{{short description|Special vehicle to fly in air just above sea or ground}} {{redirect|Ekranoplan|the music album|Ekranoplan (album)}} {{Lead too short|date=August 2021}} {{Use mdy dates|date=December 2021}} [[File:Ekranoplan A-90 Orlyonok - edit.jpg|thumb|300px|Ekranoplan A-90 Orlyonok]] A '''ground-effect vehicle''' ('''GEV'''), also called a '''wing-in-ground-effect''' (WIGE or '''WIG'''), '''ground-effect craft/machine (GEM)''', '''wingship''', '''flarecraft, surface effect vehicle''' or '''ekranoplan''' ({{langx|ru|экранопла́н – "screenglider"}}), is a vehicle that makes use of the ground effect, the aerodynamic interaction between a moving wing and the stationary surface below (land or water). Typically, it glides over a level surface (usually over water). Some models can operate over any flat area such as a lake or flat plains similar to a hovercraft. The term Ground-Effect Vehicle originally referred to any craft utilizing ground effect, including what later became known as hovercraft, in patent descriptions during the 1950s. However, this term came to exclude air-cushion vehicles or hovercraft. GEVs do not include racecars utilizing ground-effect for increasing downforce.
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== Ground effect == {{Excerpt|Ground effect (aerodynamics)}}
== Takeoff == Any airfoil passing through air increases air pressure on the underside, while decreasing pressure on the upper side, which generates lift. The high and low pressures are maintained until they flow off the ends of the wings, where they form vortices that are the major source of lift-induced drag—normally a significant portion of the total drag.
In GEV, the angle of attack is the angle between its chordline (a straight line from the leading edge to the trailing edge) and the ground. On takeoff, airplanes pitch their noses up to increase the angle of attack to reach the ideal of 12-20 degrees (depending on wing design and other factors).
== Design == {{More citations needed section|date=March 2018}} Placing the wing near a surface has the same effect as increasing the aspect ratio because the surface prevents wingtip vortices from expanding,<ref name="SPYROS">{{cite web |last1=Hirdaris |first1=Spyros |last2=Guerrier |first2=Mark |name-list-style=amp |date=November 2009 |title=Technology Developments in Ground Effect Craft |url=http://www.iirpresentations.com/A1041/pdf/D1-1400-SpyrosHirdaris.pdf |url-status=dead |archive-url=https://web.archive.org/web/20100307092846/http://www.iirpresentations.com/A1041/pdf/D1-1400-SpyrosHirdaris.pdf |archive-date=7 March 2010 |access-date=30 December 2011 |website=2nd Annual Ship Tech}}</ref> but without the complications associated with a long, slender wing. The stubby wings on a GEV can produce as much lift as the much larger wing on a transport aircraft, though only while close to the earth's surface. Once sufficient speed has built up, some GEVs can function as conventional aircraft until approaching a destination. However, they are unable to land or take off without a significant amount of help from the ground effect, and cannot climb until they have reached a much higher speed. The greater the wingspan, the less drag created for each unit of lift and the greater the efficiency of the wing.
GEVs are not statically supported upon a cushion of pressurized air from a downward-directed fan. Some GEV designs, such as the Russian ''Lun'' and ''Dingo'', blew air under the wing using auxiliary engines to assist takeoff; however they still require forward motion to generate sufficient lift to fly, unlike hovercraft, also lacking low-speed hover capability. GEVs also have no contact with the surface when in flight.
thumb|WIG-wings configurations: (A){{nbsp}}Straight wing; (B){{nbsp}}Reverse-delta wing; (C){{nbsp}}Tandem wing. thumb|300px|A Russian light ekranoplan Aquaglide-2
===Straight wing=== Used by the Russian Rostislav Alexeyev for his ekranoplan. The wings are significantly shorter than those of comparable aircraft, and this configuration requires a high aft-placed horizontal tail to maintain stability. The pitch and altitude stability comes from the lift slope<ref group="note">Cl/da, with Cl = lift coefficient, and a = angle of incidence.</ref> difference between a front low wing in ground-effect (commonly the main wing) and an aft, higher-located second wing nearly out of ground-effect (generally named a stabilizer). A design by REGENT uses a related design in the form of an approximately L-shaped wing attached to the top of the fuselage, with a pontoon at the end for water landings.
===Reverse-delta wing=== Developed by Alexander Lippisch, this wing allows stable flight in ground-effect through self-stabilization. This is the main Class B form of GEV. Hanno Fischer later developed WIG craft based on the configuration, which were then transferred to multiple companies in Asia, thus becoming one of the "standards" in GEV design.
===Tandem wings=== Tandem wings can have three configurations: * A biplane-style type-1 utilising a shoulder-mounted main lift wing and belly-mounted sponsons similar to those on combat and transport helicopters. * A canard-style type-2 with a mid-size horizontal wing<ref group="note">Not a stabilizer because destabilizing.</ref> near the nose of the craft directing airflow under the main lift airfoil. This type-2 tandem design is a major improvement during takeoff, as it creates an air cushion to lift the craft above the water at a lower speed, thereby reducing water drag, which is the biggest obstacle to successful seaplane launches. * Two stubby wings as in the tandem-airfoil flairboat produced by Günther Jörg in Germany. His particular design is self-stabilizing longitudinally.<ref>{{cite journal |last1=Rozhdestvensky |first1=Kirill V. |title=Wing-in-ground effect vehicles |journal=Progress in Aerospace Sciences |date=May 2006 |volume=42 |issue=3 |pages=211–283 |doi=10.1016/j.paerosci.2006.10.001 |bibcode=2006PrAeS..42..211R}}</ref>
==Advantages and disadvantages== {{More citations needed section|date=January 2024}}
Given similar hull size and power, and depending on its specific design, the lower lift-induced drag of a GEV, as compared to an aircraft of similar capacity, will improve its fuel efficiency and, up to a point, its speed.<ref name=":0">{{Cite web |last=McFadden |first=Christopher |date=2017-04-04 |title=Here's a Closer Look at the Soviet Navy's 1987 Lun-Class Ekranoplan |url=https://interestingengineering.com/innovation/a-closer-look-at-the-soviet-navys-1987-lun-class-ekranoplan |access-date=2024-01-26 |website=interestingengineering.com |language=en-US}}</ref> GEVs are also much faster than surface vessels of similar power, because they avoid drag from the water.
On the water the aircraft-like construction of GEVs increases the risk of damage in collisions with surface objects. Furthermore, the limited number of egress points make it more difficult to evacuate the vehicle in an emergency. According to WST, the builders of the WIG craft WSH-500, GEVs furthermore have the advantage of avoiding conflict with ocean currents by flying over them.
