Ekranoplan

Ground effect vehicle – Wikipedia, the free encyclopedia

A ground effect vehicle (GEV) is one that attains level flight near the surface of the Earth, made possible by a cushion of high-pressure air created by the aerodynamic interaction between the wings and the surface known as ground effect. Also known as a wing-in-ground-effect (WIG) vehicle, flarecraft, sea skimmer, ekranoplan, or wing-in-surface-effect ship (WISE), a GEV can be seen as a transition between a hovercraft and an aircraft. The International Maritime Organization, (IMO), has classified the GEV as a ship.[1] A GEV differs from an aircraft in that it cannot operate without ground effect, so its operating height is limited relative to its wingspan.

In recent years a large number of different GEV types have evolved for both civilian and military use. However, these craft are not in wide use as yet.

An ekranoplan (Russian: экранопла́н, French: ecran screen + plan plane ) is a vehicle resembling an aircraft but which operates solely on the principle of ground effect (in Russian эффект экрана effekt ekrana – from which the name derived). Ground effect vehicles fly above any flat surface, with the height above ground dependent upon the size of the vehicle. Ekranoplan design was conceived by revolutionary Soviet engineer Rostislav Alexeev.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 severe ditching. However, this particular configuration is difficult to fly even with computer assistance. Flying at very low altitudes, just above the sea, may be dangerous if the craft banks too far to one side while making a small radius turn.

A take-off must be into the wind, which in the case of a water launch, means into the waves. This creates drag and reduces lift. 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, some of 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.

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