Re: Do winglets produce thrust?

Jon Meyer wrote:

> You could describe it as 'interfering with the formation
> of the tip vortex and thereby reducing drag', but an
> easier to understand explanation (and just as accurate)
> is that of the Thrust component of the force vector
> produced by the winglet. The crossflow component generated
> by the tip vortex means that the angle of incidence
> of the winglet relative to the flow is different to
> that relative to the line of flight. If this angle
> is large enough then the winglet itself will no longer
> produce a force component opposing the direction of
> travel, but will instead produce a small 'Thrust' component
> in the direction of travel. The fact that the winglet
> is in fact producing a force in the direction of travel
> is why the term 'Thrust' is perfectly correct. 
> Its easier to explain using a diagram, and plenty of
> textbooks have them if you really are that interested.
> The important thing to remember is that because of
> the influence of the tip vortex, the flow striking
> the winglet is not travelling in the same direction
> as the freestream velocity. Thats what makes it all
> possible.

Ok, so my diagram of the winglet isn?t ok, because the airflow has an
inbound direction. And so it?s possible that it?s lift can be divided
into a inbound component an a thrust-component. I think now I got it.
See also: http://www.ich-habs-doch-gleich-gesagt.de/winglet2.gif

Greetings

Bernhard