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WIG / EKRANOPLAN RESEARCH PROJECTS

Graham Taylor

is

"The Ekranoplan Man"

 

MEANING OF EKRANOPLAN
Ekranoplan is a Russian term that comes from the Russian word for ‘screen’ although the exact derivation gets lost in the translation.  The important thing about the term ‘Ekranoplan’ is that it is unique to the class of vehicle that is designed to fly very close to a surface (water or ground), "in Ground Effect" and that in so doing these vehicles benefit from the peculiarities of aerodynamics in that region.  There are several other terms commonly used for the same type of vehicle as explained below, but I like Ekranoplan best both because it is exclusive (and easy to find on the internet), and because I feel the Russians earned the right to have it used as the generic term when they built the worlds biggest and fastest: the 540 tonne, 500 km/h Caspian Sea Monster.
 
The 'Ground Effect' Theory
Ekranoplan vehicles benefit from the peculiarities of aerodynamics close to a surface.  The proximity of the surface both ‘compresses’ the air under the wing, giving it more lift, and reduces the drag from the wing, making it more efficient.  This effect increases as the surface gets closer and so is the basis for self-stabilisation in ‘ground effect’.  There is a relationship between strength of this effect and the wing span and wing cord.  From a theoretical perspective the effect is equivalent to adding wingspan under conventional aerodynamics.  Hence the ekranoplan requires smaller wings than a conventional aircraft.
 
Such vehicles can be thought of as a cross between an aircraft and a hovercraft, but unlike the hovercraft which drags its air cushion with it, the ekranoplan generates its ‘cushion’ as it passes.
Unfortunately there is little simple, off-the-shelf aerodynamic theory at present (although there is a lot of complex theory!).   Successful development requires a balance of forces often only achievable through experimentation.

 
The Advantages and Disadvantages of Ekranoplan/WIG
In concept, such craft offer a potential form of transport which is faster than boats and slower than aircraft.  They also offer greater fuel economy and the potential to carry heavier loads than aircraft.  The main issues to be resolved are seaworthiness and safe operation.

 
Other Terms
 ‘Ekranoplan’ is both a generic term for the general class of vehicles, a more specific term for the stubby aeroplane wing configuration used by the Russians in their research programme dating back to the 1960’s.   Other terms used for the same sort of craft include; Wing-in-ground effect (WIG), Wing-in-surface effect (WISE), dynamic air cushion (DAC), Flairboats, Wingships, Ground-effect machines (GEM) and others, with each research team tending to invent a new one.

 
Variety
WIGs & Ekranoplans come in all shapes and sizes.  The reason for the variation is the different approaches used to resolve the main design considerations, that of stability, ride height, manoeuvrability and lift-off.   The dominant configurations are illustrated on this page.   Some types are amphibious, others are clearly more like aircraft than boats.  Indeed the Korean example is able to fly well out of ground effect and so is classified as an aircraft, not a boat. 
 

MY MODELS

My interest in ground effect and Ekranoplans began over 30 years ago, my first model being of Lippisch configuration and inspired by the work of Mr Hanno Fischer in Germany and his work at RFB and with Dr Lippisch as revealed in some of the early editions of Jane's Surface Skimmers.   At this time I could only dream that one day it would be my pleasure to work closely with him to help him see his dream come to reality.

The MK1 (left) is a simple reverse-delta model for trials over flat land; playing fields, car parks etc.   One interesting feature is that it uses ducted airflow from the propeller to help create a primitive static air cushion under the model which helps reduce drag for takeoff (called in the trade 'power assisted ram', or 'PAR').  This is very effective since the model begins to on the ground as soon as the engine is running.  This photo is of the original layout with a Cox .049 glowplug engine for propulsion. Later the model was modified to accept a small twin-cylinder engine that had the benefit of a radio controlled throttle, and was further modified to a twin-boom tail arrangement.  To be honest, the original .049 engine layout was most fun, although fairly uncontrollable, particularly as it had a tendency to chase joggers in the park with complete indifference to radio control commands.   This model was discussed in 'Wise up to a WIG' Marine Modelling Monthly June 1995 pages 22 - 25 and in 'Ship & Boat International' pages 49 - 53, October 1995 (Published by RINA).  I had many ideas for follow-on models of this configuration but never got around to building them.

For more pictures of the MK1 click here.      

Some years later, after my experiments with hydrofoil models, after the fall of the Iron Curtain some information on the soviet Ekranoplan program began to leak out.  This inspired me to build a second model; MK2 (below).   The other enabling factor was the improvements in electric flight technology which meant experimentation no longer had to contend with the vagaries of temperamental glowplug engines and the destructive nature of glow fuel.  The MK2 uses two tilting electric ducted fans for propulsion and to blow air under the main wing for takeoff assistance: 'PAR'.

