Is It A Boat, is It A Plane? No, It’s The Ekranoplan?

Even though the International Maritime Organization classifies it as a ship, why isn’t the ekranoplan currently competing with conventional passenger and cargo aircraft? 

By: Ringo Bones 

Even though it has since been classified as a “ship / boat” by the International Maritime Organization after the first working examples were in limited manufacture as exotic pleasure craft by enterprising Russian émigrés in the United States during the early 1990s, for those old enough to have heard of the news of the Soviet Union’s latest secret weapon called the “Caspian Sea Monster” first hand back in 1974 when the Cold War was in full steam. You would probably call it a plane, too. But first, here’s an introduction to what is a so-called ekranoplan. 

The ekranoplan falls under the category of ground effect vehicles, or GEVs, which is defined as a vehicle that attains level flight near the surface of the earth or a reasonably sized body of water. It is also called wing-in-ground effect (WIG) vehicle or flare craft. The first vehicle to ever “fly” via the ground effect principle – albeit by design accident - was the German 12-engine Dornier Do-X of 1929 which have taken advantage of ground effect to get aloft. Similar craft, as in those early large passenger carrying seaplanes by pioneering commercial airliners around that time took advantage of the ground effect phenomena, but in most cases rather unintentionally because the effect was little understood by aerodynamicists back then. 

Back in January 1974, the public-at-large probably got their first exposure of a true purpose-built ekranoplan when Western intelligence sources who first reported the rather strange creation at the time called it the “Caspian Sea Monster”, which, many in the West believes, is a fitting name. The 10-engine flying boat that the then Soviet Union was testing over the Caspian Sea was deemed the largest aircraft of the time – with an estimated takeoff weight of 500-tons. By way of comparison, the largest adjudicated aircraft of the time, the United States’ C-5 Galaxy only has a maximum takeoff weight of 400-tons. The “Caspian Sea Monster” was, at the time, probably the most unusual flying vehicle because it operates by a deliberate combination of aerodynamic lift and “ground effect” – the air cushion phenomenon that lifts a Hovercraft. 

After the fall of the Soviet Union back in Christmas Day of 1991, the “full specifications” of the “Caspian Sea Monster” and the craft itself became finally available to Western analysts. During Soviet times, such craft were called “ekranoplans” and the Caspian Sea Monster, officially called KM or "Kaspian Monster"  by the then Soviet navy, even though it was only a proof of concept prototype and never intended to become an operational submarine hunting craft and troop carrying craft of the then Soviet navy was “mothballed” way before the collapse of the Soviet Union. The Caspian Sea Monster has a “takeoff” weight (or was it “hover” weight?) of 500-tons and as a “water craft” has an 8-ton displacement. It has a length of 100 meters and weighs 540 tons fully loaded. 

Its design was based on the work of the Third-Reich era aerodynamicist named Alexander Lippisch, the Caspian Sea Monster was originally designed by the Soviet era Central Hydrofoil Bureau during the late 1960s and was lead by Rostislav Alexeev. During Soviet era research trials, the craft was found to be most efficient when “flying” 20-meters above the water while traveling at speeds of 300 to 400 knots. The KM / Caspian Sea Monster can even operate without refueling for as long as two to three days over ranges as great as 7,000 miles. The craft has a 15 to 20 man crew just to operate safely at such speeds and altitudes and was planned to be produced in submarine hunting and ultra-swift troop carrying versions before it was mothballed around the mid 1980s. 

By the nature of the beast, an ekranoplan type ground effect craft has a fuel efficiency rating way better than that of a fixed-wing aircraft and / or helicopter flying at low level due to the close proximity to the ground or water surface dramatically reducing lift-induced drag. In practice, ekranoplans only require half or even a quarter of the power than that of a conventional fixed-wing aircraft and / or helicopter requires in getting off the ground or off the water’s surface. 

There are also safety benefits in flying close to the water’s surface as an engine failure will not result in severe ditching. However, by the nature of the beast, ekranoplans are difficult to fly even with computer assisted fly-by-wire control systems used on the F-16 Fighting Falcon and the now retired F-117 Nighthawk stealth (hence the 15 to 20 man crew of the original KM or Caspian Sea Monster) aircraft because flying at such very low altitudes just above the sea or any large body of water may be dangerous if the craft banks too far to one side while making a very tight radius turn.  

Another disadvantage of ekranoplans is that takeoffs must be performed into the wind which in the case of the craft taking off over water means “slamming” into waves while taking off – a maneuver that creates drag and reduces lift. This is the very reason why even though those 1990s era single-engine ekranoplans featured in the Discovery Channel back in 1992 to 1998, that were similarly priced to a typical single-engine Cessna at the time had very few private buyers to keep their manufacturers afloat. I mean have you ever seen hip-billionaires like Richard Branson and Mark Cuban showing off their very own single-engine ekranoplans then and now? 

Two main solutions of the ekranoplan takeoff problem have been implemented since its prototype design stage. The first was used on the original prototype of the KM or Caspian Sea Monster which placed engines in front of the wings to provide more lift. The Caspian Sea Monster has eight of its jet engines mounted on the “canard” of the plane. Some of which were not fired until the craft was fully airborne. The second approach was to use some form of an air-cushion to raise the vehicle most of the way out of the water, making takeoff much easier. This was used in the by German Hanno Fischer in the Hoverwing – successor of the Airfisch ground effect craft – which uses some of the air from the engines to inflate a skirt under the craft in a form of a sidewall or skirted hovercraft. 

The only ekranoplan that attained operational status in the Soviet armed forces was the A-90 Orlyonok, which is a “scaled-down” multi-engine propeller version of the Caspian Sea Monster and was used by the Soviet navy during the 1980s as a submarine hunting craft. Even though they are quite rare, there are post Soviet era commercial passenger ekranoplans still operating in the Caspian Sea region modeled after the A-90 Orlyonok.