The effect of sweepback on adverse yaw on flying wings

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by John Newton, Feb 26, 2013.

Help Support HomeBuiltAirplanes Forum by donating:

  1. Mar 6, 2013 #61

    captarmour

    captarmour

    captarmour

    Well-Known Member

    Joined:
    Feb 9, 2013
    Messages:
    368
    Likes Received:
    32
    Location:
    Roseau, Dominica.
    I wrote this earlier "U may find you may need to fly with the wingtip aileron free floating to see what angle it orients itself before u connect it. Don't be surprised if it is pointing down quite a bit."

    Bob Hoey said this "Left, the lead feather is set at negative 27 degrees (this is not a typo), the second is at -19 degrees, the third at -15 degress and, the remaining stationary feathers are reduced 4-5 degrees per feather until the aft one is at zero. Other combintions of angles have not worked as well as this one." HoeyVulture

    He also said this "To test this theory I built a wingtip that had the 3 forward feathers mounted on a single spanwise axis. There was a change from adverse yaw to proverse yaw as the initial bias position of the ailerons was changed. The best bias position was with the forward feather at a whopping big -27 degrees of incidence relative to the chord of the rest of the wing. I built a model of this wing tip and ran it in the NASA DFRC water tunnel. These tests confirmed that the flow over the forward tip feather was smooth at -27 degrees, but would stall (on the bottom) at -35 degrees, and stall (on the top) at -22 degrees" BirdLetters

    does this answer your question?
     
  2. Mar 7, 2013 #62

    John Newton

    John Newton

    John Newton

    Well-Known Member

    Joined:
    Dec 5, 2012
    Messages:
    430
    Likes Received:
    22
    Location:
    Derbyshire, England
    Thanks for the link, I'll take a look.
     
  3. Mar 7, 2013 #63

    John Newton

    John Newton

    John Newton

    Well-Known Member

    Joined:
    Dec 5, 2012
    Messages:
    430
    Likes Received:
    22
    Location:
    Derbyshire, England
    Just recieved a servo end point adjuster, looks like it will be ideal for setting control surfaces to go up/down only as discussed previously in this thread, could also be useful for drag rudders as well where you usually want the servo to move over half of the rudder sticks movement (the drag brake being closed when the rudder is moved the other way) to open the drag brakes.

    Servo End Point Adjuster | Model Radio Workshop
     
  4. Mar 7, 2013 #64

    John Newton

    John Newton

    John Newton

    Well-Known Member

    Joined:
    Dec 5, 2012
    Messages:
    430
    Likes Received:
    22
    Location:
    Derbyshire, England
    Just taken a look at Bob Hoey's bird gliders, what a genius!!! Amazing design and build quality! Very elegant method of sweeping the wing without effecting location of the neutral point (aerodynamic centre)
     
  5. Mar 7, 2013 #65

    John Newton

    John Newton

    John Newton

    Well-Known Member

    Joined:
    Dec 5, 2012
    Messages:
    430
    Likes Received:
    22
    Location:
    Derbyshire, England
    If I understand it correctly on the bird models both "aileron" tip feather sets are pitched downward by a very large amount, giving low thrust, when rolling the one on the outboard side of the turn has its pitch reduced slightly producing more thrust and therefore proverse yaw, am I correct? Recently joined twitt, will have to look into Bob's work more.
     
  6. Mar 7, 2013 #66

    captarmour

    captarmour

    captarmour

    Well-Known Member

    Joined:
    Feb 9, 2013
    Messages:
    368
    Likes Received:
    32
    Location:
    Roseau, Dominica.
    Exactly. Jehovah knew what he was doing when he designed the birds, extremely well thought out. I guess he had an advantage in that he had already designed the air.
     
  7. Mar 7, 2013 #67

    John Newton

    John Newton

    John Newton

    Well-Known Member

    Joined:
    Dec 5, 2012
    Messages:
    430
    Likes Received:
    22
    Location:
    Derbyshire, England
  8. Jul 23, 2019 #68

    Speedboat100

    Speedboat100

    Speedboat100

    Well-Known Member

    Joined:
    Nov 8, 2018
    Messages:
    688
    Likes Received:
    52
    Location:
    Europe
    John Newton ahoy !

    Here Albion Bowers on the same subject:
     

Share This Page

arrow_white