A Ground effect vehicle (GEV) refers to an aircraft that takes advantage of the aerodynamic principle of the Wing-in-ground effect (a form of ground effect). GEVs were originally called Ekranoplans, after the original vehicles created in the former Soviet Union pioneered by Rostislav Alexeev; this name is now used to describe the Russian designed vehicles and their variants, with GEV being used as the more generic term for this class of vehicle.^[1] Look up aircraft in Wiktionary, the free dictionary. ... The term Wing In Ground effect (sometimes misleadingly referred to simply as Ground effect - this being a generic term describing all aerodynamic effects due to a flying bodys proximity to the ground[1]) refers to the reduction in drag experienced by an aircraft as it approaches within roughly 1... The term Ground effect (or Wing In Ground effect) refers to the increase in lift experienced by an aircraft as it approaches within roughly 1/4 of a wingspans length of the ground or other level surface (such as the sea). ... An ekranoplan (Russian: , literally screen plane) is a vehicle resembling an aircraft but that operates solely on the principle of ground effect (in Russian эффект экрана effekt ekrana - from which the name derived). ... R.E. Alexeev at work (shown during Ekranoplan TV documentary) Rostislav Evgenievich Alexeev (December 18, 1916, Novozybkov, Bryansk Oblast, Imperial Russia – February 9, 1980, Nizhny Novgorod, USSR) was a designer of highspeed shipbuilding. ...

Advantages and Disadvantages

A ground effect craft may have better fuel efficiency than an equivalent aircraft flying at low level due to the close proximity of the ground reducing Lift-induced drag. There are also safety benefits in flying close to the water as an engine failure will not result in the craft falling a great distance. Despite this, the Russian Ekranoplan program had a series of disasters due mostly to pilot error showing how difficult that particular wing configuration is to fly even with computer assistance.
Another problem is the difficulty of taking off from the water, as the small wings of most ground effect craft do not provide as much lift as highly flapped wings. A take-off must also be into the wind, which in the case of a water launch, means into the waves. Two main solutions to this problem have been implemented. The first was used by the Russian Ekranoplan program which placed engines in front of the wings to provide more lift. The Caspian Sea Monster had eight such engines which were not used once the craft was airborne. A second, more elegant approach, is to use some form of an air-cushion to raise the vehicle most of the way out of the water, making take-off easier. This is used by German Hanno Fischer in the Hoverwing (successor of the Airfisch ground effect craft), which uses some of the air from the engines to inflate a skirt under craft in the style of a Sidewall Hovercraft. The square-cube law allows this easier solution. In aerodynamics, lift-induced drag, induced drag, or sometimes drag due to lift, is a drag force which occurs whenever a lifting body or a wing of finite span generates lift. ... An ekranoplan (Russian: , literally screen plane) is a vehicle resembling an aircraft but that operates solely on the principle of ground effect (in Russian эффект экрана effekt ekrana - from which the name derived). ... A Surface Effect Ship (SES) or Sidewall Hovercraft, is a watercraft or vessel that has both an air cushion, like a hovercraft, and twin hulls, like a catamaran. ... A Hovercraft, or Air-Cushion Vehicle (ACV), is an amphibious vehicle or craft, designed to travel over any sufficiently smooth surface - land or water - supported by a cushion of slowly moving, low-pressure air, ejected downwards against the surface close below it. ...

Wing configurations of Ground Effect Vehicles

Inverse Delta

These are based upon research done by the German physicist Alexander Lippisch and use a property of the delta wing shape that allows stable flight in ground effect. These have the advantage of being self stabilising. This is the main Class B form of ground effect craft. Alexander Lippisch earned his PhD in 1943 at the University of Heidelberg. ... The term Ground effect (or Wing In Ground effect) refers to the increase in lift experienced by an aircraft as it approaches within roughly 1/4 of a wingspans length of the ground or other level surface (such as the sea). ...

Ekranoplan Wing

This was the profile adopted by the Russian craft such as the Caspian Sea Monster, designed by Rostislav Alexeyev. The wings are normally significantly shorter than comparative aircraft due to the addition lift from ground effect. This configuration is pitch and altitude self stabilized thanks to a high aft placed horizontal tail, out of ground effect. Pitch stability comes from front-aft wings lift slopes differential. Flying at very low altitude above the sea may be dangerous if the craft is too much banked to achieve a small radius turn. R.E. Alexeev at work (shown during Ekranoplan TV documentary) Rostislav Evgenievich Alexeev (December 18, 1916, Novozybkov, Bryansk Oblast, Imperial Russia – February 9, 1980, Nizhny Novgorod, USSR) was a designer of highspeed shipbuilding. ...

