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Speed,Combat,Scale,Racing => Combat => Topic started by: phil c on March 26, 2007, 07:47:34 AM
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I built a new plane, and the trim is really funky. Any thoughts would be appreciated.
I located the leadouts per Bob Fogg's Leadout program. It looks like it is flying square on the circle and doesn't turn in when the engine quits. Span is 46 in. It's a very typical foamy, with equal span panels.
In moderate turns it flys pretty well, with little wing drop. I tweaked the wings to get it to fly level in turns both directions. Now it flys showing more of the top of the wing upright and less of the bottom inverted(showing a bit of left roll), but it flys like it is straight. However, in tight maneuvers it drops the outboard tip a lot, much more on inside turns than outsides(right roll).
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Nooooooooobody knows.
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So, since nobody who knows will answer, I'll put in my guess. Is there any chance you are using too much tip weight? I don't see why that would cause different results on inside and outside, but it would at least be a starting place. You might try posting the question on Stuka Stunt.
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It doesn't have any tip weight to speak of, other than the engine.
I'll try moving the leadouts forward some. That may be why it is dropping a tip so hard in tight maneuvers.
The other puzzle is why the roll trim doesn't match how it behaves in maneuvers. i.e., to make it fly evenly on insides and outsides I had to warp the wing enough that it doesn't fly straight in level flight. I'll take a closer look at the wing. Maybe I screwed up the airfoil sanding it. If the airfoils are screwed up that might explain why it behaves differently in maneuvers and level flight.
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I'm sure you've checked the stab alignment with the wing, both horiz. and vertical (sighting from behind, and from above). Misalignment there can do some funny things. Also, any flex back there? Maybe it changes under load.
--Ray