Wing In Ground-effect vehicle
Encyclopedia
A ground effect vehicle (GEV) is one that attains level flight near the surface of the Earth, making use of the aerodynamic interaction between the wings and the surface known as ground effect.
GEV are also known as a wing-in-ground-effect (WIG) vehicle, flarecraft, sea skimmer, ekranoplan, SkimMachine, or a wing-in-surface-effect ship (WISE).
Static and dynamic lift
A GEV is sometimes characterized as a transition between a hovercraftHovercraft
A hovercraft is a craft capable of traveling over surfaces while supported by a cushion of slow moving, high-pressure air which is ejected against the surface below and contained within a "skirt." Although supported by air, a hovercraft is not considered an aircraft.Hovercraft are used throughout...
and an aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...
, although this is not technically correct. A hovercraft is statically supported upon a cushion of pressurised air (from an onboard downward-directed fan). A GEV needs some velocity producing a "dynamic" lift; moreover the principal effect of the proximity of the ground to a lifting wing is not to increase its lift but to reduce its lift-dependent drag
Lift-induced drag
In aerodynamics, lift-induced drag, induced drag, vortex drag, or sometimes drag due to lift, is a drag force that occurs whenever a moving object redirects the airflow coming at it. This drag force occurs in airplanes due to wings or a lifting body redirecting air to cause lift and also in cars...
.
Additional lift
Some GEV designs, such as the Russian Lun and Dingo, have used "power assisted ram" -- forced blowing under the wing by auxiliary engines—to achieve a hovercraft-like effect or to assist the takeoff. A GEV differs from a conventional aircraft in that it cannot operate efficiently without ground effect, and so its operating height is limited relative to its wingspanWingspan
The wingspan of an airplane or a bird, is the distance from one wingtip to the other wingtip. For example, the Boeing 777 has a wingspan of about ; and a Wandering Albatross caught in 1965 had a wingspan of , the official record for a living bird.The term wingspan, more technically extent, is...
. Some GEVs are, in fact, able to climb out of ground effect.
In recent years a large number of different GEV types have been developed for both civilian and military use. However, these craft are not in general use.
History
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 during a landing operation. In 1934 the US National Advisory Committee for AeronauticsNational Advisory Committee for Aeronautics
The National Advisory Committee for Aeronautics was a U.S. federal agency founded on March 3, 1915 to undertake, promote, and institutionalize aeronautical research. On October 1, 1958 the agency was dissolved, and its assets and personnel transferred to the newly created National Aeronautics and...
issued Technical Memorandum 771, Ground Effect on the Takeoff and Landing of Airplanes, which was a translation into English of a summary of research up to that point 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 . . "
Small numbers of experimental vehicles were built in Scandinavia
Scandinavia
Scandinavia is a cultural, historical and ethno-linguistic region in northern Europe that includes the three kingdoms of Denmark, Norway and Sweden, characterized by their common ethno-cultural heritage and language. Modern Norway and Sweden proper are situated on the Scandinavian Peninsula,...
, particularly Finland
Finland
Finland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...
, just before World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
. By the 1960s, the technology started to improve, in large part due to the independent contributions of Rostislav Alexeyev
Rostislav Alexeyev
Rostislav Evgenievich Alexeyev , Russian Empire – February 9, 1980, Gorky, USSR) was a designer of highspeed shipbuilding. He invented and designed the world's first Ekranoplans. His work has been compared to that of A.N. Tupolev in aviation and S.P...
in the Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
and German
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
Alexander Lippisch
Alexander Lippisch
Alexander Martin Lippisch was a German pioneer of aerodynamics. He made important contributions to the understanding of flying wings, delta wings and the ground effect. His most famous design is the Messerschmitt Me 163 rocket-powered interceptor.Lippisch was born in Munich, Kingdom of Bavaria...
, working in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
. Alexeyev worked from his background as a ship designer whereas Lippisch worked as an aeronautical engineer. The influence of Alexeyev and Lippisch is still noticeable in most GEV vehicles seen today.
Soviet Union GEVs
Led by Alexeyev, the Soviet Central Hydrofoil Design Bureau (CHDB) was the center of ground-effect craft development in the USSR; in RussianRussian language
Russian is a Slavic language used primarily in Russia, Belarus, Uzbekistan, Kazakhstan, Tajikistan and Kyrgyzstan. It is an unofficial but widely spoken language in Ukraine, Moldova, Latvia, Turkmenistan and Estonia and, to a lesser extent, the other countries that were once constituent republics...
