Techniques > Misc
HQ35/12 Airfoil
Alan_Perse:
Fernando got there before me :D . Doh!! :D . Yes there is more to lift generation than camber.
IceWind:
Ahh!
I changed back mine because your explains way better! :)
Happy Days:
Yes,..........I'm fine with the concept of lift being derived from having pressure exerted on the underside of a wing. As I remember from my school days (circa 1897) about 25% of a wing's lift comes from air 'hitting' the underside of the wing.
However. I'm sure we were taught that 75% of the lift comes from air having to travel over the greater distance over the top camber of the wing and thereby ahving to travel faster than the air traveling under the wing This causes a reduction of pressure on that top camber due to what I think was called the "Venturie" effect. (The same effect that causes petrol to rise from the float chamber in a carburettor. But let's not get bogged down with internal combustion engines. Horrid smelly things.)
This then leaves the wing with relatively higher pressure on the botton, and relatively lower pressure on the top, hence LIFT.
Am I right so far???
Fred:
The lift is generated by the top surface (difference of speed between the top and the bottom of the traveling air), usually, on the first 1/3 of the root (then, the air layer simply don't stick to the surface).
So, basically, you don't need camber to generate lift (Clark Y and so on..) but... :D
...Adding camber to a wing will generate more lift ! Same story, the air travel further, generating more lift, increasing also the critical angle of attack before stalling (a cabered profile generate lift, even at 0 degrees of angle of attack)
All perfect in the good world ? Well, not really, as adding camber, generate more drag too... Question of compromise ! :D
Fred:
--- Quote from: "Happy Days" ---Yes,..........I'm fine with the concept of lift being derived from having pressure exerted on the underside of a wing. As I remember from my school days (circa 1897) about 25% of a wing's lift comes from air 'hitting' the underside of the wing.
However. I'm sure we were taught that 75% of the lift comes from air having to travel over the greater distance over the top camber of the wing and thereby ahving to travel faster than the air traveling under the wing This causes a reduction of pressure on that top camber due to what I think was called the "Venturie" effect. (The same effect that causes petrol to rise from the float chamber in a carburettor. But let's not get bogged down with internal combustion engines. Horrid smelly things.)
This then leaves the wing with relatively higher pressure on the botton, and relatively lower pressure on the top, hence LIFT.
Am I right so far???
--- End quote ---
Yep, you are right !
The lift is created by the difference of pressure between the top and the bottom.
Generaly, most of the lift is generated by the first 1/3 of the profile, on the upper surface.
This is the air speed difference between the top and bottom that create the lift.
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