I recently rediscovered an old Clarke book called “Profiles of the Future” where he basically details what he thinks the big technological breakthroughs of the next century are. In one of the chapters, he seemed very enthusiastic about a technology he called “Ground Effect Vehicles”, what is now termed the hovercraft. He seemed to think that we were on the verge of a transportation breakthrough with hovercrafts making present day motor cars obsolete.
Just why has hovercraft technology stagnated and died? was it a technological issue, a social issue or some vast conspiricy by Detroit?
Safety - how do you control them - no such thing a steering/braking as in a wheeled vehicle (not to mention the idea of propellors on every vehicle - you want to check the tension on the drive belt, son?)
Economy - defeating gravity is expensive. MUCH cheaper to let the thing roll around on wheels. How much power to move something on wheels vs. lift and move it on an air cushion?
Preacticality - ever try to go up a hill on a GEM (ground effect machine)?
I believe hovercraft have found some use as high-speed ferries (although somewhat more conventional hydrofoils or catamarans seem more common in such applications). Hovercraft are also now used by the U.S. military (Marine Corps) as amphibious assault vehicles.
I don’t think there’s any conspiracy behind them not being as ubiquitous as people once thought they would be. It’s just another idea that didn’t pan out (or at least hasn’t panned out yet–the technology may still advance), just like flying cars and robot butlers and giant, wheel-shaped space stations complete with Hilton Hotels.
Hovercraft may not have been what Clarke was talking about.
There’s a phenomenon called “ground effect” that all pilots know about. As a plane gets close to the ground (about one-and-a-half times the wingspan), it develops a cushion of air beneath it. It’s not a big deal, just something you have to be aware of, and prepare for, when landing.
It can come in handy. In the days when intercontinental air travel was in large flying boats (seaplanes where the bottom of the fuselage was the main hull when landing on the water), Lufthansa pilots in the South Atlantic discovered they could extend their range by 50 percent if they flew only a few feet over the water. World War II pilots who were low on fuel could descend into the ground effect layer and gain enough extra range to get back to their bases.
This did not go unnoticed by aeronautical engineers. Over the years there have been planes built specifically to fly this way.
The Soviet Union made some impressive ground-effect planes or Ekranoplan for use on lakes, esp. on the Caspian Sea.
But if Clarke was talking about ground-effect vehicles replacing cars, I think he had something like the hovercraft in mind. I don’t see why you’d want one for personal transport though - they are less energy efficient than automobiles and have no advantages that I can think of. (Other than being cool and fun, or so I hear.)
Sorry, submitted too soon. Picking up where I left off…
This did not go unnoticed by aeronautical engineers. Over the years there have been planes built specifically to fly this way. They’re called WIGs, for Wing In Ground effect. You’ll also see PAR-WIG, for Power-Augmented Ram Wing In Ground effect, and the Russian term, “ekranoplan”. My information’s rather old, but aparently the Soviet Union did quite a bit of work in this field, mostly on the Caspian Sea.
Some of the numbers are rather staggering. One PAR-WIG studied by the U.S. Marine Corps would travel at 250-350 knots, almost 7,000 mile range, and with up to 850,000 pound payload (and a total weight of 2,000,000 pounds). That would dwarf current airliners, and a civilian version could revolutionize trans-oceanic travel. You can see why something like that might interest a futurist like Clarke.
So where are they? Good question. They’ve been tested over the years in various types and sizes, but I guess nobody’s ever worked out all the bugs. They have to take off from water, so they could only serve some cities and only a few of those could be made convenient with connecting flights. They wouldn’t fly above the weather as current airliners do, and I’m sure there’s a limit to the height of waves they can fly over and maintain their efficiency. Fascinating idea, though. Check here for an interesting site. Click the “Overview of WIG craft” link to see some pictures. Look for the KM, apparently the largest built during the Soviet experiments.
