China today confirmed it has developed a "Wing In Ground" (WIG) sea-skimming aircraft, state media reports. According to Reuters, the Chinese version of the Caspian Sea Monster is capable of flying at 300km/h (180mph) at a mere half metre above the surface while carrying four tonnes of cargo. It relys on the WIG effect effect …
Use as directed: Inland watermasses only
At 1/2 a metre clearance, this concept is only really viable for large land-locked lakes and seas; anything remotely resembling waves or crosswinds could turn this into a fast (and rapidly disintegrating) submarine quicker than the stewardess can say "In the unlikely event of landing on water...".
If the plane flies just half a meter above the surface, it would only be able to fly over sea on days where the water is extremely still.
Over land it is not much better, few natural land surfaces are flat enough that you don't have things sticking half a meter above ground from time to time.
So I guess it will be limited in much the same way as hovercrafts. It will be a lot faster, though, and probably more efficient.
Look out Taiwan...
If I were a defense planner for Taiwan, then this little development just made my life more miserable...
Waves don't worry me...
... it's the off-course oil tanker 2 miles away (which at 180 mph is 40 seconds) which would get me saying my prayers...
At 0.5m above sea level, and at such high speed, would a craft like this be able to manouver around it? I'm assuming that this 0.5m is the peak value, so maybe 0.75 - 1m is possible to keep the craft airborne, but i'm guessing the wing design means that it must be parallel to the water's surface?
Kind of like trying to change the direction of a swamp boat, but at 5 x the speed and god knows how heavier...
0.5m above the surface is very low for a WIG craft - you drop the coefficient of drag by a factor of 0.6 with a height/wingspan ratio of ~0.2 and even on a light aircraft (wingspan around 10m) this is a height of 2m and I'm guessing a 50-seat craft will have a somewhat greater wingspan.
I'm not sure why "Xinhua notes 'the Civil Aviation Administration of China has yet to confirm aviation regulations at such low altitudes'" - flight isn't normally considered to take place until you are outside of ground effect. This is why you don't need a pilots licence to; bounce on a pogo stick, jump off a curb on a skateboard, etc (all activities that involve using a mechanical device to leave the earth's surface).
As a result WIG craft have normally fallen under the official classification of 'water craft' and not 'air craft'.
Wouldn't this work on roads too? Have a long road, which shouldn't have anything sticking out of it high enough to damage the "plane", and you'd have a technology for bulk transportation over land at 300km/hr!
Really about Taiwan
Why would the Chinese bust their balls over technology that the fiendishly clever Russians couldn't get to work in decades of trying?
National pride. No, not topping the Russians, but topping (in a different sense) the Taiwanese. Somebody in the PRC has realised it might just be a great way to fly 10,000 armed men a red flag into the middle of Taipei, under the radar, in less time than it takes to knock up a stir-fry.
It flies high
The trains that use WIG and retractable wheels are better to me, they use a small amount of energy compared to Maglev or TGV and can be built around existing lines just needing some barrier to keep the air in a trough.
I remember from reading about WIG the waves aren't a problem with the giant 400ton cargo WIG planes, they fly quite high and can skip over stormy sections by powering up and reducing range. Also only the really heavy massive cargo versions make financial sense, I can't find the rule of thumb at the moment so may be wrong.
Slow moving (relative to modern anti-aircraft capability) fragile targets that can't get over tank traps? Fairly easy to counter, I'd've thought. Easier than choppers to bring down. The only issue would be detection and I think if the sea's flat enough for a Ground Effect plane to fly, it's not going to be cluttering up watch radar.
Not so much the cushion of air ...
WIG craft don't so much ride on a cushion of air as cheat drag by using the ground to break up wingtip vortices.
What I'd like to see, impractical as it might be, is something related to the swing-wing trick that F14s use to alter their aerodynamic properties to permit a greater range of airspeeds. Could something like this allow the wings to be extended a little to permit flight outside of ground effect?
The comment about a rapidly disintegrating submarine makes me wonder if submerisble capabilities could actually be designed in too. A sub/boat/WIG/plane - there's no denying *that* would be a useful military vehicle.
