This unusual craft was a secret Russian project built by Central Hydrofoil Design Bureau, led by Rostislav Alexeyev, a pioneer in hydrofoil and hovercraft design. It was nicknamed "Korabl´ Maket", Russian for "Ship Model", to satisfy the curiosity of those who saw it roaring across the Caspian Sea from 1964 to 1978, and explained away as a testing platform for new jet-engines for high-speed ships. When it was discovered on the Caspian Sea by a worried American spy-sattelite, it was in turn nicknamed "Caspian Sea Monster".
In reality it was a gargantuan ground-effect vehicle, an ekranoplan (Russian word meaning "screen glider". It weighed almost 500 tons, more than any aircraft of that time, capable of cruising at over 270 Kts at upto 60 feet above the sea´s surface... well under radar detection height. Furthermore, its sea-worthiness has so far been unequalled, as no other ekranoplan has been able to cope with wave heights of 3.5 metres.
Ample technical and historical information is available on the Internet, to be found by entering "Ekranoplan", "Caspian Sea Monster", "Ground Effect", "Korabl´Maket", "The WIG Page", into a search engine.
Ekranoplans create a cushion of air below them as they move along. This is known "WIG" - Wing In Groud effect, whici is also noticeable on all aircraft just as they are about to touch down.
The accummulated air below the aircraft has more difficulty in being pushed away, creating an extra lift, which gets stronger as the aircraft nears the ground. The drag, however, does not increase, and pilots have to throttle back considerably to overcome this effect before touchdown, especially on low-wing aircraft.
Ekranoplan wings have an aspect ratio of 1 or 2, being shorter and wider than a normal aircraft wings. Further development has provided some ekranoplans with wings that enable flight above ground-effect as well.
The KM had 10x98 kN (10x21,952 ft/lbs thrust) turbojet engines: 2 cruise-engines mounted on the sides of the tail-fin, and 8 lift-off engines on stub-wings behind the cabin in the nose. The latter considerably reduced take-off time by deflecting airflow downward, under the wings, thus increasing lift at low speeds.
Once cruising speed was reached, the 8 forward engines were either left to idle or shut down completely, and the craft continued flying at about 30 ft, on its 2 rear cruising-engines only, in "economy-mode cruise".
The reasons for an ekranoplan´s existence are its low operating cost, high payload and high speed. It is faster than a ship, train, hydrofoil or hovercraft. It is cheaper to build and operate than an aeroplane, can carry larger loads and has a greater range.
Normal aircraft need a minimum of 60% power to maintain level flight, whereas only 40% is necessary in ground-effect (taker-off power being 100%).
The most effective height for ground-effect flying is about half the length of wing-chord. For the KM this was about 36 ft.
FS2002´s handling of power, lift and drag parameters in ground effect, allow a very realistic emmulation the KM´s behaviour. Even the "Econocruise" speed of 217 Kts at 36 ft on only the two aft engines could be adjusted to the closest approximation of 55% of full power, which is not bad at all!
There seems to be some confusion with respect to the KM´s different speeds. "Econocruise" speed on two engines is quoted at 214, 217 or 243 Knots, at heights of 10 or 30 ft, depending on the source. Some sources also quote maximum speed at 270 Kts, whereas others quote 270 Kts for high-speed cruise, and yet others, quote a cruising speed of above 270 Kts at 50 ft, adding that even 297 Kts and 60 ft could be reached. These speeds obviously involved all engines.
The following specifications have been taken for the virtual model:
Top speed : 297 Kts. (N1=100% on all engines)
High-speed Cruise: 274 Kts. (N1= 85% on all engines)
Econocruise : 217 Kts. (N1= 85% aft engines, fore engines idling)
Lift-off and touch-down: Around 95 Kts without flaps, 60 Kts with.
The KM is a very unusual craft, and I hope you will enjoy using it.
Stephan Scholz. August 2003.
scholzrittermann@SoftHome.net
