Raked Wingtips - How do they work?

[kiwi_pilot_12]

Hi all,

I understand that both winglets and raked wingtips are for the same function (from what I have read) - to reduced the amount of induced drag.

I understand the principles behind winglets, however I am uncertain how raked wingtips actually achieve this? Could anyone please explain the aerodynamics behind it.

Thanks

[garyscott]

A little light bedtime reading, hopefully what you seek may be contained within??

http://www.smartcockpit.com/docs/Wingtip_Devices.pdf

https://www.diva-portal.org/smash/get/diva2:547954/FULLTEXT01.pdf

[JammedStab]

An interesting comparison on the effect of a 744 winglet versus a 777-300ER raked wingtip.

If departing with one winglet missing on the 744, the CDL has a weight penalty of approximately 9500 kg.

If departing with a raked wingtip missing on the 777, the penalty is a little over 11,000 kg(or more than 26,000 kg above 2000') but there is a MTOW restriction of over 50,000 kg. Plus other penalties such as reduced MQTW, a max altitude decrease, slightly higher V-speeds, and a reduction in CG envelope.

[underfire]

Thanks Gary...

Interesting to compare the documents. The Boeing doc only provides Mach .78
It would be very interesting to see the drag numbers at other velocities.

now about those vortex tabs running down the wings....