How airplanes generate lift

[dunnrite]

what kind of magic?

The magic of whodo

[Yossarian]

I was going to type out a long response, but I cba right now.  I wrote a report on what causes lift for a school report (high-school equivalent, so nothing too strenuous ) a year or so ago, if you want a copy send me a PM.  basically, many of the theories floating around are wrong, such as the Bernoulli one, the 'skipping stone' one and the 'Venturi nozzle' as well.  However, a large amount of lift is made by 'flow turning' (i.e. the air which is moving horizontally relative to the wing is deflected by the wing, and given a downward component of velocity.  The downward acceleration of the air is what produces the force) and also by the circulation of air around the wing (I kinda suck at putting this into words, but for reasons I've forgotten, when a wing (or just flat piece of material) moves through the air, a circulation pattern is set up (but due to the high speed of the wing relative to the air mass, the resultant effect is that the velocity is lower on the bottom of the wing, and higher on the top, and therefore the pressure is higher on bottom & lower on top) and because of this there's a net upwards force).

if you want a superb website to begin understanding aerodynamics, here's where you should start, IMO: http://www.grc.nasa.gov/WWW/K-12/airplane/bga.html

[Meatwad]

what kind of magic?

magic dust, man!

[Golfer]

I was going to type out a long response, but I cba right now.  I wrote a report on what causes lift for a school report (high-school equivalent, so nothing too strenuous ) a year or so ago, if you want a copy send me a PM.  basically, many of the theories floating around are wrong, such as the Bernoulli one, the 'skipping stone' one and the 'Venturi nozzle' as well.  However, a large amount of lift is made by 'flow turning' (i.e. the air which is moving horizontally relative to the wing is deflected by the wing, and given a downward component of velocity.  The downward acceleration of the air is what produces the force) and also by the circulation of air around the wing (I kinda suck at putting this into words, but for reasons I've forgotten, when a wing (or just flat piece of material) moves through the air, a circulation pattern is set up (but due to the high speed of the wing relative to the air mass, the resultant effect is that the velocity is lower on the bottom of the wing, and higher on the top, and therefore the pressure is higher on bottom & lower on top) and because of this there's a net upwards force).

if you want a superb website to begin understanding aerodynamics, here's where you should start, IMO: http://www.grc.nasa.gov/WWW/K-12/airplane/bga.html

So Bernoulli is wrong but your theory, which is actually a fairly good explaination of a practical application of Bernoulli's principal related to aerodynamics is right?

[Yossarian]

So Bernoulli is wrong but your theory, which is actually a fairly good explaination of a practical application of Bernoulli's principal related to aerodynamics is right?

I'm not quite sure what you mean, but I don't have any special theory of lift...I was essentially rephrasing (possibly incorrectly) what I remember from a year or 2 ago.  That said, the commonly-used 'explanation' involving equal transit times for particles above and below the wing is wrong (if that's what you were referring to by Bernoulli).

Also, here's what I was on about:https://docs.google.com/viewer?a=v&pid=explorer&chrome=true&srcid=0B6lxyC60vLUdYWJkNjllMzQtNzA1Ni00MjE0LWFkNDYtNDM2ZDg4ZDM4YjA1&hl=en&authkey=COXu8cEM

[Beefcake]

I just eat a lot of beans and my body takes care of the rest.

[Somerled]

I was going to type out a long response, but I cba right now.  I wrote a report on what causes lift for a school report (high-school equivalent, so nothing too strenuous ) a year or so ago, if you want a copy send me a PM.  basically, many of the theories floating around are wrong, such as the Bernoulli one, the 'skipping stone' one and the 'Venturi nozzle' as well.  However, a large amount of lift is made by 'flow turning' (i.e. the air which is moving horizontally relative to the wing is deflected by the wing, and given a downward component of velocity.  The downward acceleration of the air is what produces the force) and also by the circulation of air around the wing (I kinda suck at putting this into words, but for reasons I've forgotten, when a wing (or just flat piece of material) moves through the air, a circulation pattern is set up (but due to the high speed of the wing relative to the air mass, the resultant effect is that the velocity is lower on the bottom of the wing, and higher on the top, and therefore the pressure is higher on bottom & lower on top) and because of this there's a net upwards force).

if you want a superb website to begin understanding aerodynamics, here's where you should start, IMO: http://www.grc.nasa.gov/WWW/K-12/airplane/bga.html

You sir are correct.

The whole concept of 'air moves faster to catch up with the slower air' crap is wrong. THIS is why airplanes can fly upside down without falling out of the sky. Otherwise, the vector of lift would be pointing downwards along with gravity.

[Rino]

     Some planes are so ugly that the Earth repels them, the Stuka is a fine example 

[Motherland]

Couple NASA articles on the production of lift

'Flow turning'- what, according to NASA, produces lift
http://www.grc.nasa.gov/WWW/K-12/airplane/right2.html

What somerled is talking about, the most popular myth about the production of lift
http://www.grc.nasa.gov/WWW/K-12/airplane/wrong1.html

Venturi Theory
http://www.grc.nasa.gov/WWW/K-12/airplane/wrong3.html

'Skipping'
http://www.grc.nasa.gov/WWW/K-12/airplane/wrong2.html

Mis-application of Bernoulli's principles...
http://www.grc.nasa.gov/WWW/K-12/airplane/bernnew.html

[CAP1]

     Some planes are so ugly that the Earth repels them, the Stuka is a fine example 

nonononono silly sapp person dood. you're thinking of helicopters, and me-109's. 

[Stalwart]

An even better question... 

How can a man pour a glass of ice tea, without spilling a drop, while piloting an aircraft through a barrel roll.   

Check it out, and don't miss the passage beginning at about 2:30

http://www.youtube.com/watch?v=9ZBcapxGHjE&feature=player_embedded#!

[Tupac]

Its alright, all 800,000 certificated pilots in the US were taught false information about the Bernoulli Principle. It makes so much sense, it has to be incorrect!

[CAP1]

get a low speed fan, a smoke machine, and an r/c model. you don't need to run the model. just run the smoke across the wing. you'll see how it works.

[Somerled]

Its alright, all 800,000 certificated pilots in the US were taught false information about the Bernoulli Principle. It makes so much sense, it has to be incorrect!

If they are being taught that lift is generated by having to go faster to catch up with slower air under the wing, then yeah, they are being taught incorrectly.

Ask yourself this: Why does air going over the top of a wing care what speed air going under the wing is going? Why does it want to catch up?

[Cougar68]

Ask yourself this: Why does air going over the top of a wing care what speed air going under the wing is going? Why does it want to catch up?

You have to look at air as a fluid, and also as being in a static state.  Before the air moves over the wing it is basically stationary in relation to the airplane.  If you were to move a wing through water the displaced molecules would try to rejoin at their original spot after the wing passes.  It's the same for air.