The MK2 was deliberately quite a large model, and closer to the Russian/Soviet ekranoplan configuration.  One of the design objectives was to make it appear less like an aircraft and more like a fast ship or hovercraft.  I sought a clear statement "This is a marine vehicle".   I figured that market resistance in the full size arena would to have a lot to do with whether passengers and operators perceived the craft to be a boat of aircraft; the closer to boat the less industry resistance.    Indeed, I'd go so far as to say the quest for commercially successful WIG design is about stripping the aeroplane out of the boat, in the same way that hovercraft were handicapped by first being considered as aircraft. 

Another primary feature of the MK2 design was the interchangeable main parts.  As I figured it unlikely to get the design right first time, so needing a lot of trial and error all the main parts were made removable for easy substitution.  Thus the main wing, sponsons and tail assembly are separate component and can be set to different angles of attack as necessary or replaced by alternative designs.  The centre of gravity can be varied over a wide range by moving the batteries around in the hull.  Click here for more pictures.

Many trials of the MK2 took place, mostly under PAR, but in spite of the the inherent adaptability of the MK2 it soon became apparent that I was barking up the wrong tree and than no amount of substitutions of parts would get it to work properly, for the time being. The main issue was the refusal to accelerate to a speed at which ground effect took over from PAR so that the PAR fans could be rotated from their PAR position to horizontal thrust position. I put this down to drag of the main wing and the fact that when in PAR mode much of the forward thrust was lost in favour of upward thrust.    I needed a whole new approach.   This led to the MK3.

The MK3 is a longer model of KM like proportions in which the PAR fans are located further ahead of the main wing, which enables a lower PAR tilt angle so more of the PAR vector is forward thrust.   A thin flat plate section is used for the main wing.  Despite being pretty it turned out to be little more susuccessful than the MK2.   In PAR mode it was OK, but became unstable when trying to accelerate to ground effect speed.  Many modifications were tried; the PAR fans substituted for propellers, a third tail motor added etc. but still no real improvement.  MK3 still holds some promise and one day I will return to this model and do some modifications that will make it work.  

For more pictures of the MK3 click here.  Interestingly both the MK2 and MK3 suffered with the same embarrassing fault.  Both would dunk their motors at the end of a speed run.  This in spite of the voluminous bow of the MK2 and long stepped bow of the MK3.   So a MK4 design was made to address these problems.

MK4 (right) incorporated the lessons of the earlier models, and it was the first model to truly work.  It was designed to fly in 'extreme ground effect' (XGE) which means very close to the surface.  This model featured in 'EKRANOPLAN' Marine Modelling Monthly December 1997 pages 56 - 59, and also in Discovery TV 'Model Mania' program.   The emphasis in MK4 was on simplicity, aimed at something that absolutely will work.   MK4 makes use of very economic and reliable electric motors, the tail motor giving enough thrust to get the model  beyond PAR mode mode and into XGE.  Also a canard planing/aerofoil is fitted under the bow to assist takeoff and PAR/XGE transition and stop the motors from being dunked when decelerating.  More pictures of the MK4 can be found here.

The MK5 (left) is pretty much identical to the MK4 in overall form but has quite a different construction method (hence slightly different shape) and improves upon stability in many respects.  The designs of MK5 and MK6 form the 'WhizzyWig XGE' plans pack which may be purchased from me, should you wish to build one of these models - MK5 is the first WhizzyWig XGE.  More details on the WhizzyWig XGE plans pack can be found here WIG MK5\ekranoplan_mk5.htm.

MK6 is a build to the WhizzyWig XGE plans but has been modified to try out some experimental features, notably 'through-wing-flaps' which were intended to help turn the craft at high speed.  This works to some extent, but not as well as I anticipated.   More pictures of the MK6 can be found here.

My next experiment was with a 'Bixel double-wing' configuration.  The originator of this configuration, Mr Chuck Bixel, had been in touch with me about his design many years earlier but his work was not being taken seriously by others in the WIG community.  I had wanted to experiment with this for some time but other commitments got in the way. 

Eventually my 'Bixel Gem' was designed with the aim of exploring the basic 'double-wing' configuration and a range of scope of other lift off aids such as retractable air cushions and hydrofoils.   In its original guise (left) it featured an ACV type air cushion under the main hull with a retractable bow skirt.  This cushion was fed from a duct in the engine pylon that supported two electric motors mounted back-to-back so that their propellers contra-rotated; the layout being inspired a mix of Bixel and Fischer HoverWing. It was my first proper attempt at a skirted model and held a lot of promise.  Unfortunately insufficient cushion strength a whole raft of other issues prevented it from doing anything spectacular on water.  The model was then continuously and extensively modified, with weeks of deep thought going into each step, only to be disproved after moments on water.   More pictures of the Bixel GEM can be found here.  One day I might try this configuration again with a whole new model.

MK7 is a return to the WhizzyWig XGE, but built an entirely new, experimental construction method, and the intention to upgrade to latest electric propulsion technology of brushless motors.  

MK7 used the basic WhizzyWig XGE plans yet instead of the standard balsa build-up the entire hull is made from carved blue foam, then covered with PVA & paper.  This technique is often used for model aircraft, but I have never heard of it being used for a boat.  MK7 is slightly longer than WhizzyWig and has the canard wing fitted under the bow instead of through it.  XGE trials of MK7 are underway but have already lead to the cutting out and re-setting of the main wing incidence as somehow I managed to goof on the alignment of main wind and sponsons.  Subsequent trials show great promise and the model is currently awaiting new trials with her new brushless motor setup.   You have to admit, she does look pretty!  More pictures of the MK7 can be found here.

All above images of my models copyright of Graham Taylor. & may not be reproduced without my permission.

"WhizzyWig" gallery - other peoples models on a WhizzyWig theme #to follow#

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For further information on WIG/Ekranoplans

EKRANOPLAN - Further Discussion Material
 

I am often asked where further information on the technical design of WIG craft can be found. The following contain interesting discussion on the technology:

  • Ship & Boat International 1995. Issues: May, June, July/August, October. The Royal Institution of Naval Architects. Four part WIG series.
  • Proceedings of International Conference International Workshop (1998) ‘Ekranoplans & Very Fast Craft'  The Institute of Marine Engineers - The University of New South Wales, Australia.
  • Proceedings of International Conference on Wing-In Ground Effect Craft (1997) Royal Institution of Naval Architects, London, and China International Boat Show April 1998
  • Proceedings of International Conference  International Workshop (1998) ‘Wise up to Ekranoplan GEMs’  The Institute of Marine Engineers - The University of New South Wales, Australia.
  • Also, check out the papers that can be downloaded from the Hypercraft Associates website, my specialist Consultancy for commercialising the full-size craft. 
  • Some general advice for modellers: General Comments and Advice for Building WIG/Ekranoplan models

  • Join the Yahoo WIG Group.  This group is a mix of amateurs, professionals and learned people that discuss and keep abreast of development in Wing in Ground Effect technology around the world.
  • Author Bibliography: Professional and amateur papers published on Ekranoplan, WIG and high speed model and full size marine craft.
 

Some of My Models

Above: left to right: MK4, MK1, MK3, MK2.

Some types of Ekranoplan/WIG Vehicles

'Ekranoplan' stub-wings configuration:

 

The awesome Soviet/Russian KM "Caspian Sea Monster"

of 1970's, 550 tonnes 250km/h

The Soviet/|Russian A90 Orlyonok of 1980's

Korean WIG/Aircraft circa 2005

Russian Volga II river Ekranoplans circa 2005

Russian Aquaglide (Amphistar) circa 2008

 

WIG train concept from Japan circa 2000

Tandem Wing Configuration:

Jörg TAF tandem wing circa 1990

Focus 21 concept from France circa 2007

Lippisch Reverse Delta Configuration:

 

Fischer Flugmechanik Airfish 8 circa 2009 

 

Russian Ivolga using PAR, lippish main wing and high aspect-ratio winglets for free-flight capability circa 2009

 

'Bixel Double Wing' Confirmation:

Universal Hovercraft USA 2009 "HoverWing"

Rudy Heeman's "Hoverwing", New Zealand circa 2008

 

Photos of my experimental ekranoplan models

Some readers wonder why there are not more pictures of the models in action.  Because the models are experimental they are often tested when there is no one else about.  Its not that I'm hung up on secrecy, its because they can be a bit unpredictable, sometimes dangerous and even the source of ridicule!  Anyway, what I'm trying to say is that it is extremely difficult to operate a radio control set in one hand and a camera in the other.

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Above - No More Mr Nice Guy.  The 100 knot HoverWing 20 MIL. 

 

WIG/EKRANOPLAN VIDEO CLIPS

Three Passes (1,300 kb): The WhizzyWig prototype model makes three passes in XGE (eXtreme Ground Effect) mode.  Watch as the wake disappears and there is just a ripple from the wing tip vortices.  Classic extreme ground effect! 
Into the Bushes (778 kb): A really great run of the WhizzyWig prototype model in XGE, but see what happens when there is no drag and no brakes!  If you look closely you will see that the propellers stopped spinning well before the end of the run. 

Amphistar (1,296 kb)
An action clip of the full size Russian Amphistar ekranoplan by Dr Sinitsyns' team.  Check out the wing tip vortex trail on the water.  (I have Dr Sinitsyn and Mr Fischer to thank for their advice that enabled me to improve the running of the MK5)
The KM - Caspian Sea Monster
 
The KM - Caspian Sea Monster. This craft was built ‘flown’ in 1964, so you can see a bit of history in the making.  Very impressive.  1,47 KB
MK4 first test on water First tests of MK4 on water. 235 KB
MK5 trials on grass MK5 trials on grass.  Not bad for a boat!  851 KB
MK5 climbs grass bank MK5 climbs grass bank.  Quite a steep bank too. 714 KB
MK5 in France
(Temporarly removed)
MK5 demonstration at EAGES Ground effect Symposium France June 2001.  The model gets into ground effect just as it passes the camera - it is a little difficult to see but note look how the wake disappears.  By the end of the run there is hardly a ripple. 2,132 KB
MK5 up snow covered hill
 
This short clip was made just to demonstrate the amazing ability of the model to climb snow covered hills. 3.2 KB 

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