, the vehicle came to be known as an Ekranoplan . The military potential for such a craft was soon recognized and Alexeyev received support and financial resources from Soviet leader Nikita Khrushchev
Nikita Khrushchev
Nikita Sergeyevich Khrushchev led the Soviet Union during part of the Cold War. He served as First Secretary of the Communist Party of the Soviet Union from 1953 to 1964, and as Chairman of the Council of Ministers, or Premier, from 1958 to 1964...
.
Some manned and unmanned prototypes were built, ranging up to eight tons in displacement
Displacement (ship)
A ship's displacement is its weight at any given time, generally expressed in metric tons or long tons. The term is often used to mean the ship's weight when it is loaded to its maximum capacity. A number of synonymous terms exist for this maximum weight, such as loaded displacement, full load...
. This led to the development of the "Caspian Sea Monster", a 550-ton military ekranoplan of 240 feet (73 m) length. Although it was designed to travel a maximum of 3 m (9.8 ft) above the sea, it was found to be most efficient at 20 m (65.6 ft), reaching a top speed of 300 kn (365.3 mph; 588 km/h) (400 kn (487.1 mph; 783.9 km/h) in research flight).
The Soviet ekranoplan program continued with the support of Minister of Defence Dmitriy Ustinov
Dmitriy Ustinov
Dmitriy Feodorovich Ustinov was Minister of Defense of the Soviet Union from 1976 until his death.-Early life:Dimitry Feodorovich Ustinov was born in a working-class family in Samara. During the civil war, when hunger became intolerable, his sick father went to Samarkand, leaving Dimitry as head...
. It produced the most successful ekranoplan so far, the 125-ton A-90 Orlyonok
A-90 Orlyonok
-External links:* * * * * *...
. These craft were originally developed as high-speed military transports, and were usually based on the shores of the Caspian Sea
Caspian Sea
The Caspian Sea is the largest enclosed body of water on Earth by area, variously classed as the world's largest lake or a full-fledged sea. The sea has a surface area of and a volume of...
and Black Sea
Black Sea
The Black Sea is bounded by Europe, Anatolia and the Caucasus and is ultimately connected to the Atlantic Ocean via the Mediterranean and the Aegean seas and various straits. The Bosphorus strait connects it to the Sea of Marmara, and the strait of the Dardanelles connects that sea to the Aegean...
. The Soviet Navy ordered 120 Orlyonok-class ekranoplans. But this figure was later reduced to fewer than thirty vehicles, with planned deployment mainly in the Black Sea and Baltic Sea
Baltic Sea
The Baltic Sea is a brackish mediterranean sea located in Northern Europe, from 53°N to 66°N latitude and from 20°E to 26°E longitude. It is bounded by the Scandinavian Peninsula, the mainland of Europe, and the Danish islands. It drains into the Kattegat by way of the Øresund, the Great Belt and...
fleets.
A few Orlyonoks served with the Soviet Navy
Soviet Navy
The Soviet Navy was the naval arm of the Soviet Armed Forces. Often referred to as the Red Fleet, the Soviet Navy would have played an instrumental role in a Warsaw Pact war with NATO, where it would have attempted to prevent naval convoys from bringing reinforcements across the Atlantic Ocean...
from 1979 to 1992. In 1987 the 400-ton Lun-class ekranoplan was built as a missile launcher. A second Lun, renamed Spasatel, was laid down as a rescue vessel, but was never finished.
Minister Ustinov died in 1985, and the new Minister of Defence, Marshal Sokolov, effectively stopped the 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
Kaspiysk
Kaspiysk , until 1947 known as Dvigatelstroy , is a city in the Republic of Dagestan, Russia, located on the Caspian Sea, southeast of Makhachkala. Population: 43,000 ....
.
The two major problems that the Soviet ekranoplans faced were poor longitudinal stability and a need for reliable navigation.
Since the fall of the Soviet Union, ekranoplans have been produced by the Volga Shipyard in Nizhniy Novgorod.
After the collapse of the Soviet Union
Dissolution of the Soviet Union
The dissolution of the Soviet Union was the disintegration of the federal political structures and central government of the Union of Soviet Socialist Republics , resulting in the independence of all fifteen republics of the Soviet Union between March 11, 1990 and December 25, 1991...
, 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.
German GEVs
In Germany, Lippisch was asked to build a very fast boat for AmericanUnited States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
businessman Arthur A. Collins
Arthur A. Collins
Arthur A. Collins was an American entrepreneur, who founded Collins Radio Co., which is now Rockwell Collins, Inc..Art Collins' father owned several thousand acres of farmland. After graduating from Washington High School in Cedar Rapids, Iowa, Collins attended several colleges although he never...
. 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 a German company called Rhein Flugzeugbau (RFB) which further developed the model.
