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0 pointsIIAOPSW10y ago0 comments

I think you meant to cite the third law "For every action there is an equal and opposite reaction".

In aggregate a force is applied to all the air in a way that is equal and opposite to the force applied on the plane. However "Ergo, air is moving downwards so that the plane will move upwards." is not quite complete. One need only look at an airfoil in a windtunnel to see that the action of an airfoil is not the simple "air based rocket" you would have us envision.

If what you said were true, the most efficient wing design would just be a flat plank strapped in at a 45 degree angle of attack.

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lutorm10y ago

What he said is an absolute truth. Momentum conservation is a fundamental law of nature, and if the air is exerting a upward force on the wing, transferring upward momentum to the wing, the wing is transferring downward momentum to the air. "Transferring downward momentum to the air" is pretty much the definition of "throwing air down". There is simply no way around that.

But it says nothing about the how a wing is throwing air down.

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