit #2: Just realized from [link=http://www.rcuniverse.com/forum/m_7125594/tm.htm]this thread (contains a prop-chart)[/link] that my 10x6 3-blade must have been recommended for my 46 2-stroke (don't have the manual for the engine). I could get an 11x8 3-blade or larger for my 70 4-stroke.
Cheers