HISTORICAL BACKGROUND
The term Ekranoplan literally means screen plan
in Russian. The term is a descriptive one regarding the effect that a
screen in close proximity to the earth's surface generates a higher
pressure
underneath it than the surrounding atmosphere. The English term for
machines
which operate under this effect is the Wing-in-Ground Effect (WIG)
craft
or wingship. The basic physics behind the principle is that the closer
a winged craft flies to the surface of a body of water, the less air
resistance
it encounters. Thus, a large, heavy craft could achieve a speed of
several
hundred knots with much less power than either a ship or an aircraft.
The Russians began their pioneering efforts in WIGs in the early 1960s.
The U.S. and Germany have also experimented with small-scale craft.
Ekranoplans Produced by the Central Hydrofoil Design Bureau:
- SM-1: A three-seat full scale testbed powered by a single
turbojet mounted above the fuselage.
- SM-2: A three-seat experimental craft with a ship-like
bow and an internal turbojet. Intake for the turbojet was
dorsal-mounted
ahead of the tailplane.
- SM-2P7: This craft was designed to explore the possibility
of using jet vectoring to assist in lift. The SM-2P7 was a single-seat
machine with a nose intake for the turbojet.
- SM-3: The SM-3 was designed with a large-chord wing and a
ski-shaped nose.
- SM-4: Two-seat ekranoplan with multiple air inlets and
a small dorsal rudder on the nose.
- SM-5: A step forward in WIG design through the use of
turbojet powered lift and vectored nozzles directing airflow under the
wings. The craft was fitted with a spray shield ahead of the main
dorsal turbojet intake.
- SM-8: A large WIG with four jet nozzles mounted on each
side of the fuselage just aft of the cockpit fed by air from a
chimney-like inlet on the top of the fuselage. The cruising engine was
mounted just ahead
of the dihedral tailplane.
- KM: This craft was known in the West as the Kaspian
Monster. The KM weighted almost 500 tons making it practically a small
ship. It had eight starting turbojets mounted aft of the cockpit, four
on each side like the SM-8. There were two cruising jets on each side
of the tail.
Two of the machines were lost in crashes, one in 1969, and another in
1980. Dimensions: Wingspan 131ft; Length 348ft. Engines: 10 VD-7
turbojets.
Weight: 495 tons; Max load 540 tons. Performance: Max speed 311mph;
Range
1900 miles; Cruising speed 248 mph.
- Lun: The Lun or Spasatel was designed as a cruise missile
platform and, later, a search and rescue vessel (the Spasatel). The Lun
was powered by only the eight lift engines mounted similarly to the KM.
There was a control station mounted on the fin to oversee missile
launches or rescue operations. The craft carried six SS-N-22 Sunburn
missiles or could rescue up to 500 people. First flight occurred in
1987. Dimensions: Wingspan 144ft, 4in; Length 242ft; Engines: 8 NK-87
turbofans; Weight: 400 tons loaded; Performance: Max speed 342mph;
Cruising speed (with 3 rescue pods) 280 mph; Range 1900 miles; Cruise
height 13ft.
- A-90: The A-90 Orlyonok (Eaglet) was built with military
and commercial uses in mind. The craft was designed in 1979 as an
amphibious assault vehicle, having a pair of retractable frontwheels
and 10 main wheels in two rows along the fuselage. Lift is provided by
two turbofans with vectored thrust on the hull to the aft and down from
the flight deck. A turboprop engine mounted on the tailplane is the
source of cruising propulsion. The A-90 has a crew of 5. The cargo hold
is accessible through a ramp and hinged nose. The Russian navy received
approximately 30 machines. The SM-6 is
a scaled-down version with smaller engines. Dimensions: Wingspan 103ft,
4in.; Length 190ft, 3.5in; Wing area 3,279 sq.ft; Engines: Starting 2
NK-8-4K turbofans; Cruise NK-12MK turboprop; Weights: Empty 85 tons;
Loaded 125-140 tons; Performance: Cruising speed 217-249 mph; Range 684
miles (cargo), others 1900 miles.
Selected Bibliography
- Conway's All the World's Fighting Ships: 1947-1995.
Naval Institute Press: Annapolis, 1995. p. 414.
- Dane, Abe. "Wingships." Popular Mechanics, May 1992. p.
35.
- Gunston, Bill. The Osprey Encyclopedia of Russian Aircraft:
1875-1995. Osprey Books: London, 1995. p. 511-21.
- Jane's Fighting Ships: 1995-96.
Author's Note: If you are interested in Russian aircraft, I highly
recommend Gunston's book. It is the most comprehensive book I have ever
seen on the subject.
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