Interesting Australian Ultralight Amphibian Twin

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by rotax618, Jan 26, 2020.

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  1. Jan 26, 2020 #1

    rotax618

    rotax618

    rotax618

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    This amphibian was built some years back by John Stevens, it used 2 direct drive 2strokes with handmade alloy props. The wings had no ailerons but pivoted independently in the centre to give a more responsive roll. E12F2CB4-6C3B-43B7-9FD8-95970924C6CF.png 47EBB572-4B06-4E45-B042-5F33DBAC5A1E.png 5841156C-EE91-4AC7-9C83-03AAE5EA5FF2.png 03E5AFC1-4575-4420-95E0-E8D6AA802F8D.png 82F74F02-9874-4256-B8F0-8D3C17382C51.png
     
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  2. Jan 26, 2020 #2

    henryk

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  3. Jan 26, 2020 #3

    rotax618

    rotax618

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    They are JPX motors from France about 20HP, the builder reported that he could just maintain height with one motor (ground effect?) but if one motor stopped he didn’t have to paddle back to the ramp.
     
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  4. Jan 26, 2020 #4

    rotax618

    rotax618

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    Maybe one pf these:-
    448DB941-8C9E-478A-9528-D261841BC9CB.jpeg
     
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  5. Jan 26, 2020 #5

    Riggerrob

    Riggerrob

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    That pretty little green amphibian reminds us of the seaplane version of the Curtiss Pusher ...1930s vintage.
     
  6. Jan 27, 2020 #6

    cluttonfred

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    Interesting layout like the Hinkler Ibis.

    [​IMG]
     
  7. Jan 27, 2020 #7

    blane.c

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    If he puts a third engine on it maybe he can go somewhere.
     
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  8. Jan 27, 2020 #8

    rotax618

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    I cant post the video because I do not own the rights, but the builder explains that this is the third iteration of the amphibian and he has been making refinements in each model.
    From the video it appears to fly well, after a days flying he trailers it home. 287141DA-A497-4E01-A73C-DC6EC6E63FD1.png FBE4BCA4-61D4-4846-B038-7DC0EB7E88A3.png 7A59CD1C-B54B-4AB7-B057-8E93DCFDDD6B.png 510528C5-855B-4EB6-9457-6B54028E1862.png
     
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  9. Jan 27, 2020 #9

    delta

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    John Stevens seems to be a true pioneer. Good on him...
     
  10. Jan 27, 2020 #10

    blane.c

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    So I commented about the three engine idea but the later pictures show it climbing out just fine on two. Looking at the pictures of the man though we may have to strap on another engine if we put me in the plane.
     
  11. Jan 27, 2020 #11

    blane.c

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    It is interesting that you rotate the wing(s) for bank. I wonder how simple that is as they wouldn't have to rotate much especially if they rotated in opposite directions at the same time.
     
  12. Jan 27, 2020 #12

    blane.c

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    I wonder if they rotate opposite each other if the tendency would be to increase the roll rate or to rotate back to neutral?
     
  13. Jan 27, 2020 #13

    cluttonfred

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    Check out Daniel Dalby’s non-Mignet designs (Cubchel, Scoutchel, Demoichelle) for a good example of roll control by differential wing incidence.

    B2246A30-B887-43D8-8DD5-79932D97831C.jpeg

    EDIT: Fixed autocorrect typo and added photo
     
    Last edited: Jan 28, 2020
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  14. Jan 28, 2020 #14

    JohnB

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    Check out Daniel Daley’s non-Mignet designs (Cubchel, Scoutchel, Demoichelle) for a good example of roll control by differential wing incidence.[/QUOTE]



    AND the Spratt Controlwing and more recently the Spratt103 I worked briefly with a couple of aero engineers while trying to bring the Spratt103 to the States but both begged off the project as they saw the moveable wings as a massive flutter potential. I Pleaded " IT'S ALREADY BEEN DONE 50 YRS AGO !" was met with "My mind is made up. Don't confuse me with facts" I REALLY wanted to do that project. John B
     
  15. Jan 28, 2020 #15

    cheapracer

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    Makes me wonder if he started with the idea from the Spratt Amphib ..

    Spratt amphib.jpg
     
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  16. Jan 28, 2020 #16

    jedi

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    I like where this is going but it is seriously off topic. Getting rid of ailerons makes wing folding easier and roll control more positive IMHO.
     
  17. Jan 28, 2020 #17

    blane.c

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    Well … it may be an old idea but it is a new idea to me. Hmmmmmmmmm.
     
  18. Jan 28, 2020 #18

    cheapracer

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    Not sure how it's off topic, I'm suggesting that's where some of the original thought for his design may have come from.
     
  19. Jan 28, 2020 #19

    jedi

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    Spratt's ideas go back much further than that. Spratt was a consultant to the Wright brothers. Spratt's ideas were developed and used in the Wright wind tunnel tests to measure L/D of their airfoils. The rights did not give Spratt the credit he deserved in order to protect their patent rights. The wing warping was the Wright brothers version of differential Spratt AOA roll control.

    Wing warping increased the adverse yaw problem causing the Wright brothers to invent the roll/yaw rudder interconnect to overcome that issue. It is that that dam roll/yaw coupling and rudder solution that creates so many issues with modern flight training and aircraft design and loss of control accidents.
     
    Last edited: Jan 28, 2020
  20. Jan 28, 2020 #20

    blane.c

    blane.c

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    Yes … asymmetrical thrust, still need a rudder. Not so much a reason on this airplane but it needs a rudder to help keep it from weathervaning.
    a real problem for float planes taxiing down wind. I imagine that back in the days of round field runways you could of with a different arrangement got away without the rudder but now a'days needing to keep things lined up on the runway kinda' requires a rudder?
     

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