Low wing pusher configuration?

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by BBerson, Nov 20, 2016.

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  1. Nov 27, 2016 #81

    BJC

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    Always liked the concept.

    Good link, thanks.


    BJC
     
  2. Nov 27, 2016 #82

    BBerson

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  3. Nov 27, 2016 #83

    cluttonfred

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    I have always thought of wing position as relative to the fuselage not the engine position. So most airliners are low wing even though the engines are even lower. In light aircraft where the occupants can often be taller than the fuselage, the people become the reference point, hence "shoulder wing," since a fuselage has no shoulders. YMMV!
     
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  4. Nov 27, 2016 #84

    Himat

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    Most books I have seen only consider the relationship wing – fuselage when differing between low, shoulder, high or parasol wing position. This is when describing monoplanes layout or the position of one of the wings on a biplane. Pylon mounted wing is if mentioned put together with parasol mounted wings although a wing mounted on a pylon below the fuselage is possible. For whatever reason the designer should chose that.

    Gudmundssons book describe most possibilities quite well, both wing and engine placement.
     
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  5. Nov 27, 2016 #85

    BBerson

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    Sure, that's correct. But for a pusher it gets more complex.
    The questions are mostly with prop/wing interference. So the terminology needs to describe where the wing is relative to the prop and the fuselage if it has a fuselage.
    I want my wing completely below the prop to shield it from rocks, water etc. The wing will be mounted to a low 10" tall tail boom. The wing will be just inches from the ground, even if on top of the boom. Hardly seems logical to describe as high wing just because it's on top of boom.
    See post 71. If that wing was moved above tail boom, it would hardly matter.
     
  6. Nov 28, 2016 #86

    autoreply

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    Interesting... no mention of the elephant in the room; laminar flow.

    There's a reason the Avanti is 80 kts faster than a 350 with the same engines...
     
  7. Nov 28, 2016 #87

    BBerson

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    The two seat Seeker pusher is about the same performance as the four seat C-172: http://www.seabirdaviation.com.au/pages/seeker/

    The Avanti has about twice the wing loading of a King Air, sort of a private jet alternative. A King Air can haul more into dirt strips. I don't know if the Avanti has laminar wings. Usually the boots or stainless heaters (or bugs) trip the flow. A small wing is always faster.
    If I use pusher, it will be for utility, not performance.
     
  8. Nov 28, 2016 #88

    Himat

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    The drag created by the wing – fuselage intersection is probably first determined by how the wing is placed relative the fuselage. It would then matter if the wing was moved to the top of the boom on the airplane pictured. And said airplane would then probably have the wing –fuselage drag changed from the typical low wing pattern to high wing pattern. At least for the part of drag created at the wing trailing edge.
    [​IMG]
     
  9. Nov 29, 2016 #89

    BBerson

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    Probably correct. But with a smaller tail boom, at some point a small tail boom is like a wing with no fuselage at all, I think.
    My wing is 9" thick, about the same as the tail boom so it would likely cover the whole tail boom from top to bottom. Guess they might call that a blended wing/body with lowest drag?
     
  10. Nov 29, 2016 #90

    Swampyankee

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    How would you classify something like the Douglas Dolphin? 1013px-Douglas_RD-4_Dolphin.jpg
     
  11. Nov 29, 2016 #91

    cluttonfred

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    Shoulder wing with high-mounted engines?
     
  12. Nov 29, 2016 #92

    Aviator168

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    According to auto, that's a low wing. LoL.
     
  13. Nov 29, 2016 #93

    BBerson

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    So why did Douglas put the props so high? Did they want the prop blast above the wing for less drag or some other reason?
     
  14. Nov 29, 2016 #94

    Jay Kempf

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    To get them out of the spray normally on this sort of design.
     
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  15. Nov 29, 2016 #95

    bmcj

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    For my own purposes, I have always defined high/low/mid(shoulder) wing by whether there is a substantial section of fuselage below or above the wing, or both. I similarly define the engine location in relation to the fuselage, not in relation to the wing (though that can serve as a secondary classification).

    (I suppose that would define most Northrop and Bernoulli planes as just "wing". :gig:)
     
  16. Nov 29, 2016 #96

    BBerson

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    Looks much higher than a similar Grumman Goose with engines in the wing leading edge. Those pedestals have a bunch of drag, compared with the Grumman.
    I know NACA did tests of best prop/wing location for typical twins and airliners.
    I wonder if NACA tested prop location of the aft part of the wing for pushers?
     
  17. Nov 29, 2016 #97

    Jay Kempf

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    Every designer has his own likes and dislikes in design. Every designer has these subjects that they are convinced are the ONLY way you can do something. We are all guilty of these things. If we are talking about different eras of design then the understanding of what works best or better might have changed in time. Having the prop pulling directly on the camber line of the wing certainly makes for a neutral and stable flying airplane. I wonder if the lower wing position was thought of as helping to use ground (or proximity to water in this case) effect to get the hull out of the water, break suction and get it on the step quicker?
     
  18. Nov 29, 2016 #98

    Himat

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    Yes, I follow your argumentation there. If the tail boom is no thicker than the wing and not wider than high you are getting closer to something that look like a wing only. The thing to consider is then the interface fuselage/engine pod – wing.
    How you describe your suggested layout made me remember this one.
    148943.jpg

    (Illustration grabbed from the internet, I am not that good visualizing.)
    With a thinner tail boom, would it match your layout?
     
  19. Nov 30, 2016 #99

    BBerson

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    Yeah, that's about it. Of course, a full scale will look a bit cruder to fit a pilot.
    Here is another I found from France. Called Exel.
    http://www.alpaero.com/
    image.jpeg
     
    Last edited: Nov 30, 2016
  20. Dec 9, 2016 #100

    REVAN

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    The Terrafugia Transition is a low wing pusher that comes to mind.
    https://www.terrafugia.com/the-transition/

    I think of the Transition as an enlarged modern remake of Lewis Jackson's J-10.

    Also, I think the Learjets and other similar aircraft can be included in this general description (low wing pusher with engine above wing).
     

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