TRIMMING ISSUE ???

[Greg L Bahrman]

Hi Guys,
 I have a G Nobler that flys pretty good. The problem I'm having is hunting when flying level while inverted. Not radical just uncomfortable. It constantly keeps you on your toes when doing the 6 inverted laps. By the time you get to the last inverted lap your just glad it's over. Upright level laps are a pleasure, it just locks in and does it without input from the pilot. Outside squares are not a problem because the distance it has to travel inverted is not very far and the hunt is not noticed. Outside and inside maneuvers are all equal. It's something I've never encountered before. OS LA46, Bolly 3 blade, 10 3/4 x 4 1/4 cut down from 12 x 4 1/4. Engine runs are sweet and consistent........First flights it hunted upright and inverted so I added some down trim and that cured the upright but the inverted problem still lingers, but not as bad as it was originally. Still scratching my head. ?? Thanks

[Howard Rush]

First, are your controls free of friction, and are your flaps and elevator taped?

[Greg L Bahrman]

Hi Howard,
Yes, controls are smooth without friction (ball links)......No tape.....I will tape before my next flight and see what happens. Should I try another half turn of down trim...... Thanks

[Dan McEntee]

  I would tend to think that if a model is solid in level flight upright, it should be in level flight inverted also. Perhaps a bit of handle adjustment in in order? I have a model that was similar and once I thought about it a bit and paid attention to how the handle and neutral position felt in upright level flight, I made a tiny adjustment to add a tiny bit more down and that cleared it up. If it's off just a fuzz and you have don't recognize it, you fight the natural "fear" of it going in inverted and you fight it a little bit. In other words, you are more apt to be comfortable with a slight out of trim adjustment upright, but not inverted. If the model hunted in both modes of flight originally, maybe you had a balance issue and a more forward balance point would help. Maybe even a recheck of the alignment of the thrust line and wing /stab alignment. If something is wrong there, a simple elevator adjustment in one direction won't help in the otherbut that would include the inside and outside maneuvers also. I would try a bit a nose weight and see what happens.
  Good luck and have fun,
   Dan McEntee

[Howard Rush]

I would put on the tape first.  It probably won't fix it, but it makes further steps more predictable. 

If the CG is in the design location, something is wrong. 

[Bootlegger]

  I have a Nobler ARF that was doin' the same thing, huntin' in inverted flight, had a suggestion to put in some downthrust using a .010 shim, I did so and the huntin' went away.
  Might try this also...

[Allan Perret]

Should I try another half turn of down trim...... Thanks

Thats what I was going to suggest.
Great looking bird, really like what you did with the gear and pants.
Nice trim scheme.

[Chris McMillin]

I am in the downthrust increase camp as well.
Chris...