General expression of wind force on a sail....

[vinnie78]

I believe your trying to understand lift in aviation better.

I will try to explain the principle.
So the wing design causes the wind flow to move over the top of the wing at a faster rate. Compared to the flow of air under the wing. The increased speed causes an are of lower pressure above the wing. Not being a closed system like in hydraulics this is the case. The reaction is the same as when you draw on a straw. You lower the ambient air pressure inside the straw. The greater ambient air pressure on the remaining fluid being greater. The fluid is pushed up into the straw for you to drink. With a wing the same effect is expressed. Lower pressure above the aircraft raises up and achieves lift.

If the lift value is greater than gravitational weight of the object.

 

[berkeman]

I will try to explain the principle.
So the wing design causes the wind flow to move over the top of the wing at a faster rate. Compared to the flow of air under the wing. The increased speed causes an are of lower pressure above the wing. Not being a closed system like in hydraulics this is the case. The reaction is the same as when you draw on a straw. You lower the ambient air pressure inside the straw. The greater ambient air pressure on the remaining fluid being greater. The fluid is pushed up into the straw for you to drink. With a wing the same effect is expressed. Lower pressure above the aircraft raises up and achieves lift.

https://www.physicsforums.com/insights/airplane-wing-work-primer-lift/

Discussion thread: https://www.physicsforums.com/threa...e-wing-work-a-primer-on-lift-comments.845786/

 

[vinnie78]

So your asking or saying?

Air density changes a wings lift value. I fly in colder more dense air, I get better lift and max elevation from my aircraft. Hotter less dense air, I get less lift and a lower max elevation. Overcoming oxygen requirements, should I fly in different environments such as another planet. Density of air will change my lift. The atomic weight of mass may change due to gravitational differences requiring more lift overall.

With hydrofoil lift.
A positive nose down attitude from rear wing just behind center of gravity is best. Rear wing carrying most of the weight. The forward wing will require a drastic angle of attack increase to counter act expected Stern over Bow effect.

 

[berkeman]

Thread closed temporarily for Moderation...

 

[berkeman]

So your asking or saying?

My point was that how a wing produces lift is fairly complicated, and has been discussed at length here at PF. By giving you that reference I wanted to be sure that you had good information to go on in the future.

After some Moderation chores, the thread is reopened.

 

[cjl]

I believe your trying to understand lift in aviation better.

I will try to explain the principle.
So the wing design causes the wind flow to move over the top of the wing at a faster rate. Compared to the flow of air under the wing. The increased speed causes an are of lower pressure above the wing.

Yes... ish. This often leads to further misunderstandings though, such as the equal transit time assumption (which is just flat out wrong), or the belief that "bernoulli" and "Newton" are somehow two separate effects that compete to explain lift. In reality both are effectively conservation statements and in any (reasonably incompressible) flowfield, the bernoulli relation will hold everywhere around the wing, the lower pressure region on top will be flowing faster (in keeping with the bernoulli relation), and you can completely calculate the lift if you know the velocity field around the wing just by applying bernoulli and integrating the resulting pressure around the wing surface. However, you can also entirely calculate the lift by measuring downwash behind the wing and applying a Newton's 3rd relationship to relate the upward force on the wing to the downward momentum flux applied to the flow. These are not competing explanations, they are both just part of the overall physics, and, importantly, neither actually gives you a way to figure out what that lift or flowfield looks like in the first place.

Getting a more complete explanation of exactly why a wing directs flow downward effectively and creates a high velocity region above the wing requires discussion of viscosity, circulation around the wing (which is what that ring of arrows is showing in the diagram on the prior page, as was already correctly surmised), and the fact that a sharp trailing edge effectively enforces the location of the rear stagnation point in the flowfield.

This complexity and common confusion is a large part of why boneh3ad wrote that post years ago in the first place, so as to have an easy article to link when people ask about lift generation here.