Well I'm getting to the finish line with my TF Corsair. I have an RCV90 SP on the nose and it's been broken in with a Zinger 18x12. I had Otto do the upgrade on this engine and it ran great. He recommended a MAS 19x12 prop and was able to get a 20x12 from him with instructions to take 1/2 in off the tips. The photos show before and after trimming. I have drilled the prop for the 5/16 shaft and grossly balanced it by sanding most of the polyurethane off it. I'm painting the prop black with 21 Century spraypaint and will use yellow for the tips. Final balancing will be with paint like I do on my gasser props.

I tried to get a good taper at the tips and carry the same thickness along the TE. It looks ok to me but I've not done one of these before. Any comments up or down appreciated.

Pete

As long as the reshaped tips mimic the original, you should have a good running prop. I don't know what your expectations are, but I think the optimum treatment is to soak some thin CA into the TE of the blades from about mid span on out and sand them to a razor edge. I only work the top of the airfoil. Some of the benefit might come from reducing excess mass as well as any aerodynamic gain? If you've got a good handling plane that doesn't tend to ever nose over, then prop work can be worthwhile, otherwise I would just do a quick chop and balance job and call it good.

Thanks for th e feedback. The RCV can turn these larger props. My goal is to have a scale looking prop on the Corsair.

Thrust Hp gives 1.396 Hp for the 19x12 and 1.125 Hp for the 18x12 with thrust in lbs 9.22 and 7.43 respectively.

I want to fly scale so all out speed isn't the goal.

Pete

Hello!
I have been into pylonracing for many years and there it is common to modify props.
I have also flown scale and have modified many wooden props. When I look at your prop tips I can see that they are nicely rounded...and thats good. What is not so good is that you have the tips a little thick..at least to my liking.
I would suggest that you file away some wood (only on the upper part of the prop) so that the prop tips gradually becomes thinner toward the outer most tip. There the tip should be sharp as a knife...or there about.
Also see to that you keep the airfoil shape of the propeller.
A good method to achieve a good finish on the prop is to pour thin and medium CA glue (Flash)on it and then smear it out with a finger...do it fast or else you get stuck. Do this a couple of times so that the prop is totally covered...then sand the prop with finer and finer sand paper. If you want mirror gloss finish sand it with wet 1500-2000 paper and buff it with "3M Perfect-it nr 2 and nr 3, or something like it. This will make the prop shine like a mirror.
Plastic props could ofcourse be modified in the same way.

Regards!
Jan K
Sweden

Contrary to the positive replies you've already received, I think you'll lose some efficiency. Most of the thrust is produced from the outside diameter inwards. Pylon racers are more interested in speed than thrust. I'd play with diameter/pitch combinations until I found a good one before I started modifying props.

Dr.1