You're welcome.

As to the pitch, the old wood props have a flat airfoil so it is a lifting section and the actual pitch is several degrees higher at each station of a pitch gauge. That being said, no decent model prop is the same pitch (so called "True Pitch") along the entire blade. That overly simplistic design just doesn't perform as well for a variety of reasons. More modern designs like the APC can use much better airfoils, tailored for the requirements of the position in the blade. An idea of the actual pitch might be closer to the mold parting lines. At the hub, the requirement is for strength and low drag, while further out the airfoil can be set up for the actual speed of the blade which changes rather a lot over the length of the blade. It would be quite expensive to do this degree of machining on each wood prop, but for a mold the time used in the mill is amortized over many thousands of props.


Rev-up's were usually slightly lower pitch than some of the competitors props. Machin knew that to get more power out of the engines, you needed more RPM. He kind of got started down that path (under pitch) because of Johnson combat engines were a little less torquey than some of the others back in the day. He also knew that people would not put a smaller prop on the engine to get it into the power band because of herd psychology, so he under pitched some props and put them into the field to great success.

Funny thing though, he once told me if I ever got the chance to bet on a pulling contest between two airplanes, just put the biggest diameter, lowest pitch prop on so I could drag the other airplane all over the field. This was decades before 3D, but I said he was a free flight guy which as he put it 'was just a vertical drag race'. He wanted to max out even if the wing fell off because the airplane would be so high.