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Old 8th Jan 2011, 10:01
  #15 (permalink)  
Join Date: Mar 2005
Location: Uh... Where was I?
Posts: 1,342
Hi, CliveL

I think I understand what the CP and the AC are, at least for practical purposes. Basically the first is where Lift can be considered to act, the second is where changes in Lift can be considered to act. More or less.

But I have always had difficulties in grasping what the Aerodynamic Moment is. I see that you talk about lift due to AoA or incidence, as it is different than the lift due to camber. That is what I don't understand well.

Symmetrical airfoils have no aerodynamic moment because their camber is null, but I don't understand why camber does creates it and AoA alone does not.

What is the origin of the aerodynamic moment? I thought that the circulation around the airfoil created an equal and opposite "circulation" of the airfoil, as I read in a nice Darroll Stinton book. I mean, it is not a "theoretical" moment of a force about a point, but a "pure" moment, like that of a pair of forces with zero net force but a given resultant moment which "phisically exists".

However I can't explain why the circulation due to camber is different to the circulation due to AoA.

I hope you can enlighten me with this thing that has always puzzled me.

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