Since most GEVs are designed to operate from water, accidents and engine failure typically are less hazardous than in a land-based aircraft, but the lack of altitude control leaves the pilot with fewer options for avoiding collision, and to some extent that negates such benefits. Low altitude brings high-speed craft into conflict with ships, buildings and rising land, which may not be sufficiently visible in poor conditions to avoid.<ref name=":1">{{Cite web |last=Katz |first=Justin |date=2022-05-27 |title=DARPA's revolutionary seaplane wants to change how the Pentagon hauls cargo |url=https://breakingdefense.sites.breakingmedia.com/2022/05/darpas-revolutionary-seaplane-wants-to-change-how-the-pentagon-hauls-cargo/ |access-date=2024-01-26 |website=Breaking Defense |language=en-US}}</ref> GEVs may be unable to climb over or turn sharply enough to avoid collisions, while drastic, low-level maneuvers risk contact with solid or water hazards beneath. Aircraft can climb over most obstacles, but GEVs are more limited.<ref name=":1" />
In high winds, take-off must be into the wind, which takes the craft across successive lines of waves, causing heavy pounding, stressing the craft and creating an uncomfortable ride.<ref>{{Cite web |date=2018-09-04 |title=Could the Airfish-8 finally get the Wing In Ground Effect Vehicle up and running? |url=https://newatlas.com/wigetworks-airfish-8-ground-effect-vehicle/56184/ |access-date=2024-01-26 |website=New Atlas |language=en-US}}</ref> In light winds, waves may be in any direction, which can make control difficult as each wave causes the vehicle to both pitch and roll. The lighter construction of GEVs makes their ability to operate in higher sea states less than that of conventional ships, but greater than the ability of hovercraft or hydrofoils, which are closer to the water surface.
Like conventional aircraft, greater power is needed for takeoff, and, like seaplanes, ground-effect vehicles must get on the step before they can accelerate to flight speed.<ref name=":0" /> Careful design, usually with multiple redesigns of hullforms, is required to get this right, which increases engineering costs. This obstacle is more difficult for GEVs with short production runs to overcome. For the vehicle to work, its hull needs to be stable enough longitudinally to be controllable yet not so stable that it cannot lift off the water.
The bottom of the vehicle must be formed to avoid excessive pressures on landing and taking off without sacrificing too much lateral stability, and it must not create too much spray, which damages the airframe and the engines. The Russian ekranoplans show evidence of fixes for these problems in the form of multiple chines on the forward part of the hull undersides and in the forward location of the jet engines.
Finally, limited utility has kept production levels low enough that it has been impossible to amortize development costs sufficiently to make GEVs competitive with conventional aircraft.
A 2014 study by students at NASA's Ames Research Center claims that use of GEVs for passenger travel could lead to cheaper flights, increased accessibility and less pollution.<ref>{{cite web|url=https://nari.arc.nasa.gov/sites/default/files/attachments/IFAR_AeroAcademy_2014.pdf|title=Ground Effect Vehicle Transoceanic Civil and Cargo Transport Network|first1=Leo|last1=Byun|first2=Kiley|last2=Donohue|first3=Michael|last3=Mayo|first4=Julian|last4=McCafferty|first5=Ruth|last5=Miller|name-list-style=amp|date=August 21, 2014|website=NASA Aeronautic Academy}}</ref>
==Classification== One obstacle to GEV development is the classification and legislation to be applied. The International Maritime Organization 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 GEV design is based. However, in 2005, the IMO classified the WISE or GEV under the category of ships.<ref name="IMO">{{cite web|url=https://www.imo.org/en/OurWork/Safety/Pages/WIG.aspx|title=Wing-in-Ground (WIG) craft|author=Sub-Committee on Ship Design and Equipment (DE)|date=November 2001|website=International Maritime Organization|access-date=16 January 2014|archive-url=https://web.archive.org/web/20140116131124/http://www.imo.org/OurWork/Safety/Regulations/Pages/WIG.aspx|archive-date=16 January 2014|url-status=live}}</ref>
The International Maritime Organization recognizes three types of GEVs:<ref name="IMO" /> {{ordered list | list_style_type=upper-latin | A craft which is certified for operation only in ground effect; | A craft which is certified to temporarily increase its altitude to a limited height outside the influence of ground effect but not exceeding {{convert|150|m|ft|-1|abbr=on}} above the surface; and | A craft which is certified for operation outside ground effect and exceeding {{convert|150|m|ft|-1|abbr=on}} above the surface. }}
At the time of writing, those classes only applied to craft carrying 12 passengers or more,<ref name="IMO" /> and (as of 2019) there was disagreement between national regulatory agencies about whether these vehicles should be classified, and regulated, as aircraft or as boats.<ref>{{cite news |url=https://www.revolution.aero/editorial-1/2019/8/29/exclusive-uk-at-odds-with-eu-and-us-over-classification-of-wing-in-ground-effect-craft|title=Exclusive: UK at odds with EU and US over classification of wing-in-ground effect craft|date=August 29, 2019|website=Revolution.aero}}</ref>
==History== [[File:An artist's concept of a Soviet wing-in-ground effect vehicle.jpg|thumb|300px|Artist's concept of a ''Lun''-class ekranoplan in flight]] By the 1920s, the ''ground effect'' phenomenon was well-known, as pilots found that their airplanes appeared to become more efficient as they neared the runway surface during landing. In 1934 the US National Advisory Committee for Aeronautics issued Technical Memorandum 771, ''Ground Effect on the Takeoff and Landing of Airplanes'', which was a translation into English of a summary of French research on the subject. The French author Maurice Le Sueur had added a suggestion based on this phenomenon: "Here the imagination of inventors is offered a vast field. The ground interference reduces the power required for level flight in large proportions, so here is a means of rapid and at the same time ''economic'' locomotion: Design an airplane which is always within the ground-interference zone. At first glance this apparatus is dangerous because the ground is uneven and the altitude called skimming permits no freedom of maneuver. But on large-sized aircraft, over water, the question may be attempted ..."{{sfnp|Garrison|2011|pp=80–83}}
By the 1960s, the technology started maturing, in large part due to the independent contributions of Rostislav Alexeyev in the Soviet Union<ref>{{cite web|url=http://news.bbc.co.uk/1/hi/magazine/7638659.stm|title=Riding the Caspian Sea Monster|first=James|last=May|date=27 September 2008|website=BBC News |url-status=live|archive-url=https://web.archive.org/web/20080930051437/http://news.bbc.co.uk/1/hi/magazine/7638659.stm|archive-date=30 September 2008}}</ref> and German Alexander Lippisch, working in the United States. Alexeyev worked from his background as a ship designer whereas Lippisch worked as an aeronautical engineer. The influence of Alexeyev and Lippisch remains noticeable in most GEVs seen today.
