Caspian Sea Monster

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Экраноплан КМ.jpg
Artist's illustration of the KM
Role Ekranoplan
National origin Soviet Union
Manufacturer Central Hydrofoil Design Bureau
Designer Rostislav Alexeyev
First flight October 16, 1966
Status Destroyed in 1980
Primary user Soviet Navy
Produced 1964–1966
Number built 1

The KM (Korabl Maket) (Russian: Корабль-макет, literally "Ship-prototype"), known colloquially as the Caspian Sea Monster, was a Soviet experimental ground effect vehicle (ekranoplan) developed by the Central Hydrofoil Design Bureau in the 1960s. The KM began operation in 1966, and was continuously tested by the Soviet Navy until 1980, when it was destroyed in a testing accident and sank into the Caspian Sea.

The KM was the largest and heaviest aircraft in the world from 1966 to 1988, and its surprise discovery by the United States and the subsequent attempts to determine its purpose became a distinctive event of espionage during the Cold War.


The KM was an experimental aircraft developed from 1964 to 1966, during a time when the Soviet Union saw interest in ground effect vehicles - airplane-like vehicles which use ground effect to fly several meters above surfaces, primarily bodies of water. It was designed at the Central Hydrofoil Design Bureau, by the chief designer Rostislav Alexeyev and the lead engineer V. Efimov, and manufactured at the Red Sormovo plant in Gorky.[1][2][3][4] The KM was one of the first major ekranoplan (Soviet ground effect vehicles) projects and was notable for its massive size and payload, becoming the largest aircraft in the world when it was completed in 1966. The ekranoplan had wingspan of 37.6 metres (123 ft), length of 92 m (302 ft), maximum take-off weight of 544 short tons (494 t), and was designed to fly at an altitude of 5–10 metres (16–33 ft) to use the ground effect. The KM was also undetectable to traditional radars, as it flew underneath the typical search range. Despite technically being an aircraft, it was considered by authorities to be closer to a boat and was assigned to the Soviet Navy, but operated by test pilots of the Soviet Air Force. The KM was documented as a marine vessel and prior to the first flight a bottle of champagne was broken against its nose, a tradition for the first voyage of a boat.

On June 22, 1966, the completed KM began transportation to the testing grounds in the Caspian Sea near the town of Kaspiysk. It was transported from Gorky along the Volga in secret, covered in camouflage and moved along the river at night. The aircraft's first flight was on October 16, 1966, performed by V. Loginov and Rostislav Alexeyev himself, which was very unusual as most Soviet aircraft designers never piloted their own creations. All the works were conducted under patronage of the Ministry of Shipbuilding Industry. The KM was determined to have an optimum (fuel efficient) cruising speed of 430 km/h (267 mph, 232 knots), and a maximum operational speed of 500 km/h (311 mph, 270 knots). The maximum speed achieved was 650 km/h (404 mph, 350 knots), although some sources claim up to 740 km/h (460 mph, 400 knots).[5] [6]


The KM was at first seen as a promising vehicle specialized for use by military and rescue workers but its design caused many difficulties, progress slowed and Alexeyev moved on to other ekranoplan projects. It was tested at the Caspian Sea for an extensive 15 years until 1980, when it was destroyed following a crash caused by pilot error. There were no human casualties, but the KM was damaged and no attempts were made to save it, being left to float before it eventually sank a week later. The KM was deemed to be too heavy to recover and has remained underwater at the crash site ever since, with no plans to build a second ever made.[7] However, the KM later became the basis for the Lun-class ekranoplan developed by Central Hydrofoil Design Bureau in the 1980s that saw one example, the MD-160, enter service with the Soviet Navy and later the Russian Navy before being decommissioned in the late 1990s.

The KM remained the largest aircraft in the world during the entirety of its existence, and was not surpassed until the Antonov An-225 in 1988, eight years after its destruction.

