Kline–Fogleman airfoil

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Sooner Boomer

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Has anyone built a rocket glider using a Kline–Fogleman airfoil? https://en.wikipedia.org/wiki/KF_airfoil

Most rocket gliders use either a slab airfoil or one carefully sanded from balsa (most of the foam wings use slabs - except conversions). The KF airfoils are a way to modify a slab airfoil by layering another slab (or more than one) on top of or under an existing airfoil, usually along the leading edge. The idea being that these additional layers add steps which approximate a curved airfoil profile. Another advantage is that they increase stiffness down the length of the wing. According to the Wikipedia article, the KF airfoils add performance to small model aircraft, but have not proven to be effective in full-scale versions. I'm thinking of trying a couple of designs out using corrugated cardboard. With the corrugations running the length of the wing (parallel to the leading edge), the stiffness should be improved considerably (at least that's the hope). I'll also need to make a leading edge "round-over" from typing paper to help reduce drag and cover any voids created by the corrugations.

Pictures of the KF airfoil variations:
kfm-family-of-airfoils-gif_1395057126.jpg
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yes, all the time, primarily I use them for stiffening in the leading edge rather than a performance boost, and a way to hide a spar. On my klingon Battlecruiser I did that and it flies very well. Of course I didn't build one without the kf doubler on the bottom so I can't say that it flew better than it would without, but it does fly better than I expected:)

Frank
 
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