===Canada=== It is said that the research hydrofoil HD-4 by Alexander Graham Bell had part of its dynamic lift contributed by its pair of wings operating in ground effect.<ref>{{Cite web |title=HYDROFOIL HD-4 - For Posterity's Sake |url=http://www.forposterityssake.ca/Navy/HYDROFOIL_HD-4.htm |access-date=2024-12-15 |website=www.forposterityssake.ca}}</ref> However it is dubious whether the designer was aware of its existence due to the relative infancy of aerodynamics.
Avro Canada investigated into aircraft with a Coanda-effect propulsion system. Such jets were supposed to create an air cushion below the airframe that will allow them to hover on the ground. In fact, of the only test aircraft built, this was the only mode they could possibly operate from due to stability issues when taking off. The designs were later further developed by the United States, while Convair could have possibly been inspired by them to create a preliminary design of a large ocean-going ground-effect ship called Hydroskimmer.<ref>{{Cite web |date=2020-07-06 |title=Экраноплан Convair "Hydroskimmer" с атомными ракетами — GunMan |url=https://gunm.ru/ekranoplan-convair-hydroskimmer-s-atomnymi-raketami/ |access-date=2024-12-15 |language=ru-RU}}</ref>
===Soviet Union=== [[File:Beriev VVA-14 in 2010.jpg|thumb|300px|The Bartini Beriev VVA-14, developed during the 1970s]] [[File:Taganrog Beriev Aircraft Company Beriev Be-2500 (model) IMG 2050 1725.jpg|thumb|300px|Model of the Beriev Be-2500 concept aircraft]] Led by Alexeyev, the Soviet Central Hydrofoil Design Bureau ({{langx|ru|ЦКБ СПК}}) was the center of ground-effect craft development in the USSR. The vehicle came to be known as an ekranoplan ({{langx|ru|экранопла́н}}, экран ''screen'' + план ''plane'', from {{langx|ru|эффект экрана}}, literally ''screen effect'', or ''ground effect'' in English). The military potential for such a craft was soon recognized, and Alexeyev received support and financial resources from Soviet leader Nikita Khrushchev.
Some manned and unmanned prototypes were built, ranging up to eight tonnes in displacement. This led to the development of a 550-tonne military ''ekranoplan'' of {{convert|92|m|ft|abbr=on}} length. The craft was dubbed the ''Caspian Sea Monster'' by U.S. intelligence experts, after a huge, unknown craft was spotted on satellite reconnaissance photos of the Caspian Sea area in the 1960s. With its short wings, it looked airplane-like in planform, but would probably be incapable of flight.{{sfnp|Garrison|2011|p=82}} Although it was designed to travel a maximum of {{convert|3|m|ft|0|abbr=on}} above the sea, it was found to be most efficient at {{convert|20|m|ft|abbr=on}}, reaching a top speed of {{convert|300|-|400|kn|km/h}} in research flights.
The Soviet ''ekranoplan'' program continued with the support of Minister of Defence Dmitriy Ustinov. It produced the most successful ''ekranoplan'' so far, the 125-tonne A-90 ''Orlyonok''. These craft were originally developed as high-speed military transports and were usually based on the shores of the Caspian Sea and Black Sea. The Soviet Navy ordered 120 ''Orlyonok''-class ''ekranoplans'', but this figure was later reduced to fewer than 30 vessels, with planned deployment mainly in the Black Sea and Baltic Sea fleets.
A few ''Orlyonoks'' served with the Soviet Navy from 1979 to 1992. In 1987, the 400-tonne ''Lun''-class ''ekranoplan'' was built as an anti-ship missile launch platform. A second ''Lun'', renamed ''Spasatel'', was laid down as a rescue vessel, but was never finished. The two major problems that the Soviet ''ekranoplans'' faced were poor longitudinal stability and a need for reliable navigation.
Minister Ustinov died in 1984, and the new Minister of Defence, Marshal Sokolov, cancelled funding for the program. Only three operational ''Orlyonok''-class ''ekranoplans'' (with revised hull design) and one ''Lun''-class ''ekranoplan'' remained at a naval base near Kaspiysk.
Since the dissolution of the Soviet Union, ''ekranoplans'' have been produced by the Volga Shipyard<ref>{{cite web|url=http://www.volga-shipyard.com/index.php?section=&lang=eng|title=Volga Shipyard|date=2011|website=Joint Stock Company Volga Shipyard|access-date=30 December 2011|url-status=dead|archive-url=https://web.archive.org/web/20120206061431/http://www.volga-shipyard.com/index.php?section=&lang=eng|archive-date=6 February 2012}}</ref> in Nizhniy Novgorod. 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 is developing a smaller version called the Amphistar. Beriev proposed a large craft of the type, the Be-2500, as a "flying ship" cargo carrier,<ref>{{cite web|url=http://www.beriev.com/eng/Be-2500_e/Be-2500_e.html|title=Be-2500 amphibious aircraft|website=Beriev Aircraft Company|access-date=20 November 2013|archive-url=https://web.archive.org/web/20071203182743/http://www.beriev.com/eng/Be-2500_e/Be-2500_e.html|archive-date=3 December 2007|url-status=live}}</ref> but nothing came of the project.
