Very low aspect ratio planes?

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by Inverted Vantage, Oct 30, 2009.

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  1. Sep 27, 2015 #561

    Starman

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    In my drawing the pilots eyes are close to the leading edge of the wing, so he can look almost straight down (of course to the side a little bit) and by moving his head forward a couple of inches the pilot can look straight down. Also there is only a gearbox in front of the pilot's feet, not a whole engine so the visibility ahead is much better too. It's like being in a sailplane. Also, the fuselage is directly in front of the fat wing for much less frontal area. Your design has a 'house' on top, which is not nearly as aerodynamically efficient. The Arup type wings also blocks your view downwards 100%.

    So, should I say it? My design is much better =)
     
  2. Sep 27, 2015 #562

    Sockmonkey

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    I would like to stick with tailless if possible for the sake of simplicity and structual strength if possible, so yeah I'll have to move some stuff around.
    Maybe go with a delta wing like an upside-down version of the verheese delta.
    [​IMG]

    At some point I'd try sticking all-flying nub fins outboard of the nacelles just behind the props to see what kind of maneuvering tricks you could pull off.

    Well, pulling the center bit back doesn't restrict visibility much if it's still using the center body engine and shaft-driven prop. You could try a version of the hatfield little bird with that engine setup or go extra crazy with a high-winged version of the arup.
    [​IMG]
    There's all your visibility problems solved.
     
  3. Sep 27, 2015 #563

    Norman

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    I don't think so. If you make the skin above the cockpit transparent you'll have some upward visibility but the wing still blocks most of the upward view. The blades of a spinning prop count as fins whether the power is on or not so puting it up front makes it necessary to increase the size of the vertical fin. A pusher prop allows you to get the pilot's eyes up front, where they belong, and it increases stability a little bit. If the airfoil is fairly thick you could put the pilot's head inside the wing behind a transparent leading edge.
     
  4. Sep 27, 2015 #564

    Sockmonkey

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    Increasing the size of the vertical fin is perfectly acceptable. As for upward visibility, a small transparent panel could be added to the wing on either side of the engine.
    Really, I'm more concerned with side and downward visibility as those are most critical for landing. Particularly if you want a high AOA STOL.
     
  5. Sep 27, 2015 #565

    Topaz

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    If you want a STOL airplane, tailless is a very poor choice. Tailless is at its finest for a high-thrust-loading cruising airplane. STOL requires maximum possible lift coefficient across the entire span at takeoff or landing and, in a tailless airplane, your pitch control surfaces are going to ruin that plan simply by using them.
     
  6. Sep 27, 2015 #566

    Sockmonkey

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    That was in reference to airplanes with poor upwards visibility in general, but yeah you really can't do STOL with this one.
    High AOA takeoff and landing is doable though.
     
  7. Sep 27, 2015 #567

    Topaz

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    Do you see some particular advantage in doing so?
     
  8. Sep 27, 2015 #568

    WonderousMountain

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    Pretty useful technique for reducing landing speed.
     
  9. Sep 27, 2015 #569

    Sockmonkey

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    Made some tweaks to make it more sexy and added more rudder.
    [​IMG]
     
  10. Sep 27, 2015 #570

    Topaz

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    True, except that you're "committed" at that stage. Well on the back side of the power curve. Doesn't give the pilot a lot of options if, for example, hit with a sharp gust late in the process.
     
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  11. Sep 27, 2015 #571

    BJC

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  12. Sep 28, 2015 #572

    henryk

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  13. Sep 28, 2015 #573

    cluttonfred

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    BJC, henryk, what do these clips of heavy, jet-powered take-offs, landings, and crashes have to do with low aspect ratio light aircraft?

    I don't see these as any more relevant than radio-controlled flying lawn mowers or other RC examples that simply show that with high power and low weight you can make almost anything fly.

    Arup, Zimmerman, Hoffman, Eshelman, Vought V-173, etc. are relevant to light aircraft discussions in terms of wing and power loadings, but the clips you posted don't really provide much useful information for light aircraft.
     
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  14. Sep 28, 2015 #574

    henryk

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    -see "vortex augmented lift"...
     
  15. Sep 28, 2015 #575

    erkki67

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    We are approaching the concept of the flying horseshoe of the Arup design :)
    image.jpg
    It had an engine up in front, but it was a simple direct drive, with good flying characteristics.
    I'm wondering what banned Topspeed100 would have come up with for a LAR plane!
    Rki
     
  16. Sep 28, 2015 #576

    Doggzilla

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    I was actually sitting in my truck looking out at the sky a few months ago waiting for a few hours, and realized that some of Topspeed's ideas were actually feasible if he wasnt trying to power them by 300 obese tourists.

    It wasnt that the designs were bad, it was that he was considering the wrong materials, and the wrong goals. And I dont mean he needed to use titanium with spider silk, he was actually using too stiff of materials.
     
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  17. Sep 28, 2015 #577

    BJC

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    Matthew:

    Responding to the comments about high alpha landings. The aerodynamics that lead to high alpha landings for the Concorde, a fine example of a low aspect ratio airplane, would also apply to a low AR light plane.

    There was also a comment about getting behind the power curve at high alpha. The second link showed an example of that.

    Thanks for asking.


    BJC
     
  18. Sep 28, 2015 #578

    Sockmonkey

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    Yep, that's exactly what I'm getting at, only with a high wing.
     
  19. Sep 29, 2015 #579

    WonderousMountain

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    Screenshot 2015-09-28 at 15.54.32.jpg AR 2.712 , I measured the semispan in eights, and the semichord as 20ths. If you look closely you'll see the rib positions.
     
  20. Sep 30, 2015 #580

    WonderousMountain

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    Screenshot 2015-09-30 at 09.15.34.jpg

    Drew in a potential substructure. I like it a good bit. fits the many pieces theme without becoming too messy.

    LuPi
     

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