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Thread: PVC lift strut fairing installation and painting

  1. #1
    N14ND's Avatar
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    Default PVC lift strut fairing installation and painting

    Flipping through my task cards and looking at installing the PVC fairings to the lift struts. I like the look of the large struts with the fairing material on the round struts. I have seen bare sanded and painted and also fabric covered struts. Wondering advantages/disadvantages to either. Primarily wanting the paint to stay on the fairings, second is less time. Also, if the external channels/grooves that are visible can be sanded out or if a filler material needs to be added so as to not remove too much material and weaken the PVC. Easiest would be to get out the oscillating sander and smooth the outside, wet sand to 400 and paint. Thanks.

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    Default Re: PVC lift strut fairing installation and painting

    The factory sands and paints when they use the PVC. John said that it usually takes him about 30 hours to do a pair but being my first pair its taken quite a bit longer. Time consuming but very worth the time, most have seen 10+ MPH increase so likely the best bang for the buck on getting better performance and substantially cheeper than the other option.

  3. #3
    N14ND's Avatar
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    Default Re: PVC lift strut fairing installation and painting

    If anyone has the builders manual portion for the assembly of the PVC to strut directions I would greatly appreciate it. The online builders manual doesn't have that portion of the assembly. Thanks.
    “I wish I knew now as much as I thought I knew when I was 18”

    Building Kitfox 5 (25 yrs and counting)
    0-200
    A&P, ATP

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    Senior Member Maverick's Avatar
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    Default Re: PVC lift strut fairing installation and painting

    I just reviewed my KF5 manual and could find no instructions for installing strut fairings. Since they were not there I just put them on, took them off, put them on, took them off until I was ready to put them one and leave them. . . Also, and I don't know the current thinking on this but, I was told by SkyStar years ago that the ridges on the struts were there for a reason. It had to do with laminar flow and I was advised not to remove them. I guess it depends on how much time you want to spend on them.

  5. #5
    N14ND's Avatar
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    Default Re: PVC lift strut fairing installation and painting

    The instructions are in the Speed Fairing Kit for the Series 5. It was a separate section.

    Laminar flow? Usually span wise ridges and valleys aren't too good for flow. Even a paint line running length wise of a wing can cause separation. Anyway at 100mph I am not that worried about the laminar effects. I have a note in my builders manual that has the streamlined tube lift struts at $316 each...that was a while ago.
    “I wish I knew now as much as I thought I knew when I was 18”

    Building Kitfox 5 (25 yrs and counting)
    0-200
    A&P, ATP

  6. #6
    Administrator DesertFox4's Avatar
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    Default Re: PVC lift strut fairing installation and painting

    I too left the ridges as was told the same story as Maverick. Not sure if it worked but I did have a fast model 4.


    DesertFox4
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  7. #7

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    Default Re: PVC lift strut fairing installation and painting

    I have some pics of how I did mine starting around post 42:

    https://teamkitfox.com/Forums/thread...-rebuild/page2

  8. #8
    Senior Member jiott's Avatar
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    Default Re: PVC lift strut fairing installation and painting

    As I recall, for the SS7, the PVC struts have 3 grooves (not ridges); 2 are fairly shallow and easily sanded out; the 3rd is quite deep and can be sanded out, but requires removal of a lot of material. Many folks have sanded out all 3 grooves and have not had any problems with weakening that I have heard. I took a middle-of -the-road approach and sanded out the 2 shallow groves and maybe half the depth of the deep groove. Time spent was reasonable and I think the one remaining groove actually looks fine since it is not very deep.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
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  9. #9
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    Default Re: PVC lift strut fairing installation and painting

    Are you still looking for the assembly instructions? Only 2 pages are for the lift struts the others are for the landing gear.

    Rick

  10. #10
    Senior Member
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    Default Re: PVC lift strut fairing installation and painting

    I've spent so much time playing with Sailplane airfoils, and cutting my own foam cores, I look
    at the PVC struts, and I'm pretty convinced that the only designing that went into them is
    "Yup, that looks about right ..."

    There are much better airfoils available for the struts than what we use, if you are willing
    to cut your own cores, and do some research into "which" airfoil might be best.

    Here's some links, the second can be used to plot various airfoils, at different size, and scale
    into pdf's. These can then be cut/glued to template material for hotwiring foam cores. Which
    is what I did, and then I glassed them with West Systems Epoxy system.

    https://m-selig.ae.illinois.edu/ads/coord_database.html
    http://airfoiltools.com/plotter/index?airfoil=ag36-il

    Jeff


    Here's a couple pics from when I did mine, the pictures are not high quality

    lf2.jpg

    lf5-800.jpg

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