Ground effect vehicles (GEV) is a vehicle which can achieve level flight close to on the Earth using the aerodynamic interactions between wings and the surface that is known as the ground effect. Best known are the Soviet ekranoplanes, but names like wing-in-ground-effect (WIG), flarecraft, sea skimmer, or wing-in-surface-effect ship (WISE) are also used. In recent times, a vast variety of GEV models have been designed for military and civilian usage. However, these types of craft aren’t yet in the mainstream of use.
Design
Ground effect vehicles require some forward velocity in order to generate lift dynamically. The primary reason to operate an wing with ground effect is the reduction of its drag that is dependent on lift. The principle behind design follows that the further the wing is towards an exterior surface, such that of the ground which is believed to be ground effect and the better it will be.
A plane’s aerofoil that is passing through air raises the pressure of the air lower side, while reducing pressure on the top. The pressures at the high and low remain constant until they reach the wing’s ends and form vortices that can be the primary reason behind the lift-induced drag, which is usually a significant proportion of the drag that impacts the aircraft. The greater the ratio of aspect (or the length and thickness) the wings are, the lower the drag is created by each unit of lift , and more efficient the specific wings. This is the main reason gliders are characterized by their long and narrow wings. A wing that is placed close to an object like ground or water can result in expanding the angle ratio however, it does not have the problems that come with a lengthy and thin wing. This means that the stubs of an Ekranoplan will produce as more lift as the bigger wing of an aircraft for transport, but it is only able to do so near the surface of the earth. When enough speed has been developed it is possible that certain GEVs might be able to leave the ground effect, and function as an ordinary aircraft until they reach their final destination. Its distinctive feature is that it is not able to take off or land without significant support from the cushion. Additionally, it is unable to ascend until it has reached an even higher speed.
Wing configurations
Inverse delta
The wing was developed through Alexander Lippisch, this wing allows for stable flight with ground effect via self-stabilization. This is the primary Class B model for ground effects craft.
Ekranoplan wings
This is the profile that was designed by Rostislav Alexeyev. The wings are considerably smaller than comparable aircraft and the configuration needs an extremely aft-located horizontal tail to keep stability. The stability of the pitch and altitude is determined by the lift slope [note 1] of the front low wing that is that is ground-effect (commonly the main wings) in contrast to an advanced higher-positioned second wing that is almost free of ground effect (generally known as stabilizer).
Tandem wings
Tandem Wing can have two options:
A biplane-style Type-1 that has a shoulder-mounted lift wing as well as belly-mounted sponsons akin to those used on transport helicopters and combat helicopters.
A canard-style type-2 that has an oversized horizontal wing [note 2] that is located near the nose of the craft that directs airflow underneath the Main Lift Airfoil. This type-2 tandem design is an important improvement in takeoff, as it helps create an air cushion that allows you to lift the craft off it at slower speed, thus reducing drag caused by water. This is the main issue to successful seaplane launches. A Tandem Wing Style with double-wing system as used in Tandem Airfoilboat constructions made by Jorg. It is a system is self-stabilizing and offers security, comfort and high-efficiency operation.
