Maximum lift coefficient from Polar chart.. how ?

[Pook]

Hiya guys

Ive been having a look into some of the maths involed with flight in an atempt to educate my self a little. :) & ive come accross a problem.


On Martin Hepperle's website there is an equation to calculate the Lift Coefficient

http://www.mh-aerotools.de/airfoils/howdoi.htm#LiftCoefficient

Part of the text says by looking at the polar chart for the selected airfoil, you can find maximum lift coefficient. There is even a link to another page that explaines the polar charts but I still cant figure out what the maximum would be as there dosent seem to be a peak of any kind..

If anyone could poin me in the right direction i would be most grateful.

Piers

[Dick Huang]

Piers,
I could not find any info on Clmax either on your suggested web site. Try reading Clmax from the polar plots on this web site
http://eiss.cnde.iastate.edu/calcs/frames.shtml/
Dick Huang:)

[Pook]

Thanks Dick, ... maybe its just i dont know what im looking for but i still cant figure it out.. hmm


Piers

[Sail 'n Soar]

Better yet, try this one. This gives available calculated and wind tunnel test results for a multitude of airfoils over the range of Reynolds numbers from ~40,000 (small and slow) to full scale range. The CL vs. CD polars will cover well past the useful CL range for any given foil.

http://www.nasg.com/afdb/search-airfoil-e.phtml

Gerry

[Ollie]

Look at the coefficient of lift vs. angle of attack polar. The coefficient of lift increases as the angle of attack increases, along a more or less straight line, until just before the stall where the coefficient of lift reaches its maximum.

[Pook]

Ahh now I understand :) Its all to easy once you know ... thanks very much Ollie

Thanks for that link as well Gerry

Piers

[DLC]

For info on airfoils, I suggest you download the Profili2 software,
at

www.profili2.com

In my opinion it is a real bargain for $10.