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> It's pretty obvious that the wings push air down The air being pushed down is actually a side-effect of the lift-creation process, not the cause of it. A ni

> It's pretty obvious that the wings push air down The air being pushed down is actually a side-effect of the lift-creation process, not the cause of it. A nice "counter example" is a wing in ground effect (flying very close to the ground), where there is less downwash, because of the ground, and yet the wing produces more lift. It's an effect that can make high aspect-ratio airplanes tricky to land.

deleted 2y ago
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JumpCrisscross 2y ago
> air being pushed down is actually a side-effect of the lift-creation process, not the cause of it The turning of the gas is absolutely what causes lift. (Where the Newtonian explanation is misleading is in “neglect[ing] the physical reality that both the lower and upper surface of a wing contribute to the turning of a flow of gas” [1]. Put another way: if you know the mass and acceleration of the gas about the wing, you can calculate lift. (This is impractical for many reasons.) > a wing in ground effect VTOL aircraft also experience ground effect due to the fountain effect. [1] https://www.grc.nasa.gov/www/k-12/VirtualAero/BottleRocket/airplane/bernnew.html https://www.grc.nasa.gov/www/k-12/VirtualAero/BottleRocket/a...
- HPsquared 2y ago
  Curvature of streamlines is related to pressure gradient across said streamlines.
  - JumpCrisscross 2y ago
    > Curvature of streamlines is related to pressure gradient across said streamlines Sure. Ultimately just considering pressure or mass deflection doesn’t work without elaborate workarounds. Because neither describes the reality of an airfoil turning a moving viscous fluid.
- fransje26 2y ago
  > The turning of the gas is absolutely what causes lift. No. What causes lift is the differential in pressure between the top and the bottom surface of the wing. The rest is broadly speaking a side effect. If the turning of the gas was the necessary mechanism for lift, planes in supersonic flight would fall out of the sky. Instead of relying on an airfoil shape for lift, you could fly by sucking air from the top of your wing and dumping out the back of your plane.
  - dan_hawkins 2y ago
    > No. What causes lift is the differential in pressure between the top and the bottom surface of the wing. How do you explain airplanes that can fly with wing with symmetrical cross-section profile? How do you explain airplanes flying upside-down?
    - bbojan 2y ago
      > How do you explain airplanes that can fly with wing with symmetrical cross-section profile? > How do you explain airplanes flying upside-down? Angle of attack is what causes lift. If you have a surface angled against the relative wind, it will produce lift.
      - dan_hawkins 2y ago
        I know all of that. I wanted to provoke parent commenter to let them see that the Bernoulli effect doesn't explain my two examples.
    - bdamm 2y ago
      The Bernoulli effect only contributes to making wings more efficient. It isn’t fundamentally why lift occurs. You can make almost anything fly if you have enough power and a tail. But how efficient will it be? Not as efficient as an airfoil that takes advantage of all the fluid motion properties.
      - dan_hawkins 2y ago

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JumpCrisscross 2y ago

> air being pushed down is actually a side-effect of the lift-creation process, not the cause of it The turning of the gas is absolutely what causes lift. (Where the Newtonian explanation is misleading is in “neglect[ing] the physical reality that both the lower and upper surface of a wing contribute to the turning of a flow of gas” [1]. Put another way: if you know the mass and acceleration of the gas about the wing, you can calculate lift. (This is impractical for many reasons.) > a wing in ground effect VTOL aircraft also experience ground effect due to the fountain effect. [1] https://www.grc.nasa.gov/www/k-12/VirtualAero/BottleRocket/airplane/bernnew.html https://www.grc.nasa.gov/www/k-12/VirtualAero/BottleRocket/a...

HPsquared 2y ago
Curvature of streamlines is related to pressure gradient across said streamlines.
- JumpCrisscross 2y ago
  > Curvature of streamlines is related to pressure gradient across said streamlines Sure. Ultimately just considering pressure or mass deflection doesn’t work without elaborate workarounds. Because neither describes the reality of an airfoil turning a moving viscous fluid.
fransje26 2y ago
> The turning of the gas is absolutely what causes lift. No. What causes lift is the differential in pressure between the top and the bottom surface of the wing. The rest is broadly speaking a side effect. If the turning of the gas was the necessary mechanism for lift, planes in supersonic flight would fall out of the sky. Instead of relying on an airfoil shape for lift, you could fly by sucking air from the top of your wing and dumping out the back of your plane.
- dan_hawkins 2y ago
  > No. What causes lift is the differential in pressure between the top and the bottom surface of the wing. How do you explain airplanes that can fly with wing with symmetrical cross-section profile? How do you explain airplanes flying upside-down?
  - bbojan 2y ago
    > How do you explain airplanes that can fly with wing with symmetrical cross-section profile? > How do you explain airplanes flying upside-down? Angle of attack is what causes lift. If you have a surface angled against the relative wind, it will produce lift.
    - dan_hawkins 2y ago
      I know all of that. I wanted to provoke parent commenter to let them see that the Bernoulli effect doesn't explain my two examples.
  - bdamm 2y ago
    The Bernoulli effect only contributes to making wings more efficient. It isn’t fundamentally why lift occurs. You can make almost anything fly if you have enough power and a tail. But how efficient will it be? Not as efficient as an airfoil that takes advantage of all the fluid motion properties.
    - dan_hawkins 2y ago