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# Lift-induced drag question

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## Lift-induced drag question

(OP)
Hello people,

Please excuse me for showing on the forum while not being classified as an engineer. :)

However, aerodynamics is something of my interest, and I am studying aeronautical engineering.

Now, something about lift-induced drag is confusing me, I am not going to explain my whole confusion, but just ask a few simple questions that should hopefully clear things up for me.

1. Is the direction of flight always parallel and opposite to the effective relative wind or parallel to the undisturbed stream?
2. If a plane is in climbing flight and flying a path under an angle, is the undisturbed stream then also under this same angle? As far as I know, the plane moves parallel to the undisturbed stream, so if it climbs, the undisturbed stream should also be under an angle relative to the horizon?
3. Is lift always perpendicular to the effective relative wind?
4. Is lift-induced drag always parallel to the effective relative wind or parallel to the undisturbed stream?

### RE: Lift-induced drag question

The answer to all your questions is, mostly, "yes".
Basically, the concept of lift wouldn't make sense (logically or mathematically) if it wasn't perpendicular to the direction of motion, and likewise with drag, which is parallel to the motion. And, of course, a body in motion through air is equivalent to air moving over a body, as far as aerodynamics are concerned.

Since student postings are discouraged on this site, that's as far as I'll go with that. You're always welcome to continue learning by reading here, of course, but I think there are MOOC's that would better serve your curiosity.

STF

### RE: Lift-induced drag question

As STF, mentioned the internet is rife with websites. One that specifically intended for educational purposes with relatively simple math is:
http://wright.nasa.gov/airplane/shortw.html

TTFN
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