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Why do plains, shuttles, & man made things that fly have 3 wings?

  1. Jan 24, 2008 #1
    why do plains, shuttles, & man made things that fly have 3 wings? My parents told me it was so the craft doesnt go into a constant spin. But like i wanta know more like in layman's turms and in picktures and stuff. Can any one help me please?
     
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  3. Jan 24, 2008 #2

    Astronuc

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    Well, the B-2 is one giant flying wing.

    The three wings, I'm guessing are the pair of wings proper, which protrude horizontally or at a slight upward angle from the fuselage and provide the lift, the elevators, which are small wings in the rear of the aircraft which provide for control of pitch, and the tail and rudder which provide for turning and yaw control.

    http://www.grc.nasa.gov/WWW/K-12/airplane/airplane.html
     
    Last edited: Jan 24, 2008
  4. Jan 25, 2008 #3

    Janus

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  5. Jan 25, 2008 #4

    Astronuc

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    The Space Suttle has a single pair of wings and tail. It mainly glides, or 'falls' to the landing site.
     
  6. Jan 25, 2008 #5

    FredGarvin

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    Not necessarily true. The shuttle is a lifting body. The entire fuselage acts as a wing.

    I can only assume that the OP is referring to a wing, a vertical and horizontal stabilizer. It's tough to say though. The last time I saw anything with three wings was WW1.
     
  7. Jan 25, 2008 #6

    Astronuc

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    True the Shuttle's fuselage and wing undersurfaces are continuous. I only indicated that it had continuous wings as opposed to wings and elevators (in the rear). I think the Shuttle is mainly a glider. It is transported piggy-back on a special 747, or it lifts vertically on thrust.

    In the atmosphere, I believe it simply glides since there is no SSME thrust (MESO with ejection of external tank), and I don't believe the orbital RCS thrusters are used during descent in atmosphere. They have one shot at landing - there is no second chance.

    That's what I assumed too.
     
  8. Jan 25, 2008 #7

    Danger

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    Cool; I'd forgotten how old you are.
    If memory serves, the shuttle has about the same glide ratio as a brick.
     
  9. Jan 27, 2008 #8
    thank you that does help alot but also from what ive reserched it can be a called an empennage. Does any one know why there alwase in the rear of the craft?
     
  10. Jan 27, 2008 #9

    jambaugh

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    Don't think of it as 3 wings but rather as two plane surfaces (horizontal wings and vertical stabilizer).

    Then think of what you want an aircraft to do and what you want it not to do.
     
  11. Jan 27, 2008 #10
    thank you, also from what ive reserched it can be a called an empennage. Does any one know why there alwase in the rear of the craft?
     
  12. Jan 27, 2008 #11

    Astronuc

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    http://en.wikipedia.org/wiki/Empennage
    Well the tail is always at the rear, where is provides the maximum stability. The vertical stabilizer, or tail, controls the sideways motion or 'yaw'. The elevators, horizontal stabilizers, controls the pitch of the aircraft (nose up or down). The elevators provide maximum moment located as from the center of gravity of the aircaft. Placing them at the rear also provides more stability.
     
  13. Jan 27, 2008 #12

    russ_watters

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    It isn't always the case, just most of the time. But for a demonstration of why, try throwing a dart backwards...
     
  14. Jan 27, 2008 #13

    RonL

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    A cannard design has control at, or near the nose of the craft.
     
  15. Jan 28, 2008 #14

    FredGarvin

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    Their location is always going to be a function of the forces created during flight. They are put where they need to be most effective. The original Wright Flyer used a canard system with the main control surfaces in front of the aircraft.
     
  16. Jan 28, 2008 #15
    Thank you all.
     
  17. Jan 28, 2008 #16

    jambaugh

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    It just occurred to me that the Wright Flyer's canard system probably resulted from their experience with stability of bicycles and other wheeled vehicles with front steering. A bad analogy as it turns out.

    The main virtue of the canard system, if I am not mistaken, is that in a stall the nose looses lift first and drops allowing the craft to gain speed before the stall occurs in the main lift wings.

    I suppose this came in quite handy in those early flights with a too heavy, underpowered craft.
     
  18. Jan 28, 2008 #17
    now if the empennage was moved to the front and the back wings are still in the back couldnt the craft have a better turning ratio? Also wouldnt the lift be not only in the back of the craft but in the front as well?
     
  19. Jan 28, 2008 #18

    DaveC426913

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    There is always an uneasy tog-of-war between stability and manueverability.

    You want an excellent turning radius, put the tail on the nose. It'll turn on a dime. Well, a good fraction of it will, anyway...
     
  20. Jan 28, 2008 #19

    DaveC426913

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    It occurs to me that control surfaces that trail the bulk of the plane are relatively well-protected from damage. After to the pilot, they're the next most important thing to keep the plane from making unscheduled landfall.
     
  21. Jan 28, 2008 #20
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