Karl Nickel's Falter 1 tailless aircraft

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by danmoser, Feb 16, 2014.

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  1. Feb 16, 2014 #1

    danmoser

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    I've always been intrigued by the late Dr. Karl Nickel's "Falter 1" ultralight aircraft design.
    Only two pages of his book, "Tailless Aircraft in Theory and Practice", co-authored by Micheal Wohlfahrt, had mentioned it... scanned pages attached here:
    p160.jpg p161.jpg

    Karl, a protege of the Horten brothers, had apparently never quite bought into their bell-shaped lift distribution (BSLD) concept, as his book seems focused on the attainment of elliptical lift distribution as being the ultimate desired goal.

    The Falter 1, a cooperative effort with a fellow named Ali Schmidt, reportedly attained full 3-axis control by manipulating induced drag, and without the use of any vertical control surfaces, or the Hortens' BSLD methods.
    Even deliberate side slips were demonstrated under full control.

    Why Karl's book did not go into more detail on this promising design concept is a mystery.

    I've always wanted to know more about the Falter 1 design, but my research has come up empty thus far.

    So I start this new thread as a plea for more information about the Falter 1.
    I'm hoping our friends from Europe on this forum will know more about this unique aircraft design.
     
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  2. Feb 16, 2014 #2

    ThadBeier

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    Seems impossible to have independent control over all three axes with only two controls surfaces. Just sayin'
     
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  3. Feb 16, 2014 #3

    danmoser

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    I believe there are actually 4 control surfaces.. inboard & outboard.. left & right.. but I could be mistaken.. adequate details were not provided.
     
  4. Feb 16, 2014 #4

    Aerowerx

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    Thad:

    Yes, it is possible. If you read the text and carefully study the pictures you will see that what appears as 'normal' ailerons is actually two (on each side) separate controls with a single fabric covering. Notice in one picture that there is a slight twist to the 'aileron'. Elsewhere in the book he talks about multiple control 'flaps' on a flying wing, working together in different combinations to produce the 3-axis control functions.

    Dan:

    I am intrigued by this also, and have been unable to find any other information either.
     
  5. Feb 16, 2014 #5

    Aerowerx

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    You beat me to it, Dan! You must have been typing at the same time as I was.

    As I stated, elsewhere in the book he talks about multiple 'flaps' on each side with an elaborate mixing system. In this case I think he simplified it to only 2 on each side. What tricks people is the continuous covering which makes it look like only one control.
     
  6. Feb 16, 2014 #6

    danmoser

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    Yes, I agree.. in sections 4.4, 4.5 and 4.6 of the book, he provides hints.. there is a reference to the mid-span and outboard control surfaces as elevators and ailerons, respectively ..
    This gives me a clue as to how he connected the Falter 1 control system linkages.. but no specifics given.
    Apparently Frise nose devices can be used on the ailerons, but not on the elevators.. makes sense!

    BTW, I've seen the German language version of this book free online.. but I don't have the link handy.
     
  7. Feb 16, 2014 #7

    Aerowerx

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    I got a copy of the English version from the local public library, by interlibrary loan.

    Took me two tries (could only keep it for 2 weeks at a time), but I managed to read clear through it and then scan in the chapters of most interest to me. I think there where only 2 or 3 that I did not scan. (You are allowed to make copies for your own 'research' purposes, according to USA copyright laws.)

    I took 'translating written German' in college, but that was 28 years ago. So I would be interested in the free German version. Maybe I could read it with a dictionary in my lap!
     
  8. Feb 17, 2014 #8

    nickec

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    "On each side it had two independently working control surfaces."

    The second image you posted is annotated with the above quote from page 161. So definitely four surfaces in total - two per panel.

    That book is full of very interesting information. Just my opinion.
     
  9. Feb 17, 2014 #9
  10. Feb 17, 2014 #10
  11. Feb 17, 2014 #11

    Aerowerx

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    These were in the OP.


