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Originally Posted by fish314  Now, to correct some errors about induced drag from above. Induced drag is NOT the result of wing tip vortices, although it is affected by wing tip vortices. But even if there were no wing tip vortices, there would still be some induced drag. There would just be less. |
Well, you've just contradicted every aerodynamics book that I own. I will provide you with innumerable references when I get home.
Interesting that wing section data provided by NACA does not include induced drag. Why? No wing tips, no vortices. Check out "Theory of Wing Sections."
The induced drag equation is Di = Cl^2/(Pi*e*AR). Note that as AR (Aspect ratio) goes to infinity, meaning no wing tips, then induced drag goes towards zero.
One thing you might be confusing is "Induced drag" vs. "Drag due to lift". There is one other component thrown into "Drag due to lift" that is not induced drag, and that is the extra parasite drag due to a larger angle of attack.