tl;dr: trying to find propeller efficiency with thrust, velocity and power and see which propeller length to pitch ratio is efficient.
Hello, I'm a high school student working on an extended essay for my physics class. What I've basically done is took a bunch of propellers (7x4E, 7x5E, 7X6E, so on and so forth). Propellers of lengths: 7, 8, 9, 10 inches and pitches: 4, 5, 6, 7, 8. (Fixed pitch propellers).
I've taken these propellers and hooked them up to a motor and a weighing scale to try and find how much thrust they produce. Then, I put them on to a control line aircraft to see how fast the plane goes.
Basically, Im trying to find the efficiency of these propellers and the data I have is the thrust produced by the propeller at different power levels and the velocity at different power levels. I'd really like to know if there's a relationship that I could employ to find the efficiency!
It doesn't have to be complex! Just needs to work from a physics standpoint. My deadline's coming up soon and any help would be greatly appreciated.