At 01:27 PM 11/7/2005, you wrote: >I would like to see that reference, I would be >surprised if the center of lift didn't move some with >changes in AoA.
These last few posts have mixed a number of different aero terms. The 1/4 chord location is located 0.25 times the chord back from the leading edge and on the chord line. In x/c , y/c coordinates that means 0.25, 0.0 The aerodynamic center is the point at which the pitch moment is constant. It is near the 1/4 chord location but generally a little behind it. It can be above or below the chord line but it is generally near the chord line. This is the point where all most all modern aero design is based. It does not move to any significant degree over any angle of attack below stall. On a symmetrical airfoil, the 1/4 chord is the aerodynamic center. Based on my calculations, the aerodynamic center of the AS series in x/c , y/c coordinates is: AS5045 0.2533, -0.0006 AS5046 0.2539, -0.0007 AS5048 0.2566, -0.0012 and for comparison, the RAF48 is 0.2528, -0.0005 The center of lift and center of pressure are older terms that mean a point at which the pitch moment is equal to zero. These move with the angle of attack. They are difficult to use in any real aeronautical calculation but they still show up in older reference books. Don Reid - donreid "at" peoplepc.com Bumpass, Va Visit my web sites at: AeroFoil, a 2-D Airfoil Design And Analysis Computer Program: http://aerofoilengineering.com KR2XL construction: http://aerofoilengineering.com/KR/KR2XL.htm Aviation Surplus: http://aerofoilengineering.com/PartsListing/Airparts.htm EAA Chapter 231: http://eaa231.org Ultralights: http://usua250.org VA EAA Regional Fly-in: http://vaeaa.org
