Why the REALLY big winglets on CO aircraft?
 

As we were driving aimlessly around the EWR taxiways in our 738 last Sunday prior to liftoff, I had the opportunity to observe a wide range of aircraft.

I noted that the retrofitted winglets on our 738 and on a CO 757 were much larger than those on a 744 and an A330 (at least they seemed to be--optical illusion?), not to mention the baby winglets on A320s that extend both up and down.

I seem to recall that the retrowinglets on Southwest 737s are also huge.

Is this a case of: If small winglets are good, giant winglets must be better? Any aerotechgeeks out there?

The goal of the winglet is basically nothing more than reduce induced drag - which occurs when the air flowing across the top of the wing curls downwards at the wingtip and wraps around the air flowing across the bottom of the wing which wraps upwards - creating the horizontal tornado flows called wingtip vortices....which at slow speeds and low altitudes create the wake turbulence that can cause accidents with smaller aircraft

The winglets interfere with this air flow phenomenon. As far as big versus small - I think it's just a design feature that takes into account the balance between the amount of induced drag created by that particular airfoil versus the trade off of additional parasite and form drag caused by the winglet itself.

The small winglets were earlier iterations of this concept - the A300 has tiny winglets, while the A319/320 has slightly larger versions of the same shaped winglet.

These new generation blended winglets might also provide additional lift while reducing drag, making them more efficient than the block-style winglets that just reduce induced drag. That is my best guess - I dont know enough about this new product to say what the specific technical advantage is.

LOL what a fabulous explanation - although to make it simplier the blended winglets on the 738s save about 10% on fuel consumption.

-Vincent

Being one that doesn't like change, I am surprised how much I like the looks of the newest winglets. Now when I see a 737 without them they look like they are missing something.

Don't want to start an argument because I only know a little about this from what I've read, but I was under the impression that it is supposed to save about 5% on fuel. Which is why Boeing never bothered with it originally. But then again .... well, see my sig line ;)

EmailKid

I think it is about 10% improvement at cruise, but with a small penalty when taking off and climbing because of the extra weight. I've seen claims of an overall 8% extension in range somewhere on the manufacturer's website IIRC. Obviously, the net benefit on a short flight is going to be very small or even negative. Can anybody comment on the "breakeven" length of a flight?

The official word:

"The addition of Aviation Partners Blended Winglets to the 737 Next Generation has demonstrated drag reduction in the 5 to 7% range that measurably increases range and fuel efficiency . In addition, the Blended Winglets allow the 737-NG to take off from higher, hotter airports with increased payload. "

"By increasing Payload Range and Overall Performance, Blended Winglets add flexibility to fleet operations and route selection. Air Berlin notes, "Previously, we'd step-climb from 35,000 to 41,000 feet. With Blended Winglets, we can now climb direct to 41,000 feet where traffic congestion is much less and we can take advantage of direct routings and shortcuts which we could not otherwise consider."

"Winglets lower drag and improve aerodynamic efficiency, thus reducing fuel burn. Depending on the missions you fly, blended winglets can improve cruise fuel mileage up to 6 percent, especially important during a time of rising fuel prices. "Were saving a minimum of 4% on fuel and up to 6% on our longer flights," says Air Berlin Technical Director Sigfried Olivo."

http://www.aviationpartnersboeing.com/main.htm
http://www.aviationpartners.com/index.html

I'm afraid to say everyone is wrong. The winglet is designed to better rip through the wing mid section of any aircraft that gets too close or is awaiting takeoff at EWR. :D

http://www.flyertalk.com/forum/showthread.php?t=460791

Are you sure they aren't there for airlines to paint their logo on? Or if they keep losing money, ad space for sale? ;)

This forum is in desperate need of a coke alert smilie!! :D

Everyone turn to face Burt Rutan...
 

...bow low and repeat "We're not worthy, we're not worthy!" :D

He started the whole winglet development back in his Vari-EZ days before he decided to build rubber burning rocket ships.

The chicks just dig em' :D

when i was a kid making paper airplanes, i always folded up winglets. why did it take the aerospace engineers so long to figure this out?

Isnt that the truth!

'Cause on a traditional arrow shaped paper plane, the folded wingtips act like vertical stabilizers and add longitudinal stability. Remember, they're on the very back of an extreme delta wing. If you were a model airplane hotdog (like I was), you could trim out your paper plane for longest flight or a circular path by bending the trailing edges slightly for yaw control.

Rutan was the innovator of controlling wingtip vortices and converting that wasted force into lift. Not much of a tip vortex on a paper plane. ;)

BTW, the tip vortex is from high pressure air under the wing spilling out toward the top of the wing, not vice versa. I flew into a tip vortex coming from a C-130 while on final approach to Huntsville AL. It flipped my Cheetah completely inverted in a right roll in less than a second but I instinctively added full right aileron to complete the roll and landed uneventfully. Took 10 minutes to get my underwear out of my tush.