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Thread: Aileron Balance Weights

  1. #1

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    Default Aileron Balance Weights

    My model 2 has the balance weights at the ends of the ailerons. I notice h newer ones are located nearer the center of the ailerons. It seems to me that this would be better for flutter resistance (half length is stiffer). Is it worth changing?

  2. #2
    Senior Member jiott's Avatar
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    Default Re: Aileron Balance Weights

    The model 7 SS has balance weights at BOTH mid and ends.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  3. #3
    Administrator DesertFox4's Avatar
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    Default Re: Aileron Balance Weights

    Micro- my model 3 had the single weights out on the end and had no ill effects.
    When I built my model 4, I used the single weight on the end of the flapperons and have been to vne many times with no problems. I've flown basic aerobatics with it also. The Speedsters had the two smaller weights and one was about 50 % and the other near the end. Their mass ( weight ) added up to the single counter balance weights.

    You should be fine. Most early Kitfoxs have your set up.


    DesertFox4
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  4. #4

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    Default Re: Aileron Balance Weights

    Thanks!

  5. #5

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    Default Re: Aileron Balance Weights

    How critical is the location of the inboard Mass Weight? Can it be moved in or out an inch or two? Mine just happens to line up with a rivet installed in the aft edge of the flaperon.
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    Senior Member PapuaPilot's Avatar
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    Default Re: Aileron Balance Weights

    You better check with the factory about moving it. But I don't think it would matter where they are installed, unless there is harmonic flexing that could happen along the length of the flaperon. The purpose its to balance the flaperon on the hinge point.

    Would it be possible for you to remove the rivet and use the existing hole to mount the balance weight, that is to go through the skins and counter weight? Another option might be to install a countersunk rivet so it doesn't interfere with the balance weight.
    Phil Nelson
    A&P-IA, Maintenance Instructor
    KF 5 Outback, Cont. IO-240
    Flying since 2016

  7. #7
    kitfoxnick's Avatar
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    Default Re: Aileron Balance Weights

    Don't forget to consider a possible interference when the wings are folded back. The flapperons are vertical and the mass balance weights need to be offset so that they don't hit when back to back.
    Nick W
    IV 1200
    912Ul
    Warp Taper Tip

  8. #8
    Senior Member Esser's Avatar
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    Default Re: Aileron Balance Weights

    I just had this issue. Factory said try to use the same hole (which I couldn't) but if I had to, move them. I moved them a half inch out board.

    Anyone doing this step soon, drill your flapperon trailing edge after.

  9. #9
    Senior Member jrevens's Avatar
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    Default Re: Aileron Balance Weights

    Quote Originally Posted by PapuaPilot View Post
    ...
    Would it be possible for you to remove the rivet and use the existing hole to mount the balance weight, that is to go through the skins and counter weight? ...
    That's what I ended up doing on one of mine... wasn't thinking ahead. Just as an educated guess, I don't think you'd want to move them too far as it seems like they are positioned over internal foam ribs if they are placed where the instructions say to do it. If necessary I think you could drill out the rivet you have already installed, fill the hole with Hysol, let it cure, then drill another hole to line up with the existing holes in the counterweight assembly. Even if the old hole is very close to where you want your new hole, there is probably no harm in doing that. Keep in mind that you would still have 2 really "good" holes (they'd all look "good"). Also consider that the weight assemblies were only attached with rivets on the earlier models (at least on the mod. IVs I've seen) and yours will also be bonded to the flaperon (I'm assuming you're building a 7 SS). I think it's best to have those weights directly over the ribs, but I'm not sure how critical it is. These are just my personal opinions & thoughts, & you can use them at your own risk.
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE
    EAA Lifetime
    Chap. 43 honorary Lifetime

  10. #10
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    Default Re: Aileron Balance Weights

    On my KF 5 project, the original manual said the outer mass weight is set at 3" from outer hinge. The new kitfox build manual has it at 6 1/4". Anyone know the reasoning? Any reason to not put it at the newer measurement?

    Also, the original build manual has the flaperon control arm set at 5 1/4" from the end flaperon hinge. The new manual has it at 4 3/4". Any reason to not use the newer measurement? The original manual shows the use of a flaperon bearing, but I understand that this has been eliminated on the newer kits and I wasn't planning on using it.

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