YouTube - Caspian Sea Monster
10 x 35,000 lbs. ea.
348 ft. 11 in.
141 ft. 3 in.
210 mph (est.)
The Caspian Sea Monster, officially the Soviet Korabi Maket ekranoplan, was the world's largest and heaviest airplane-like vehicle to be operated in ground effect.
The term Caspian Sea Monster came about when U.S. satellites first spotted the large vehicle with stubby wings skimming over the waters of the Caspian Sea. Initially they thought it to be a prototype flying boat.
Ground effect is the reduced drag on a vehicle due to the interruption, by the surface, of air flowing from under its wings tips, around them, to their tops. When not interrupted, the air flowing to the top of the wings forms a high pressure area over the wings, pushing the vehicle downward.
Today's aircraft use specially shaped wings and winglets on their tips to reduce the air flow. Prior to the discovery of the effects of specialized wing shapes and winglets, during the era of the Caspian Sea Monster, aircraft had to use more power to continue to fly at a given speed and not lose altitude when not in ground effect.
Ground effect vehicles, such as the Caspian Sea Monster, are more like hydrofoils, and unlike hovercraft. Hovercraft must use the thrust of their engines pointed downward to lift them from the surface, in addition to horizontal thrust for forward motion. The engines of the Caspian Sea Monster propelled it forward to provide horizontal thrust only.
Caspian Sea Monster
You can get an idea of the size of the Caspian Sea Monster and its engines by the above picture. The size of the vehicle makes the people walking on it seem very small.
By running at up to 66 feet above the surface, the Caspian Sea Monster was able to propel its huge mass at speeds up to 460 mph.
The Caspian Sea Monster needed to build up sufficient speed to get into ground effect. This could be complicated by rough seas. Not getting the vehicle into the air quickly enough could result in its nose being buried in a wave. Maneuvering the huge vehicle was about what you would expect. Responses to control inputs took a while, and were more like steering an ocean liner than an airplane.
Reducing the speed of the Caspian Sea monster so that it would stop flying was like putting down very effective flaps on an aircraft. The drag of the water on the hull of the vehicle caused it to slow quickly.
The ten turbojet engines of the Caspian Sea Monster used large quantities of fuel to fly the aircraft at cruising speed.
The Soviets used Caspian Sea Monster vehicles on the Caspian and Black Seas to transport troops, their vehicles, supplies, and heavy equipment. One Ekranoplan was built as a guided missile platform, able to launch cruise missiles against enemy shipping.
It is believed that a total of eight Caspian Sea Monster type vehicles were produced by the Soviet Union in various lengths, wingspans, and power arrangements. They were operated from about 1966 through the late 1980's.