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Creating aerodynamic twist by using a trailing edge slot?

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Grimace

Well-Known Member
Joined
Jan 2, 2009
Messages
319
Location
Chicago, IL
I'm designing a wing for a very light, mid-performance aircraft with a heavy emphasis on being easy/cheap to build. Sort of a love child between the Hummelbird and the AR5, if you will, with a little bit of Cri-Cri and Questair Venture thrown in. I know those are very different aircraft. Basically, small wing, small fuselage and fixed gear (cheap and simple to build)... then take this tiny little thing with high-performance-type dimensions and tame it down as much as possible. Some design specs:

Engine: 38-60hp
Gross weight: 650lbs
Wing Area: 36sq ft
AR: 9
Taper ratio: 1 (no taper)
Airfoil: NACA 63-218

Flipping through Abbot & Doenhoff many years ago, I began thinking about using a slot just ahead of the ailerons as a way of increasing the CLmax and also the stall angle on the outboard portion of the wing without resorting to twist. Obviously, this would come with a drag penalty at the high end, but the benefit would be greater simplicity in building the wing due to there being no span-wise changes in a "hershey bar" wing.

As we all know, as a wing approaches stall, the "challenge" is to maintain aileron effectiveness. The slots, as far as I can tell, would do this in two ways. First, they would have the increased CL and about a 2 degree higher stall angle as compared to the rest of the wing. Second, when deploying the ailerons, the down aileron makes use of the slot, helping to offset the increase in camber caused by the downward deflection... while the up aileron effectively closes off the slot, but is less likely to stall due to the decreased camber.

As far as I can reason, this should make the aircraft more spin-resistant. Of course, I know this wouldn't work on something like a Lancair or even a KR2... but I'm shooting for a rather modest cruise and in the slightly lower speed range (cruise under 175mph), it looks like a rather attractive option.

Does anybody know of any aircraft that uses this approach to creating aerodynamic twist? Anybody have any thoughts on it?
 
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