RCU Forums - View Single Post - Help aligning semisymetrical wing and stab
Old 03-03-2007 | 02:55 PM
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BMatthews
 
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From: Chilliwack, BC, CANADA
Default RE: Help aligning semisymetrical wing and stab

That would give you a 0-0 wing to stab difference. Maybe not a good thing. It would trim in the end but it would do so with some up elevator trim. And many consider permanent trim on a surface to be unsightly. You'd be better off to set the stabilizer about 1.5 to 2 degrees negative to the airfoil centerline that you described. Which, incedentally is how we all describe the airfoil center line and if very proper.

If it'a a sport model then 1.5 to 2'ish would be enough since you'll likely put the CG back far enough to make it balance out the trim. If it's more of a trainer with a higher degree of pitch stability then 2.5 to 3 difference would be a good starting point.

The closer to 0-0 you set all this the less downthrust you'll need. As it gets more into the trainer realm you'll find you need more downthrust to avoid a strong nose up reaction to changes in speed related to throttle use. With a 3 degree incidence angle difference in the wing and stab it would not be unusual to use 4 or 5 degree of downthrust angle in relation to that wing center line.