Decalage angle

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by Eugene, May 29, 2017.

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  1. May 30, 2019 #921

    poormansairforce

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    How do you think they would look on top of a wing? Its hard to see the front tuffs but most look like they are in turbulent air. Being on the bottom I would expect them to lay down better. I had mentioned VGs earlier to check this but thats a fantastic shot. Look at some tuft videos and see if the rear ones look better or worse than yours.
    The rear ones on the flat underside remind me of a wing approaching stall.
     
    Last edited: May 30, 2019
  2. May 30, 2019 #922

    poormansairforce

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    Look at 1:05 in this video:

    With flaps down those rear tufts look a lot like yours. Just invert it for your situation.
     
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  3. May 30, 2019 #923

    Doggzilla

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    Yes, with such a high curve there is no way the air is remaining laminar unless he had boundary layer suction control.
     
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  4. May 30, 2019 #924

    poormansairforce

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    Eugene mentioned it felt like flaps down all the time and it shows.
     
  5. May 30, 2019 #925

    Eugene

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  6. May 30, 2019 #926

    BBerson

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    If the forward fuselage is creating nose down lift, maybe that lift could be "spoiled".
     
  7. May 30, 2019 #927

    poormansairforce

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    Thats not good either.

    If its lift then yes but then would we be creating outright drag and is that better? There is turbulence so it might already be drag.? Tough situation to deal with. I wonder if VGs would show which direction to go?
     
  8. May 30, 2019 #928

    poormansairforce

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    A fairing would solve everything on the bottom but that is involved. It seems all the curves on this plane are just too severe.
     
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  9. May 30, 2019 #929

    BBerson

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    VGs improve the lift with energy input. The spoiler is opposite. About a 1" high spoiler might work without much drag (from my glider experience). But this is all WAG*. :eek:

    *Wild Ass Guess (aerodynamic term)
     
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  10. May 30, 2019 #930

    poormansairforce

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    I guess what I was asking is that if we spoil the lift will it make the entire curve a drag section vs getting some airflow around the curve and dealing with the lift created? It would be easy to test a spoiler as well.
     
  11. May 30, 2019 #931

    BBerson

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    I think a proper design would reset the fuselage incidence for zero fuselage lift at cruise.
    That requires setting the wing incidence more negative in this case. That would bring the nose up in cruise.
    The horizontal would also need to be reset more negative to follow almost the same decalage.
    Another idea is reshaping the fuselage nose to provide more normal positive camber. Sort of a drooped snoot adds positive camber.
    Probably should do all this with a 1/4 scale RC model.
     
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  12. May 30, 2019 #932

    AdvenJack

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    Eugene, I truly applaud your motivation to experiment on your airplane.
    We all see your determination to achieve your performance and efficiency
    goals. I just wonder how much time and money you're willing to put into
    your present airplane, to make what seem to be the necessary changes,
    in order to hit the marks that you've decided on. I refer you to the below
    attachments, that you've in essence said, you really favor. Would you see
    yourself making such significant changes to your airplane, that it ends up
    looking like the below? I'm just curious is all. I appreciate very much what
    you've tried thus far. BELIEVE ME!!!

    Sure, a guy can make enough changes to a Volkswagen Beetle made in 1965
    to get it to perform like a Porsche 911. But the number of parts changed,
    the time, effort and money expended, to get such performance is just not a
    fair trade off. A guy might instead, just build a performance car from a raw
    chassis and still be able to "experiment" along the way to great satisfaction! AirplaneDrawn Unique.png 1TwinBoom HighHorizntl.png 2TwimBoom HighHorizntl.png
     
  13. May 30, 2019 #933

    AdvenJack

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    Eugene's Amazing modification to horizontal stabilizer to see experimented with: HorizStab Modification.png
     
    Last edited: May 30, 2019
  14. May 30, 2019 #934

    Eugene

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    As always, time and money is my limitation as well. To me Skyboy is affordable 15-25K project were I did learn so many things and tried many things relatively inexpensive. That is priceless to me. I can pretend to be one of them without spending 200K - 2Mil.

    Big surprise was to find out that nobody have 100% answer for my question. I send picture of this twin boom reed airplane to Russian designer, who designed and build aircrafts below, as potential perfect pusher design. He replied to me, that he spend a lot of time trying to design similar aircraft. But decided not to do it, because at high AOA horizontal tail not getting airflow , and this is when you need it the most = at low speed. So, there is no "perfect" airplane out there.
    fullsizeoutput_1470.jpeg fullsizeoutput_148e.jpeg 31288520_328347941026741_3178055063490789376_o.jpg
     
  15. May 30, 2019 #935

    Eugene

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  16. May 30, 2019 #936

    Eugene

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    Found Seamax picture in level flight

    Screen Shot 2019-05-30 at 07.35.51.png
     
  17. May 30, 2019 #937

    Doggzilla

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  18. May 30, 2019 #938

    Doggzilla

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    But with pusher props I wonder if that's still such an issue, as the airflow during a stall will clearly be different with propwash back there.
     
  19. May 30, 2019 #939

    BJC

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    I see your problem, Eugene; you are missing an engine.


    BJC
     
  20. May 30, 2019 #940

    AdvenJack

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    Shared By Eugene *Spectacular Looking Airplane!!!
    TwinEngine SkyBoat.png
     
    Last edited: May 30, 2019

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