Soviet Central Hydrofoil Design Bureau KM / Caspian Sea Monster
The Lun-class ground effect vehicle (GEV), or sea skimmer, was developed by Russian engineers at the Alexeyev Hydrofoil Design Bureau.
During the Cold War, ekranoplans were sighted for years on the Caspian Sea as huge, fast-moving objects. The name Caspian Sea Monster was given by U.S. intelligence operatives who had discovered the huge vehicle, which looked like an airplane with the outer halves of the wings removed. After the end of the Cold War, the “monster” was revealed to be one of several Russian military designs meant to fly only a few meters above water, saving energy and staying below enemy radar.
The KM, as the Caspian Sea Monster was known in the top secret Soviet military development program, was over 100 m long (330 ft), weighed 540 tonnes fully loaded, and could travel over 400 km/h (250 mi/h), mere meters above the surface of the water.
These craft were originally developed by the Soviet Union as very high-speed (several hundred km/hour) military transports, and were mostly based on the shores of the Caspian Sea and Black Sea. The largest could transport over 100 tonnes of cargo. 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.
MAUW: 540 tonne