=== United States === During the 1950s, the US Navy investigated into anti-submarine vessels operating on the ram effect, a product of ground effect. Such vessels were to use this to create an air cushion below the hulls that will allow hovering. If this is not possible, additional engines were to be used to artificially blow air underneath the craft. The project was designated RAM-2. Several other projects were proposed throughout the early Cold War, some using a similar mix of wings and lift engines while others are more akin to Russian types. More than a decade later, General Dynamics designed catamaran vessels equipped with ground-effect and filed them as patents.<ref>{{Cite patent|number=US3390655A|title=Patrol craft|gdate=1968-07-02|invent1=Quady|invent2=Schillreff|inventor1-first=John C.|inventor2-first=George H.|url=https://patents.google.com/patent/US3390655A/en}}</ref> The military looked at the Boeing Pelican proposal in the early 2000s timeframe, which would have produced a large ground-effect aircraft which would not have taken off or landed from water; but, the proposal was not adopted.<ref>{{cite magazine |last1=Sweetman |first1=Bill |title=Monster at 20 ft. Look up, but not way up: Boeing's massive cargo carrier would fly very, very low indeed. Here's how. |pages=68–72 |volume=262 |archive-url=https://web.archive.org/web/20180929020041/http://popsci.com/military-aviation-space/article/2003-01/monster-20-ft |access-date=January 4, 2019 |magazine=Popular Science |number=2 |publication-date=February 2003 |date=January 22, 2003 |issn=0161-7370 |oclc=96033212 |url=https://books.google.com/books?id=iDdUVbjhXTsC&pg=PA68 |archive-date=September 29, 2018 |url-status=live}}</ref><ref name="Wired2011">{{cite news |last1=Shechmeister |first1=Matthew |title=The Soviet superplane program that rattled Area 51 |url=https://www.wired.com/2011/06/ekranoplan/ |at=Slide 10 |access-date=2 August 2018 |magazine=Wired |date=June 10, 2011 |quote=Boeing briefly entertained the idea of building an enormous military cargo plane along the lines of the great Soviet ekranoplans. The aircraft, dubbed the Pelican, got as far as a cheesy 3-D rendering, and, according to a representative, Boeing has no plans to pursue the project further. |url-status=live |archive-date=August 2, 2018 |archive-url=https://web.archive.org/web/20180802223725/http://wired.com/2011/06/ekranoplan/}}</ref> A DARPA project from mid-2022 was funding the Liberty Lifter concept, which would involve a similar aircraft that can operate from water.<ref>{{cite web|url=https://www.thedrive.com/the-war-zone/cargo-hauling-ekranoplan-x-plane-is-being-developed-by-darpa |title=Cargo Hauling Ekranoplan X-Plane is being Developed by DARPA|date=19 May 2022 |publisher=Thomas Newdick, The Drive, May 19, 2022|access-date=2023-05-25}}</ref> That program was cancelled in 2025.<ref>{{Cite web |title=DARPA Ends Liberty Lifter Program {{!}} Aviation Week Network |url=https://aviationweek.com/defense/aircraft-propulsion/darpa-ends-liberty-lifter-program |access-date=2025-07-07 |website=aviationweek.com}}</ref>
=== Germany ===
====Lippisch Type and Hanno Fischer==== thumb|The Rhein-Flugzeugbau X-114 in flight. In Germany, Lippisch was asked to build a very fast boat for American businessman Arthur A. Collins. In 1963 Lippisch 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 though it was successfully tested, Collins decided to stop the project and sold the patents to the German company Rhein Flugzeugbau (RFB), which further developed the inverse delta concept into the X-113 and the six-seat X-114. These craft could be flown out of ground effect so that, for example, peninsulas could be overflown.<ref>{{cite book|title=Jane's All the World's Aircraft 1978–79|last=Taylor|first=John W. R.|year=1978|publisher=Jane's Yearbooks|location=London, UK|isbn=0-35-400572-3|pages=70–71}}</ref>
Hanno Fischer took over the works from RFB and created his own company, Fischer Flugmechanik, which eventually completed two models. The Airfisch 3 carried two persons, and the FS-8 carried six persons. The FS-8 was to be developed by Fischer Flugmechanik for a Singapore-Australian joint venture called Flightship. Powered by a V8 Chevrolet automobile engine rated at 337 kW, the prototype made its first flight in February 2001 in the Netherlands.<ref>{{cite web|url=http://www.se-technology.com/wig/html/main.php?open=showpic&code=&pic=360|title=FS-8|date=2008|website=The WIG page|access-date=30 December 2011|url-status=dead|archive-url=https://web.archive.org/web/20110718175215/http://www.se-technology.com/wig/html/main.php?open=showpic&code=&pic=360|archive-date=18 July 2011}}</ref> The company no longer exists but the prototype craft was bought by Wigetworks,<ref>{{cite web|url=https://www.wigetworks.com/|title=WigetWorks/AirFish/Wing-in-Ground|date=2020|access-date=13 January 2022}}</ref> a company based in Singapore and renamed as AirFish 8. In 2010, that vehicle was registered as a ship in the Singapore Registry of Ships.<ref>{{cite web|url=http://www.wigetworks.com/|title=Introducing the AirFish 8|website=Wigetworks Private Limited|access-date=22 August 2011|url-status=live|archive-url=https://web.archive.org/web/20110203172024/http://www.wigetworks.com/|archive-date=3 February 2011}}</ref>
The University of Duisburg-Essen is supporting an ongoing research project to develop the ''Hoverwing''.<ref>{{cite web|url=http://www.dst-org.de/projekte/projekte/hoverwing/hoverwing_eng.htm|title=The Ground Effect Craft 'Hoverwing'|date=1 March 2000|website=Technical development of ground-effect vehicles, University of Duisburg-Essen|access-date=1 October 2007|url-status=dead|archive-url=https://web.archive.org/web/20071009181224/http://www.dst-org.de/projekte/projekte/hoverwing/hoverwing_eng.htm|archive-date=9 October 2007}}</ref>
====Günther Jörg-type tandem-airfoil flairboat==== [[File:Skimmerfoil Jorg IV-001.jpg|thumb|A tandem flarecraft Skimmerfoil Jörg IV located at the SAAF Museum, Port Elizabeth, South Africa. <br />(It has since been removed from the museum)]] German engineer Günther Jörg, who had worked on Alexeyev's first designs and was familiar with the challenges of GEV design, developed a GEV with two wings in a tandem arrangement, the Jörg-II. It was the third, manned, tandem-airfoil boat, named "Skimmerfoil", which was developed during his consultancy period in South Africa. It was a simple and low-cost design of a first 4-seater tandem-airfoil flairboat completely constructed of aluminium. The prototype was in the SAAF Port Elizabeth Museum from 4 July 2007 until 2013, and is now in private use. Pictures of the museum show the boat after some years outside the museum and without protection against the sun.<ref>{{cite web|url=http://www.saafmuseum.org.za/aircraft/2012/taf-skimmerfoil-arrives-in-port-elizabeth|title=TAF Skimmerfoil arrives in Port Elizabeth|date=5 July 2007|website=South African Air Force Museum|access-date=29 September 2013|url-status=dead|archive-url=https://archive.today/20130929162942/http://www.saafmuseum.org.za/aircraft/2012/taf-skimmerfoil-arrives-in-port-elizabeth|archive-date=29 September 2013}}</ref>
The consultancy of Günther Jörg, a specialist and insider of German airplane industry from 1963 and a colleague of Alexander Lippisch and Hanno Fischer, was founded with a fundamental knowledge of wing in ground effect physics, as well as results of fundamental tests under different conditions and designs having begun in 1960. For over 30 years, Jörg built and tested 15 different tandem-airfoil flairboats in different sizes and made of different materials.