[sub]Most of my information comes from "Jane’s 1982-1983 Aviation Review, edited by Michael J. H. Taylor, pages 135-140.[/sub]
Chris-Craft, experimented with hovercrafts back in 1950s. They built a model that was designed to replace the family car. It was big, hideously ugly, and had the annoying habit of drifting when there was a cross-wind. Not exactly characteristics one looks for when buying a new car. The size and appearance could be corrected, of course, but the drifting nature of the beast has been problematic to solve. (Imagine how hellish rush hour would be with cars drifting all over the place!)
Some of the advantages that clarke listed were that they removed the neccessity for roads, they worked equally as well on water as on land, they were far more energy efficient than boats, did not reqiure the elaborate safety requirements of hydroplanes, better at handling rocks and stuff on a road.
Christ, I can see it now. People whipping around all over the place (between houses, through neighborhoods) in vehicles that cannot be steered or stopped easily. :eek:
Chris Cockerell is credited with the invention of the hovercraft (1953) and one of his prototypes made the Channel crossing (Dover-Calais) in 1959.
For some years a commercial ferry for cars and foot-passengers was operated on the cross-channel route by Hoverspeed from 1981 but this service was terminated (2001?) and the hovercraft were replaced by Seacat hydrofoils.
The hovercraft service was plagued by service disruptions due to weather conditions in the channel, as the skirts which made the vehicle practicable could not cope with waves above a certain height.
A few years ago there were blizzards in the Wyoming/Dakotas area and thousands of cattle starved because the ranchers couldn’t get feed to them in their trucks. I wondered then if hovercraft could have been used to carry feed to the stranded animals.
The big problem is that the tend to become full of eels. The problem is so acute that Hungarian phrasebooks usually carry a useful phrase about the problem that you can use at the tobacconist’s.
They certainly wouldn’t remove the need for roads. You’d still have to have paths for traffic, stoplights, et. all.
A few years ago there were blizzards in the Wyoming/Dakotas area and thousands of cattle starved because the ranchers couldn’t get feed to them in their trucks. I wondered then if hovercraft could have been used to carry feed to the stranded animals.
Not sure… Could you even get the damn thing out of the garage? Woiuld it work in that cold weather? Will the snow hills and mounds affect its handling?
smiling bandit: I’ve never been to that part of the country, but from the news footage it looked pretty flat. I’m sure a large-ish hovercraft (say, an eight-person model) could have handled the terrain. And since the farmers were not snowed in (just their cattle were stranded and the roads were covered with deep snow), I’d assume that they would ahve been able to get the machines out of the garage. Of course, hovercraft are not extremely popular except to a few hobbiests and some Canadian businesses (and the USMC, of course). But it seemed to me that it would have been a good solution to feeding the cattle, had they been available.
RealityChuck: On the upside, eels are edible and tasty.
Back in the mid '70’s I rode in one of those things across the English Channel. The one thing I remember about it was how bumpy it was. You would think that riding on air would be smooth, but I was knocked all over the place.
Operating a GEV in snow creates an instant blinding cloud of snow around the vehicle. I have lived that area, and it’s not so flat as you think. Further, they still have the issue of crossing fences, cresting drifts, and the like. A sno-cat is what was called-for.
One place they use hovercraft is for ice rescues. Sometimes the ice is too thick for a boat and too thin for even ATVs/snowmobiles. Or the thickness varies. (or it may be thick ic,e then water, then ice again). Helicopter could be used for the same purpose, but a LOT more expensive to operate/maintain/crew
Hovercraft may be usefull in swampy/mucky terrian (say 1 inch of water over soft mud)
To use the other definition of “taken off”, the FAA has determined GEVs (wherth thy use lifting fans ir WIGs) are not airplanes. If they “take off” (leave ground effect), they are no longer hovercraft, but planes. (sorry, couldn’t resist)
Certainly up until 1997 there were small (~40-seater) commuter hovercraft crossing Hong Kong harbour. Probably still are. They looked rather uncomfortable.
