Announcement

Collapse
No announcement yet.

A bit of walking the walk

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

  • A bit of walking the walk

    This guy Mark Stull has a series of unusual ultralight designs behind him. Always for his personal fun and experimentation, no commercial slant.

    This guy is an example of someone who 'walks the walk' in ultralight aeroplanes.

    His latest and in may ways most conventional project - the Ringtial ultralight.

    http://www.eaa.org/lightplaneworld/articles/1104_ringtail.asp

    Paul

  • #2
    A bit of walking the walk

    More interesting info about the "problems" Mark has experienced with this design

    http://www.homebuiltairplanes.com/forums/light-stuff-area/9013-ring-tail.html

    Comment


    • #3
      A bit of walking the walk

      Old post I know but Mark is now dead. After his successful 'Ring-tail', he went on to build a new plane using a hang glider type wing. On the first flight it zoomed, stalled and came straight down. Mark didn't have time to think about it. RIP Mark.

      Comment


      • #4
        A bit of walking the walk

        this is what he built

        Attached files
        Disclaimer- Opinions of others will vary depending on what they are selling
        the-grand-design.com

        Comment


        • #5
          A bit of walking the walk

          Thanks for the pics. I had seen one before but it wasn't good resolution and difficult to see exactly the construction and controls.

          It's important for all of us interested in lightweight unorthodox design, to try and learn from such tragic accidents. So here goes for my thoughts:

          It appears that there was no aerodynamic roll control, and that rudder was intended to provide yaw / roll.

          But a flexwing doesnt exhibit a yaw / roll couple like a conventional wing with dihedral. They are generally set up to have a neutral or even anhedral response to yaw. The sweep back provides some roll to yaw coupling in the positive sense - but this diminishes as angle of attack is reduced.

          You can see this by using the nosewheel in a flexwing to act as a rudder. At cruise or elevated speeds most flexwings will respond with a few wheel angle with yaw to the left, but roll to the right. At low speed this can reverse to a left roll.

          So using rudder as a turn control in marks machine may have been a fundamentally flawed idea. I did hear that he rolled and hit the ground, which would be consistent with this.

          But Doug says it was zoom and stall. CG eyeballs not far off, but then again the flexwing is deliberately sensitive to CG - just an inch or two of bar displacement is used to adjust speed by 20mph or so in a modern trike, so it's certainly possible this could have been a cause. - or mis rigging of that inverted aerofoil tail.

          Mark was always keen to try new ideas, such a shame this one bit him.

          Paul

          Comment


          • #6
            A bit of walking the walk

            Why is that sailing dinghy following him? ;-)
            Dave

            Comment


            • #7
              A bit of walking the walk

              Looking at the stabiliser, supported only by two poles, it looks awfully weak torsionally. (Shades of the 1982 Scorpion 3-axis??)
              Dave

              Comment


              • #8
                A bit of walking the walk

                Good spot - in fact the tail looks twisted form the prop wash and rudder deflection in the first photo

                Paul

                Comment

                Working...
                X