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What exactly are winglets for ???

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  • What exactly are winglets for ???

    What are winglets installed in aircrafts for ?? Except for making them prettier and looking cool

    And also why winglets look different ??

    For example why the winglet on

    Airbus A340

    [photoid=288018]

    is different that the one on A380

    [photoid=495927]

    and different that the 737NG

    [photoid=5619029]

    and why does MD-11 has the "extra" one on the bottom??

    [photoid=309855]

    What's the difference between them excpet for the look ?

  • #2
    Well, the first and (I think) last are winglet fences. What winglets and wingtip fences do is help stop air from flowing from the bottom of the wing (high pressure) to the top of the wing (low pressure). When this happens, lift decreases because some of the pressure is equalized. Keep in mind, these are lamens terms.
    A profesional want to verify this?
    Cheers,
    A.M.

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    • #3
      Winglets are designed to reduce induced drag, a type of drag that is a result of the creation of lift. AM has summed up why this occurs, the larger the wingtip the more drag it incurs.

      Adding some sort of fence reduces spanwise flow and reducing the intensity of the wingtip vortice, thereby reducing drag. The other option is to reduce the width of the wingtip, such as Boeing's 'raked wingtip' on the 767-400/777-200LR/777-300ER/787.

      The lowest induced drag is incurred behind long, slender wings, which is why gliders have the wings they do. Unfortunately for airliners these wings are hard to manufacture for strength and are no good for high speed flight so an alternative was sought. Winglets/fences etc proved to be the most efficient for thier weight and the fact that they do not dramatically increase wingspan.

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      • #4
        Thanks AM and AJ for info. yeah winglets are very cool looking but now I know that they are very usefull too

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        • #5
          Some aircraft come without winglets for a good use...

          The B747-400D does not have winglets to decrease its OEW (Empty Weight) because it is a high cycle aircraft, weight needs to be reduced to increase landing gear and airframe life...

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          • #6
            Originally posted by Myriad
            Some aircraft come without winglets for a good use...

            The B747-400D does not have winglets to decrease its OEW (Empty Weight) because it is a high cycle aircraft, weight needs to be reduced to increase landing gear and airframe life...
            That and the fuel savings from winglets are really only noticable on longer flights. If you put winglets on a short range aircraft, it is my understanding that it might actually cause an increase in burn because the weight of the winglet would cause you to burn more fuel (more lift required, which creates more induced drag which means you need more power). This extra fuel you would burn is more than you would save for the short time that the aircraft is in flight...at least that's how I understand it.

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            • #7
              You did understand it correctly . Fact of the matter is: Just putting winglets on a plane means just additional weight that you have to put in the air. An example: On short hops like ATL-BHM or the such, winglets on a 738 would have no advantage, on the contrary. Now, put the plane on a route like ATL-CCS, and voila, the fuel-saving kicks in and easily offsets the added weight. Of course, winglets also allow the plane to do steeper climb-outs, which can be an added bonus, particularly out of noise-sensitive airports like SNA.

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              • #8
                The winglets always "work" and the added weight you speak of is actually nil because the winglets partially generate lift themselves...

                Alot of reasons for not installing winglets is just that they cost more money. Its something extra on the aircraft which requires maintenance.

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                • #9
                  Originally posted by Myriad
                  The winglets always "work" and the added weight you speak of is actually nil because the winglets partially generate lift themselves...
                  key word, partially

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