Re: prop dia.
Blades are 120 degrees apart and obviously form a circle. The outer diameter of the blade forms that outermost circle. Not a prop design engineer, but to me, I'd get a ruler, and directly behind the LU measure the outer most dimension of the prop directly to the center of the prop shaft.....probably eyeballing it as the max diameter sometimes occurs prior to the trailing edge of the prop where it would be easy to get to the prop shaft. That gives you the radius and the diameter is merely 2 x the radius.
The prop could be a fancy SS with high rake, cupping, progressive pitch and all that stuff, but diameter is diameter. Usually on the front or back of the prop, just out from the brass insert is where the diameter and pitch are stamped in inches.....prop has to be removed to read it. Some stamp it on the outer hub toward the rear of the prop so it can be read with the prop installed....still diameter x pitch.
HTH,
Mark
