Quote:
Originally Posted by jakobnev
On a more serious note:
But in the end people just went with winglets that reduce the formation of vortices in the first place.
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Barnard and Philpott (
Aircraft Flight, 1995) describe how wingtip feathers on birds give thrust from wingtip vortices. They also make the point that the number of feathers is always an odd number.
![](https://www.researchgate.net/profile/Simona_Fialova/publication/337748046/figure/fig2/AS:870028303949826@1584442320949/Rising-feathers-at-the-periphery-of-an-eagles-wings.png)