The University of Duisburg-Essen
University of Duisburg-Essen
The University Duisburg-Essen is a public university in Duisburg and Essen, North Rhine-Westphalia, Germany and a member of the new founded University Alliance Metropolis Ruhr....
is supporting an ongoing research project to develop the Hoverwing.
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, but has not been produced beyond a prototype. The consultancy of Dipl. Ing. Günther Jörg was founded with a fundamental knowledge of Wing in Ground Effect physics, as well as results of fundamental tests under different conditions and designs that began in 1960. In 1984 Jörg received the "PHILIP MORRIS AWARD". In 1987, the Botec Company was founded.
GEVs since 1980s
GEV developed since the 1980s have been primarily smaller craft designed for the recreational and civilian ferry markets. Germany, RussiaRussia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
, and the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
have provided most of the momentum with some development in Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
, and Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
. In these countries, small craft up to ten seats have been designed and built. Other larger designs as ferries and heavy transports have been proposed, but have not been carried to fruition.
Current development
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, isotropic or ultrasonic altimeters.
Mississippi River
The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...
, near Cordova, Illinois
Cordova, Illinois
Cordova is a village in Rock Island County, Illinois, United States. The population was 633 at the 2000 census.-Geography:Cordova is located at ....
. Since 1999 the company has offered plans, parts, kits and manufactured GEV hovercraft called the Hoverwing.
In Singapore, Wigetworks has continued the development of the technology and has obtained certification from Lloyd's Register for entry into class. AirFish 8 - 001 was successfully registered into Singapore Registry of Ships (SRS) on 31 March 2010. It is the first WIG craft to be flagged with the SRS which is one of the world's top 10 largest ship registry. Wigetworks has also partnered with National University of Singapore's Engineering Department to develop higher capacity WIG craft.
Iran deployed three squadrons of Bavar-2 two-seat GEVs in September, 2010. This GEV carries one machine gun and surveillance gear, and reportedly incorporates stealth technology.
Classification
One difficulty which has delayed GEV development is the classification and legislation to be applied. the International Maritime OrganizationInternational Maritime Organization
The International Maritime Organization , formerly known as the Inter-Governmental Maritime Consultative Organization , was established in Geneva in 1948, and came into force ten years later, meeting for the first time in 1959...
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 hydrofoil
Hydrofoil
A hydrofoil is a foil which operates in water. They are similar in appearance and purpose to airfoils.Hydrofoils can be artificial, such as the rudder or keel on a boat, the diving planes on a submarine, a surfboard fin, or occur naturally, as with fish fins, the flippers of aquatic mammals, the...
s, hovercraft, catamaran
Catamaran
A catamaran is a type of multihulled boat or ship consisting of two hulls, or vakas, joined by some structure, the most basic being a frame, formed of akas...
s 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 crafts under the category of ships.
The International Maritime Organization recognizes three classes of ground effect craft:
- Type A: a craft which is certified for operation only in ground effect;
- Type B: a craft which is certified to temporarily increase its altitude to a limited height outside the influence of ground effect but not exceeding 150 m above the surface; and
- Type C: a craft which is certified for operation outside of ground effect and exceeding 150 m above the surface.
These classes currently only apply to craft carrying 12 passengers or more.
Advantages and disadvantages
A ground effect craft may have better fuel efficiency than an equivalent aircraft due to its lower lift-induced dragLift-induced drag
In aerodynamics, lift-induced drag, induced drag, vortex drag, or sometimes drag due to lift, is a drag force that occurs whenever a moving object redirects the airflow coming at it. This drag force occurs in airplanes due to wings or a lifting body redirecting air to cause lift and also in cars...
. There are also safety benefits for the occupants 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, is dangerous if the craft banks too far to one side while turning, or if a large wave occurs.
Contrary to an aircraft, a GEV is able to enter at slow speed a harbour into or near a centertown.
An important issue is the probability of collision with others conventional "slow" boats, in bad visibility conditions on dense traffic routes, due to the difference of speed.
A takeoff 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 engines could be tilted so their exhaust blast was directed under the wing leading edge). The Caspian Sea Monster had eight such engines, some of which were not used once the craft was airborne. A second approach is to adopt a hybrid concept using some form of an air-cushion (see hovercraft
Hovercraft
A hovercraft is a craft capable of traveling over surfaces while supported by a cushion of slow moving, high-pressure air which is ejected against the surface below and contained within a "skirt." Although supported by air, a hovercraft is not considered an aircraft.Hovercraft are used throughout...
) to raise the vehicle out of the water, making take-off easier. This is used by Hanno Fischer in the Hoverwing (successor to the Airfisch ground effect craft), which uses some of the blowing air coming from the propellers to inflate a skirt under the craft in the style of a sidewall hovercraft.
