Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by BD6, Aug 9, 2019.
you test flew without a cowl?????
That was the voice in my head, too.
And check for differential seams on the forward portion of the upper wing. A friend (crop duster) had a Stearman that exhibited the same rolling tendencies you described. We looked for all of the usual subjects, and then finally found that a spanwise tape (from a fabric repair) was causing enough flow disturbance that he got a roll tendency. Rather than redo that wing, we doped on a piece of tape on the other wing and it fixed the problem.
I got a strong roll to the right on my Grob. Took about half aileron to level. But it only happened in rain. It was because I painted the right wing with shiny new paint and the left wing was still the old oxidized paint. Rain beaded on the right shiny wing and flowed smooth on the left wing.
Lets see, results from last test flight were encouraging.
1 installed cowl witch was off for extension after shimming the engine.
still heavy left wing but getting somewhat better.
2 centered the ball. Added trim tab to rudder.
made more improvement.
3 added more surface to trim tab on upper surface of left wing aileron.
More incremental improvement.
4 balanced rigging on ailerons(equalized position on both sides)
This made a bigger change easier to hold in level flight. less pressure required to make steep turns.
So at this point it is flyable but not perfect. Work will continue next week to see if we can get rid of the 5 degree
flaps put into the left flap.
The engine is a Rotax 912UL 80 hp
Thanks to all for your assistance I will post the continuing changes as they are made.
Sounds like you now have a handle to hold on to.
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