Tandem Wings

Tanddem Wing can refer to two configurations. First a Bi-plane style Type-1 utilizing a shoulder mounted Main Lift Wing and a belly mounted sponsons (Boeing 314, Dornier Do X) similar to those on combat and transport helicopters such as AH-1 COBRA, AH-64 Apache, AS-332 Super Puma, KA-50 Black Shark, MH-53 Pave Low, MI-24 Hind, MI-28 Havoc, SH-3 Sea King. Second being a canard-style type-2. A mid-size Horizontal stabilazer near the nose of the craft directing airflow under the Main Lift Airfoil magnifying the static air-pressure used in Boyle's Law to generate lift based upon relative pressure differential. Rostislav Industies used a dual-bank of 4x2 turbojets situated laterally-opposed at the nose of the Russian Ekranoplan KM [1] to direct addition air volume under the Lift Wing during take-off and then swivel to horizontal during level flight to increase velocity and air speen over the Lift Wing to lower dynamic air pressure (Boyle's Law.) This Type-2 tandem design is a major improvement during take-off as it creates an air cussion to lift the craft above the water at a lower speed, thereby reducing water drag which is the biggest obsticle to successful seaplane launches. Type-1 designs act as an hydrofoil until the belly breaks the water's surface tension, then produces excess drag in conflict with the basis of Ground-effect Theory (elliminating downdraft & trailing vortices.)

Bell & Boeing are also testing tandem winged tiltrotor aircraft based on CH-47 Chinook and V-22 Osprey http://en.wikipedia.org/wiki/Bell_Boeing_Quad_TiltRotor

Ram-wing

Please add any corrections beneath this post if you have additional info.

The F-117, F-4 Phantom, and B-2 Spirit all have airduct inlets atop the front leading edge of their lift wing airfoils. This reduces the volume of air above the airfoil creating a relative vaccuum causing lift do to pressure differentials specified by Boyle's Law. http://en.wikipedia.org/wiki/F-117_Nighthawk http://en.wikipedia.org/wiki/B-2_Spirit

Unlike conventional military aircraft which attempt to mask their InfraRed signitures; if the Turbofan engines duct a portion of their pre-combustion exhaust beneath the airfoil, thereby increasing air volume and pressure they benefit from marginal "groung effect" air cushioning. This is minimal due to the lack a a solid surface w/in .2-.5 wingspan height above ground level. http://www.aerospaceweb.org/question/aerodynamics/ground-effect/induced-drag.jpg However, pre-combustion air ducting like used in Harrier JumpJets [2] and lift-fan ducting in F-35C Lightning II [3] use low heat gases to produce the lift-cushion needed for VSTOL Launch and Recovery under speeds to low to produce adequate lift. Conversely the B-2 Spirit uses High-Bypass Fanjets and post-combustion inlets to cool the exhaust temperatures. Alternately, by installing high-bypass fanjets at 05* angle of attack within the wing body, air from the top of the airfoil can be exhausted beneath the wing from the first-stage low-pressure compressor/impeller and diffused just behind and below the leading edge slats. This would provide added low-pressure air volume to increase lift w/o needing to employ thrust vectoring.

Ref: Bell X-14 Rockwell XFV-12 Yakovlev Yak-38 Yakovlev Yak-41 Boeing X-32 Lockheed Martin X-35

http://en.wikipedia.org/wiki/Bell_Boeing_Quad_TiltRotor http://en.wikipedia.org/wiki/AV-8_Harrier_II http://www.hovercraft.com/content/index.php?main_page=index&cPath=53 http://www.hovercraft.com/content/index.php?main_page=index&cPath=2

Production and development

Currently in production are two small hovercraft/GEV hybrids, the UH-18SPW and 19XRW Hoverwings™ by Universal Hovercraft, but most ground-effect air-vehicles are still in one stage of development or another. A Hovercraft, or Air-Cushion Vehicle (ACV), is an amphibious vehicle or craft, designed to travel over any sufficiently smooth surface - land or water - supported by a cushion of slowly moving, low-pressure air, ejected downwards against the surface close below it. ... There are very few or no other articles that link to this one. ...

The development of the ekranoplans slowed towards the end of the Soviet Union. However some development into the vehicle is still ongoing.

Other GEVs are currently being developed such as the Boeing Pelican,^[2] and the French supported 'Aéroptère' (also being referred to as a 'wingboat') built by the company Focus 21.^[3] An ongoing research project by German company Fischer-Flugmechanik (FF), in collaboration with the university of Duisburg-Essen, involves the development of a ground-effect craft, which the researchers have also named Hoverwing. Boeing Pelican The Boeing Pelican is a concept Wikipedia:Ground effect plane ...

External links

• The WIG Page, an extensive resource on Wing In Ground effect vehicles.
• RIA Novosti article on Soviet WIG research
• Airliners.net Photos of Alekseyev A-90

References

1. ^ Ground Effect and WIG Vehicles (English). http://www.aerospaceweb.org/+(2003-06-29).+Retrieved on 2006-07-01.
2. ^ The Pelican (English). Boeing Frontiers Online (2002-09). Retrieved on 2006-07-01.
3. ^ Bremner, Charles. "Is it a boat? Is it a plane? It's the ferry of the future", Times Online (UK), 2006-07-01. Retrieved on 2006-07-01. (in English) 

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