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Thread: Dihedral Question

  1. #11
    Senior Member SkyPirate's Avatar
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    Default Re: Dihedral Question

    I don't believe any of the model's of kitfoxs have an off set on the vertical stab. unless someone modified it after it left the factory.

    Chase

  2. #12
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    Default Re: Dihedral Question

    OK, Boys, here's the latest on my heavy wing 3. We brought the high wing down to the same degree as the lower wing. both are 1.8 -1.9 degrees. The washout slightly favors a correction to the problem and the sweep is fine. I flew it this morning and the problem has not been rectified in the least. So I'm thinking that if the wings are good then it must be something influencing the wings, ... the flaperons. Would the recommendations be to adjust the flaperons of use a fixed trim tab? Or any other suggestions.....?

    thanks, R

  3. #13
    Senior Member HighWing's Avatar
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    Default Re: Dihedral Question

    For what it's worth, this is what I would do first if this was my airplane. I'd adjust the washout to see what effect that has. It just seems to me that if flaperon input is needed to correct a roll tendency, there is some fundamental wing issues creating that tendency. Keep in mind that the jigging for the early Kitfoxes was not the massive box jigs that were made for the V (when certification was being considered) and later and welding warpage is real. I seriously doubt that every fuselage is identical in measurement - the problem might just be the angle of attack at the wing root. To have the dihedral the same and the washout the same and still a roll tendency, there still has to be a wing issue. The wing would be my focus unless, as was mentioned previously, you find yourself at the limits of the rod end fittings, then a trim tab or as was mentioned tweaking the trailing edge.

    We put a cockpit adjustable tab on the Lancair ailerons, but this was to compensate for wing rigging - not correctable after assembly - and differential fuel burn as all fuel is in the wings. In other words it was at first a patch, then a convenience.

    Just an opinion.

    Lowell

  4. #14
    Senior Member SkyPirate's Avatar
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    Default Re: Dihedral Question

    good point Lowell ,..if it is the root of the wing ..if the wing isn't often folded ..either front of rear connect point could be modified to correct the AOA,.prefered the rear because it stays bolted regardless if the wing is folded or not ..
    you could grind off a little top or bottom of the connect point to correct the AOA then put a shim on the opposite side ..but you might have to make a new inner spar tab due to the bolt hole that goes thru the spar and connect point might end up being elongated
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  5. #15
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    Default Re: Dihedral Question

    Here's the latest on my heavy winged 3. I put 2 turns in the washout with no apparent results, still wanted to roll smartly to the right. Then I taped a trim tab on the heavy side flaperon to push it down and the wing up. Again, little to no results. So I moved the trim tab to the underside of the other flaperon and "bingo", there was a notable improvement. It was not a complete fix so I added another couple of inches of tab which added even more correction. I need to adjust the location and size of the tabs as they are adding some drag, but the machine will finally fly straight.

    Thanks to you all for your input.

    robin g

  6. #16
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    Default Re: Dihedral Question

    Robin,
    Right wing heavy, tweak the trailing edge of the RIGHT flaperon UP and the trailing edge of the LEFT flaperon DOWN. Like I mentioned earlier, work your way along the trailing edges using just hand (thumb?) pressure and push just hard enough to feel the aluminum give a bit. Probably not even enough to really see. A little bit goes a long way. Try..and...fly......try...and...fly ...you get the picture?

    Good luck!
    JimS

  7. #17
    Senior Member jdmcbean's Avatar
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    Default Re: Dihedral Question

    I have not been watching the threads very closely so this may have already been mentioned.

    There are several issues that can cause roll (heavy wing) one being wing rigging and another being rudder. How is the yaw in level cruise flight ? if you were to hold the wings level and take your feet off the pedals then switch hold the yaw straight and release the controls. One will affect the other. The trick can be to determine which one and how much.
    John McBean
    www.kitfoxaircraft.com
    208.337.5111

    "The Sky is not the Limit... It's a Playground"

  8. #18
    Senior Member HighWing's Avatar
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    Default Re: Dihedral Question

    John,

    You make an excellent point. There was an article on dihedral it's effects on rudder input and roll in the Wind Tunnel column in Sport Pilot a month or two ago. Definitely worth the read. It cleared up some misconceptions for me.

    Lowell

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