Thrust From United States of America, joined Sep 2003, 2691 posts, RR: 9 Posted (10 years 7 months 3 days 2 hours ago) and read 4118 times:
I was just wondering what the differences in benefits are between the following: raked wingtips, wingtip fences, the winglets on the Airbus A330s and A340s, and Boeing's blended winglets. Yes, they are designed to reduce cruise efficiency and allow a slight increase in range, but why not choose all blended winglets? Please tell me the specific benefits of winglets, raked wingtips, winglet fences, etc. I just want to know what each of these is best at, and not good at.
Starlionblue From Greenland, joined Feb 2004, 17296 posts, RR: 67
Reply 2, posted (10 years 7 months 2 days 18 hours ago) and read 4002 times:
The simplest way to put it that one flavor does not suit all planes. For example, you could of course put raked wingtips on the A380, but this would bump the wingspan above 80m, an unacceptable width for the airport.
QantasA332 From Australia, joined Dec 2003, 1500 posts, RR: 24
Reply 8, posted (10 years 5 months 4 weeks 19 hours ago) and read 3419 times:
They're called "spiroids," and they were pioneered by the engineers at Aviation Partners. I'm not 100% as to whether they can technically be classed in the category of winglets, as the device surfaces may or may not be designed to produce forward lift - thrust - which is the basic determining characteristic of winglets. Rather, they're simply yet another design in the ever-growing group of effective aspect-ratio devices.
At any rate, spiroids sort of operate along the lines of drooped tips. Drooped tips deflect the wingtip vortices away from the wing as they begin to rotate up and around, thus distancing them from, and reducing their effect on, the wings. While spiroids aren't really deflecting the vortices away from the wing, they diffuse the vortices and reduce vortex interaction with the departing airstream. This has the obvious drag-reducing effects, as it limits downwash and accordingly reduces induced drag. On the particular design shown in the pictures above, it was said that the spiroids reduced drag in cruise by as much as 10%.
Lehpron From United States of America, joined Jul 2001, 7028 posts, RR: 20
Reply 14, posted (10 years 5 months 3 weeks 4 days 3 hours ago) and read 3300 times:
You know, a forward swept wing could kill off all of the induced drag simply becuase the induced flow would be going inwards instead of outwards, the vortex has NO interaction with the wing, if anything it will enhance the lift features by sucking down the back of the fuselage. You can cut the drag by up to 29%! The difficulty comes from its loading, most happens at the tips and not the roots.
With winglets, to be perfectly honest (and I will get slamed for this) I see them all as functionally the same. Their names and shapes almost don't matter to me. But some people/customers are asthetically obcessive apart from justifying the costs/weight.
From what I can tell, there are currently two different kinds, one decreases the rotation of the induced vortex itself and the other is actually a micro delta surface that spins its own vortex as it trys to produce lift and the main induced flow gets caught up in it reducing the size of the whole.
The first is either vertical or curved up and might be for allowing closer separation of large planes. The latter is usually parallel with the wing and may reduce the impact of the vortex on the plane's wing downstream, as QantasA332 stated, the " they diffuse the vortices and reduce vortex interaction with the departing airstream".
I think another can be designed within the next few decades, one where it severely disturbs the rotation of a vortex, killing it's effect on anything. The only way I can think of is to mix the rotating flow in one direction with the other direction; it should cancel out. I guess this would be curved down or going in an inverted ringlet arraingment...just an idea...that I thought of a long time ago but since subsonics weren't my thing then, well...
The meaning of life is curiosity; we were put on this planet to explore opportunities.
57AZ From United States of America, joined Nov 2004, 2586 posts, RR: 2
Reply 16, posted (10 years 5 months 2 weeks 6 days 21 hours ago) and read 3214 times:
In answer to Santhosh's question, winglets are manufactured by private aerospace companies. NASA has performed a significant amount of research on airfoil designs, including winglets and forward swept wings. In the United States. the two largest manufacturers of winglet mod packages are probably Aviation Partners and Riley Aircraft Modifications (RAM). As winglets require modification to the airframe, modifications have to be approved by the Federal Aviation Administration for each different aircraft model. Due to the costs involved, very few aircraft are modified with winglets. Our airplane, a 1981 Cessna 414A is one of only a few high performance piston twins to have the RAM winglets added. Its not a full RAM modified aircraft as it does not have the liquid cooled engines. Most winglets that appear on corporate jets are designed as an integral part of the airframe and are either manfactured by the aircraft builder or a factory installed modification provided by an outside supplier such as Aviation Partners or RAM.
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