Machines | How do Wings generate LIFT ?

videos | at work | information | view | construction

1. As to why the top streamline accelerates, that is due to Bernoulli's principle an the fact that the air is taking energy from the aircraft's forward motion. But it is due to the drop in pressure and not the other way round that generates lift. That's the misconception.
2. i dont understand what ur saying at 4:05-4:30
   why should the pressure increase as we go towards the airfoil from the bottom side?
   and pressure may not be the reason for the curvature of the air flow
   
   for the water spray on bottle experiment it may be due to waters adhesive nature which is why it tries to wet surfaces
3. Water does not follow the curvature of the bottle for the same reason the wind curves over the wing.
4. Very Interesting, but I think that the truth is between theses two theories. As you shown airflow above the wing is faster, so along this streamline Bernoulli principle applies and lower the pressure of the air flowing above the wing. In the mean time the airflow below the wing is not as fast so the pressure doesn't drop as much, this creates lift too! So Bernoulli principle can explain lift even if equal time argument is wrong.
   Speaking about the equal time argument. I agree that in a wind tunnel where there is an airflow over a stationnary wing nothing tells us that the air should travel the same distance. But there is two things to take in consideration. First (I'm not sure about that ) the air flow above the wing go through a narrower path, and since the pressure doesn't go up(no flux) , it must flow faster to conserve the flux. Second, in real airplane it's the wing that is moving through relatively static air, in that case the equal time argument makes sense because the air is displaced verticaly but not horizontaly, so the horizontal position relative to the wing stays the same for all the air (due to inertia). In that case the geometry of the wing lead to a longer path for the same horizontal distance.
   And at last I'm not convinced by your argument about the reversed shape, yes the third law of motion is stronger in your example but none of your wings are aerodynamic and the dragging that this generate could counter any lift produced by Bernoulli principle.
   I'm no physicist so any feedback are welcome.
5. Hi Learn Engineering.... thanks for your video... I'm like it very much.. but I'm confuse about one thing.. this Coanda effect should affect the downforce of a supercar in the same manner... I mean in opposite direction right?... but how come the supercar like Ferraris and McLarens have the same convex surfaces on top with flat surfaces on the bottom in order to achieve a greater downforce? should it be another way around? Thanks...
6. Great video! I would love to learn more about how to do cfd myself. Are there any resources you'd recommend? Take care!
7. when the vilosity is high as on the front top of the wing section the the pressure is low also when velosity is low the pressure is high creating lift on the bottom of the wing
8. Is this the exact same theory for a wind turbine? as for regarding, the upper and lower pressure for the wing on a turbine, because, the wing is vertical, and therefore the pressure, is constant on both the sides?
9. it is funny how can physicist debate about how plane can fly? it's like someone can make machine to fly and it is worked very well but they still debate how this machine it work.
10. So why is the tip of the wing not sharp, to have less drag?
11. The answer is Bernoulli. =D
12. 1:55
    But if the air is at rest and the plane is moving, in the referential of the plane, shouldn't the particles reach the end of that trajectory at the same time, since they don't have a horizontal component of the velocity?
13. that's a very naive explanation, very simplistic ...
    Read this book: Understanding Flight , by David Anderson
    One error: The profile of a wing has nothing to do with lift, it does affect its efficiency only....again, read the book
14. how to know air flow vellocity?
    can i use sensore?
15. hi there learn engineering,
    
    i just read all of nasa's parts on lift theories and they explain that the explanation using Newton's third law om motion is false due to something called Leenward(parts of the solid body facing anotherway and deflecting air that way)? could you confirm and or explain this?
16. I spent many years windsurfing and studying sail design. In windsurfing, you can feel all the forces on the sail, when it's in the sweat spot, powered up and pulling the way you want. When the draft is moving around and how a little downhaul or a carbon mast can make a lot of difference. 10 times more than on most sailboats with a fixed rig. Speaking of sails and not wings the equal and opposite forces make a lot of sense to me. Over the years, as sail technology advances and the mast become more streamlined with the sail the corresponding performance increase comes up short possibly because they are always counting on two-thirds of the lift coming from the lee side of the sail? I think like you said, it's simply how much force/ air you can bend... or stall in at times. It doesn't matter what side of the sail the power comes from. Often a larger sail will do more good than one with a more streamlined entry.
    Also not mentioned, and sailors know, as you get closer to the water surface the wind speed drops on average but also becomes erratic and full of flaws, eddies and swirls. Hard to generate lift in those conditions and easier to get a push.
17. well, I guess everything I knew about airfoils was wrong. Or not everything, but the reasons behind it. Thanks!
18. there is nothing to slow the air down going over the top for riddle at the end
19. I don't know if I'm super smart or anything but this is super easy for me. (I'm 14)
20. Thanks ,if you have translation for chinese.