why does air travel faster over the top of the aerofoil than the bottom?
dodi142004 asked:
I know it is related to the pressure differences but why does the air actually travel faster? please no answers containing the ‘equal transit time’ or ‘venturi nozzel’ theories.
Jade
I know it is related to the pressure differences but why does the air actually travel faster? please no answers containing the ‘equal transit time’ or ‘venturi nozzel’ theories.
Jade
September 2nd, 2009 at 7:49 pm
Mallory
have u observed when u dip a thin glass tube in a beaker of water what happens? water rises in the inner end of the tubes right? what force pushes the water up? its the same force that will drive the air faster. if u wanna know how that force is generated then u have to learn the ‘equal transit time’ or ‘venturi nozzel’ theories, which u dont want!!
September 3rd, 2009 at 12:40 am
Brianna
Does it really? I remember the old argument that the air had to travel a longer distance over the top curved part of the airfoil in order to meet up with the air that had traveled along the bottom, so the air had to go faster over the top part, leading to lower pressure there and therefore lift.
Then I read arguments that said this was a fraudulent argument. The most convincing one was that planes can fly upside down. There’s clearly lift then in the ‘wrong’ direction!
Right now I am most satisfied by the simple idea that the angle of attack of the wing deflects air downward and then the wing receives an upward impulse as a result. Newton’s 3rd law makes me happy.
[I know I haven't answered your question. Sorry.]
September 5th, 2009 at 10:00 am
Jasmine
here’s why: the density of air IN FRONT of the wing is the same as the density at BACK. the path length over the top is, however, much longer than by the bottom, so air finding itself distributed to the top has to travel much FASTER to meet its bottom-travelling counterpart again at the back.
September 6th, 2009 at 8:28 pm
Octavio
first of all you should know that pressure differnce is the result of this effect. so one can’t explain this effect by pressure.
ok?
we know that the density of air is constant below 1 mach. if some molecules of air hit the wings they will be sepreted. some of them will go through the upper surface of wing and some thrugh the downer. since the length of the down is less than the upper surface ( because of the curve) the upper molecules should go faster to make the velocity be constant after they quit the wing.
September 7th, 2009 at 9:48 am
Cora
It has to cover a greater distance in the same time span than the air below the leading edge.