Squawk7777
20th Sep 2006, 01:15
I am mulling over the statement that a winglet adds a small lift force that angles forwards the direction of flight. I found a good explanation on wikipedia:
The exact upward angle (called cant) of the winglet, and its inward angle (or toe) is critical for correct performance, and is determined for each aircraft application. The vortex which rotates around from below the wing strikes the angled surface of the winglet, generating a small lift force that angles forwards relative to the direction of flight - thus the energy in the vortex contributes to thrust rather than drag as it normally would. This is analogous to a sailing boat sailing very close to the wind. This small contribution can be very worthwhile on long-distance flights.
I am still not entirely getting it. Does somebody have a good vector diagram how a winglet adds the small lift force in a forward direction or how this can be compared with a sailing boat sailing close to the wind?
Thanks,
7 7 7 7
The exact upward angle (called cant) of the winglet, and its inward angle (or toe) is critical for correct performance, and is determined for each aircraft application. The vortex which rotates around from below the wing strikes the angled surface of the winglet, generating a small lift force that angles forwards relative to the direction of flight - thus the energy in the vortex contributes to thrust rather than drag as it normally would. This is analogous to a sailing boat sailing very close to the wind. This small contribution can be very worthwhile on long-distance flights.
I am still not entirely getting it. Does somebody have a good vector diagram how a winglet adds the small lift force in a forward direction or how this can be compared with a sailing boat sailing close to the wind?
Thanks,
7 7 7 7