The Lun-class ekranoplan (also called Project 903) is the only ground effect vehicle (GEV) to ever be operationally deployed as a warship. It was designed by Rostislav Alexeyev in 1975 and used by the Soviet and later Russian navies from 1987 until sometime in the late 1990s. It flew using lift generated by the ground effect acting on its large wings when within about above the surface of the water. Although they might look similar to traditional aircraft, ekranoplans like the Lun are not classified as aircraft, seaplanes, hovercraft, or hydrofoils. Rather, craft like the Lun-class ekranoplan are classified as maritime ships by the International Maritime Organization due to their use of the ground effect, in which the craft glides just above the surface of the water. The ground effect occurs when flying at an altitude of only a few metres above the ocean or ground; drag is greatly reduced by the proximity of the ground preventing the formation of wingtip vortices, thus increasing the efficiency of the wing. This effect does not occur at high altitude. The name Lun comes from the Russian word for the harrier. Design and development The Lun-class ekranoplan was developed on the basis of the experimental KM ekranoplan, which was nicknamed the "Caspian Sea Monster". The Lun was powered with eight Kuznetsov NK-87 turbofans, mounted on forward canards, each producing of thrust. It had a flying boat hull with a large deflecting plate at the bottom to provide a "step" for takeoff. It had a maximum cruising speed of . Equipped for anti-surface warfare, it carried the P-270 Moskit (Mosquito) guided missile. Six missile launchers were mounted in pairs on the dorsal surface of its fuselage with advanced tracking systems mounted in its nose and tail. The only model of this class ever built to completion, the MD-160, entered service with the Soviet Navy Caspian Flotilla in 1987. It was retired in the late 1990s and sat unused at a Caspian Sea naval base in Kaspiysk until 2020. The second Lun-class ekranoplan was partially built in the late 1980s. While its construction was underway, it was redesigned as a mobile field hospital for rapid deployment to any ocean or coastal location. It was named the Spasatel ("Rescuer"). Following the collapse of the Soviet Union in 1991 and cancellation of military funding, construction of the second craft was halted. As of 2021, the uncompleted Spasatel