Source of Induced Drag

A couple of recently read articles described different sources for
induced drag.

One attributed the drag to the wingtip vortices ... increased angle of
attack created bigger vortices.

Another said the drag was the result of the lift vector tilting
backwards at higher angles of attack ... creating a rearward 'induced
drag' resultant.

I have heard the tip vortex explanation before ... the induced drag
vector seems plausible ... does it have any merit.

If induced drag is a result of both of these effects ... what is the
relative weight of each?

gracias'

KK

Ken Kochanski wrote:
A couple of recently read articles described different sources for
induced drag.

One attributed the drag to the wingtip vortices ... increased angle of
attack created bigger vortices.

Another said the drag was the result of the lift vector tilting
backwards at higher angles of attack ... creating a rearward 'induced
drag' resultant.

I have heard the tip vortex explanation before ... the induced drag
vector seems plausible ... does it have any merit.

If induced drag is a result of both of these effects ... what is the
relative weight of each?

They are pretty much two different explanations of the same effect. The
tip vortex creates a downwash on top of the wing, which means it has to
tilt back to fly in the downward flow, which tilts its lift vector aft...

Hey Ken - You need a copy of Jud Milgram's translation and extension
of Thomas' "Fundamentals of Sailplane Design". So does anyone else
interested in these matters (interested enough to get better calibrated
answers than RAS ;-). Available from Knauff & Grove, Amazon, Sailplane
Homebuilder's Association, etc.

Happy 2004, Best Regards, Dave "YO"

(Ken Kochanski) wrote in message . com...
A couple of recently read articles described different sources for
induced drag.

One attributed the drag to the wingtip vortices ... increased angle of
attack created bigger vortices.

Another said the drag was the result of the lift vector tilting
backwards at higher angles of attack ... creating a rearward 'induced
drag' resultant.

I have heard the tip vortex explanation before ... the induced drag
vector seems plausible ... does it have any merit.

If induced drag is a result of both of these effects ... what is the
relative weight of each?

gracias'

KK