Western discovery[edit]

The secret Soviet KM project was discovered by the United States in 1967, when photographs taken from spy satellites showed the KM taxiing during testing near Kaspiysk. The strange aircraft puzzled Western intelligence agencies, noting the small stubby wings despite its large size, as well as the KM and flag of the Soviet Navy on its fuselage. The CIA branded the aircraft the "Kaspian Monster" after the KM markings, later becoming known as the "Caspian Sea Monster", while it actually stood for "Korabl-maket" meaning "Prototype ship" in Russian. The discovery, at the height of the Cold War, greatly concerned the CIA, who set up a dedicated task force and developed a purpose-built unmanned drone, Aqualine, just to determine what the secret behind the vehicle was. The KM was initially assumed to be an unfinished conventional aircraft, but it was quickly determined that the vehicle could not fly high. In the 1980s, after the KM was already destroyed, the United States discovered it was a large ekranoplan. The development of ground effect vehicles was not as widespread in the West as in the Soviet Union.[citation needed]

Specifications (KM)[edit]

Data from The Osprey Encyclopedia of Russian Aircraft 1875 - 1995,[8] Russia's Ekranoplans:The Caspian Sea Monster and other WiG Craft[9]

General characteristics

  • Length: 92.00 m (301 ft 10 in)
  • Wingspan: 37.60 m (123 ft 4 in)
  • Tail stabilizer span: 37 m (121 ft 5 in)
  • Height: 21.80 m (71 ft 6 in)
  • Wing area: 662.50 m2 (7,131.1 sq ft)
  • Empty weight: 240,000 kg (529,109 lb)
  • Max takeoff weight: 544,000 kg (1,199,315 lb)
  • Powerplant: 10 × Dobrynin VD-7 turbojet, 127.53 kN (28,670 lbf) thrust each


  • Maximum speed: 500 km/h (311 mph; 270 kn)
  • Cruise speed: 430 km/h (267 mph; 232 kn)
  • Range: 1,500 km (932 mi; 810 nmi)
  • Ground effect altitude: 4–14 m (13 ft 1 in–45 ft 11 in)
  • Maximum sea state: 1.2 m (3 ft 11 in)

In media[edit]

See also[edit]


  1. ^ Sergey Komissarov; Russia's Ekranoplans: The Caspian Sea Monster and Other WIG Craft; (2003)

    "As such they promptly attracted the attention of the military and thus have been veiled in secrecy until recently .The book describes in detail the many series of WIGE vehicles developed by various design bureaus, including the Orlyonok, the ..."

  2. ^ National Research Council; Reducing the Logistics Burden for the Army After Next Committee to Perform a Technology Assessment Focused on Logistics Support Requirements for Future Army Combat Systems; Page 68 (1999)

    "The Russians have developed this technology to the point of demonstrating large WIG aircraft, notably the Caspian Sea Monster, which has a maximum takeoff weight of 540 metric tons. This large aircraft has flown at 650 km/h (350 knots) just ..."

  3. ^ Liang Yun, Alan Bliault; High Performance Marine Vessels; Page 89 (2012)

    "NATO called this flying object the “Caspian Sea Monster”. Analysis suggested the craft was actually double the size of a Boeing 747, weighing about 500 t, so that it could possibly accommodate about 900 marine troops (Fig. 3.1)."

  4. ^ Anne H. Cahn; Killing Détente: The Right Attacks the CIA; Page 65 (1998)

    "It depicted "the Great Caspian Sea Monster," purporting to be the largest aircraft in the world, weighing five hundred tons. Like the hovercraft, the ship was to ride on an air cushion at speeds up to 350 miles per hour. Flying only twenty-five to ..."

  5. ^ National Research Council; Reducing the Logistics Burden for the Army After Next Committee to Perform a Technology Assessment Focused on Logistics Support Requirements for Future Army Combat Systems; Page 68 (1999)

    "This large aircraft has flown at 650 km/h (350 knots) ..."

  6. ^ "Caspian Sea Monster". Archived from the original on 16 January 2014. Retrieved 16 January 2014.
  7. ^ The Register; In search of the Caspian Sea Monster; Lester Haines; 22 September 2006
  8. ^ Gunston, Bill (1995). The Osprey Encyclopedia of Russian Aircraft 1875-1995. London: Osprey Aerospace. pp. 512–513. ISBN 978-1855324053.
  9. ^ Komissarov, Sergey (2002). Russia's Ekranoplans:The Caspian Sea Monster and other WiG Craft. Hinkley: Midland Publishing. ISBN 978-1857801460.
  10. ^ Monsters: Ekranoplans

External links[edit]