Prop Lenght and rpm turned sets your Static Thurst, and Prop Pitch used sets your Speed. Like I recently emailed Warp Drive for a Prop for a Rotax 277 rated 26hp@6250rpm with the 2.0 Gear Drive. It was also rated 28hp@6400rpm. They recommended a 54" x 18 Prop. A 54" x 18 prop, tuened 6250/2= 3150rpm Pitched for -100rpm = 3050rpm at 77F and using .82CF makes 171.07 lbs Static Thrust and needs 23.602 hp. Estimated flying speed = 51.5 mph or 44.7 knots! using the same Data but changing the Pitch.
Recommended 54" x 18, 171.07 lbs Static Thrust and needs
23.602 hp. Estimated flying speed =
51.5 mph or
44.7 knots.
A
54" x 19, 171.07 lbs static Thrust and needs
24.913 hp. Estimated flying speed =
54.4 mph or
47.2 knots.
A
54" x 20, 171.07 lbs static Thrust and needs
26.224 hp. Estimated flying speed =
57.2 mph or
49.7 knots.
A
54" x 21, 171.07 lbs static Thrust and needs
27.535 hp. Estimated flying speed =
60.1 mph or
52.2 knots.
A
54" x 22, 171.07 lbs static Thrust and needs
28.847 hp. Estimated flying speed =
63.0 mph or
54.7 knots.
Part 103 is
55 knots /
63.2 mph!
The 54" x 22 needs 28.847 hp - 26 hp = 2.847 hp you would need to find. Just a Bigger 36mm to 38mm Carb change can give you a 10+% Increase. 26hp +10% = 28.6hp! Porting the Case & Cylinder can give you 10-15% Increase. 28.6hp + 10% = 31.46hp@6250rpm! A better Exhaust Muffler can Gain you more hp also!
Static Thrust Calc.