Inverse delta
Developed by Alexander LippischAlexander Lippisch
Alexander Martin Lippisch was a German pioneer of aerodynamics. He made important contributions to the understanding of flying wings, delta wings and the ground effect. His most famous design is the Messerschmitt Me 163 rocket-powered interceptor.Lippisch was born in Munich, Kingdom of Bavaria...
, this wing allows stable flight in ground effect through self stabilization. This is the main Class B form of ground effect craft.
Ekranoplan wing
This was the profile designed by Rostislav AlexeyevRostislav Alexeyev
Rostislav Evgenievich Alexeyev , Russian Empire – February 9, 1980, Gorky, USSR) was a designer of highspeed shipbuilding. He invented and designed the world's first Ekranoplans. His work has been compared to that of A.N. Tupolev in aviation and S.P...
. The wings are significantly shorter than comparable aircraft, and this configuration requires a high aft-placed horizontal tail and front-aft wings to maintain stability.
Tandem wings
Tandem Wing can have two configurations:- a biplaneBiplaneA biplane is a fixed-wing aircraft with two superimposed main wings. The Wright brothers' Wright Flyer used a biplane design, as did most aircraft in the early years of aviation. While a biplane wing structure has a structural advantage, it produces more drag than a similar monoplane wing...
-style Type-1 utilizing a shoulder-mounted main lift wing and belly-mounted sponsonSponsonSponsons are projections from the sides of a watercraft, for protection, stability, or the mounting of equipment such as armaments or lifeboats, etc...
s similar to those on combat and transport helicopters - a canard-style type-2 with a mid-size horizontal wing not a stabilizer because destabilizing 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.
- a Tandem Wing Style with double-wing system as built in Tandem Airfoilboat constructions by Jörg. This system is self-stabilizing and provides secure, comfortable and high-efficiency operation.
Design
- The basic design principle is that the wing drag decreases as the operating altitude decreases (see ground effect).
- The pitch and altitude stability comes from the lift slope Cl/da, with Cl = Lift coefficient, and a = angle of incidence 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).
- Once moving at speed, the ekranoplan is no longer in contact with the water, and can move over ice, snow or level land with equal ease, though flight over land would involve extreme risks unless the surface is dependably flat.
See also
- Ground effect in aircraft
- Ground effect trainGround effect trainA ground effect train is an alternative to a magnetic levitation train. In both cases the object is to prevent the vehicle from making contact with the ground...
- List of ground effect vehicles
- HovercraftHovercraftA hovercraft is a craft capable of traveling over surfaces while supported by a cushion of slow moving, high-pressure air which is ejected against the surface below and contained within a "skirt." Although supported by air, a hovercraft is not considered an aircraft.Hovercraft are used throughout...
- Tupolev N007 ground effect aerosled
- Aerodynamically Alleviated Marine Vehicle
- SeaplaneSeaplaneA seaplane is a fixed-wing aircraft capable of taking off and landing on water. Seaplanes that can also take off and land on airfields are a subclass called amphibian aircraft...
External links
- AirFish 8 - 001 The only WIG craft fully certified by Lloyd's Register and registered with Singapore Registry of Ships
- Ground effect vehicle "AQUALET" New ground effect vehicle development (2011)
- Australian Military Research and Studies on Wing in Effect Craft
- WingShip Development Roadmap By US Army
- Airliners.net Photos of Alekseyev A-90
- RIA Novosti article on Soviet GEV research
- Skimmerfoil Jörg IV at the SAAF Museum in Port Elizabeth, South Africa
- The Boeing Pelican
- The Authority Website for all GEV development
- GEV Development in Indonesia
- The Lun class on FAS
- The WIG Page, history of Wing-In-Ground craft
- Short overview of Soviet ekranoplan creation and development
- Commemorating the 85th anniversary of Rostislav Evgenievich Alexeyev, an outstanding designer of high-speed ships
- Between Wind and Waves: Ekranoplans
- Graham Taylor's Model Research featuring footage of both model- and full-size ekranoplans
- Volga Shipyard The only producer in the world of Ekranoplans
- BBC video story on Ekranoplans
- Airfoil Flairboat page
- Ekranoplanes: Soaring above the waves
- Ekranoplan Moscow Top News
- Sungwoo Engineering (Korea) Wing in the Ground Effect Ship
- http://jalopnik.com/5490175/ekranoplan-mega-gallery/gallery/1 The Lun, sitting in drydock
- Numerical Investigation of Airfoil in Ground Proximity
- aerospaceweb.org - Ground Effect and WIG Vehicles
- IMO interim guidelines for wing-in-ground craft, December 2002