Dynam SU-26M cant find CG HELP!

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  • Shywolf
    Member

    • Dec 2015
    • 10
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    #1

    Dynam SU-26M cant find CG HELP!

    I can not get my SU-26M to balance, it is tippy like a sea saw. i can hold it to get it close but if it goes to one side or other it tips in that direction immediately. Ive tried for hours trying to get it to balance and it will not stay on its own on the balance machine, its close to level at the point it wants to stay balanced but it wants to fall off one way or the other wont stay on its own. what am i doing wrong? Ive tried inverted as well no luck. PLEASE HELP thanks.
    Shywolf
  • fhhuber
    Senior Member

    • Aug 2015
    • 1476
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    #2
    make a big loop of string such that when pulled to a double line its almost the wingspan.
    cradle the fuselage forward and aft of the wings in the loop with the ends held in a hook

    Add a weighted string to the same hook The weight will point at the CG. The plane doesn't even have to be level. Angle the plane a few different ways and you can find the exact POINT of CG



    The "Vanessa" rig only finds fore-aft because it prevents roll... But all lines to one point finds CG in 3 dimensions.
    FF gliders and rubber power since 1966, CL 1970-1990, RC since 1975.

    current planes from 1/2 oz to 22 lbs

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    • WintrSol
      HobbySquawk Pilot

      • Nov 2013
      • 499
      • Florissant, MO
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      #3
      +1 on the Vanessa machine; I find it's the only way to find the CG on a model with the center of mass on the center line of the wing. My SabreX is the same way.

      You can use it to find a heavy wing, too, by routing the strings under the fuselage in front and behind the wing.

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      • Shywolf
        Member

        • Dec 2015
        • 10
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        #4
        Thanks I will give it a try.

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        • stevepmcg
          Hobby Squawk Crash Test Pilot

          • Mar 2015
          • 68
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          #5
          Shywolf - just for nosiness sake what balance machine are you using?

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          • Shywolf
            Member

            • Dec 2015
            • 10
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            #6
            A homemade one is all i have two dowels with soft tips and sturdy base level in all directions.

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