The following tandem-airfoil flairboat (TAF) types had been built after a previous period of nearly 10 years of research and development: # TAB VII-3: First manned tandem W.I.G type Jörg, being built at Technical University of Darmstadt, Akaflieg # TAF VII-5: Second manned tandem-airfoil Flairboat, 2 seater made of wood # TAF VIII-1: 2-seater tandem-airfoil flairboat built of glass-reinforced plastic (GRP) and aluminium. A small serie of 6 Flairboats had been produced by former Botec Company # TAF VIII-2: 4-seater tandem-airfoil Flairboat built of full aluminium (2 units) and built of GRP (3 units) # TAF VIII-3: 8-seater tandem-airfoil Flairboat built of aluminium combined with GRP parts # TAF VIII-4: 12-seater tandem-airfoil Flairboat built of aluminium combined with GRP parts # <!-- New designs: ← since when and significance? -->TAF VIII-3B: 6-seater tandem-airfoil flairboat under carbon fibre composite construction
Bigger concepts are: 25-seater, 32-seater, 60-seater, 80-seater and bigger up to the size of a passenger airplane.
===1980-1999=== Since the 1980s GEVs have been primarily smaller craft designed for the recreational and civilian ferry markets. Germany, Russia and the United States have provided most of the activity with some development in Australia, China, Japan, Korea and Taiwan. In these countries and regions, small craft with up to ten seats have been built. Other larger designs such as ferries and heavy transports have been proposed but have not been carried to completion.
Besides the development of appropriate design and structural configuration, automatic control and navigation systems have been developed. These include altimeters with high accuracy for low altitude flight and lesser dependence on weather conditions. "Phase radio altimeters" have become the choice for such applications beating laser altimeter, isotropic or ultrasonic altimeters.<ref>{{cite journal|title=Comparative Analysis of Design Variants For Low Altitude Flight Parameters Measuring System|first1=Alexander|last1=Nebylov|first2=Elizaveta|last2=Rumyantseva|first3=Sharan|last3=Sukrit|name-list-style=amp|date=June 2007|journal=IFAC Proceedings|volume=40|issue=7|pages=663–668|doi=10.3182/20070625-5-FR-2916.00113|doi-access=free}}</ref>
With Russian consultation, the United States Defense Advanced Research Projects Agency (DARPA) studied the Aerocon Dash 1.6 wingship.<ref>{{cite news|last1=Gaines|first1=Mike|title=USA joins Russia on Wingship|url=https://www.flightglobal.com/FlightPDFArchive/1992/1992%20-%200575.PDF|access-date=31 August 2018|work=Flight International|issue=11 March 1992|page=5|archive-url=https://web.archive.org/web/20130929043946/http://www.flightglobal.com/FlightPDFArchive/1992/1992%20-%200575.PDF|archive-date=29 September 2013|url-status=live}}</ref><ref>{{cite book|author1=Advanced Research Projects Agency (ARPA)|author-link1=DARPA|title=Technology Roadmap|volume=3|date=30 September 1994|location=Arlington, Virginia|url=http://apps.dtic.mil/dtic/tr/fulltext/u2/a294980.pdf|access-date=31 August 2018|series=Wingship Investigation}}</ref>
thumb|A Hoverwing
Universal Hovercraft developed a flying hovercraft, first flying a prototype in 1996.<ref>{{cite web|url=http://www.hovercraft.com/content/index.php?main_page=index&cPath=195 |title=18SPW Hoverwing|website=Universal Hovercraft of America, Inc|access-date=14 March 2011|url-status=live|archive-url=https://web.archive.org/web/20110415145522/http://www.hovercraft.com/content/index.php?main_page=index&cPath=195|archive-date=15 April 2011}}</ref> Since 1999, the company has offered plans, parts, kits and manufactured ground effect hovercraft called the Hoverwing.<ref>{{cite web|url=http://www.hovercraft.com/content/index.php?main_page=index&cPath=191|title=19XRW Hoverwing|website=Universal Hovercraft of America, Inc|access-date=14 March 2011|url-status=live|archive-url=https://web.archive.org/web/20110602054411/http://www.hovercraft.com/content/index.php?main_page=index&cPath=191|archive-date=2 June 2011}}</ref>
=== 2000-2019 === Iran deployed three squadrons of Bavar 2 two-seat GEVs in September 2010. This GEV carries one machine gun and surveillance gear, and incorporates features to reduce its radar signature.<ref>{{cite web|url=http://news.blogs.cnn.com/2010/09/28/iran-unveils-squadrons-of-flying-boats/|title=Iran unveils squadrons of flying boats|first=Brad|last=Lendon|date=28 September 2010|website=CNN |access-date=11 October 2010|url-status=dead|archive-url=https://web.archive.org/web/20101001032222/http://news.blogs.cnn.com/2010/09/28/iran-unveils-squadrons-of-flying-boats/|archive-date=1 October 2010}}</ref> In October 2014, satellite images showed the GEV in a shipyard in southern Iran. The GEV has two engines and no armament.<ref>{{cite web|url=http://www.businessinsider.com/iran-is-developing-a-new-flying-boat-2015-7|title=Iran is developing a new flying boat|first=Chris|last=Biggers|date=6 July 2015|website=Business Insider|url-status=live|archive-url=https://web.archive.org/web/20150707111655/http://www.businessinsider.com/iran-is-developing-a-new-flying-boat-2015-7|archive-date=7 July 2015}}</ref>
In Singapore, Wigetworks obtained certification from Lloyd's Register for entry into class.<ref name=SPYROS/> On 31 March 2011, AirFish 8-001 became one of the first GEVs to be flagged with the Singapore Registry of Ships, one of the largest ship registries.<ref>{{cite web |last=Young |first=Lam Yi |date=25 April 2010 |title=Speech at the christening of the Wing-In-Ground craft, AirFish 8-001 |url=http://www.mpa.gov.sg/web/portal/home/media-centre/news-releases/speeches/detail/36491f61-3f5c-4eb0-bc7f-c84bcefb1a4d |url-status=live |archive-url=https://web.archive.org/web/20160923010201/http://www.mpa.gov.sg/web/portal/home/media-centre/news-releases/speeches/detail/36491f61-3f5c-4eb0-bc7f-c84bcefb1a4d |archive-date=23 September 2016 |access-date=30 December 2011 |website=Harbor and Port Authority of Singapore}}</ref> Wigetworks partnered with National University of Singapore's Engineering Department to develop higher capacity GEVs.<ref>{{cite web |date=2009 |title=Engineering students to help in developing future WIG vessels |url=http://www.eng.nus.edu.sg/ero/news/index.php?id=718 |url-status=dead |archive-url=https://web.archive.org/web/20110716141141/http://www.eng.nus.edu.sg/ero/news/index.php?id=718 |archive-date=16 July 2011 |access-date=30 December 2011 |website=Faculty of Engineering, National University of Singapore}}</ref>
