I have been flying a roc hobby foam corsair for fun scale and am having trouble getting it to fly level well. I have balanced further foward and still not good enough. I will try a 2 blade prop again to see what that does? I did read that the stab is at zero degrees and the wing could have positive incidence maybe 2 or 3 degrees?

I have not heard of any issues with 4 blade props causing problems for level flight.  I fly multiple electric scale models with 3 blade props with no issues.

The problem is likely in setting the vertical and horizontal location of the leadout guide. I  suggest that you hang the model from your garage ceiling to help determine the proper vertical and horizontal location of the leadout guide.  See the attached article that was in Model Aviation for details.

Additionally, I have very little elevator throw on my scale models.  After all, I am not flying a stunt pattern with my scale model.

Let me know if this corrects the problem.

Joe Gilbert helped me make some changes last Sunday after he observed what was needed  I also changed handles to improve things further. Plane is flying much better. Put 4 blade prop on again and It was never a problem .  Went back to stranded metal lines as required by the rules. Not noticing much if any difference between stranded and spectra. No point in trying to submit a rules change for this as I think it is too much work for c.d.'s and ama to get this done.

Quote from: Matt Curtis on December 25, 2025, 05:31:26 PM
Joe Gilbert helped me make some changes last Sunday after he observed what was needed  I also changed handles to improve things further. Plane is flying much better. Put 4 blade prop on again and It was never a problem .  Went back to stranded metal lines as required by the rules. Not noticing much if any difference between stranded and spectra. No point in trying to submit a rules change for this as I think it is too much work for c.d.'s and ama to get this done.

Great Matt - I was talking with Joe and he mentioned helping out.  Glad that is all worked out.

Wing with positive incidence will cause all kinds of problems at different speeds.


MM

When the model won't stay level it's not a function of the propeller, sometimes positive incidence in the horizontal can cause problems.

Also try a handle with smaller line spacing, longer bellcrank or move the pushrod to the inner most hole on the bellcrank. Also look how long the control horn is on the elevator, short ones give lots of movement, maybe more than you really want or need. It might that you have too much elevator movement. My Spitfire it tricky to fly because it was so pitch sensitive.

Fred

So I did reduce elevator control by handle spacing and pushrod adjustments and moving the bar further out on the handle.  Plane is flying much better. less is better for scale more fun to fly .