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Airplanes that fly a few feet above the surface of the sea

  1. Apr 24, 2004 #1
    Is anyone still developing the airplanes that fly a few feet above the surface of the sea to get increased lift?
     
  2. jcsd
  3. Apr 24, 2004 #2

    wolram

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    http://www.aanet.ru/iiaat/main_cvpn.shtml
    HTHL aerospace planes; statement of the efficiency of modern generation of ekranoplanes (WIG-craft) with more perfect means of automatic control; the concept of ekranoplane use for aerospace plane launch and landing (has been developed together with Japanese colleagues); the concept of ekranoplane "Spasatel" construction finishing.
    I'm not sure if any of these craft are in construction, or if they are
    economical, but I'm sure i have read that hobbyists are building
    small scale ones
     
  4. Apr 24, 2004 #3

    drag

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    I heard about the Russian cargo plane.
    How about missiles - short and medium range for marine
    warfare, any of those out there ?

    Would seem like a great idea - saving fuel and partially
    evading detection and countermeasures.

    Live long and prosper.
     
  5. Apr 25, 2004 #4

    wolram

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  6. May 4, 2004 #5
     
  7. May 4, 2004 #6

    enigma

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    How is it that flying at such a low altitude increases lift?
     
  8. May 4, 2004 #7

    LURCH

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    Is called "ground effect" or "flare". It can be understood as a pocket of air trapped underneath the aircraft, although the situation is slightly more complicated than that.
     
  9. Jul 3, 2004 #8
    Wing in Ground Effect

    Them easy explanation of ground effect is to be found in how a wing actually produces lift. When one uses a Langrangian coordinate system to look at the flow around the wing you will detect that the air actually circulates around the wing. So a vortex system exist around the wing across the entire length of the wing. At the wing tip the vortx is shed a 90 deg angle giving rise to the term: "horse-shoe vortex". If we look at the plan view of the aircraft the vortex system would approximate a horse-shoe. When the vortex is shed from the wing tip it does work on the wing, which is to say that the vortex is applying a force on the wing. This force can be and is used in modern airliners. The winglets at the tip of the wing of a Boeing 747 is at an angle which is calculated in such a way that when the vortex applies force to the wing during shedding the force is transimitted through the wing structure in such a way that a component of that force is in the same direction than the direction of the thrust vector, therefore adding to the thrust of the aircraft (remember this is energy that would have been to lost to elastic deformation in the wing so no magic here). This same vortex system is resposiable for ground effect. When the wing is close enough to the ground the vortex cannot shed in the normal way and a force is exerted on the underside of the wing resulting in a addition to the lift force. A aircraft using ground effect is very, very efficient but there are severe problems with control and stability and off course the sheer size of the airplane is also a major design challenge. One more trivial fact, WIG vehicles are actually classified as ships and not aircraft.
     
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