Burt Rutan in 2011<ref>{{cite web|url=http://www.flightglobal.com/news/articles/dubai-burt-rutan-reveals-secret-ekranoplan-project-364803/|title=DUBAI: Burt Rutan reveals secret ekranoplan project|first=Stephen|last=Trimble|date=14 November 2011|website=Flight Global|access-date=6 April 2018|archive-url=https://web.archive.org/web/20180407182615/https://www.flightglobal.com/news/articles/dubai-burt-rutan-reveals-secret-ekranoplan-project-364803/|archive-date=7 April 2018|url-status=live}}</ref> and Korolev in 2015 showed GEV projects.<ref>{{cite web|url=http://www.flightglobal.com/news/articles/maks-can-russias-caspian-sea-monster-rise-again-416156/|title=MAKS: Can Russia's 'Caspian Sea Monster' rise again?|first=James|last=Drew|date=28 August 2015|website=Flight Global|access-date=6 April 2018|archive-url=https://web.archive.org/web/20180407053634/https://www.flightglobal.com/news/articles/maks-can-russias-caspian-sea-monster-rise-again-416156/|archive-date=7 April 2018|url-status=live}}</ref>
In Korea, Wing Ship Technology Corporation developed and tested a 50-seat passenger GEV named the WSH-500. in 2013<ref>{{Cite web |title=Wing Ship Technology develops and manufactures world's first middle class commercial WIG Craft |url=http://www.wingship.com/ |url-status=live |archive-url=https://web.archive.org/web/20130719152250/http://wingship.com/ |archive-date=19 July 2013 |access-date=19 July 2013 |website=Wing Ship Technology Corporation}}</ref>
Estonian transport company Sea Wolf Express planned to launch passenger service in 2019 between Helsinki and Tallinn, a distance of 87 km taking only half an hour, using a Russian-built ekranoplan.<ref>{{cite web|url=https://news.err.ee/652445/estonian-company-hopes-to-launch-tallinn-helsinki-gev-service-in-2019|title=Estonian company hopes to launch Tallinn-Helsinki GEV service in 2019|date=5 January 2018|website=ERR|access-date=6 April 2018|archive-url=https://web.archive.org/web/20180120233432/https://news.err.ee/652445/estonian-company-hopes-to-launch-tallinn-helsinki-gev-service-in-2019|archive-date=20 January 2018|url-status=live}}</ref> The company ordered 15 ekranoplans with maximum speed of 185 km/h and capacity of 12 passengers, built by Russian RDC Aqualines.<ref>{{cite web|url=https://www.mtv.fi/uutiset/kotimaa/artikkeli/virolaisyrityksella-hurja-visio-helsinki-tallinna-vali-puolessa-tunnissa-pintaliitajalla/6717716|title=Virolaisyrityksellä hurja visio: Helsinki–Tallinna-väli puolessa tunnissa pintaliitäjällä?|trans-title=Estonian company has a wild vision: Helsinki-Tallinn distance in half an hour with a surface connector?|language=fi|date=4 January 2018|website=MTV3|access-date=6 April 2018|archive-url=https://web.archive.org/web/20180205193244/https://www.mtv.fi/uutiset/kotimaa/artikkeli/virolaisyrityksella-hurja-visio-helsinki-tallinna-vali-puolessa-tunnissa-pintaliitajalla/6717716|archive-date=5 February 2018|url-status=dead}}</ref>
===2020–present=== {{See also|REGENT Viceroy}} Around mid-2022, the US Defense Advanced Research Projects Agency (DARPA) launched its Liberty Lifter project, with the goal of creating a low-cost seaplane that would use the ground-effect to extend its range. The program aims to carry 90 tons over {{Convert|6500|nmi|km}}, operate at sea without ground-based maintenance, all using low-cost materials.<ref>{{cite web|url= https://www.msn.com/en-us/news/technology/cargo-hauling-ekranoplan-x-plane-is-being-developed-by-darpa/ar-AAXtV1J?ocid=msedgntp&cvid=ea993245d2c44b53a49be3daf9905414 |title=Cargo Hauling Ekranoplan X-Plane is being Developed by DARPA|publisher=Thomas Newdick, The Drive, May 19, 2022|access-date=May 19, 2022}}</ref><ref>{{Cite web |last=Blain |first=Loz |date=2022-05-24 |title=DARPA Liberty Lifter aims to bring back heavy-lift ground effect seaplanes |url=https://newatlas.com/aircraft/darpa-liberty-lifter-ground-effect/ |access-date=2022-05-24 |website=New Atlas |language=en-US}}</ref><ref>{{Cite web |last=Lagrone |first=Sam |date=1 February 2023 |title=DARPA Awards Contracts for Long-Range 'Liberty Lifter' Flying Boat Design |url=https://news.usni.org/2023/02/01/darpa-awards-contracts-for-long-range-liberty-lifter-flying-boat-design# |access-date=25 January 2024 |website=USNI News}}</ref>
In 2025, reports of a Chinese 'Ekranoplan' surfaced in the Naval News magazine.<ref>{{Cite web |last=Sutton |first=H. I. |date=2025-06-30 |title=China Builds New Large Jet-Powered Ekranoplan |url=https://www.navalnews.com/naval-news/2025/06/china-builds-new-jet-powered-large-ekranoplan/ |access-date=2025-07-12 |website=Naval News |language=en-US}}</ref> According to the magazine, the aircraft features a flying boat hull with a distinctive T-tail arrangement with two vertical stabilizers. This configuration is not found on regular aircraft but has been used on several Ekranoplans including some in China. It appears to have a comparatively short wingspan and large tail, typical of Ekranoplans. Four jet engines are mounted above the wing. These have slightly flattened nozzles suggesting downward angled thrust. This too is indicative of an Ekranoplan design. The engines may have a second scoop intake above the main intake, but the photo's angle does not show this fully. This has caused significant concerns in Taiwan, which believes that this craft is essentially being built to ferry forces across the Taiwan Strait, during an invasion by the People's Liberation Army of China.
