Airfoil(2d) vs wing(3d) & aspect ratio

August 17, 2005, 22:52

Hi,

I know that for an airfoil, air is not able to flow up and around the wingtip to create trailing vortices, as compared to a finite wing.

The amount of difference in cl and cd(?) is dependent on the aspect ratio (AR).

However, in practice, below what AR value 'll the difference be unacceptable? Most books just use "large" or "small" with no actual values...

thanks

August 18, 2005, 01:27

Nicolai "Fundamentals of aircraft design", pp 9-12 defines High Aspect ratio wing as one where

AR is greater than 4/(c1+1)/cos(LEsweep angle)

where c1 is a function of taper ratio and is given is US DATCOM or Nicolai.

I will just list a few number as I read from the figure (there might be some error in reading)

c1(taper ratio)

0(0) .25(.1) .5(.2) .4 (.4) .2 (.6) .05 (.8) 0 (1)

I hope this helps

August 17, 2005, 22:52	Airfoil(2d) vs wing(3d) & aspect ratio	#1
quarkz Guest Posts: n/a	Hi, I know that for an airfoil, air is not able to flow up and around the wingtip to create trailing vortices, as compared to a finite wing. The amount of difference in cl and cd(?) is dependent on the aspect ratio (AR). However, in practice, below what AR value 'll the difference be unacceptable? Most books just use "large" or "small" with no actual values... thanks

August 18, 2005, 01:27	Re: Airfoil(2d) vs wing(3d) & aspect ratio	#2
Guest Guest Posts: n/a	Nicolai "Fundamentals of aircraft design", pp 9-12 defines High Aspect ratio wing as one where AR is greater than 4/(c1+1)/cos(LEsweep angle) where c1 is a function of taper ratio and is given is US DATCOM or Nicolai. I will just list a few number as I read from the figure (there might be some error in reading) c1(taper ratio) 0(0) .25(.1) .5(.2) .4 (.4) .2 (.6) .05 (.8) 0 (1) I hope this helps

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