I am now in possession of my new Culver Prop. This prop is a 74" diameter and 39" pitch. I specified the prop based on what I felt was a very conservative best guess. I felt the absolute minimum pitch I would want is 39". A full 5" less the original prop. To be sure I also brought in the diameter from 80" to 74", a full six inches. So combining pitch and diameter a full 11 " of change. Back to rules of thumb. It is estimated that anywhere from 50 to 100 rev improvement at the prop per inch would be realized. So I might have overcompensated, by a lot--if the factor is 100.
Today's result is the prop developed 395 lbs. of thrust at about 5800 engine RPM. The prop RPM was about 2230. Both also achieved at full throttle. So this prop improves the thrust by about 50 lbs. and takes full advantage of the engine HP. It seems like a good choice at this point for initial testing. This will be my climb prop.
Using the 1/3 to 1/4 rule of thumb I now exceed both. I should have enough power to easily lift up to 1200 lbs.
