[wigs] these are not worn on the head

Wing In Ground is a strange name for a type of aircraft … well, boat … allow me to explain.

My friend in Russia was once on the bank at the confluence of the mighty Kama and Volga rivers. He looked out over the water and saw a sight which blew him away.



In the distance, zooming across his line of vision were three Orlyonoks, just above water level, so they were planes flying and yet they never took off, never flew up to the sky. They were huge, carrying banks of six huge engines at the front of the fuselage and were moving twice as fast as a plane in takeoff.

Quickly he was told that it was worth his job even to mention that name, to forget what he’d seen.

As you’ve gathered, it was a surface effect craft or WIG [wing effect in ground] as they’ve come to be known for some obscure reason and they were one solution to the age old aquadynamic problem.



Let’s face it, any boat has surface area drag, i.e. the water, acting on the surface, creates friction which prevents forward movement. There are all sorts of formulae which govern aquadynamics. Someone discovered that a boat in the water [displacement craft] had severe limitations due to both this drag and a thing called a bow wave, i.e. the boat creates its own wave which it must effectively climb over to free itself.

If it can achieve this, it does what is termed ‘planing’ – it sits on top of the water and skims. This is the principle behind windsurfers, one of which currently holds the world speed record of over 50 knots. The formula for planing is:

… one and a third times the square root of the length at the water line.

Against this was the rule that the longer the boat, the higher speed or ability to overcome the bow wave. Either way though, it was an unsatisfactory situation and so conventional boat travel has always been limited in scope.

For most people, the leisurely cruise is fine but for the companies, it’s very fuel inefficient. So they had to come up with ways to break the nexus of water, surface area and drag. As you see below, there were three main solutions.


Hydrofoils

Excellent solution but they do cause instability; the picture of Hypdroptere on a lovely day illustrates the upside. Commercially, the fuel efficiency makes these craft viable.




The downside is that it crashed not long after this and broke it’s beams due to wave and wind stress. Essentially, when yours is a boat with passengers moving round, to have it suspended at three or four tiny points in the water, via blades, is dependent on the wave action at the time.

I’m sure you can see this principle in the clip below.



Hovercraft

Using banks of air thrusters below and ‘skirts’ around this to hold the air in, the boat sits on a cushion of air, which immediately gives it an advantage over the hydrofoil, in that you can move from sea to land without fuss.

The downside is cost and the necessity for the craft to be very close to the surface, making it prone to rocking in a big sea.

Surface effect

Using aeroplane technology, the craft takes off as a flying boat does but then vertically stops, riding a cushion of air created by its huge wings. You’ve noticed, when you land, that the plane pauses momentarily before finally coming to the tarmac.

This is ground effect. Watch the short clip to see it in action:



The benefits are obvious. With virtually no drag, the craft has a smooth ride and long range. You’ve probably gathered that there are disadvantages though which are explained in the clips below. You might have to click on them to read them properly.







In fact, the Russian version had those banks of engines actually angled downwards at takeoff and one version had two separate sets of engines. The huge cost of this precluded short journeys and those not carrying a large payload long distances.

Also, the craft was again subject to wave action but not only that, wind unsteadiness as well. So it needed to be very long and very heavy, to avoid flipping over, a phenomenon associated with these craft, as with the Donald Campbell speedboat.

This made them ineffective except within a narrow range of usage, mainly military.



To date, no other solution to the age old problem has become commercially viable, except perhaps for ‘outrigger technology’.

This is what I use in my designs and it works on the basis, which you can see in the craft in the pic below, of enabling a very narrow hull at waterline, broadened above for passengers. The reduction in overall area creates the efficient plus the formula of LWL versus beam getting up to the very efficient range of 14:1.

Another very clever move is that if you look at the outrigger ‘amas’, they are just logs, of neutral buoyancy, i.e. they sit on the water on their own but when pressure is put on them, they sink.



This is clever because when you have a sea coming abeam or side on, the alternate sinking and rising either side of a power boat creates overall stability and gives a smoother ride through rough seas.

To a point.

When you have very rough wind and wave action, the boat turns over and people die. You’ve all heard about Philippine ferry disasters.

The navy has been interested in both trimaran and hydrofoil technology as well, as can be see below and so the ongoing struggle for efficiency continues.





Here's one site on the subject.

Here's another. [Between the Wind and the Waves, Julian Edgar, Issue 170, 5 Mar, 2002]