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Over-Thick Control Surfaces

Discussion in 'IMAC>>>Aircraft, Techniques, Equipment, etc.' started by Wacobipe, Sep 23, 2014.

   
  1. Bartman

    Bartman Defender of the Noob!

    yes, the aileron LE and the TE cove of the wing will have to be tapered to suit the taper of the wing.
     
  2. Pistolera

    Pistolera HEY!..GET OUTTA MY TREE!

    Kendall Simpson just posted (on FB) a nice pic of him flying an S1-T in (very) close formation with Rob Holland.  This pic shows the "fat" rounded leading edge of the "T" aileron fairly well.[​IMG]
     
  3. Pistolera...thanks for that...and good catch! I saw that photo on Facebook when Kendall posted it but I didn't catch the good detail of the aileron.
     
  4. I think if I remember right, That the Germans used thicker Elevators and Ailerons back it the 1930s on the Bucker Bi-planes.

    Thanks Van
     
    Wacobipe likes this.
  5. WMcNabb

    WMcNabb 150cc

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  6. Pistolera

    Pistolera HEY!..GET OUTTA MY TREE!

    That design is referred to as Frise-type ailerons. A bit from Wikkipedia;

    Frise ailerons
    Engineer Leslie George Frise (1897–1979) of the Bristol Aeroplane Company developed an aileron shape that is pivoted at about its 25 to 30% chord line and near its bottom surface [1], in order to decrease stick forces as aircraft became faster during the 1930s. When the aileron is deflected up (to make its wing go down), the leading edge of the aileron dips into the airflow beneath the wing. The moment of the leading edge in the airflow helps to move up the trailing edge, which decreases the stick force. The down-moving aileron also adds energy to the boundary layer. The edge of the aileron directs air flow from the under-side of the wing to the upper surface of the aileron, thus creating a lifting force, which adds to the lift of the wing. This reduces the needed deflection angle of the aileron. The popular American Piper J-3 Cub light aircraft of 1938 possessed Frise ailerons as designed, and helped introduce them to a wide audience.

    The Frise aileron bonus is often described as its ability to counteract adverse yaw. To do so, the leading edge of the aileron has to be sharp or bluntly rounded, that adds significant drag to the going up aileron and helps the aircraft to yaw (turn) in the desired direction, but adds some unpleasant, non linear effect and or potentially dangerous aerodynamic vibration (flutter). In fact the use of differential aileron movements — as with the famous de Havilland Tiger Moth biplane — is much more efficient to decrease adverse yaw moments.
     
  7. WMcNabb

    WMcNabb 150cc

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    Thanks Earle!

    Based on the subject at hand, the question goes back to whether an aileron thicker than the airfoil would be more responsive, cause less adverse yaw, or even be noticeable in scale form.
     
  8. Pistolera

    Pistolera HEY!..GET OUTTA MY TREE!

    If it is noticeable, I would think it may be a bit more responsive. I don't think it would do anything regarding adverse yaw though. I think the recessed hinge, referred to as the "SS" style earlier in this thread would be more responsive than anything in a scale form. You can see this on the Sukhoi below. The left aileron is deflected up and you can see through the gap where the leading edge is beneath the wing. Conversely, the right one is down and you can clearly see the leading edge raised up above the wing.
    SU-31.jpg
     
  9. WMcNabb

    WMcNabb 150cc

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    I'm sure the same occurs with the Extra. I didn't have any full scale photos but did have the factory 3-view. Notice the deep gaps for the recessed hinges in the ailerons.

    image.jpg
     
  10. Pistolera

    Pistolera HEY!..GET OUTTA MY TREE!

    Yep...they're fairly common these days....I just didn't have any shots that showed it like the SU-31 above.

    Oh....and other interesting thing that you can see on the 3-view you posted, is the reverse taper of the ailerons! They get larger in chord toward the tip....(not counting the aerodynamic balance at the tip) :). Haven't seen any RC planes with this.....kinda wish Krill would've done it.
    You can see it again in this shot of Mike's 330SC.
    330SC top view in tight turn.jpg
     
    Last edited: Dec 2, 2014
    WMcNabb likes this.
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