    The Kasper wing has vertical rudders on each wing tip. The Falter does not, but has two 'flap' surfaces on each side, with a no gap between them.


    What the OP, and myself, want to know is how the mixer system works that allows 'normal' 3-axis control with the 4 (two on each wing) control surfaces.
     
  12. Feb 17, 2014 #12

    danmoser

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    Thank you for finding those pictures, Henryk!

    It looks kind of like a Kasperwing ultralight, but trikes and control systems are completely different in how they work.
    Both wing designs were obviously derivatives of Klaus Hill's "Fledgling" and "Voyager" hang gliders, which had 18 deg. of sweep, weight shift pitch control, and vertical tip rudders.
    Grossruck reduced the sweep to 13 deg. and inclined the Kasper-type tip rudders 30 deg. when he made the original Kasperwing A & B models, but implemented 3-axis control & spoilers on the C model.
    Nickel/Schmidt increased the sweep to 25 degrees, removed dihedral, and eliminated the tip rudders & weight shift completely to make the Falter 1.

    Now I need to study those pictures & see if I can glean any details from them..

    It would be great to find pilot reports from the test flights.
    Does anyone know if Mr. Ali Schmidt is still around?
     
  13. Feb 17, 2014 #13

    ThadBeier

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    Ah, indeed. I completely misread that! And it couldn't have been any more clear...Thanks Dan.
     
  14. Feb 17, 2014 #14

    danmoser

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    No worries..

    Looking over the museum pictures Henryk sent, it looks like an inverted joystick (pivots above pilot's head) and "rudder" pedals .. but I still can't figure out how the linkages & controls work. :think:
     
  15. Feb 17, 2014 #15

    bmcj

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    I'm still trying to figure that out too. One thing I think I see is the rudder cables tied into the aileron cables so the left rudder pulls a bend into the left cable, thereby pulling more on the left cable. (Obviously, the same holds true for the right side)

    Mixer.jpg

    BTW... The glove is holding the stick (not near from the pilot's hand... see the other photo). I can only surmise that the pilot's ungloved right hand is poised for holding a can of beer. :gig:
     
    Last edited: Feb 18, 2014
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  16. Feb 17, 2014 #16

    henryk

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    =ask Museum to send moore photos?...
     
  17. Feb 18, 2014 #17

    Aerowerx

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    What is that connection about half way up the stick? In the middle of the picture.
     
  18. Feb 18, 2014 #18

    bmcj

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    That appears to be the pivot mount for the stick. The upper end appears to be free of any attachments other than the control cables.
     
  19. Feb 18, 2014 #19

    danmoser

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    Speculating in the absence of data:

    It seems as though the rudder pedals are coupled to the ailerons (outboard control surfaces) and are actuated independently.. I assume both pedals could be simultaneously actuated as well for extra elevator effect .. such as landing flare

    The pitch-up effect of pushing one rudder pedal down would have to be counteracted by down elevator command .. so to initiate turn, step on the rudder pedal in the desired turn direction and push the joystick forward to compensate pitch with elevators (inboard control surfaces) .. use side-to-side stick motion to control bank angle with ailerons as needed.. you probably don't need to use much "rudder" once in the banked turn.
    That should work to eliminate adverse yaw as described in Nickel's book..
    In other words, the rudder pedal controls allow pitch-neutral differential aileron..

    I'm not sure about this, but it seems to make sense.. now if we could just get a volunteer in Germany to go to that museum and take measurements! ;)
     
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  20. Feb 18, 2014 #20

    danmoser

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    Studying Henyk's pictures from the museum a bit more, it looks like the elevators (inboard control surfaces) are mixed into the aileron inputs too, making them elevons.

    So I think we are looking at elevons as the mid-span control surface and pure ailerons at the tips, with the two foot pedals able to actuate ailerons individually.

    perhaps you see something else?:ponder:
     
    Last edited: Feb 18, 2014

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