In recent years a large number of different WIG craft have evolved for both civilian and military use. However, these craft are not in wide use as yet.
The Central Hydrofoil Design Bureau (CHDB), led by Alexeev, was the center of ground-effect craft development in Russia. The military potential for such a craft was soon recognised and Alexeiev received support and financial resources from Soviet leader Nikita Khrushchev. This led to the development of the Caspian Sea Monster, a 550 ton military ekranoplan. Before it, some manned and unmanned prototypes were built, ranging up to eight tons in displacement.
The Russian ekranoplan program continued and led to the most successful ekranoplan so far, the 125 ton A-90 Orlyonok. A few Orlyonoks were in service with the Soviet Navy from 1979 to 1992. In 1987, the 400 ton Lun-class ekranoplan was built as a missile launcher. The second Lun was renamed to Spasatel, as a rescue vessel, but was never finished. These craft were originally developed by the Soviet Union as very high-speed military transports, and were based mostly on the shores of the Caspian Sea and Black Sea. The largest could transport over 100 tonnes of cargo. The development of ekranoplans was supported by Dmitri Ustinov, Minister of Defence of the USSR. About 120 ekranoplans (A-90 Orlyonok class) were initially planned to enter military service in the Soviet Navy. The figure was later reduced to fewer than thirty vehicles, planned to be deployed mainly for the Black and the Baltic Soviet navies. Marshal Ustinov died in 1985, and the new Minister of Defence Marshal Sokolov effectively stopped the funding for the program. The only three operational A-90 Orlyonok ekranoplans built (with renewed hull design) and one Lun-class ekranoplan remained at a naval base near Kaspiysk.
The two major problems that the Soviet ekranoplans faced were poor longitudinal stability, and a need for reliable navigation.
WIG craft developed since the 1980s have been primarily smaller craft designed for the recreational and civilian ferry markets. Germany, Russia and the US have provided most of the momentum with some development in Australia, China, Japan and Taiwan. In these countries small craft up to 10 seats have been designed and built. Other larger designs as ferries and heavy transports have been proposed, though none have gone on to further development.
After the collapse of the Soviet Union, smaller ekranoplans for non-military use have been under development. The CHDB had already developed the eight-seat Volga-2 in 1985, and Technologies and Transport developed a smaller version by the name of Amphistar.
In Germany, Lippisch was asked to build a very fast boat for Mr Collins from Collins Radio Company in the USA. He developed the X-112, a revolutionary design with reversed delta wing and T-tail. This design proved to be stable and efficient in ground effect and even if it was successfully tested, Collins decided to stop the project and sold the patents to a German company called Rhein Flugzeugbau (RFB) which further developed the model.
Hanno Fischer took over the works from RFB and created his own company called Fischer Flugmechanik. Their two seat Airfisch 3 and their later model to seat 6 passengers have been a successful design. This craft, the FS-8 will soon be produced by a Singapore-Australian joint venture called Flightship. The company no longer exists, and the ship is out of production. An ongoing research project in collaboration with the university of Duisburg-Essen, involves the development of the Hoverwing. Günter Jörg in Germany, working on the first designs by Alexeyev, developed a WIG vehicle with two wings in a tandem arrangement, the Jörg-II. This tandem WIG is a simple and low cost design, however has not been produced due to commercial problems.
A number of companies have been heavily lobbying governments for development funding to pursue research and development of WIG craft exceeding 500 tonne. The current world wide trend in the decline in military research and development spending since the end of the cold war era has not been conducive to funding the development of WIG craft. The perceived development risk is very high due to the untested nature of the technology and the uncertainties in; the development process, the operational costs and performance outcomes. WIG craft have been suggested as the solution to a number of possible operational roles. With heavy lift being the most appealing to the WIG craft attributes. WIG craft have been proposed, as an alternate to the very large aircraft needed to fulfil these transportation goals. The US Air Force report “Airlift 2025” looked at using WIG craft as heavy lift platforms with the capabilities of insertion into remote locations, long range and good survivability. In the report, WIG craft where cited as inappropriate for the intended use as there was a need for another method of transport from the coast to the required destination. Another study by the US Navy’s “Strategic Studies Group XVI” also looked at the possibility of using small WIG craft as insertion and extraction craft or naval gunfire teams. Also discussed where the advantages of using WIG craft for transoceanic cargo craft, where their increased speed would reduce resupply times by at least 60%.
Civilian roles for WIG craft have been heavily promoted at a number of conferences held since 1993. WIG craft have been suggested as recreational craft, small to large ferries and large transport craft. A number of small companies have emerged designing and constructing WIG craft for these purposes. A number of large Russian and US companies have gone as far as the preliminary design of a number of concept WIG craft mainly for the transport and heavy lift market.
Theoretical research into WIG craft aerodynamics, ground effect and WIG craft stability has proceeded at a number of research centres. Performance enhancement of take off and landing distances as well as methods to increase sea state limitations have been analysed on prototypes and with model tests. Research continues into the determination of the most efficient planform configuration.
Besides the development of appropriate design and structural configuration, special automatic control systems and navigation systems are also being developed. These include special altimeters with high accuracy for small altitude measurements and also lesser dependence on weather conditions. After extensive research and experimentation, it has been shown that "Phase Radio-altimeters" are most suitable for such applications as compared to laser, isotopic or ultrasonic altimeters.
Even today R&D activities are being carried out for such vehicles in many countries which include Russia, USA, China, Germany, UK, Australia and many others. Other future projects include the horizontal take-off and horizontal landing of Aerospace Planes (ASP) using ekranoplans.
One of the problems that have delayed the development of these craft is the classification and legislation to be applied. The International Maritime Organization (IMO) has studied the application of rules based on the International Code of Safety for High-Speed Craft (HSC code) which was developed for fast ships such as hydrofoils, hovercraft, catamarans and the like. The Russian Rules for classification and construction of small type A ekranoplans is a document upon which most WIG design is based. However in 2005, the IMO classified the WISE or WIG crafts under the category of ships.
The International Maritime Organization recognizes three classes of ground effect crafts:
WIG craft are not aircraft and can be certified as boats.
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.
An ekranoplan (экранопла́н, 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 (GEV) 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.
The ekranoplan has a lifting power of , among the largest ever achieved. The KM, as the Caspian Sea Monster was known in the top secret Soviet military development program, was over long, weighed fully loaded, and could travel over , mere meters above the surface of the water. Another model was the Lun-class, entering service with the Black Sea Fleet in 1987; the Lun-class vehicles had a top speed of .
The important design principle is that wing lift is reduced as operating altitude of the ekranoplan is increased (see ground effect). Thus it is dynamically stable in the vertical dimension. Once moving at speed, the ekranoplan was no longer in contact with the water, and could move over ice, snow, or level land with equal ease, though flight over land would have involved extreme risks unless the surface were dependably flat.
US Patent Issued to Keck Technologies on Aug. 16 for "Surface Effect Sea Train" (North Carolina, Maryland, Virginia Inventors)
Aug 23, 2011; ALEXANDRIA, Va., Aug. 23 -- United States Patent no. 7,997,370, issued on Aug. 16, was assigned to Keck Technologies LLC...