that teaches you to think like an engineer.

At the height of the Cold War, with nuclear anxiety at a fever pitch, the United States

launched their first spy satellites, the Corona. Tasked with photographing deep inside the

Soviet Union. US Intelligence was focused on searching for signs of nuclear weapon development

and testing, but found a lot more than they bargained for. These early satellites were

launched with rolls of film with no-way of transmitting the data contained within them

to earth through electronic means, and thus the films had to recovered and developed here

on earth. Once the film was filled the satellite would eject a re-entry vehicle, containing

the precious undeveloped photos, back to earth where they were caught by a passing plane

as they drifted down.

On one such mission a strange object began to emerge from the Caspian Sea as the film

developed. A gigantic aircraft, nearly 100 metres long with short stubby wings, much

too short to fly like a conventional aircraft. US Intelligence had never seen anything like

it.

As they received more pictures, it was clear that the craft was moving at the same speed

as a traditional aircraft, while outsizing even the largest of modern day American military

planes like the Lockheed C-5M. It was even emblazoned with the flag of the Soviet Navy,

not the Soviet Air Force.

This discovery set alarm bells off within US intelligence. Had the Soviets developed

a breakthrough in propulsion which would give them the upper hand in naval combat?

Confused on what they were seeing the US dubbed the machine the “Caspian Sea Monster”,

but the Soviets weren't developing a gigantic hydrofoil or seaplane. This giant aircraft

secretly being developed was actually an 'ekranoplan', a gigantic vessel capable of skimming across

the ocean's surface at high speeds.

In 1962, the Central Hydrofoil Design Bureau assigned chief designer Rostislav Alexeyev

to begin working on a prototype plane. Alexeyv had cut his teeth developing hydrofoil planes,

like the Raketa. These craft could easily be defined as a boat. They used a hydrofoil,

essentially a wing designed to act in water, to lift the boats hull out of the water as

it gained speed, allowing it to reduce drag and increase top speeds, but the Soviets wanted

to take it a step further. The Ekranoplan would make use of something called “ground

effect” to fly at a very low altitude above the ocean's surface.

Ground effect occurs when a fixed winged aircraft flies at an altitude less than the length

of it's wingspan. As the large masses of air come into contact with the aircraft, the

profile of the wing deflects the air downwards, compressing the air between the wing and the

ground. This trapped air causes an area of higher than normal pressure underneath the

wing resulting in a boost to lift. This happens with all aircraft during take off and landing,

and is something all pilots have to learn to deal with. For example, some planes can

get off the ground when overloaded, but won't be able to climb past the altitude where ground

effect is in play. Ekranoplans are designed in such a way to maximise this effect, and

never leave the ground effect zone. Just as our plane can get off the ground when overloaded,

the Ekranoplan can be heavier without the need for extra power.

An aircraft with this ability would be a powerful tool in open-sea combat. It would fly under

enemy radar for much longer [1], due to radar shadow under the earth's curvature.

It would be capable of transporting tonnes of equipment and personnel quickly, while

avoiding enemy mines and torpedoes, or it could be fitted with weapons of its own to

quickly attack enemy ships before escaping. Imagine if a vehicle like this was available

for the D-Day landings, the largest amphibious assault in history. The allies would have

been able to transport tonnes of equipment and troops across the channel in a 15 minute

trip.

The appeal of the technology was enormous, and the first prototype named the 'KM'

was built and secretly transported to the Caspian Sea to begin testing[2].

This enormous vehicle instantly became the largest aircraft ever built with a wingspan

of 37.6 metres and a length of 92 metres. It weighed a massive 240 tonnes but it could

take-off with almost double that. Powered by eight Dobrynin VD-7 turbojets mounted at

the front and two on the tail which provided a total of 1,275 kilonewtons of thrust, about

30% more than a Boeing 747.[3].

The first test flight of the KM took place on the 16th October 1966 with Chief Designer

Alexeyv on board. At the time, it was forbidden for Soviet aircraft designers to be on board

test vehicles like this, in case they were involved in an accident[4]. But Test Pilot

Vladimir Loginov lobbied for Alexeyev to be on board to allow him to experience and refine

his designs.

The first tests were successful, showing that the KM could fly with optimum fuel efficiency

at 430km/h and with a maximum operational speed of 500km/h. During some high speed tests,

it's claimed that it achieved a speed of 650 km/h. [13]

The KM was a valuable proof of concept and laid the groundwork for all future Ekranoplans.

Alexeyv took the les sons learned and began to develop a new transport version design

specifically for the transport of military equipment and troops, called the Orlyonok.

