ORIGINAL: Deadeye
ORIGINAL: da Rock
ORIGINAL: Campy
In addition, 3 and 4 blade props are VERY ineffecient.
Would you be so kind as to supply some numbers?
Or just a source that describes what the efficiencies are?
da Rock, while I have no specific site to send you, you could try the search function on RCU. I have read on many threads here where a 3 blade will not perform like a 2 blade, and 4 blades are for static only. It has something to with the Reynolds number, which has something to do with the size of air molecules and their effect on full scale vs models (rough definition). This month's RC Report had an article explaining how to make a four blade for static.
And therein lies the rub.
As much as we would like to think otherwise, the wisdom we find on the internet sometimes isn't really a good reflection of the truth.
Sometimes what everybody says has gone through a number of interpretations. And the fact is that this efficiency idea is getting out of hand.
For example, the Reynolds numbers each blade of a prop sees is going to be virtually the same for each blade, no matter how many blades are on the hub. And a reduction in scale isn't going to apply differently from a 2 to a 3 to a 4blade prop. And whomever backed his argument on efficiency with Reynolds numbers really laid it on.
I included pictures of two popular airplanes that fly excellently with 3bladers up front. If there is a difference in their performance from the 2bladers that've been on those same airplanes, it beats me what it is. As for a difference in efficiency, whatever that is, I've not even noticed a difference in fuel usage. But haven't actually done anything to test that as that aspect of "efficiency" is totally irrelevant to my choice of props.
It actually appears that the only real problem with choosing a 3blade or 4blade prop for our engine/airplanes is the lack of those props in different sizes and pitches.