Originally Posted by Daniel 11000
I simply highlighted the fact that lift is generated by ‘deflection’ , therefore ‘Deflecting’ is the correct word, independently of how/ who /what deflects whatever fluid. In order to ‘lift’ , a wing must deflect – no deflection, no lift – everybody must agree on that !
Daniel 11000, "deflect" is a poor word choice. Deflect typically means to change something's direction by putting a barrier in its way. You could use the word to describe what the wing does to the air hitting the underside, but it does not describe what happens to the air going over the top of the wing. That's what John means when he says that deflection of air can't account for all of the lift, because it ignores the upper airflow, and that is very important. A better way to describe lift is to say that the air mass is turned or accelerated by the wing. When I say accelerated I mean in its strict physics sense, that is, its vector is changed. By accelerating the airmass downward, lift is generated, F=MA. You can also use Bernoulli to calculated the pressure differential around the wing and come up with the same answer, but that is neither here nor there.