What are the factors affecting the coefficient of l.ift?

What are the factors affecting the coefficient of l.ift?

 

I'm no expert but I have recently had occasion to do some studying on the lift coefficient at some pages @ NASA. I found them very informative and perhaps you'll find them helpful as well.

 

The Lift Coefficient

The lift coefficient is a number that aerodynamicists use to model all of the complex dependencies of shape, inclination, and some flow conditions on lift. This equation is simply a rearrangement of the lift equation where we solve for the lift coefficient in terms of the other variables. The lift coefficient Cl is equal to the lift L divided by the quantity: density r times half the velocity V squared times the wing area A.

Cl = L / (A * .5 * r * V^2)

The quantity one half the density times the velocity squared is called the dynamic pressure q. So

Cl = L / (q * A)

The lift coefficient then expresses the ratio of the lift force to the force produced by the dynamic pressure times the area.

 

I'm no expert but I have recently had occasion to do some studying on the lift coefficient at some pages @ NASA. I found them very informative and perhaps you'll find them helpful as well.

 

The Lift Coefficient

I don't mean based on the lift force. I mean the factors that affect the coefficient of lift itself

Edited September 21, 201312 yr by Endercreeper01

I don't mean based on the lift force. I mean the factors that affect the coefficient of lift itself

 

I don't understand your equivocation. The entire article at the link goes further into the mathematical constraints/techniques at play, and if that doesn't help you then it doesn't help you.

 

I don't understand your equivocation. The entire article at the link goes further into the mathematical constraints/techniques at play, and if that doesn't help you then it doesn't help yo

It doesn't help very much. I wanted a list of factors.

Edited September 21, 201312 yr by Endercreeper01

It doesn't help very much. I wanted a list of factors.

 

So then it helped some. In what specifics was it helpful? Also, define factors as you intend the term please. I fail to understand your distinction.

Edited September 21, 201312 yr by Acme

 

So then it helped some. In what specifics was it helpful? Also, define factors as you intend the term please. I fail to understand your distinction.

It actually didn't help at all. And I mean factors as in different things that affect it.

It actually didn't help at all. And I mean factors as in different things that affect it.

 

But you said it didn't help much? Were you mistaken? Confused? Changing your mind? Purposefully posting contradictory statements?

 

Again, the link I gave goes into great detail about the 'things' that affect the coefficient of lift. Do you think those 'things' are wrong? Do you think there are other 'things' needed to determine coefficient of lift? I honestly do not understand the difficulty you are having. Perhaps you have some specific example in mind for which the source I gave is inadequate. If so, please give it so I can understand the issue.

 

 

 

 

But you said it didn't help much? Were you mistaken? Confused? Changing your mind? Purposefully posting contradictory statements?

 

Again, the link I gave goes into great detail about the 'things' that affect the coefficient of lift. Do you think those 'things' are wrong? Do you think there are other 'things' needed to determine coefficient of lift? I honestly do not understand the difficulty you are having. Perhaps you have some specific example in mind for which the source I gave is inadequate. If so, please give it so I can understand the issue.

 

 

 

I changed my mind. And It doesn't go into much detail.

I changed my mind. And It doesn't go into much detail.

 

Ok. You still haven't made it clear what the issue is for you? Are you trying to solve/find a specific coefficient of lift for a specific airfoil? Are you trying to find fault and/or discredit the 'standard' use of the term 'coefficient of lift'? Propose changes? What is the problem?

 

 

 

 

Edited September 21, 201312 yr by Acme

 

 

Ok. You still haven't made it clear what the issue is for you? Are you trying to solve/find a specific coefficient of lift for a specific airfoil? Are you trying to find fault and/or discredit the 'standard' use of the term 'coefficient of lift'? Propose changes? What is the problem?

 

 

 

 

 

I'm simply trying to find the factors that affect the coefficient of lift

I'm simply trying to find the factors that affect the coefficient of lift

 

I simply gave them. Good luck.

For a wide wing and a small angle of attack, this coefficient departs little from its theoretical value as theorized by Joukowski, that is pi*angle (in radian, measured from zero lift angle).

 

If the wing isn't much wider than long, the coefficient drops slowly.

 

Most importantly, there is a maximum value; if the angle still increases, lift drops brutally. The maximum value depends much on the profile design and on added gear, typically landing flaps. Slightly less than 1 for wing profiles optimized for other uses, it reaches 1.3 and little more for thick asymmetric profiles.

 

Beware that many landing flaps also increase the lifting area a lot, but the lift coefficient uses to still multiply the area of the wing with the flaps retracted, in which case the lift coefficient can exceed 1.3 a lot.

 

Beware also that in some books or languages, the lift coefficient does not include the angle of attack.

If you really want to study what affects lift and drag, then get hold of a copy of

 

Physical Fluid Dynamics

 

D J Tritton

 

Oxford University Press

For a wide wing and a small angle of attack, this coefficient departs little from its theoretical value as theorized by Joukowski, that is pi*angle (in radian, measured from zero lift angle).

 

If the wing isn't much wider than long, the coefficient drops slowly.

 

Most importantly, there is a maximum value; if the angle still increases, lift drops brutally. The maximum value depends much on the profile design and on added gear, typically landing flaps. Slightly less than 1 for wing profiles optimized for other uses, it reaches 1.3 and little more for thick asymmetric profiles.

 

Beware that many landing flaps also increase the lifting area a lot, but the lift coefficient uses to still multiply the area of the wing with the flaps retracted, in which case the lift coefficient can exceed 1.3 a lot.

 

Beware also that in some books or languages, the lift coefficient does not include the angle of attack.

Why does the coefficient of lift decrease after that maximum value?

Why does the coefficient of lift decrease after that maximum value?

Stall

 

http://en.wikipedia.org/wiki/Stall_(flight)