centre of pressure

[kinex]

I am doing my final uni assignment on Determining the "Stick Fixed Neutral Point "on an aircraft
Can anyone tell me how to calculate the distance from the leading edge to centre of pressure and Aerodynamic Centre on the aerofoil or any information that i can look up from the Internet.
(Assuming that L is linear up to 12 AoA and Coef Lift is 0 if AoA = 0)

thanks
Kinex

[Genghis the Engineer]

Centre of pressure


k(cp) = x(ac)/c =

Cm
--------------------------------
Cl.cos(alpha) + Cd.cos(alpha)

= centre of pressure position.


Aerodynamic Centre

Work out k(cp) for a series of values of Cl. Then plot a graph of k(cp) on the horizontal axis against Cl on the vertical axis. Cl will apparently diverges to infinity at a value of k(cp) that is likely to be somewhere between 0.15 and 0.3 - for most aerofoils about the quarter chord point.

That value of k(cp) is the position of the aerodynamic centre, k(ac).

(If you want to look at it another way, k(cp) asymptotes to k(ac) at normal to high Cl values.

G



Suggestion to the moderator, would this thread not be better off in tech-log?