Talk:Lift-induced drag

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According to what is written it could be understood that there is two sources of induced drag: Due to lift generation( could be understood that it appears in 2-Dimentional flow) Due to tip effect (could be understood as 3-Dimentional since tip vortices are 3-d) the question is:

what is the equation of induced drag in 2-D flow?
what is the equation of induced drag in 3-D flow?

IF ANY ONE CAN HELP ME please mail me at mohamadcharif@yahoo.com

The 2-D flow means the same as a wing od infinite span to chord ratio - and in this case the lift induced drag is zero.

In real 3-D case induced drag is the function Ci=(Cy)^2/Pi*A and is caused by the tip vortexes (mainly) and other trailing vortexes.

andrzejmat 16:13, 7 April 2006 (UTC)

[edit] Simplification

I'm thinking of adding this, early in the article: "Lift induced drag is caused by the lift component of the wing being rotated backwards relative to the aircraft's motion, resulting in a drag component." Seem reasonable? Mat-C 16:31, 24 August 2005 (UTC)

This is how the article originally defined Lift-Induced drag, but since then others have taken issue with this approach saying that it's an over-simplistic picture and not reflective of what's truly going on. If you check through the history you'll see this, inclusing a diagram (which I drew) which is no longer used in the article. Graham 00:11, 25 August 2005 (UTC)

[edit] Error

"k is the factor by which the induced drag exceeds that of a wing of infinite span typically 1.05 to 1.15" is not true of course. Not" a wing of infinite span", but should be there "a wing of otimum (eliptical) planform."

andrzejmat 16:13, 7 April 2006 (UTC)

Agreed.--FHBridges 17:12, 13 June 2006 (UTC)

[edit] Edit of 05.10, 9 October 2007

In this I chose to Undo the immediately prior edit on the grounds: 1) The wingtip vortex is not the Source of induced drag, it is a manifestation of the spanwise flow which is the Source. 2) The later section of the Undone text essentially repeated what was previously said in the Section. While it is true that the energy content of the tip vortex is equal to the energy loss due to induced drag, and of mathematical value to the aerodynamicist, it is confusing to a lay reader to see two apparently conficting statements as to the source in the section 'Source'. Geoffrey Wickham 05:32, 9 October 2007 (UTC) Ref: 'Theory Of Flight', Richard Von Mises (Dover Books) sections VIII & IX. Geoffrey Wickham 05:51, 9 October 2007 (UTC)