Slashdot Mirror
Flying Trains
leb writes: "Engineers in Japan are developing trains that really do fly. Using the 'wing-in-ground' (WIG) effect, in which a high-pressure cushion of air forms underneath flying objects as they approach the ground, they believe they will be able to create trains that use only a quarter of the power required for magnetically levitated (maglev) trains. Read about it in this New Scientist article." This is rather nifty, but it isn't as cool as the flying train at the end of BTTF III. Put a flux capacitor on this baby, and we'll talk.
I'm going to go play with 'X-Plane' (which is at least half a hardcore aerodynamic engineering sim) and design myself a ground-effect car. And see what sorts of terrain I can fly it over :) vroom, whoosh! I think it's sort of pointless to design in a non-ground-effect tail seeing as the thing is supposed to _not_ actually take off fully. I'm thinking in terms of three wings and flat plates for the sides, perhaps some form of drag rudder.
I wonder if you could make the 'slots' for the Japanese train version in x-plane? It is sort of technically possible but would be absurdly hard to get the tolerances close enough...
Anybody have a long steep hill, some bicycle wheels and aircraft spruce or aluminum tubing? No engine required! You just have to live near a big, _straight_ hill ;) oh, plus you'll have no brakes of any sort due to not even touching the ground, so busy streets would _not_ be the place to try this ;)
That's exactly the kind of ramscoop-thing I used to make as a kid! Wow- this slashdot article is a strong contender for my favorite slashdot article _ever_ :)
"Flipping over backwards" is not typical of overloaded airplanes. The most common thing is to simply not be able to climb out of ground effect. This is most common in hotter, more humid, and higher altitude environments than the pilots are used to, as each of these factors reduces the density of the air; reducing the density of the air then reduces thrust and lift capacity at the same time.
Taking off tail-heavy is very easy will make the aircraft difficult to control, and may cause a stall, particularly at low speed. However, it is more likely to cause a stall at approach to landing, as most aircraft store lots or all of their fuel in the wings, and as they use up fuel their center of gravity shifts slowly backwards. While the horizontal stabilizer ("tailwing") has sufficient effectiveness to prevent at stall at cruise speed, the airplane will be more likely to stall when it slows down for approach to landing, and will be hard to control in any case. Fortunately, certified aircraft generally have significant margin of error.
Finally, I strongly doubt that the fat man you saw put your plane in danger. The crew will feel no compunction about asking folks to move around whenever there is a weight and balance problem; I've been on quite a few flights when this has happened. In this case, he might have been undercounted, but not completely ignored for W&B calculations. There is an "FAA standard passenger" that can be used for these calculations so that they do not have to ask you to stand on a scale, and at a minimum it is likely that he had been accounted in this manner. If they were very close to the W&B envelope, they would have known it and would likely have re-run their calculations.
Folks interested in reading some of the best technical writing ever created and in learning more about the theory of flight should read Stick and Rudder by Wolfgang Langeweische. Only beware, as aviation is an addictive persuit, and you might get hooked. :-)
PPSEL (Private Pilot, Single-Engine Land); Experimental Pulsar N456LT
-- "Ever wonder why the SAME PEOPLE make up ALL the conspiracy theories?"
You didn't actually read the article, did you?. The Japanese have maglev trains as well. old news. If you had actually read the article, you would have noticed they mention that the whole point is to reduce energy consumption.
See:
"Inductrack"
Maglev: A New Approach, Scientific American (January 2000) - article not available online.
"Track to the Future," Popular Mechanics (May 1998), pp. 68-70.
I don't read ACs: If a post isn't worth so much as a nom de plume to its author then I wont bother either.
-jwb
-jwb
In this case, the wing simply needs to be wider than the designed flight altitude (Altitude measured from ground level, not sea level) to take effect of Ground Effect. It does not have anything to do with the total length of the train or traincar.
Essentially, this means that a wing, such as one on an airplane, gets double lift when the wing is as close, or closer, to the ground (vertically) as the wing is wide (horizontally). In other words, if a wing is 75 feet wide, and the plane is 75 feet or less from the ground, the wing will be able to generate twice the normal (above 75 feet) lifting force.
This can create a lethal effect on overloaded or badly balanced (front to back) aircraft: The wings will generate double-lifting force while within the ground-effect zone, but as soon as the plane gets above the ground effect layer, the plane will flip over backwards and splatter all of the runway. Not a fun way to die. Always do those Weight-And-Balance calculations carefully!