Rhode Island-based Ocean Glider is developing an electric-powered design called REGENT (Regional Electric Ground Effect Naval Transport) with a standard hull for water operations, with fore- and aft-mounted hydrofoil units that lift the craft out of the water during takeoff, to lower liftoff speeds.<ref name="REGENT" /><ref>{{Cite web |date=August 13, 2025 |title=REGENT breaks ground for RI Seaglider Manufacturing Facility |url=https://www.compositesworld.com/news/regent-breaks-ground-for-ri-seaglider-manufacturing-facility |website=www.compositesworld.com}}</ref> The design is used in two craft, the 12-seater REGENT Viceroy and 100-seater REGENT Monarch. In 2021 Brittany Ferries announced that they were looking into using REGENT ground effect craft<ref name=REGENT>{{cite web|url=https://www.regentcraft.com|title=Coastal Travel - 100% Electric|access-date=13 January 2022}}</ref> for cross English Channel services.<ref name=channelFF>{{cite web|date=15 June 2021|title=Cross-Channel 'flying ferries' concept revealed for Portsmouth route|url=https://www.bbc.co.uk/news/uk-england-hampshire-57483039|work=BBC News |access-date=15 June 2021}}</ref> Southern Airways Express also placed firm orders for seagliders with intent to operate them along Florida's east coast.<ref>{{cite news|date=31 December 2021|title=Southern Airways Express Purchases 20 REGENT Seagliders for their U.S. East Coast Ops in $250M Deal|url=https://www.aerospacetechreview.com/southern-airways-express-purchases-20-regent-seagliders-for-their-u-s-east-coast-ops-in-250m-deal/|work=Aerospace Tech Review|access-date=31 December 2021}}</ref><ref>{{cite web|url=https://observer.com/2021/12/boston-startup-regent-flying-boat-seaglider-test-florida-tampa/|date=16 December 2021|via=The Observer|author=Sissi Cao|title=Is It a Flying Boat?|access-date=13 January 2022}}</ref> In May 2024, Ocean Glider announced a deal with UK-based investor MONTE to finance $145m of a $700m deal to begin operating 25 REGENT seagliders between destinations in New Zealand.<ref>{{Cite news|url=https://www.newshub.co.nz/home/new-zealand/2024/05/kiwi-startup-ocean-flyer-signs-145m-deal-to-operate-seagliders-in-new-zealand.html|archive-url=https://web.archive.org/web/20240514222436/https://www.newshub.co.nz/home/new-zealand/2024/05/kiwi-startup-ocean-flyer-signs-145m-deal-to-operate-seagliders-in-new-zealand.html|url-status=dead|archive-date=May 14, 2024|title=Kiwi startup Ocean Flyer signs $145m deal to operate seagliders in New Zealand|newspaper=Newshub |via=www.newshub.co.nz}}</ref><ref>{{Cite web|url=https://www.odt.co.nz/business/entrepreneur%E2%80%99s-vision-future-travel|title=Entrepreneur's vision for future travel|first=Sally|last=Rae|date=May 26, 2024|website=Otago Daily Times }}</ref> In March 2025, REGENT completed its first taxi test of a full-sized vehicle that carried passengers.<ref>{{Cite web |first=Abhimanyu |last=Ghoshal|date=2025-03-10 |title=Revolutionary ground-effect electric seaglider gets passengers flying |url=https://newatlas.com/aircraft/regent-viceroy-electric-seaglider-passengers-test/?utm_source=New+Atlas+Subscribers&utm_campaign=9f71e55ea4-EMAIL_CAMPAIGN_2025_03_10_01_37&utm_medium=email&utm_term=0_65b67362bd-9f71e55ea4-90065621 |access-date=2025-03-13 |website=New Atlas |language=en-US}}</ref> In August 2025, REGENT announced plans to deliver its first Monarchs to United Marine Egypt (UME) shipping by 2030.<ref>{{Cite web |title=UME Shipping Will Be First Delivery Customer of REGENT's Monarch Seaglider |url=https://www.regentcraft.com/news/ume-shipping-will-be-first-delivery-customer-of-regents-monarch-seaglider |access-date=2025-12-15}}</ref> The Viceroy completed hydrofoil tests in June 2025, but suffered a crash while foil testing in October 2025. As of April 2, 2026, the Viceroy had not flown.<ref>{{Cite web |last=Hawaii |first=Beat of |date=2026-03-07 |title=Hawaii Seaglider Wing Hits Water In Testing. Military Moves Ahead. |url=https://beatofhawaii.com/hawaii-seaglider-wing-hits-water-in-testing-military-moves-ahead/ |access-date=2026-04-19 |website=Beat of Hawaii |language=en-US}}</ref> That month REGENT completed the maiden flight of Squire, its autonomous, electric variant.<ref>{{Cite web |last=Szondy |first=David |date=2026-04-14 |title=Autonomous wing-in-ground effect aircraft has US military in its sights |url=https://newatlas.com/military/regent-autonomous-wing-in-ground-effect-aircraft-us-military/ |access-date=2026-04-19 |website=New Atlas |language=en-US}}</ref>
==See also== * Aerodynamically alleviated marine vehicle * Flying Platform * Ground effect (aerodynamics) * Ground-effect train * Hovercraft * List of ground-effect vehicles * Surface effect ship * Caspian Sea Monster
==References==
===Notes=== {{reflist|group=note}}
===Citations=== {{Reflist}}
===Bibliography=== {{refbegin}} *{{cite journal |url=http://www.ptmts.org.pl/abramowski-2-07.pdf |title=Numerical Investigation of Airfoil in Ground Proximity |first=Tomasz |last=Abramowski |date=2007 |journal=Theoretical and Applied Mechanics |location=Warsaw |volume=45 |number=2 |pages=425–436 |issn=1429-2955|archive-url=https://web.archive.org/web/20100922210513/http://www.ptmts.org.pl/abramowski-2-07.pdf |archive-date=September 22, 2010 }} *{{cite book |title=Easy Ways to Study Ground Effects |first1=S.Y. |last1=Aubin |first2=John |last2=de Monchaux |date=June 2001 |location=Toulouse, France |publisher=EAGES 2001 International Ground Effect Symposium}} * {{cite book |last=Dole |first= Charles Edward |title=Flight Theory and Aerodynamics |location=Hoboken, New Jersey |publisher=John Wiley & Sons, Inc |date= 2000 |isbn=978-0-471-37006-2}} *{{cite book |title=Low Flying Boats |first=Simon |last=Fishwick |date=2001 |location=Thorpe Bay, Southend-on-Sea, Essex, UK |publisher=Amateur Yacht Research Society |isbn=0-85133-126-2}} *{{cite book |title=The Arms Production Dilemma: Contraction and Restraint in the World Combat Aircraft Industry |first=Randall |last=Forsberg |date=1995 |location=Boston, MA |publisher=The MIT Press |isbn=978-0-262-56085-6}} *{{cite magazine |url=https://www.flyingmag.com/aircraft-technicalities-faster-boat/ |last=Garrison |first=Peter |author-link=Peter Garrison |date=September 