"The comment about a rapidly disintegrating submarine makes me wonder if submerisble capabilities could actually be designed in too. A sub/boat/WIG/plane - there's no denying *that* would be a useful military vehicle."
Already been done:
Very much a cushion of air (and not too)
Don't forget that there is more than one WIG - SDGE and CDGE.
Span Dominated Ground Effect leads to smaller top vortices, as the ground physically gets in the way (diameter of vortex can't be greater than height of tip above ground level).
Chord Dominated Ground Effect increases lift by creating a cushion of air. When a 747 travelling at 400MPH hits some air there is about 35,000ft under the wing for the part pushed under the wing to move into. When in ground effect the space below the wind is somewhat more crowded and so you generate a positive pressure under the wing, in addition to the more common negative pressure over the wing. As lift is the pressure different across the wing you generate more lift in ground effect.
The following site covers it quite well (along with showing that F1 powerboats AREN'T WIG craft..at least not very good ones!) - http://www.se-technology.com/wig/html/main.php?open=aero
...may take a while before becoming feasible, and the Russians seem to have a knack for these 'feasible' ideas pretty often...
Take the helicopter for instance... Sikorsky didn't invent the concept, he just turned it into something practical. Now it can be seen everywhere...
I bet WIG aircraft is not a Russian idea, but they built a proof-of-concept in the Caspian Sea Monster. From feasibility to practicality, perhaps the Chinese may come up with something useful after all.
As I recall, the Caspian Sea Monster was inherently unstable/dangerous, back in the day when there were no computers to make it stable e.g. no waves allowed. The same goes for the F-16, that relies on its computers to fly in low speeds, when it becomes unstable.
Perhaps the Chinese will add some serious computing power on it, to make it stable/safe.
There, your IT angle about it.
It's not what you think it is ! This is not the point !
As the Russians found out this technology is just not practical.
1) You need water as flat as a mill pond.
2) Engines don't much like having several tons of salt water thrown at them at high speed.
3) In the event of an in-flight contact with the surface it would be every rivet and panel for itself.
4) A mass that size cannot respond quickly enough to say, a rolling swell or chop.
5) Turning is a problem as banking over is to be avoided !
Now a few technical notes;
Ground Effect is generally considered to begin within 1.5 wingspans of the surface depending on wing shape. Delta wings have an astronomical GE.
Aircraft do not encounter "crosswinds," it is the ground that has crosswinds. Aircraft move in a straight line relative to the airmass. This is excepting inertia effects though.
Regarding licencing, you do not need a licence to fly per se, no matter what the height. You need a licence to operate specified aircraft.
I'm afraid though that this whole subject is boswelox. The point has been totally missed. They won't be setting up production of these things.
The Chinese are an emerging industrialised nation. They are flexing their technical wings. This is a repeating pattern with them. They are proving to the world and themselves that they can match other countries' acheivements. In the future expect to see a supersonic passenger plane and other milestones.
Fear of Music
"the Caspian Sea Monster is capable of flying at 300km/h (180mph) at a mere half metre above the surface while carrying four tonnes of cargo"
According to Boeing's website, a Boeing 747-400 freighter can carry 124 tons of cargo at over 500mph (albeit that Boeing might be using a different ton to the article's tonnes), over a distance of 4,400 miles, regardless of rough seas. The article predicts big things for the Wing in Ground vessel come 2016-2017, but that's a lot of time and money in the future.
And this is without mentioning freight container ships, which are much slower than 180mph, but can carry tens of thousands of tonnes of freight. When on put on my businessman's hat, this WiG thing doesn't seem a compelling prospect as a freight carrier. Perhaps it could carry rich passengers instead, lots of rich passengers, over a long period of time.
Barrage balloons? Offshore wind farms?
Re: Good Ideas : Early use of ground effect
The use of ground effect out at sea has a quite old history: Dornier flying boat pilots on pre-WWII transaltantic passenger service new that flying low conserved fuel, and used it to increase range.
Boeing actually is looking into ground effect as well, see