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Thread: Vortex Generator position VG

  1. #21
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    Default Re: Vortex Generator position VG

    Not yet and not really planning to at this point though that was my plan before I flew it. Slow flight AOA is so extreme that I can't imagine needing more elevator. A full stall landing, stick all the way back would cause the tailwheel to touch long before the mains as is.

  2. #22

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    Default Re: Vortex Generator position VG

    Just chiming in here with another report on the Stolspeed VGs. jrthomas helped me install the Stolspeed VGs on my Model 4 Speedster. We installed them at the same location (about 2" back from leading edge). Basically we just put the nose of the VG on the leading edge tape line. We did not stagger them, and we used the 60mm spacing. My Speedster has the short wing and it worked out to exactly 60 vg's per side.

    First flight test showed very noticeable difference. No flaps p/off stall went from 47 to 43, full flaps from 41 to 37-38ish. Also the stall characterics improved. It used to buffet/shake when it stalled and now it just hangs. Very smooth/solid feel as the nose just bobs. P/on stall is ridiculous. The AoA feels like i'm standing on the tail and it stalls in the low 20's. If I am ever in that situation on takeoff, i've got much more to worry about than stalling.

  3. #23
    Senior Member Norm's Avatar
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    Default Re: Vortex Generator position VG

    This is something I have been considering for some time as my Model IV at 700Lbs empty has the 47 mph stall.
    2 inches sounds very close to the leading edge as 10% of the chord is what the instructions say, however you are not the first to say this. I just want to confirm, if I take a carpenters square, place it on the leading edge (including the vinyl cuff) I can place the VGs two inches back. A five mile/hour drop in stall is a huge drop. I am always envious of my friend in his Savage cub landing so slowly. Seems like his stall is just above 30 or so.
    I hope I am reading this right.
    Norm
    Airdrie Ab, Can
    North of Calgary
    Flying SuperFox Model IV

  4. #24

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    Default Re: Vortex Generator position VG

    I'll measure exactly today as i'm out at the hangar. I used the leading edge tape line as a straight line and put the nose of the VG on it. See the attached pic.

    https://photos.app.goo.gl/CMspYPCzbWQ8rL5R8

  5. #25
    Senior Member efwd's Avatar
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    Default Re: Vortex Generator position VG

    how long before those turn to urine yellow color and become brittle? Maybe they are built better than that? Can anyone speak to this?
    Eddie Forward
    Flying
    SS7, 912iS, Garmin G3X

  6. #26
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    Default Re: Vortex Generator position VG

    Quote Originally Posted by efwd View Post
    how long before those turn to urine yellow color and become brittle? Maybe they are built better than that? Can anyone speak to this?
    I can. One of my friends put the StolSpeed vg's on his "Swick T" Taylorcraft 7 or 8 years ago. They're all still there and look just like the day they were put on. I did some research before installing mine. If I remember right, the wings are about 43 inches wide and 4% worked out to something like 1.72 inches. I just used the finishing tape as a line to follow which was 2 inches or so back from the leading edge. I remember reading that people that put the vg's farther back saw very little if any improvement. Brian's improvements pretty much match mine so I think we're onto something. What's even more impressive than the much lower stalling speed is the way it will hang in the air at an AOA that I never came close to before. "Standing on its tail" is the way Brian put it. I went out for a while this morning and as I was on final I heard myself say out loud "how slow can you go". I'm much more confident coming in slow and it even seems to touch down softer doing a full stall 3 point. Oh, one more thing. SlolSpeed calls it 120 vg's but we put 120 on Brian's and I think we still had 9 left. Nice of them to put in extras I thought. Another thing. I didn't loose any speed and I don't think Brian did either. I'm a believer!

  7. #27

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    Default Re: Vortex Generator position VG

    Not sure. But they were only $97 shipped for 120 of them. And they just stick on with 3M sticky tape. I would imagine they would be easily replaceable. It took us about 45 minutes to install them.

  8. #28
    Senior Member efwd's Avatar
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    Default Re: Vortex Generator position VG

    $97?! Thats a good buy for the results your showing. Ill probably do it later.
    Eddie Forward
    Flying
    SS7, 912iS, Garmin G3X

  9. #29
    GMKman's Avatar
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    Default Re: Vortex Generator position VG

    Quote Originally Posted by GMKman View Post
    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.
    I need to retract some of this statement. I installed Stolspeed vg's on my wing now in pretty much the same place Bryan did in his video and DEFINITELY like the improvements in lower stall speeds, low speed stability, and no real drag increase. Not sure why the other vg's I tried didn't work as well but I'm glad I have these on my wing now.
    Brad Smith
    KF Vixen IO-240
    Flying when I have gas money

  10. #30

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    Dec 2018
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    Granada Hills, CA
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    Default Re: Vortex Generator position VG

    Ed, did you end up yet with these being installed?

    I don't remember looking for them on Saturday.

    Or will you fly first, get some measurements, and then install at a later date, so you can note and log the stall speed difference between clean and Stohlspeed installed a few inches back?
    Last edited by NinerBikes; 12-10-2018 at 02:03 PM.

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