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> Surely you’ve seen birds flying without flapping? Isn't that when they just "ride" the winds? The wind pushing against the back of their wings which is hold
by 21 9y ago
> Surely you’ve seen birds flying without flapping?
Isn't that when they just "ride" the winds? The wind pushing against the back of their wings which is hold angled thus pushing it higher (like a boat sail).
- mikeash 9y agoSorry, I don’t really understand what you’re saying here. Birds and airplanes work on the same principles. Airflow over the wings produces lift. That airflow also produces drag, which must be counteracted with thrust to maintain altitude. The only difference is that birds produce thrust by flapping, and airplanes produce thrust with engines. A non-flapping bird is equivalent to an airplane with the engines shut off.
- 21 9y agoI was referring to this theory, which NASA calls wrong: https://www.grc.nasa.gov/www/k-12/airplane/wrong2.html https://www.grc.nasa.gov/www/k-12/airplane/wrong2.html Most interestingly, NASA also calls wrong what you seem to defend, or maybe there are some subtleties that I'm missing: https://www.grc.nasa.gov/www/k-12/airplane/wrong1.html https://www.grc.nasa.gov/www/k-12/airplane/wrong1.html
- mikeash 9y agoNo, that second link describes the equal time fallacy, which I called out as wrong in my original comment.
- mannykannot 9y agoThere is no equivalent, in flying (other than balloons), of a sailboat running before the wind. A gliding bird is always facing into the relative airflow.