Scientific Background

What is the wing-in-ground effect?

The term “wing-in-ground effect” is used for the particular physical properties of the air just above the ground. In this border layer between two media – either air and firm ground or air and water – the air develops special load bearing characteristics.

What differentiates air in the wing-in-ground effect from air in general?

It is in particular the combination of air and water which results in saturated damp air near the water surface with a particularly high density and considerably better carrying properties than higher air layers. That means that, with the same weight, a plane could fly considerably more economically near the ground than in higher layers of air. Airplanes are not able to do this on account of their design.

How high is this layer and is there a limit for the wing-in-ground effect?

Basically the wing-in-ground effect for a vehicle depends on its size. One can imagine the physical wing-in-ground effect as a roll of air rolling under the vehicle, restricted from underneath by a defined “mirror surface”.

The limit for this effect would be about at the height of an imaginary axle, relative to the size of the wing-in-ground effect vehicle (also shortened to WIG)

What is a wing-in-ground effect vehicle?

The term „wing-in-ground effect vehicle“ (also “WIG-craft” for short) describes a vehicle which is able to use the air near the ground to its technical advantage.

For practical purposes, this means that a wing-in-ground effect vehicle has to be designed to use the particularly good carrying properties of the air near the ground safely and economically. In practical use there are two different versions:

Wing-in-ground effect airplanes and pure wing-in-ground effect vehicles.

What types of design are there?

Basically, we differentiate between the wing-in-ground effect airplanes, which can be flown either using the ground effect but also at greater heights, and the pure wing-in-ground effect vehicles, whose design does not enable them to leave the area of the ground effect.

What is a wing-in-ground effect airplane?

As a rule these are airplanes with particularly good carrying qualities. They include all forms of single-wing, wing-in-ground effect vehicles with a delta-wing design. Despite their improved flying characteristics and their ability to fly using the ground effect for a short time, they are still airplanes. Examples are: all vehicles designed on the Lippisch principle, the Russian Ekranoplan or Orlyonok (also known as the Caspian Sea Monster), the Airfish, SeaWing, Flightship etc.

What is a pure wing-in-ground effect vehicle?

Pure wing-in-ground effect vehicles are all those designs which are not able to leave the ground effect area. These vehicles count as ships and are treated as such, which means the requirements for ship approvals and operating permits are less stringent.

Tandem Airfoil Flairboats are included in this category of Type A wing-in-ground effect vehicles with less stringent approval requirements. The Tandem Airfoil Flairboat can be driven with a normal motor boat driving license.

What is the difference between WIGs with delta wings and WIGs with tandem wings?

There are differences in use, in classification, in economic efficiency, in handling, in flairing stability and thus also in safety.

Basically, the main difference is that research and development of WIG craft with delta wings has drawn on knowledge gained in aviation and has applied airplane design to the ground effect area. One could say the designs are WIG-enabled airplanes. However, it has not been possible to solve the problems connected with the low height of the ground effect and the resulting loss of three-dimensional “flight” space, e.g. when flying curves, whereby the dreaded problem of the shifting pressure point leads to problems with stability.

The tandem wing design is built on the principle that two symmetrical pairs of wings are arranged so that a self-stabilizing wing system is always in optimal harmony.

What is an Ekranoplan?

Ekranoplan is the Russian name for WIG craft.

Who was Mr Alexeev ?

Mr Rostislav Alexeev war the leading Russian scientist working on the development of the
Ekranoplan in the nineteen-sixties.

*03-08-2012 I. Schellhaas geb. Dipl. Wirtsch-Ing. MB ???

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