Carioca Canuck
Topic Author
Posts: 632
Joined: Sun Apr 23, 2000 4:03 pm

What Do "Winglet's" Do?

Thu Jun 22, 2000 8:36 am

I must confess that as an aviation enthusiast for the last 3 decades, I have absolutely no idea what aerodynamic benefit these devices give to aircraft.

As they look great.....and I realize that esthetics where not the reason behind it, I would appreciate some explanations.

Muito 'brigado...........

 
cedarjet
Posts: 8101
Joined: Mon May 24, 1999 1:12 am

RE: What Do "Winglet's" Do?

Thu Jun 22, 2000 8:38 am

They are there to stop careless mechanics falling off the end of the wing. This is one of the major contributions to the safety of ground personnel in recent times.
fly Saha Air 707s daily from Tehran's downtown Mehrabad to Mashhad, Kish Island and Ahwaz
 
cedarjet
Posts: 8101
Joined: Mon May 24, 1999 1:12 am

RE: What Do "Winglet's" Do?

Thu Jun 22, 2000 8:40 am

OK OK, they reduce by a high margin the drag from the wingtip, increasing the efficiency of the wing and creating the effect of an extra 10 feet of wingspan (on the 747-400), therefore greater lift.

BTW, the 767-400 has them, contrary to popular belief, but they are almost horizontal. This is the new thing, apparently.
fly Saha Air 707s daily from Tehran's downtown Mehrabad to Mashhad, Kish Island and Ahwaz
 
prebennorholm
Posts: 6430
Joined: Tue Mar 21, 2000 6:25 am

RE: What Do

Thu Jun 22, 2000 9:30 am

Aeh, winglets... The wing generates lift by accellerating air masses downwards. Outside the wing tip the air is of course not accelerated downwards. Therefore the air is put into a rotating "vortex" at the wing tip.
The winglet is not just a plate. It's has a carefully designed profile and its angle to the flight direction is carefully calculated too.
By taking energy from the vortex the winglet works much the same way as a sail on a sailboat. It Takes energy from the vortex and converts it into a little assistance to the engines pulling the aircraft forward.
Since the winglet takes energy from the vortex, it also reduces the vortex energy. And since vortex energy is all "lost lift", then the winglet also makes the wing generate a little more lift.
Exactly the same could have been achieved by a slightly increased wing span. But the further out the lift is generated, the stronger the wing must be. A stronger wing means either a heavier or a thicker wing, and both have negative influence on the aircraft performance.
It's all compromises. But when well designed winglets can save a few percent fuel.
Always keep your number of landings equal to your number of take-offs
 
Carioca Canuck
Topic Author
Posts: 632
Joined: Sun Apr 23, 2000 4:03 pm

RE: What Do "Winglet's" Do?

Thu Jun 22, 2000 9:36 am

Thank you for the explanations.

I now understand the aerodynamic benefits they bring to a design.
 
Jumbofan
Posts: 17
Joined: Thu Jun 08, 2000 8:34 am

RE: What Do "Winglet's" Do?

Thu Jun 22, 2000 3:56 pm

....therefore allowing shorter wing span and also are great guides for knowing where your wing tip is while taxiing. 
 
crjmech
Posts: 257
Joined: Wed Jun 07, 2000 6:31 am

RE: What Do "Winglet's" Do?

Thu Jun 22, 2000 5:09 pm

Besides providing aerodynamic benefits and acting as mechanic retainers, winglets are great for slowing down positional-awarness challenged bagsmashers and fuelers as they speed by in their vehicles. Think of them as kind of a "shear section" that protects the main structure of the wing from damage. This mostly holds true for CRJ's, but I imagine they could protect a Boeing or Airbus from the occasional run-in with a jetway. But seriously, I found out from the folks at Bombardier that the winglets on the new 700 series RJ have no aerodynamic benefits. Due to the fact the Challenger and CRJ have winglets, they added them on to the 700 for tradition's sake.
Thou shalt mind thine altitude,lest the ground reach up and smite thee.
 
Guest

RE: What Do

Tue Jul 04, 2000 11:03 am

Winglets reduce tip vortices, which reduce drag and thus fuel consumption. A lot of engineering goes into winglet design, they are not there just to look good. With the advances in computers, engineers can now use CFD programs in conjunction with CAD/CAM to design these highly complex curved airfoils. The benefits of retrofiting winglets on a "classic" are thus, including, in some cases, better MGTOW, climb, and cruise perf.
Amazin' what that funny looking winglet can do !
 
tupolev154b2
Posts: 1269
Joined: Mon Jun 26, 2000 9:01 am

RE: What Do "Winglet's" Do?

Tue Jul 04, 2000 12:32 pm

Here is a link where you can find a brief, concise explanation:

http://www.airliners.net/discussions/faq/read.main?id=1