16, 2011 |title=Faster than a Boat |magazine=Flying}} * {{cite book |last=Gleim |first=Irving |title=Pilot Flight Maneuvers |location=Ottawa, Ontario, Canada |publisher= Aviation Publications |date=1982 |isbn= 0-917539-00-1}} *{{cite book |last=Gunston |first=Bill |author-link=Bill Gunston |date=2000 |title=The Osprey Encyclopedia of Russian Aircraft |location=Oxford, UK |publisher=Osprey |isbn=978-1-84176-096-4}} *{{cite book |first1=Ernst Heinrich |last1=Hirschel |first2=Horst |last2=Prem |first3=Gero |last3=Madelung |name-list-style=amp |date=2003 |title=Aeronautical Research in Germany: From Lilienthal Until Today |location=Berlin |publisher=Springer-Verlag and Heidelberg GmbH & Co. K. |isbn=978-3-540-40645-7}} *{{cite book |first1=Sergey |last1=Komissarov |first2=Yefim |last2=Gordon |date=2010 |title=Soviet and Russian Ekranoplans |location=Hersham, UK |publisher=Ian Allan Publishing |isbn=978-1-85780-332-7}}. *{{cite book |title=McGraw-Hill Dictionary of Scientific and Technical Terms |location=New York |publisher=McGraw-Hill Professional |date=2002 |isbn=978-0-07-042313-8}} *{{cite book |last=Nebylov |first=A.V. |title=Ekranoplanes: Controlled Flight Close to the Sea |location=Southampton, UK |publisher=WIT Press |date=2002}} *{{cite book |last=Rozhdestvensky |first=Kirill V. |title=Aerodynamics of a Lifting System in Extreme Ground Effect |location=Berlin |publisher=Springer-Verlag and Heidelberg GmbH & Co. K. |date=2002 |isbn=978-3-540-66277-8}} *{{cite journal |title=Complex Algorithms of Parameters Measuring Systems for Motion Close to the Sea |first=Sukrit |last=Sharan |date=March 2007 |journal=IX Conference for Young Scientists |location=St. Petersburg, Russia |publisher=CSRI-ELEKTROPRIBOR}} *{{cite journal |title=Quality Measurement Criteria for Flight Close to the Sea Surface |first=Sukrit |last=Sharan |date=April 2007 |journal=Seminar on Aeronautics & Space |location=St. Petersburg, Russia |publisher=University of Aerospace Instrumentation}} *{{cite tech report |title=An overview of WIG vehicles for military operations |oclc=1085143242 |series=RTO technical report |publisher=North Atlantic Treaty Organization (NATO), Research and Technology Organization (RTO), Applied Vehicle Technology (AVT) Panel, Task Group AVT-081 |publication-date=December 2006 |doi=10.14339/RTO-TR-AVT-081 |doi-broken-date=12 July 2025 |id=TR-AVT-081 | url=https://www.sto.nato.int/publications/STO%20Technical%20Reports/Forms/Technical%20Report%20Document%20Set/docsethomepage.aspx?ID=2155}} **{{lay source |template=cite tech report |date=29 December 2006 |title=An Overview of WIG Vehicles for Military Operations |url=https://www.sto.nato.int/publications/STO%20Technical%20Reports/Forms/Technical%20Report%20Document%20Set/docsethomepage.aspx?ID=2155 |url-access=registration |id=RTO-TR-AVT-081 |website=Science & Technology Organization |publisher=North Atlantic Treaty Organization}} {{refend}}
==External links== {{Commons category|Ground effect vehicles}} *{{cite web |url=https://www.airliners.net/search?keywords=Alekseyev+A-90&sortBy=dateAccepted&sortOrder=desc&perPage=60&display=detail |title=Alekseyev A-90 |website=Airliners.net}} *{{cite journal |url=http://www.boeing.com/news/frontiers/archive/2002/september/i_pw.html |title=The Pelican: A Big Bird for the Long Haul |first=William |last=Cole |journal=Boeing Frontiers |date=September 2002 |volume=1 |issue=5}} *{{cite web |url=http://www.seadiscovery.com/mt/mtStories.aspx?ShowStrory=1005072071 |title=Sea Eagle Wing In Ground Effect Craft Provide 80 Knots Alternatives To Marine Transportation Industry |first=Francis |last=Teo |date=July 18, 2006 |website=SeaDiscovery.com |access-date=December 12, 2007 |archive-date=January 10, 2009 |archive-url=https://web.archive.org/web/20090110072601/http://www.seadiscovery.com/mt/mtStories.aspx?ShowStrory=1005072071 |url-status=dead }} *{{cite web |url=http://www.fas.org/man/dod-101/sys/ship/row/rus/903.htm |title=Project 903 Lun Missile Launcher Ekranoplane |website=FAS.org|archive-url=https://web.archive.org/web/20151207100345/http://www.fas.org/man/dod-101/sys/ship/row/rus/903.htm |archive-date=December 7, 2015 }} *{{cite web |url=http://autospeed.drive.com.au/cms/article.html?&A=1306&P=1 |title=Between Wind and Waves: Ekranoplans |first=Julian |last=Edgar |date=5 March 2002 |website=AutoSpeed|archive-url=https://web.archive.org/web/20051110013437/http://autospeed.drive.com.au/cms/article.html?&A=1306&P=1 |archive-date=November 10, 2005 }} *{{cite web |url=http://www.airfoil.de/ |title=Das Albatross-Prinzip |website=Airfoil Tandem W.I.G. Consulting |language=de}} *{{cite web |url=http://www.airforce.ru/en/ekranoplanes/ekranoplanes.htm |title=Ekranoplanes: Soaring above the waves |website=Airforce.ru}} *{{cite web |url=http://www.moscowtopnews.com/?area=postView&id=886 |title=Ekranoplan |website=Moscow Top News|archive-url=https://web.archive.org/web/20091125013536/http://www.moscowtopnews.com/?area=postView&id=886 |archive-date=November 25, 2009 }} *{{cite web |url=http://swerc.en.ec21.com/Wing_in_the_Ground_Effect--3772218_3772540.html |title=Wing in the Ground Effect Ship |website=Sungwoo Engineering}} *{{cite web |url=http://jalopnik.com/5490175/ekranoplan-mega-gallery/gallery/1, |title=The Lun, sitting in drydock |website=Jalopnik|date=March 10, 2010 }} *{{cite web |url=http://www.aerospaceweb.org/question/aerodynamics/q0130.shtml |title=Ground Effect and WIG Vehicles |website=Aerospaceweb.org}} *{{cite web |url=https://www.aerohod.ru/asvp-tungus.html |title=СВП с АР проекта А18 ("Тунгус") |trans-title=SVP with AR project A18 ("Tungus") |website=Aerohod |language=ru}} *{{cite web |url=https://bufocraft.net/wig-flying-hovercraft.htm |title=Flying hovercraft project Wig |website=MAD Hovercraft}} *{{Cite AV media |url=https://www.youtube.com/watch?v=__is4z4o4NE&feature=youtu.be |title=REGENT Begins Sea Trials of First Passenger-Carrying Seaglider |date=2025-03-06 |last=REGENT Craft |access-date=2025-03-13 |via=YouTube}}
{{Aircraft types (by method of thrust and lift)}}
{{DEFAULTSORT:Ground-Effect Vehicle}} Category:Amphibious vehicles Category:Aircraft configurations Ekranoplan Category:Soviet inventions Category:Ground-effect vehicles