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Thread: Vortex Generator position VG

  1. #11
    Senior Member efwd's Avatar
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    Wink Re: Vortex Generator position VG

    I thought we agreed that the engineers didnt get the carb synch cross tube right?

  2. #12

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    Default Re: Vortex Generator position VG

    The "engineers" also agree that somewhere between 4-12% of chord SHOULD improve flight characteristics. In this case of course, the "engineers" are any people that want to shape pieces of Lexan and be panacea salesmen. Here is a quote from the STOLspeed website,

    "So, with the wing positioned at the stall angle of attack, the VGs should be slightly forward of the highest point of the airfoil."

    So if my KF3 stalled in a 3 point attitude (I wish) that would mean it stalls in the same position as when taxiing or parked. I'm not trying to "out think" the engineers, just rephrase. That's also why I asked if anyone could look at their VG and confirm or deny.

    And furthermore, if the "engineers" are so spot on why don't we just fly Cessnas that we could buy for less than our KF? For that matter why are all the KF so different from one another?

    And if you're wondering why "engineers" is in quotes so much, it's because anyone that manufactures a solution to a problem is an engineer and level of schooling or a title is not necessarily indicative of capability. I know old school, blue collar machinists running on a GED that are far superior engineers to most Ph.D. recipients.

    Now if you'll excuse me, I need to take my soap box over by my plane so I can look at the top of the wing.
    Last edited by WurlyBird; 09-15-2017 at 08:51 AM.

  3. #13

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    Default Re: Vortex Generator position VG

    Ok point taken. Call them basket salesmen for all I care. My vgs are ahead of the highest point of the wing when sitting 3pt. I have no idea if it stalls in that attitude or not, I believe it is much more tail down when it stalls. I followed the instructions from the site I got mine from and it worked out well for me. Your mileage my vary so do what you want

  4. #14
    GMKman's Avatar
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    Default Re: Vortex Generator position VG

    You can use double sided tape to temporarily experiment with various placements ( which is what I did). I lost one or every once in a while but was worth the data. I found that the more forward/ the more effective however it came with a cost of more drag. I inevitably didn't like the look or the drag of them and didn't feel like they made much difference so off they came with no harm to the wing from the sticky tape.
    I did put some on the bottom of the elevator which made a difference in authority ( I still have the small elevator with a continental engine up front).
    I "glued" them on permanently now. I'm happy with them.
    Brad Smith
    KF Vixen IO-240
    Flying when I have gas money

  5. #15

    Default Re: Vortex Generator position VG

    Here is a video I put together showing a VG installation. Hopefully it is helpful.

    https://www.youtube.com/watch?v=vGzHZKRZi7s

    I also started a new thread for it here.

    http://www.teamkitfox.com/Forums/sho...1255#post71255
    Bryan
    Project Kitfox
    Bowen Aero LLC
    Kitfox Model 5 Lycoming O-290 D powered
    Building a Model 7 Apex powered
    Redding, CA
    http://www.youtube.com/c/ProjectKitfox

  6. #16
    Administrator DesertFox4's Avatar
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    Default Re: Vortex Generator position VG

    Great video Bryan.

    The larger elevator would be a good mod to increase elevator authority in the flair.


    DesertFox4
    Admin.
    7 Super Sport
    912 ULS Tri-gear


  7. #17
    Senior Member
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    Default Re: Vortex Generator position VG

    I installed Stolspeed vg's yesterday and thought some of you might be interested. I installed mine about 2 and a half inches from the leading edge. I used the 90mm spacing except for the 24 inches from the wingtip where I used the 60mm spacing. My flight testing was not under ideal conditions since it was mid day, well into the 90's and thermals making things pretty bumpy but the results seem to be pretty impressive so far. Stall with zero flaperons went from 45 mph to 40. There was a tremendous increase in angle of attack before stall with the vg's, especially with flaperons, so obviously they're working. I don't have any exact stall numbers with flaperons down because of the thermals and the wind changing directions. I was into the mid to upper 30's but I'd like to try it again in more calm air before giving any exact numbers. It's just amazing how it hangs in the air at that speed and AOA. Oh, I'm flying a Model 4/1200, 912ul, long wing but with all the Speedster options so it's a little heavier than some. James Thomas

  8. #18
    Hockeystud87's Avatar
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    Default Re: Vortex Generator position VG

    Great info! I was thinking about VG's at some point as well... Lowering your stall is never a bad thing!

    Any issues on the top end? Speed decrease?

  9. #19
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    Default Re: Vortex Generator position VG

    I plan on flying tomorrow so we'll see how it does and maybe post my results tomorrow night.

  10. #20
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    Default Re: Vortex Generator position VG

    Did you put any vg’s on the stab. Lower surface as well ?. This should increase overall tailplane effectiveness ...
    David
    SS7 Builder

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