Hello out there. I came to this thread seeking a good 3blade prop size for an OS 91. If you have a good combo please let me know.
In all the discussion one very important point has omitted. S -E - X !!!. NO kidding. I was very much involved in flight instruction and light aircraft sales in the 70's. When Piper came out with the Seminole, a light four place twin, 3blade props were offered as an option. The normally aspirated airplane was slower and less fuel efficient with the three blade. Not a bunch slower mind you but definitely not faster This is not a trial and error deduction. The data is in the performance charts for the aircraft. So why would someone order a new airplane with less efficient props ? As is the case with most situations involving humans that defy logic the answer is S-E-X. The plane looks like it is going 300MPH standing still with those 3blade props and chrome spinners !! You wanna impress the girls !! Walk em out to the plane with the three blades !!!!
There was one redeeming engineering plus. Vibration was reduced with the three blade. That is the primary reason you will see a three blade prop on a normally aspirated light aircraft. They are more expensive to buy, overhaul , maintain,and operate.... they weigh more, but they look cool and run noticeably smoother.
I know I will get better performance with a two blade on my P-38 but it looks S-ooo much better with the three blade. And the right three blade should only cost a small reduction in performance. Any suggestions ?