Lun-class ekranoplan MD-160
The Russians built the first large-scale WIG craft in the 1960s. The 500 tonne, so called, Caspian Monster, remained secret to the West until the late 1980s. There have been at least eight modifications to the single craft built, the number on the tail indicating the modification number. The Caspian Monster prototype is reported to have crashed and sunk in the Caspian Sea in 1980 after 14 years of service.
The craft design is ideally suited for rapid transportation of forces, with a greater payload capacity, greater range and less fuel consumption than conventional aircraft, whilst operating at a comparable speed.
A development of the Caspian Monster, the LUN design apparently went into military service in 1989, but this craft is now reported to have been withdrawn from military activities. The craft is propelled by eight NK-87 turbofan engines, and the craft is armed with six anti-ship missiles.
A number of non-military versions of the LUN craft are currently proposed. It is understood that the LUN craft currently under construction was originally conceived as a military craft but is being converted to a rescue craft named the Spasatel-2. This has similar performance characteristics to the original LUN craft with a displacement of 400 tonnes, a cruising speed of 450 to 550 km/h and a range of 4,500 km. The carrying capacity of this craft is up to 600 people. Other versions of the Spastel-2 are also proposed – a passenger-carrying craft, the LUN-P, and a cargo carrying craft, the MTER.
These plane-ship hybrids fly over water an altitude of just a few meters – well below the detection limit of most naval and shore-defense radars and below the operational altitude limit of air-to-air missiles.
Ekranoplans can transport well over a hundred of fully equipped troops, as do large amphibious assault ships. Unlike such ships, however, ekranoplans can travel at up to 500 km/h and are invulnerable to most anti-ship missiles designed to attack much slower targets. Ekranoplans are also far more efficient than transport aircraft of similar take-off weight and lifting capability. “The enhanced lift and reduced drag permits roughly a 30-40 per cent increase in payload carried over greater distance and with less fuel consumption compared to conventional aircraft.”
Types include “Orlyonok” (Eaglet) transport ekranoplans and the “Lun” (Hen Harrier) attack ekranoplan armed with the Moskit (Mosquito) supersonic anti-ship missiles with the top speed of 3000 km/h. Jane’s Intelligence Review writes about this missile: “The Moskit was the world’s first supersonic sea-skimming anti-ship missile. It preceded any comparable Western missile by almost two decades and, today, probably no anti-ship missile causes more anxiety in Western navies… It is the combination of extremely high terminal speed, low approach altitudes and terminal maneuvering in the Russian 3M80 Moskit (Mosquito), otherwise known in Western circles as the SS-N-22 `Sunburn’, which raises serious questions about the viability of many existing shipborne defences.”
The “Lun” was designed to evade all anti-ship and antiaircraft defenses and engage its targets from 90 kilometers away. Jane’s writes: “The most unusual of the vessels armed with Moskit is the Project 905 Lun (`Utka’) wing-in ground-effect (WIG) flying boat developed by the R E Alekseyev Central Hydrofoil Design Bureau in Nizhniy Novgorod. The second aircraft of this type, the S-31 completed in 1993, is armed with three twin Moskit launchers arrayed along its upper spine. The S-31 is fitted with a complicated array of fire-control radars on its tail which may be adaptations of the Monolit fire-control radar used on the Moskit-armed warships.”
The Alekseyev Central Hydrofoil Design Bureau in Nizhniy Novgorod developed these remarkable aircraft during the Khrushchev era. Nikita Khrushchev hoped that this new technology would give the USSR a decisive edge over the US carrier forces. And for a while it did. After Brezhnev replaced Khrushchev, the Alekseyev Design Bureau has quickly gone out of favor and the new Party leadership for political and personal reasons gradually terminated the ekranoplan program.
Nevertheless, during the relatively short time of sufficient funding Alekseyev and his engineers were able to create by far the largest and most deadly military ekranoplans ever constructed anywhere in the world. To this day no effective defense against these hybrid aircraft has been developed by any naval power. What makes ekranoplan such an efficient flying machine and such a difficult target?
Ekranoplans, or Wing-in-Ground (WiG) effect aircraft, glide over water or any other smooth surface by forming a cushion of air under its short but very wide wing. For initial take-off most ekranoplans use additional engines installed in the nose section of the aircraft. These engines are used to create the cushion of air under the wing and help the aircraft gain the initial speed.
After the take-off only the cruise engine is enabled – usually a tail-mounted turboprop or turbofan engine. The entire fully loaded huge aircraft is propelled at high speed by this single engine, making the ekranoplan the most efficient transport vehicle for its speed class.
Jane’s explains the flight mechanism behind the ekranoplan: “The nose-mounted jet engines have pivoted exhaust nozzles; during take-off the jet exhaust streams are directed beneath the wing to boost the ramair pressure beneath the wing. On changing to cruising flight the nozzles are redirected to provide horizontal thrust, accelerating the craft until cruising speed is reached; the take-off jet units are then shut down. The same procedure is used when landing the craft to reduce hydrodynamic loading. The fuselage nose location of the jet units allows their intakes to be positioned in the contours of the nose in such a way as to minimize aerodynamic resistance.”
Flying at an altitude of just a few meters an ekranoplan is virtually invisible to air defense radars until it’s too close. Naval radars designed to detect other ships will also be useless against ekranoplans since such radars are not designed to reliably track targets moving at ten times the speed of a ship. Ekranoplans fly to low to be engaged by air-to-air missiles from carrier-based fighters.
Even acquiring and targeting an ekranoplan for a fighter pilot would be a monumental task given the altitude resolution restrictions of air-to-air radars and the background EM noise created by radar signals reflected off the surface of the water. Air-to-ground radars and missiles carried by multi-purpose fighter-bombers such as the F/A-18 are also ill suited to engage such fast-moving “ground” targets. In other words, the ekranoplan is unlike any potential target and no air defense system has been even developed to counter this threat.
A common question is how do ekranoplans operated in the rough seas and how can amphibious assault versions of ekranoplans navigate minefields and other defenses near the shore. Ekranoplans do glide just a few meters over the water surface, but they can also leave the ground effect zone and gain an altitude of up to 300 meters – enough to clear any obstacles. Leaving the ground effect flight means higher fuel consumption, but it allows an ekranoplan a certain degree of flexibility – not as much as a plane but considerably more than a ship or a hovercraft.
A total of five “Orlyonok” ekranoplans have been built for the Russian Navy, of which three remain in service.