Originally posted by dick Hanson [P]
Bottom line - you really have to try a variety of blades to see where your particular engine/model combo works the best --for you.
All the calculating in the world won't find the "sweet spot" you may be searching for. [/B]
[P]
Nicely summarized, Dick. I know that you have tried many different props at DH Models.[P]
However, I think the simple calculation I suggested above is worth while, as a starting point, especially for a new engine or motor. The "right" pitch is directly proportional to the speed of the model and the rpm of the propeller, and therefore the correct pitch would be just about the same whether
noname uses a 0.91 or 1.0 cubic inch engine. The bigger engine could probably swing a prop of an inch greater diameter, and I would try that first instead of more pitch.
Too much pitch for the speed of the airplane results in less thrust because the high angle of attack seen by the propeller blades in this condition results in a lower lift/drag ratio.