Trimming Tips

Brett host a Stunt Clinic
Brett Buck gives the first judging clinic.
  1. The plane seems to be flying pointing out, as if the outboard wing has a lot of drag. Does that mean the lead-outs are too far behind?
    Possibly, rudder offset can also cause this. Remove rudder offset.
  2. Talking about lead-outs, how should they be positioned in relation to the CG? behind or aligned?
    They need to be behind the CG about 1.5-2 degrees (.75" +- a bit to start)
  3. On the inside loops the plane runs an even curve, but on the outside loops at around 11 o'clock (just before reaching the top) it looses tension, and then it dives, as if it was a billygoat jumping... In other words it seems to turn better inside, to get the same rate of turning on the outside loops I have to give so much command that it stalls and looses tension. I'm not sure if this last statement is exact, but that's what I guess it is.
    Check that the flap and elevator are both at neutral at the same time, or flap neutral with the elevator slightly down (maybe 1/16-1/8"). Make sure that your handle connections are equally spaced above and below the center of you hand. And make certain that the handle is vertical when the elevator is at neutral. But there is something else wrong, too.
  4. If I try to make a very sharp corner is shakes and looses tension.. By the way, the engine has 1 degree offset or less, and the rudder some 15 degrees. The CG is around 25% of the wing chord.
    Make sure the hinge lines are sealed between the hinges. Get rid of the rudder - at most 1/8" offset. Move the CG forward to 18-20% of the average chord. Move the leadouts to .75"-1" behind the CG. Set lap times to 5.0-5.2 seconds on 60-62 foot .015 lines. Start with 1-1.25 oz tip weight. Set your handle so that about +-20 degrees of hand movement moves the controls about +-20 degrees of flap movement.
    Fly level upright and inverted. If the outboard wing is high both upright and inverted, add tipweight 1/4 oz at a time until it is level. If it is low both ways, remove 1/4 oz at a time until it is level. If the outboard wing is higher one way than the other, look for and fix wing warps if you can see any. If you can't see any, bend the flap horn so that the flap is lower on the side of the airplane that hangs down in upright flight. This should get you close. Everything is of course predicated on very good alignment of the parts - tail and wing parallel in both directions, and fuselage on square to the wing. If this is not the case, then all bets are off, and you will have to consult local experts.

Brett