Results 1 to 4 of 4

Thread: VG's and montana air

  1. #1
    Member TheCubWorks's Avatar
    Join Date
    May 2010
    Location
    Lewistown Montana
    Posts
    32

    Default VG's and montana air

    Good morning,
    The other day I had the opportunity to fly with a very, very good pilot during his time. This man sprayed crops with a 150HP cub with a 90 gallon belly tank. He is getting back into flying after a 30 year sabbatical as a sign maker. When he was flying there were no VG’s, or 200+HP cubs. So today lets talk about VG’s and how I have decided they really work, we won’t cloud the issue with facts here it is just my intuition and the blue skys of Montana, your experiences may be different as the air in your state could also be different.

    When I fist put on a set of VG’s on a citabria I wanted to see just what the wings was doing so I glided with the engine and prop stopped. There is a speed when the VG’s begin to work when they are working and when the wing stops producing enough lift. You can hear them howl. There is a real and critical time element involved with getting them to work. Also because of Angle of Attack there is real speed difference with aircraft weight.

    Now back to my Cub, Same gliding test had the same results with the same howl. I was able to find the speed they began to howl (work) and the pitch of the howl when they really were working. With two people the number is 60 to begin and 47 to end. I did mention a time element. If you take the speed down quickly to 55 with flaps and chop power the VG’s don’t work for a while and you have to fight mushy controls until the VG’s eventually catch up. AND most importantly what if you are not stabilized on final, meaning airspeed control? What if the airspeed is allowed to increase past the “working point” of the VG’s then the airspeed is abruptly decreased? As the Gentleman and I found out it is the same if not worse, because invariably one bad oscillation of the nose leads to the next.

    So lesson learned, there is a TIME element to making the VG’s work optimally. Keep very, Very precise airspeed control over a period of time. Don’t let the airspeed build or decrease to fast. When you are in the airspeed range for the weight of the aircraft for the VG’s to work keep it there. When you slip keep the airspeed from building, keep the airspeed nailed.

    Noel

  2. #2
    Junior Member
    Join Date
    Apr 2010
    Location
    Goose Creek, SC
    Posts
    17

    Default Re: VG's and montana air

    I was under the impression that they worked at much lower speeds, hence a stall at around 32kts on landing, and an enhanced lift off..??

    Frank
    Goose Creek, SC

  3. #3
    Member TheCubWorks's Avatar
    Join Date
    May 2010
    Location
    Lewistown Montana
    Posts
    32

    Default Re: VG's and montana air

    my cub weighs 1240 empty add 50 gallons of fuel and two 210lb men and you have to fly faster.

  4. #4
    Junior Member
    Join Date
    Apr 2010
    Location
    Goose Creek, SC
    Posts
    17

    Default Re: VG's and montana air

    I see what you are saying, every flight is different, so let's stay on top of things and find out exactly what we are dealing with in our current condition. Good point.

    Frank

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •