Ground effect vehicles

I'm sure all the nerds and geeks out there know what these are, but in case you're neither, here is a quick explanation: An ekranoplan is a wing-in-ground-effect vehicle that flies on a cushion of air created by its wings where as a hovercraft is a ground effect vehicle that hovers on a cushion of air contained underneath the vehicle, usually by means of a big bag, termed a skirt, or envolope.


The first Ground Effect Vehicle was probably the Versuchsgleitboot (see images above) designed by an Austrian called Dagobert Müller von Thomamühl, and built by the Imperial Austro Hungarian Navy in 1915. It was 13 metres long, displaced 6½ tons and had 5 aero engines. Four to push it forwards and one to blow warm air under the hull. It was designed to be a fast torpedo attack boat specialising in anti submarine operations whose reduced water resistance gave it a top speed of over 32 knots. Unlike later hovercraft designs with their inflatable envolopes, the Versuchsgleitboot had rigid sides which meant it was a sort of half way design between the Hovercraft and Ram Wing Vehicles.

The Hovercraft

In 1931, a Finnish aero engineer named Toivo J. Kaario began to experiment with air cushion vehicles that operated by means of air trapped below the vehicle in an inflatable envolope. (technically the air cushion is not a bag as it is open underneath). Kaario's designs were true Ground Effect Vehicles, but as is often the case in Scandinavia, there was no funding available and nothing more came of Kaario's work. It took no lesser a person than Konstantin Tsiolkovsky to actually describe what was going on which he did in a book entitled Air Resistance and the Express Train. (If your not aware of Tsiolkovsky then look him up, the guy was a visionary genius!).

A Soviet engineer named Vladimir Levkov then took up the air cushion concept and over the course of the 1930's built numerous prototypes, all naturally geared towards military applications. Levkov's supporters like to claim he is the inventor of the hovercraft but even if we suppose that Müller von Thomamühl and Kaario had not already built working air-cushion designs, there is no way to argue that Levkov was unaware of Tsiolkovsky's book which was published in 1927 and readily available to Levkov.


Regardless of Levkov's status in the pantheon of invention, his pioneering credentials remain intact. One of Levkov's air-cushion designs designated the L-5 fast attack boat (see image above), achieved a speed of 70 knots. Alas for Levkov, the reality of the Second World War meant his designs were set aside for more practical military hardware and his research was shelved.


In 1953 a British engineer named Christopher Cockerall began to build air cushion prototypes using balsa wood, vacum cleaners and hair dryers. Cockerall eventually sold many of his personal possessions in order to finance his designs, and in 1959 his efforts paid off when he launched his SRN1 prototype (See image above). Capable of carrying four men it crossed the English channel to wide spread public enthusiasm. The golden age of British hovercraft was born. Cockerall's design, heralded as the first hovercraft by its British supporters, used a new method of injecting air into an inflatable envolope (this is the most common type of hovercraft today) which gave the vehicle a true All Terrain capability.

And it has to be added, there is no vehicle that can operate on all terrains better than the hovercraft.



Several variants of Cockerall's design were built, including the famous SRN5 'Mountbatten' class (see image above), and the Vickers Armstrong VA-3. I'm not sure which type they were but I regularly saw two or three commercial hovercraft in my childhood, on the beach in Southport (Merseyside, UK) from where they ferried people to Ireland and the Isle of Man. These black, red and white monstrous vehicles were truly amazing to behold, most especially when they were on the move. (Watch the video below to get an idea of what I mean). Their bags would be inflated and bulging out and their props made a most astounding noise. A friend who once travelled aboard one to France described the journey as 'very bouncy and very noisy', and told how drinking from a cup of coffee was practically impossible due to the intense vibrations.

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Noisy bugger!
Note how the rotors turn to steer the hovercraft

The SRN4 was built by BHC who also built two military versions of the Cockerall design, the SRN5 & 6. These saw action in Vietnam under the USN designation of PACV (Patrol Air Cushion Vehicle).

Today there are numerous countries still operating hovercraft, both militarily and commercially. Naturally the Russians have built the worlds largest Ground Effect Vehicle, the Zubr class amphibian assault craft which is a hybrid of the Cockerall and Levkov designs. Zubr's can carry up to 140 soldiers or three main battle tanks.

Ram Wing Vehicles and the Ekranoplan

The first Ram Wing, or Wing-in-Ground-Effect Vehicles were apparently designed in Scandinavia during the late 1930's. Not much is written about these and I haven't been able to find anything about their technical ability or even who made them, they could have been Kaario or they could have been some one else. My search for further information on early Scandinavian Ram Wing vehicles has proven fruitless. At the time they were almost certainly experimental, and the developers appear to have discarded their research for unknown reasons.

Not to scale, A is far bigger than B & C

After the war the German designer Alexander Lippisch and the Soviet designer Rostislav Alexeiev both took up the idea of Wing-in-Ground-Effect Vehicles, independently of each other. Lippisch built various designs centred around the concept of the high pressure Ram Wing (B), usually with endplates fitted to the wings in order to enhance ground effect. A Ram Wing is a wing designed to push through the air in such a way as to create a high pressure cushion of air beneath the vehicle. Once the vehicle is moving at speed, it rests upon this 'air cushion'.

As wings also give lift, Ram Wing Vehicles only have small stubby wings to prevent them from taking off. A tail plane is also essential to provide stability but unlike a conventional aircraft the tail plane on a Ram Wing Vehicle has to be an integral part of the original design as the size and shape of the tail will determine whether or not the Ram Wing Vehicle functions. If the tail is the wrong shape then the whole design fails.
Propulsion is provided by aero engines, either pushing or pulling in the same manner as with an aircraft.

X-114

To say Alexander Lippisch was big on wings is something of an understatement. In his time he built flying wing gliders, worked for Zeppelin and designed the world's first operational rocket fighter, the infamous Me-163. When Lippisch turned his attention to the Ram Wing concept he developed the reverse delta wing design (as seen on the x-114 above) which provides a great deal of stability due to the tapering rear wing edges. One of the advantages of the reverse delta wing design is it allows for a smaller tail plane, though as you can see, its still quite a big tail.

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Rostislav Alexeiev's Ekranoplan designs (A) also have Ram Wings to create a high pressure air cushion but they differ in that they have their engines mounted to the front of the wings and angled to provide additional airflow towards the Ram Wings. This makes them stronger and faster, and subsequently the Soviet Union built some of the largest ground effect vehicles (see videos above). Alexeiev employed more conventional square shaped wings, so his ekranoplans have enormous tail planes.

The Soviets really went to town with Ekranoplan development. During the cold war they were flying these secretive vehicles back and forth on the Black Sea and the CIA would get glimpses of them and wonder what the hell they were. Naturally they were developed as military transport, or high speed missile battery's, but despite being largely successful in creating these vehicles, the Soviets never really managed to field them with any great degree of success. Dimitriy Ustinov supported the concept as Minister for Defence of the USSR but economics had the final say. 120 Ekranoplans were originally planned for, but in reality only 3 A-90's and 1 LUN class were built.

The LUN class Ekronplan (see image above) is worth its own paragraph. This was a truly monstrous vehicle with an overall length of 74 metres making it one of the largest aircraft ever built. It had eight Kuznetsov turbojet engines and the sole example built was equipped for anti submarine warfare with six fixed-elevation SS-N-22 Sunburn anti-ship missile launchers.

One final German designed Ram Wing Vehicle remains, the Jorg IV 'Skimmerfoil' (C) has two sets of Ram Wings (fore and aft) and does away with the tail plane. This is known as a tandem design and gives good stability with a strong ground effect.

There are many types of Ram Wing aircraft built today, but they remain small in scale and confined to the entertainment or private sectors.

Boeing has some plans to build a giant Ram Wing vehicle, known as the Pelican, but as yet this monster aircraft (twice the size of an Antonov-224) remains a concept. Not to be outdone, Russia has its own conceptual super lifter ground effect lifter, the Beriev Be-2500. Naturally the Russian design is twice the size of the American.


edited to add:

Heres serendipty in action!

James May looks at a modern Russian Ekranoplan

BBC article on fifty years of the Hovercraft
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