One time I was on a puddle-jumper (20 seater deal prop) going from Omaha to Minneapolis. We had gotten on the plane and were waiting to begin taxiing to the run way. The door was closed. Suddenly, they open it back on and let this digustingly fat man on the plane. He must have been 500 pounds or more. The only place he could sit was on a bench all the way at the back of the plane. (The back of the plane is the worst place for weight in the first place, the tailwing doesn't create a whole lot of lift) Since he was on so late, I doubt he made it into the W&B calcs. I love to fly, but this time I about got up and got off the plane. I stayed on and was pretty scared while we passed through the ground effect zone. There has to be a significant chance (at least 10%) that we could have flipped over. One person could have moved the wrong way, or something in the luggage compartment could have shifted and we would have been a textbook case of why obsessive-compulsive people should be kept away from both McDonalds and small airplanes! :)
So, it is not surprising that the UK rail system is subject to delays, breakdowns, and extremely lethal accidents (sorry, we don't have money to fix that broken signal, we have to pay dividents, you know).
The British Rail privatization is a showcase to the world of why thatcherism is a scourge, and a lesson that (fortunately) stopped dead similar projects worldwide.
It is safe to say that thanks to the eye-opening experience of the british rail privatization, the people of England decided to kick out the little tory shopkeepers from the House of Parliament, and bring back commonsense to government (a State is NOT a business, and cannot be run as such).
--
Yawn... Old hat. Can't you slashdotters have a look at history? Otherwise, you'll be condemned at repeating it... badly.
First, a brief word about ekranoplanes (a.k.a. Wing-In-Ground effect). Here is an actual picture of such a beast in flight (Gerry Anderson fans will be delighted by this one). They have been around for almost 40 years, having been devellopped in the defunct Soviet Union . You may look at this page for historic information, as well as pictures of enormous ekranoplanes as well as the 400 ton Lun ICBM launcher . For those who worry about greenhouse gas emissions, there is also a pedal-powered WIG !!! Oh, yes, those craft are already covered by a Canadian regulation, proof that they've been around long enough to rouse the attention of regulators...
Now, about trains. Nothing really new, there either.
In the 1960's, french engineer Jean Bertin (1917-1975) pursued the développement of his ill-fated Aérotrain , which, 30 years before the recently-canned german Transrapid maglev, almost reached the realization stage (both in a commuter rail line betwen Paris and the western sububurb of Cergy, and a line between Lyon and Grenoble for the 1968 winter Olympic games). Bertin's Aérotrains ran on a single inverted T concrete rail, and used a cushion of air for sustentation. An early prototype, the Aérotrain expérimental 02 (which looks like it was inspired by this), reached the speed of 400 km/h in 1966 and 422 km/h in 1969 (not an impressive achievement, since at that time, the rail speed record was achieved in 1955, when an ordinary locomotive pulling four totally normal cars reached the speed of 331 km/h on a perfectly standard railroad line). More pictures are available here.
Despite that, Jean Bertin built more prototypes, and a 20 km long rail line (which still runs accross the countryside, completely abandoned) on which a much bigger "train", which ran not much faster than today's TGVs do (note that the record certificate is issued by the Fédération Aéronautique Internationale , and not the Union Internationale des Chemins de Fer ...).
Bertin's Aérotrain technology almost got selected in place of the current TGV, but at the last minute, State support was withdrawn from the Société Bertin. The Aérotrain (and any other newfangled guided transportation system such as maglevs and monorails - we're in the real world, here, not in Disneyland) suffered most from gross incompatibility with existing rail lines (necessary to enter the core of cities) and an extremely heavy implementation of switches, which precludes their widespread use and thus reduces the flexibility of their rail networks.
Jean Bertin never recovered from the shock of losing State support; he died a few months later, despite having built a prosperous engineering company which still thrives in high-technologies.
Throughout the Aérotrain's history, the French National Railroads (SNCF)'s attitude was extremely interesting. Despite all the media hoopla that surrounded the Aérotrain and the political interest, it did not say anything at all. Not a single word either for or against the Aérotrain was uttered in official french railroad circles. But during that time, the SNCF worked hard at perfecting what is seen today as the epitome of high-speed travel technology, the TGV.
So, it is quite safe to say that this oldfangled flying "train" will certainly not fly very far, because the theorical speed limit of ground travel, the speed of sound, is within reach of conventionnal steel-wheel-on-steel-rail technology, which without much pain, ran at 515,3 km/h on May 18th 1990 (gee! Almost 10 years ago!!!).
(What is the speed of sound at 20C at sea level anyway???)
