Close coupled tails.

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by captarmour, Mar 6, 2013.

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  1. Mar 6, 2013 #1

    captarmour

    captarmour

    captarmour

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    I have wondered for some time why so many of us like long coupled canards when close coupled canards actually increase the lift on the wing by probable 'slot' effect, as well as the circulation of both airfoils probably benefiting each other, while long coupled canards decrease the lift by creating a downwash for the wing to fly in.

    however the idea of close coupled tails came to mind when i saw the rcpowers F35(very close coupled tail) model had a problem in that it did not want to land it wanted to glide forever although it is a low AR aircraft.

    is something happening that i dont know about?
     
  2. Mar 6, 2013 #2

    autoreply

    autoreply

    autoreply

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    Non-linear effects would be my main worry. Hard to impossible to predict and I'd avoid it like the plague without FBW.
     
  3. Mar 6, 2013 #3

    captarmour

    captarmour

    captarmour

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    the RCpowers F35 was very easy to fly it was just they had to try different airbrake solutions to get it to land easily.
    i thought FBW was needed primarily to tame instability designed in to promote maneuverability?

    F-35 V2 EasyBuild (Official) - YouTube
     
  4. Mar 6, 2013 #4

    Himat

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    Why “long coupled canards”?

    Ease of design. Next on the list is centre of gravity placement and CG range. A short coupled canard could be done, but it does take more time and effort. Considerable more time and effort if the possible gains are to be realised.
     
  5. Mar 6, 2013 #5

    captarmour

    captarmour

    captarmour

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    Ok I could see that with a low sweep wing, I guess I'm thinking delta where the close coupled canard is relatively far from the AC of the delta. Understood.

    the same thing would apply with a close tail, a long chord wing would probably work better. I guess the thought is really about making a relatively low AR efficient, to take advantage of its strength to weight ratio.
     

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