ConcordeBoy
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A380 Pic: Optical Illusions?

Mon Jul 23, 2007 3:47 am

Check out this pic and its captioning:

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Photo © Michael Vaeremans



...according to the photographer, it seems that:
  • the inboard flap on the left side of the picture is rubbing against the landing gear bay-doors
  • the hydraulic lift on the inboard flap on the right side of the picture, is significantly larger than its opposite-sided counterpart.



    If, by chance, these are truly the case: then could someone in-the-know explain the purpose of having both of these features?

    My guess is however, that both of these seem to be optical illusions brought on by the photography angle.

    What say you?
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    petertenthije
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    RE: A380 Pic: Optical Illusions?

    Mon Jul 23, 2007 3:54 am

    1) that is an optical illusion. The next photo in the sequence shows there is a gap between the flap and the door, ver tiny though. http://www.airliners.net/open.file?id=0863718&size=L
    2) That is correct, and explained in the pictures caption, the extra space was needed for the ram air turbine.
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    moo
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    RE: A380 Pic: Optical Illusions?

    Mon Jul 23, 2007 3:54 am

    Quoting ConcordeBoy (Thread starter):
    # the inboard flap on the left side of the picture is rubbing against the landing gear bay-doors

    Yup, the gear door is fully open and it looks like there is a rubber strip along the inner edge of the flap for precisely that reason.

    It shows just what tolerances airliners are really built to - how much performance would be lost by reducing the flaps just enough so they dont touch?

    Quote:
    # the hydraulic lift on the inboard flap on the right side of the picture, is significantly larger than its opposite-sided counterpart.

    As it says in the caption, its because the RAT is enclosed in the leading part of the fairing on that section.

    No optical illusions, just questions that needed answering.
     
    tomcat
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    RE: A380 Pic: Optical Illusions?

    Mon Jul 23, 2007 7:56 am

    Quoting Moo (Reply 2):
    Yup, the gear door is fully open and it looks like there is a rubber strip along the inner edge of the flap for precisely that reason.

    I would rather think that the main reason for having that seal is to seal the gap between the body fairing and the inboard edge of the flap once retracted. The reason being to minimise the flow between the lower side of the wing (pressure side) and the upper side (suction side). These are common design features aiming at reducing the parasitic drag of an airliner in cruise conditions.

    The external surfaces of an aircraft are classified in various categories according to their influence on the overall parasitic drag. The more they may influence the parasitic drag generation, the more severe the design requirements are (namely "steps and gaps requirements"). To give an example, the acceptable step between to skin panels in the leading edge area is much smaller than on the rear fuselage. You could apply the same severe requirements on the whole structure but you would end with a lot of extra cost with no significant gain (valuable gain) on the parasitic drag, hence that classification.

    Nic
     
    FL370
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    RE: A380 Pic: Optical Illusions?

    Mon Jul 23, 2007 1:46 pm

    that is so wierd!! i can't see how that picture is real! can someone help me out here?


    fl370
     
    jacobin777
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    RE: A380 Pic: Optical Illusions?

    Mon Jul 23, 2007 2:21 pm

    I would have to say its probably a parallax....in this photo, on could clearly see there is a space between the two...and because of the size of the plane, the distance seems small but in reality there is probably more than enough clearing space..


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    graphic
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    RE: A380 Pic: Optical Illusions?

    Mon Jul 23, 2007 2:22 pm

    Quoting Moo (Reply 2):
    It shows just what tolerances airliners are really built to - how much performance would be lost by reducing the flaps just enough so they dont touch?

    Actually more performance would be lost if they did touch.
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    Maersk737
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    RE: A380 Pic: Optical Illusions?

    Mon Jul 23, 2007 5:28 pm

    When you look at the picture that Jacobin777 is showing in his reply 5, you could argue that the engines under the left wing are build together  Wink

    Optical illusions at it's best  Smile

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    Peter
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    GeorgL
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    RE: A380 Pic: Optical Illusions?

    Mon Jul 23, 2007 11:52 pm

    How true Big grin Great illusion with those engines indeed.
     
    Claude
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    RE: A380 Pic: Optical Illusions?

    Tue Jul 24, 2007 12:30 am

    Hi Concorde Boy, i promised you everything's allright between inboard flaps and body landing gears doors  Wink)
    And i don't what i'm speaking about  Wink)
    look the inner side of the flap, you can see a "join", it can be shake by the doors, no problems.
     
    Morvious
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    RE: A380 Pic: Optical Illusions?

    Tue Jul 24, 2007 1:16 am

    Quoting Graphic (Reply 6):
    Actually more performance would be lost if they did touch.

    Could you explain why to those simple soles out here  Wink
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    tjc2
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    RE: A380 Pic: Optical Illusions?

    Tue Jul 24, 2007 1:27 am

    i wouldn't say optical illusion, just foreshortening created by the angle the picture was taken at.

    The inboard engine pylon on the starboard wing looks further out than the inboard engine on the port wing.
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    FAEDC3
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    RE: A380 Pic: Optical Illusions?

    Tue Jul 24, 2007 8:00 am

    I think that is important to note that the doors, eventhough seem to touch, in reality they might but for a few instants. The time that the gear bay doors take to open/close are only a few seconds, in that time the door opens, and gets very close to the flap indeed; but then it closes again after letting the gear either in or out. That time I think is so marginal, it shouldn't be a aerodynamics issue.