Washout question?
08-24-2011, 11:48 AM
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Washout question?
Will be building a wing that says 1 to 2 deg washout. Not that familiar with the traits that 1deg will have or 2deg's. Could someone explain? Its swept, 16" root cord, 7.625" tip cord 52" WS. Here's the airfoil, if it my help.
08-24-2011, 12:28 PM
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RE: Washout question?
Not sure what you mean by swept or if you are refering to taper? The airfoil looks rather clean and race like. Not too far from what I use on my pylon race planes. The washout you describe will give the wing -1 degree when the root is at zero. What this does is when the wing is at a positive angle of attack and stall conditions are present the root of the wing will stall before the tips. This is obvious advantage when landing but I have seen airplanes stall out at 100 mph by simply turning too tight and exceeding the wings AOA at that speed.
08-25-2011, 09:26 AM
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RE: Washout question?
The more washout the more resistant it will be to a stall that drops the wingtip into a spiral dive or snap roll when least wanted. But at very high speeds it can result in the tips of the wings operating at zero or even negative lift if the washout is too great.
If you're doing a jet like design you may want to consider just 1 to 2 degrees but also include center section flaps. Most folks think flaps are about adding drag and lift. But an equally valuable trait of a wing with center section flaps deployed is that there is a LOT of washout twist induced by the flaps being down. This makes the wingtips much less prone to stalling. Depending on the size of your design it may be worth considering the extra complexity and weight.
If you're doing a jet like design you may want to consider just 1 to 2 degrees but also include center section flaps. Most folks think flaps are about adding drag and lift. But an equally valuable trait of a wing with center section flaps deployed is that there is a LOT of washout twist induced by the flaps being down. This makes the wingtips much less prone to stalling. Depending on the size of your design it may be worth considering the extra complexity and weight.
08-25-2011, 09:41 AM
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RE: Washout question?
BMatthews, thanks. The plane will be a similar design to the starfire. 52-53" WS, and it will have flaps. I was lucky enough to get a copy of the airfoil used on starfire, so will be using that. Don't know what the airfoil is, name, number, modifyied? What ever it is , it has worked well for a long time. Just going to reduce the root to get tip root. I think 2deg will work out OK.
