Where to draw the line - Deltas versus Flying wings - And why does it matter?

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by nerobro, May 2, 2019.

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  1. May 2, 2019 #1

    nerobro

    nerobro

    nerobro

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    So, it recently came up in another forum that flying wings were "imposible without comptuers".

    And we know that to be patently untrue. We have had flying wings from nearly the begining of aviation. But in that disucssion, it struck me, that the difference between a delta and a flying wing is not much.

    Why isn't a F102 a flying wing? Why is the YB-49, or even a vulcan, any different from say, a Mirage III or IV.

    You can build and fly a conventional plane, without a tail. (The X-36 is an example) Typically you dont' design for it, but B17's, Concordes, and even a B-52 have made it home missing most of their vertical tail. So the "no rudder and fin" thing isn't unique to flying wings. Even the flying wings that are out there, many have vertical control surfaces.

    Hang gliders, almost universally, are flying wings, depending on how you look at it.

    So.. where's the big difference? What's the useful difference? It seems to me that a B2, and a Space shuttle are just edge cases of the same thing. Which is a single flying surface airplane.

    If you'd like other "extreme" examples, the Rutan Quickie, is a Canard plane. So was the Wright Flyer. They're VERY different, but are still "canards" based on how they maintained control.

    I'm not sure this is a settle-able argument, but it'll be fun to see what you have to say.

    To ask the question directly, where does a delta or single surface plane, become a flying wing?
     
  2. May 2, 2019 #2

    12notes

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    Lack of a distinct fuselage makes it a flying wing.
     
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  3. May 2, 2019 #3

    Riggerrob

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    Most tail-less deltas (e.g. Mirage IIIM) are flying wings. Deltas are distinguished by their sharply-swept leading edges. That sweep helps with roll stability and supersonic airflow.

    Reverse-deltas (e.g. Arup) are much rarer.
     
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  4. May 2, 2019 #4

    nerobro

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    What's "distinct"? Where's the line? What does that line matter?
     
  5. May 2, 2019 #5

    12notes

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    Every example you've given either looks like a wing with the important bits (pilot, engines, etc) internalized or attached, or a tube/box containing some or all of the important bits with wings attached. The line in a mile wide, I can't think of an example that's even close to halfway in between.
     
  6. May 2, 2019 #6

    Hephaestus

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    Delta is just a planform, it's a style of wing construction.

    Flying wing is a type of aircraft without a horizontal tail or canard.

    My world anyway
     
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  7. May 2, 2019 #7

    BJC

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    Is it possible to have a delta wing without a straight leading edge? Look at the F-16 planform. Is it a delta?


    BJC
     
  8. May 2, 2019 #8

    henryk

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  9. May 2, 2019 #9

    Hephaestus

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    Isnt there an aspect ratio involved? An elyptical Delta would be sweet though.

    The real question to follow up is why didn't you guys get the f16xl which is a cranked delta :)
     
  10. May 2, 2019 #10

    RPM314

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    I'm in agreement with Hephaestus on the notion that 'delta' refers to a planform and that 'flying wing' denotes something without horizontal control surfaces. I'd say that any line you're thinking of drawing probably doesn't matter, we humans love to put things into categories and don't like it when that instinct is frustrated. All that matters is what the air thinks about it.

    F4D Skyray, maybe?
     
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  11. May 2, 2019 #11

    nerobro

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    Ok, two "well we're close to one or the other" examples, the Avro Vulcan and the Saab Drakken.

    Something I should have been clear on. We're not talking Mig-21 here, we're talking F102 versus YB-49.

    Heck, the dyke delta isn't even a delta. But people consider the Concorde to be a delta. Yes, straight leading edges aren't really what I was getting at.

    For instance, is the skyray a flying wing? I would argue it is.
     
  12. May 2, 2019 #12

    Himat

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    A delta does have a wing shaped like the Greek letter delta. If the wing tips are squared of like on the F-16 it could be questioned if it is a true delta. Especially as the F-16 wing have an aspect ratio that make it look more like an ordinary tapered wing.

    The Mirage 3 and the Mig-21 do have what could be called a “true” delta planform and illustrates that a delta wing aircraft can be either tailed or a flying wing. The early Vulcan did have squared of wing tips but otherwise a delta planform. Later marks may better be described as having a modified delta planform.
     
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  13. May 2, 2019 #13

    nerobro

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    Because I was a jerk, and wasn't clear. when I was spekaing of delta's, I was talking about tailless planes, with fuselages.
     
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  14. May 2, 2019 #14

    12notes

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    Both are tube fuselages with wings attached. Nowhere close to what I'd call a flying wing, in my opinion.

    Part of not having a fuselage is that the leading edge of the wing is also the leading edge of the aircraft.
     
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  15. May 2, 2019 #15

    bmcj

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    Let me muddy the waters a bit. Do you consider these delta, flying wing, or (marginally) conventional?

    Vought V-173
    SpaceShip One (or Two)

    And let’s not forget the other oft-overlooked category... lifting bodies.
     
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  16. May 2, 2019 #16

    nerobro

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    Why does the distinction matter?

    The Vought has me puzzling. Is it a weird shaped wing, or is it a wing with a tail on it? *boggles*

    Spaceship 1 and two both have separate wings and tails.
     
  17. May 2, 2019 #17

    TFF

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    Distinction matters if you are keeping score. If the terms are important then preciseness is important. If you want your own shape, it can be named your name. It is all about the fuselage. Fuselages add directional stability. Wing being wing, only to be pure has nothing fixed sticking up or down or out help with stability
     
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  18. May 3, 2019 #18

    12notes

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    Because one looks like a flying wing, and one looks like the familiar dart shape of recent fighter jets.
    Beyond that, ask yourself why you asked for a distinction, I can't tell you why you thought the distinction mattered enough to ask about it.
     
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  19. May 3, 2019 #19

    Tiger Tim

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    While we’re at it, where would you put the dividing line between a pot and a pan?
     
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  20. May 3, 2019 #20

    Himat

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    Just now i do miss the :ROTFL: emoj!
     
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