Bearhawk Aircraft Bearhawk Tailwheels LLC Eric Newton's Builder Manuals Bearhawk Plans Bearhawk Store

Announcement

Collapse
No announcement yet.

Who is using VGs?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • #31
    Hey Ty - I have the same streaks from my back hinges - no shame there!! Thanks for sharing those pictures!

    I see the front of your VGs are upon the forward-most (1st) rivet in the leading edge ribs.
    I installed the STOLspeed VGs this weekend just past. I placed them so the back of the VGs aligned to the fourth (4th) rivet from the front. I chose this location because (theoretically) it exposes the maximum amount of VG's tail to the airflow over the highest point of the wing at stall attitude. This allows for maximum effect, in theory. These were my results in practice:

    I tested with minimum payload and 1/2 fuel, at 3,000 ft. We installed VGs on the wing, but not the tail (yet - I have some).

    Vso before the VGs installed was 37 KIAS.
    GS was a little faster of course, but there was some wind so GPS airspeed couldn't be checked exactly. Cruise speed LOP at 9.25 gal/hr was 108 KIAS (this is how I usually x-country).

    After the install, Vso dropped clearly by 3kts, to 34 KIAS.
    GPS ground speed changed by the same 3kt margin, but again wind... Cruise speed LOP 9.25 gal/hr remains unchanged at 108. I did check the 75% cruise too, which was unchanged, but crucially I failed to record the vital fuel flow reading without VGs... so that 75% measure is worthless.

    IMG_20180107_202801.jpg

    Before VG installation
    IMG_20180105_174116.jpg

    After VG installation
    IMG_20180107_202810.jpg

    IMG_20180107_205108.jpg

    Post install:
    We are pleasantly surprised and will keep the VGs. The stall was now much clearer and well defined, and there was a clean break-point and minor nose dip, instead of the formerly mushy transition. No buffet in either case. I could fly the plane in 20 degree turns with full control (in balance of course) at 36-37 KIAS, which was something else. I felt a bit like I was flying a heavy Cub.
    It was hard to precipitate a stall without a little power on, there was not enough elevator to get the nose up the 15-16 degrees required (full flaps).
    At take-offI perceived the plane want's to lift off a fraction sooner, but I think I need more technique to take advantage of that small change.

    I re-calibrated my AoA system, this was my favorite result - instead of being audibly warned about the approaching stall AoA at 47-50 KIAS on approach, I was flying approaches (at altitude) at 40-45 KIAS before the entering the same "near-stall" realm - so that is a big improvement. This change in approach speeds makes a significant difference to my ground roll, and accuracy at touchdown time. This is the biggest benefit I perceived.
    The first real approach I flew at this speed just felt plain wrong having done about 50 circuits without VGs this month. But once I got used to it, it was no different in control-ability. I did find the AoA has a smaller "margin" between first activation and full stall post-VGs, where before hand there was a much wider band. But that makes sense - you need to be more careful if you want to fly closer to the limit.

    That was my experience at least; I am glad I tested before and after. Of course, YMMV!

    Jonathan
    Last edited by Battson; 03-02-2020, 02:33 PM.

    Comment


    • #32
      Bump - updated with new pictures of the VGs installed on the Hoerner STOL wingtips.

      She might be 6 years old now, but looking better than ever I reckon. I still get a kick out of it, every time. The build is totally worth it, guys
      Last edited by Battson; 03-02-2020, 02:36 PM.

      Comment


      • zkelley2
        zkelley2 commented
        Editing a comment
        I really like your wingtips and want a pair like that.

      • Battson
        Battson commented
        Editing a comment
        It sounds like you may be able to purchase a set in the near future - North America based.
        Last edited by Battson; 03-04-2020, 02:18 PM.

      • zkelley2
        zkelley2 commented
        Editing a comment
        Carbon concepts?

    • #33
      Hi guys,
      I have sets being made for the model "B" airfoil if your interested. They are Carbon fiber and will be 18" wide. We have a 6" straight section that can be trimmed down for less extension followed by 12" of taper to the tip. I have 2 sets spoken for so far. Im unsure of the price just yet but let me now if you want me to notify you when they are ready. Im guessing a couple weeks out yet. Please connect with me on Instagram @ bearhawk_aircraft or email at mike@bearhawkcanada.ca as Im not connected to the forum often. thx

      Comment

      Working...
      X