Design > Stunt design
Transitional Airfoils
Chuck_Smith:
Ahh yes, the classic thin vs thick airfoil theory.
So what's going on here? It's actually a lot simpler than people want to make it.
First, since ALL the airfoils are symmetrical they have the same lift coefficient and same zero lift angle of attack. The difference is in how they stall.
The thick wing has a progressive stall that starts at the trailing edge and moves forward as the angle of attack increases.
The thin wing stalls at the leading edge and stalls all at once.
If you re-read the description in Phil's post above describing flying the flat plate wing you'll have a great description of thin airfoil stall characteristics.
When you get down below 12% the leading edge radius becomes small enough that the stall initiates from the leading edge.
Nothing inherently wrong with thin airfoils. Almost every "tube and rag" light aircraft, Cub, Champ, Pitts, etc., has a very thin airfoil for the tail surfaces. This is possible because the aspect ratio of the tail is significantly less than that of the wing, so even though the airfoil is basically the diameter of the tubing used to build it, the wing will completely stall before the tail and control will be maintained.
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