Do you really understand Wing lift?

[David Megginson]

When I was a kid, I stuck my hand out of the car window. As my hand rushed through the air, my hand got pushed upward.

I'm good with that part. If I start to design airplanes, I'll go further.

As long as you noticed what happened when you tilted your hand too far up, you're good to go.

 

[Checkout_my_Six]

Here you go.....my man Doc JD...my old prof.

https://www.scientificamerican.com/article/no-one-can-explain-why-planes-stay-in-the-air/

John D. Anderson, who stated, “There is no simple one-liner answer to this.”

So....it depends. lol

 

[Snowmass]

Although it was not my original intention the many posts on this subject has started me thinking a bit more deeply even though my last general physics course was in high school. So my hypothesis is that if air were to have no viscosity all flow would be laminar.

 

[Checkout_my_Six]

Although it was not my original intention the many posts on this subject has started me thinking a bit more deeply even though my last general physics course was in high school. So my hypothesis is that if air were to have no viscosity all flow would be laminar.

why?

 

[Snowmass]

why?

Because if the air is laminar approaching (an assumption) so why should it become turbulent passing over the wing (or other structure) except for drag between layers causing it to spin (tumble) instead of just smoothly changing direction.

 

[Checkout_my_Six]

what about surface tension?

 

[Snowmass]

what about surface tension?

Maybe. But it can't be just an abrupt change in direction since the is little turbulence at the front of a wing but the air molecules make a very sharp direction change. We automatically assume that air will tumble on trailing side of an obstacle but exactly why. I have been thinking that it's the drag (shear force) between layers of different velocity that causes a turning moment which is pretty much what turbulence is. On the front of a wing the impact of the incoming molecules on the other air molecules keeps them in more order but on the trailing side the air pressure is less so less so less anti-tumbling restraint.

All this is pure speculation but I am curious about just about everything.

 

[Checkout_my_Six]

as doc Anderson was describing....the description of the flow is not linear and depends on the compressibility of the fluid.

trans-sonic and above take on different characteristics than slower, "incompressible", flows....

 

[Brad Smith]

What about knife-edge flight? The fuselage becomes a lifting surface and a very poor airfoil at that.

 

[Capt. Geoffrey Thorpe]

What about knife-edge flight? The fuselage becomes a lifting surface and a very poor airfoil at that.

Which is why it requires a lot of help from the prop along with a decent speed. If you watch the RC guys do it, they can slow down quite a bit, but end up with about a 45 degree (or more) nose above the horizon attitude.