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Flap Analysis

Adrian V
2012-02-26
2012-09-26
  • Adrian V
    Adrian V
    2012-02-26

    Hi All,

    Please help, I'm a bit confused. I have a flying wing, which has a typical LD
    ratio of 30. When I do a T7 analysis with inboard flaps going from 0 to 30deg,
    I get no change in Cm, and a wild improvement in L/D. It seems unlikely that I
    can get have no change in Cm, but have a very improved L/D. I find the same
    massive improvement when I try to model a left bank situation. My L/D goes
    from 30, which is respectable, to 70, which is highly unlikely...

    What am I doing wrong?

    Thanks
    Adrian


     
  • That's because if you use flaps as a control variable, then the analysis may
    only be non-viscous. Viscous drag is therefore completely neglected, that
    explains the jump in L/D.
    Francesco

     
  • Adrian V
    Adrian V
    2012-02-26

    hmm.. I see the screenclip (in .png format) does not display. Lets try a .JPG

     
  • Adrian V
    Adrian V
    2012-02-26

    Thank you Francesco.

    Do you know why the Cm does not change? It doesn't seem right that on a flying
    wing, I drop flaps and there is no change in Cm.

    ok, attaching imgs seems broken. Here is a direct link http://www.mediafire.c
    om/i/?f27agvmj7bgtf5m

    Many thanks
    Adrian

     
  • It seems I don't see the picture... but anyway, in a T7 analysis Cm is by
    definition zero (or very close to zero), so this is no big surprise.

     
  • Adrian V
    Adrian V
    2012-02-27

    Yes, of course that would be it! Thank you!