This was a much smaller variant, 58 metres long with a 31.5 metre wingspan, and a maximum

takeoff weight of 140 metric tonnes. It's engine layout was fascinating, with a massive

NK-12 turboprop engines mounted on the tail as far away from the salt water as possible.

These massive 6 metre diameter counter rotating turbo-propellers developed 11 thousand kiloWatts

of power, making it the most powerful turboprop engine to ever enter service. [10]

It also featured two nose mounted turbofan engines with air intakes on top of the nose

to minimise water intake. The exhaust of these engines were pointed under the wings to enhance

the ground-effect phenomenon by bolstering the air cushion with the high pressure output

of the jet engine. These engines were only needed on take-off before the plane could

gain the speed needed to develop enough lift through the wing in ground effect. Once this

was achieved they were shut down to decrease fuel consumption.

The Orlinok featured a nose mounted cargo-door and wheels to allow the plane to drive onto

land and unload. This was a fully functional Ekranoplan and actually entered and remained

in service until 1993, although only 4 were ever built. [11]

Details from here vary, and I found it difficult to find any authoritative source of information

on what happened to Alexeyev after the development of the Orlinok was complete. Some say he crashed

in the KM, others in the Orlinok, and others say he crashed in a Volga 2, a small passenger

transport Ekranoplan, but they all seem to point towards Alexeyev being fired as chief

designer as a result and dying a short time later. Whether that was from injuries from

the crash or natural causes I have no idea.

With Alexeyev out of the picture and the Soviet Union on the brink of collapse, development

of Ekranoplans in the Soviet Union slowly began to fissile out.

They managed to develop a slightly smaller version of the KM, designed to launch anti-ship

missiles while out at sea. In 1987, the first version of this vehicle was built and named

'Lun'. This vehicle weighed 286 tonnes, had a length of 74m and wingspan of 44m. The

tail mounted engines were removed completely. It was instead powered by eight NK-87 turbofans

mounted at the front of the craft, each producing 127 kilonewtons of thrust[6].

The Lun entered the Soviet Navy in 1987[7].However, with the collapse of the Soviet Union in 1991,

only one model was ever completed and it remains in its dry dock on the shores of Caspian Sea

to this day.

The idea of a wing in ground effect plane has its merits, but it simply never found

its niche in any military.

The Germans made a much smaller ekranoplan in the 70's called the X-114, but it never

made it into service[8]. The Chinese also experimented with an ekranoplan called the

XTW-4 which was built in 1999 and went through multiple tests a year later[1]. The vehicle

was once spotted in a Chinese shipping port on Google Maps but has since vanished.

While in 2002, Boeing presented their plans to build the largest ekranoplan ever, dubbed

the Pelican. They claimed the craft would be longer than a football field and capable

of hauling 17 M1 Abram tanks across an ocean. But the US congress rejected the plans in

2005. There just wasn't a need for such a plane. [9]

Wing in ground effect planes may yet find their niche, but for now safety and reliability

concerns are it's primary road block. Flying at such a low altitude provides very little

time for corrective maneuvers, and poor weather with high waves or wind prevents any ekranoplan

from operating.

Some have sought to develop smaller passenger versions, like the A-050 which the Russian

embassy of South Africa, your definitive Russian news source, claimed it would be ready for

service in the next 3 years. [12]

Vehicles like this could find a valuable niche in archipelago regions, like South East Asia,

where increasing wealth and populations combined with relatively short distances between islands

could provide a market for these temperamental craft.

However traditional planes will always remain a much more efficient and reliable form of

transport over long distances, as flying in the lower density air of the upper atmosphere

drastically decreases drag. So these passenger versions would have to operate extremely short

haul distances where airliners waste time during climbing and ascent.

This technology is perfectly viable for the right application, and we may yet see someone

solve the problem and build a successful business from it. That could be you, but you will first

have to learn how to solve problems. A good place to start is through Brilliants daily

challenges. Each day Brilliant presents with you with interesting scientific and mathematical

problems to test your brain

Each Daily challenge provides you with the context and framework that you need to tackle

it, so that you learn the concepts by applying them. If you like the problem and want to

learn more, there's a course quiz that explores the same concept in greater detail. If you

are confused and need more guidance, there's a community of thousands of learners discussing

the problems and writing solutions. Daily challenges are thought provoking challenges

that will lead you from curiosity to mastery one day at a time.

If I have inspired you and you want to educate yourself, then go to brilliant.org/RealEngineering

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