--
That's a maglev train. As the article said, this new train doesn't use magnets - it's a totally different way of levetating (using ground effect).
This train will ride between Berlin and another town, I think. It may eventually ride in other countries like the Netherlands too.
Didn't the project get cancelled recently as being to expensive, and not compatitive with the ICE - the German high speed train?
-- Abigail
Well this is only an intial design. I would think that if you take into consideration other design limitations you will end up with different perhaps beter designs. Your basic idea of WIG is correct. Turbulence under the wings, and the usual effect of Bernoulli's principle all effect to amplify the normal lift conditions caused by a wing. But your comment about size is wrong. In this case size doesn't entirely matter. Or more appropriately its not the only condition. If I remember correctly your lift is a function of speed, wing size, and wing efficency. So if my wing is effiecent, and I go fast enough I will get lift. Especially when that is multiplied by the ground effect. Ground effect does happen on normal airplanes generally when the airplane is 1/2 the wing length above the ground. Kinda nifty effect.
Odd side note is that the train would have to have an upper limit on speed otherwise it would take off. Unless there was a top part to the track....
-cpd
Thats one thing that kinda pissed me off about Austin Powers 2. I mean, come on! Yeah, your time machine is this car, they were talking about meeting your past self (a la back to the future), and then theres no 88 mph, flux capacitor, OR flames coming out from the wheels?
Sheesh. Some movies are just so unrealistic.
The sun is going down, I say we follow it out of town- We've been here for far too long.
Still not dead.
Silly me, I thought that was the Bernoulli effect.
But if the idea is to replace maglevs then noice isn't that big of a problem. The magnets in a maglev put out a lot of noise as well, even when the train isn't around. The fans would probably be a blessing to the neighbors.
Here is the fix for that broken link.
Alright... let me start debunking:
;-)...
(a) the ground effect is a very well understood phenonomenon, much more so than MAGLEV. In fact, the Russians/Ukrainians have built massive WIG aircraft, that were probably gonna be used for rapid troop landings. A quick Google finds this page.
(b) WIG has nothing to do with turbulence. In effect when a wing is closer to the ground, the space between the underside of the wing and the ground acts as a nozzle, i.e. increases air pressure much more so than the wing can do by itself (roughly 2x). Increased air pressure => higher lift (although I am over simplifying here).
(c) You don't have to have a large wingspan to take advantage of the ground effect. It just so happens, that when you fly slow, you can't produce as much difference in air pressure with a small wing, so you need a large one (again, I am over simplifying, but close enough). I.e. if you have lots of small wings, like these Japanese are trying to do, you're gonna get pretty much the same effect.
(d) The pterodactyles did not use the WIG effect... I mean come on, do you ever see illustrations of pterodactyles soaring at 2' off the ground?
I personally think this is a very interesting idea. Maglev is cool and all, but this can work just as well. If I had to find a weak spot it would be the total cost of ownership (TCO) of these things versus a Maglev train... with a maglev, electromagnets may cost more at installation, but after that you're pretty much done spending. OTOH, aircraft (particulary aircraft *engines*) are notoriously expensive to maintain...
engineers never lie; we just approximate the truth.
The W.I.G effect has been understood for a long time; this is a clever application of that effect across disciplines.
This proves an interesting reminder of the fact that "innovation" - an overused term - is so much more than the ability to spawn new ideas fully formed from your brain. Some of the most brilliant advances we have seen and will see are the fortuitous combination of two seemingly unrelated facts or areas of study. That's real genius: the ability to see patterns where a less perceptive person might see none.
I hope someone points to initiatives like this one the next time funding for pure science research is on the block. The quest for knowledge is almost never totally without payoffs.
-konstant
Yes! We are all individuals! I'm not!
-konstant
Yes! We are all individuals! I'm not!
They really, really, should look at designing a lifting-body train, instead of this monstrosity.
Something you can use on existing track designs would be optimal. Instead of vertical wing sections, shorter diagonal sections should extend from the undercarriage.
The train tracks and siderails in Japan look a lot like ours. They're too close together for one of these and another train to pass, and they frequently travel through urban areas, where the extra right of way is going to be a bitch to acquire.
-
Just because it works, doesn't mean it isn't broken.
I ride a normal train at least once a week. There are always tracks criss-crossing one-another. I'm not sure how they plan to handle cross tracks or routing, for that matter. Unless they plan to build mondo amounts of tracks and over/underpasses with existing forms of transportation.. eventually Japan could be one big spaghetti jumble of railways. At least with a normal track/train you can do some routing between different tracks. Where's the savings if you need a single track for each route for each train? You spent your environmental savings building all those tracks. Not to mention how WIDE those tracks have to be to accomodate the train + wings.
