Steering of Flying Plank

Discussion in 'Workshop Tips and Secrets / Tools' started by Stefan Franke, Jan 15, 2012.

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  1. Jan 15, 2012 #1

    Stefan Franke

    Stefan Franke

    Stefan Franke

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    Hello, i am building a Flying plank. Now i think about posiibilites for a searing mixer like the hortenmixer. Does anybody have some pictures of the stearing of an U2 Mitchelwing. Must be something like that. I have a sketch of this mixer but no photo.

    thanks
    stefan
     
  2. Jan 15, 2012 #2

    Norman

    Norman

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    Not a photo but a CAD model I got from a u-2 builder
     

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  3. Jan 16, 2012 #3

    Stefan Franke

    Stefan Franke

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    thank you but this one i already have.. but how are the tubes connected to the stearing stick... has to be something free to move because of different angles...
     
  4. Jan 16, 2012 #4

    autoreply

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    I do have some pics of the Horton underbelly/mixer, but not sure how detailed they are. Will look them up tonight.
     
  5. Jan 16, 2012 #5

    Hot Wings

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    The tubes connect via little ball joints, similar to ones on an auto lift gate. There are push-pull tubes connected to the empty holes of the bell cranks shown that go back to torque tubes for the elevons.
     
  6. Jan 16, 2012 #6

    Stefan Franke

    Stefan Franke

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    i think if i connect the tubes with the empty holes i will get much clearance? I baught some ball joints and will try to make a photo...
     
  7. Jan 16, 2012 #7

    Norman

    Norman

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  8. Jan 16, 2012 #8

    deskpilot

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    Stefan, if I understand your question correctly, the control column (stearing stick) passes through a self aligning ball race where it connects with the horizontal components. This allows it to lean without trying to twist the centre 'plate' All other joints are normal, slop free bearings.

    For what it's worth, here a a few of images of the Dyke Delta mixer system for it's elevons. The control stick is off to the left.

    Mixer4.jpg Mixer3.jpg Mixer2.jpg Mixer1.jpg
     
  9. Jan 17, 2012 #9

    Aircar

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    If your 'Plank' is of the Backstrom or Marske variety they went away from tip end elevons to a separate root end elevator and ailerons only for roll control --Marske's book "experiments in tailless aircraft design" has a lot of his development history and reasons for various ways of controlling . Generally you need aft sweep to make ele-vons the best choice and to need a mixer --the Mitchell wing type results in quite non linear elevator effectiveness due to the geometry of the linkages also and sensivity to slop as well ( I had to examine the wreckage of one many years ago and re construct the control circuit in the process --it was a U2 )
     
  10. Jan 17, 2012 #10

    Norman

    Norman

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    Marske did but Backstrom didn't. The reason for that is that Marske changed from the constant chord of his first 'wing to a swept forward tapered wing. A constant chord plank style 'wing can work either way because the pitching moment of any spanwise station has the same effect as any other part but with taper the pitching moment of the root section has a greater effect on the attitude of the aircraft than the tip. If you now sweep this tapered wing forward a bit the pitching moment and lift increment of the tip are now trying to push the attitude of the airplane in opposite directions. These two quirks of taper and sweep both argue to separate the pitch and roll functions of tapered planks. On the other hand constant chord planks would work fine with full span elevons because the more span you use for pitch control the less angular deflection you need for a given pitch trim. The attached PDF shows a collage of the cockpit of the EPB-1C. Most of his mixer is visible on the back wall. Unfortunately the stuff at the bottom of the joystick is covered up. It looks more complicated that the V-mixer that Mitchell and the Hortens used but it's functionally the same thing just a pull-pull version. Horten also used a wire V-mixer once and I've been looking for the picture but haven't found it. It's pretty simple: The stick is supported by a universal joint and two wire Vs attach to it, one above the joint and the other below. The one V is being pulled while the other relaxes.

    The pitch to roll ratio can be adjusted by changing the angle of the V. At 90 degrees the mix ratio is 50/50, sharper angles give more pitch, and obtuse angles give more roll.
     

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