-----------------------
Nicotine free Amish .sig.
The magnets in a maglev put out a lot of noise as well, even when the train isn't around.
:-) going at 500km/h or more is gonna generate a lot of noise. (Not to mention if it goes faster than sound. Booom.)
What do you mean? Electromagnets generating noise? Uh, maybe electromagnetic noise, but I doubt you can hear that with your ears only...
They may hum slightly due to vibrations, but nothing near a fan. The main cause of noise from Maglevs is shockwaves. Anything (ok ok, not spaceships
And anyway, the track magnets are turned off when the train isn't there.
-
__
Comment submitted. There will be a delay before you understand what you posted.
OK, the article stated that the prototype is 8.1 metres long. If I remember the last info I got on WIG, wouldn't a large WIG train actually have to have wings at least as wide as the train is long? I remember that the WIG effect is caused by turbulance from the high air pressure under the aerofoil being reflected by the ground. The only problem being that the wings have to be very wide. Look at the pterosaurs. They utilised the WIG effect as well as thermals to soar and glide. Their wingspan, however, was massive.
I personally don't think that this idea will ever take off (forgive the pun). Maglev is a much better understood effect and is easily controlled - the WIG craft would have to take off. Surely there is a hell of a lot of chance that serious faults will occur during lift off? It will probably need a lot of work before being produced and used by civilians, and even then I don't believe that it will be as good as maglev. Maglev will be much improved once superconductors reach the boiling point of nitrogen.
There, my (probably not-so-well-informed) two cents.
We Build Beautiful Websites
This looks like an exceptionally promising piece of technology but I question the viability of it in anything other than cross-country/continent use.
This is obviously not something that is expected to help the daily communte, and would in fact be at a severe disadvantage in the metropolitan setting of any city. The noise of an object traveling in excess of 300KMpH at ground level is likely deafening and with most cities already having bylaws controlling when Aircraft may land or takeoff it is unlikely this may receive an exemption. Additionally it makes little sense to cross even the largest city with something like this since acceleration time to get up to cruise speed would reduce the benefit acrued.
That cross-country/continent part would be interesting though. North America was built on the back of "The Train". Replacing the existing North American train routes with one of these babies would make the train once more a viable travel solution. Certainly less costly economically and environmentally - especially if this:
He says the next step will be to reduce the speed at which the Aerotrain lifts off, so that the amount of time in contact with the track is kept to a minimum. That will cut friction and therefore overall energy consumption. The goal is to reduce pollution emissions to 36 grams of carbon dioxide per person per kilometre, compared with 122 grams for maglev trains.
is a trend which continues. What I would like to see are some costs analysis, estimating what the full scale train would cost to build and to run. Not to mention how much the infrastructure upgrades would be..
As has been said in previous comments, the Wing In Ground effect is something that has actually been known about for some time. (The first evidence came from the Pilots of early Dornier flying boats.) I have found a site that deals with this effect, and the aircraft that have exploited it at:- http://www.io.tudelft.nl/~twai o/edwin/html/index.htm
In my first year of highschool I made a similar system - it was essentially the same design as in the picture, except with a R/C car with triling line to pull it along. On that scale it was trivial to make a model that would go about 2" off the ground.
For a production model of this train you would expect it to ride about 1.5 - 2 feet above the tracks. Any closer and you have to spend too much time cleaning the track path to make it financially viable.
The best solution would be to combine MagLev technology with the WIG train, have Maglev at stations, thus minimising time to get the train up to a high enough speed to use WIG. This keeps the costs of MagLev to a minimum, and the energy inefficiency of long time ground contact to a minimum.
just my thoughts - one last thing, in a MagLev train, how do they shield everything from the fields? or i guess it wouldn't matter since its not oscillating....
thats all folks
i don't know much about the WIG effect besides what's stated in the article, but it would seem to me that if the train is going to create a cushion of air underneath it to ride on, then the weather would be something very important to consider. how would this be affected by rain/sleet/snow or high and low pressure systems, or high winds in general. if this technology came to fruition could we build and transcontinental line in the USA considering mountain ranges?
-1: flamebait should really be -1: inciteful
The comments about self powered tracks seem to suggest they might be looking into a hybrid maglev solution where some form of magnet propulsion could be used (or at least some form of track mounted propulsion) with ta wing providing lift to avoid friction.
____________________
He who fights and runs away,