By Tuan Nguyen
Posting in Design
A ground-effect train, works similarly to a Meglev train excepts it floats on a cushion of air that reduces wind drag.
Much has been made about the technology behind Meglev trains and its potential to revolutionize high-speed transportation. But even those futuristic darlings, which can travel at speeds of up to 361 miles per hour, are susceptible to the slowing effects of wind drag.
Now a group of researchers at Tohoku University in Japan believe they've discovered a way around this aerodynamic inefficiency and, oddly enough, it involves slapping on some wings.
This technology, known as a ground-effect train, works similarly to a Meglev train in that it's designed to levitate across a fixed track, an approach that eliminates the problem of railway friction. However the difference is that it accomplishes this by floating on a cushion of air that propels it forward instead of the strong force of an electromagnetic field, which contributes to the drag effect whenever a Meglev is moving at slower speeds.
They've even built a robot prototype that's currently being tested, but as you can see from the video, the technology has its own inefficiencies to overcome. Since the vehicle operates more like an aircraft than a train, researchers still need to figure out how to build an autonomous three axis stabilization system that can handle the pitch, roll, and yaw-type maneuvering of flying vehicles.
Eventually, the researchers hope to scale up the model to a manned train capable of speeds of 200 kilometers per hour and test it in a more controlled track. The team's ultimate goal is to somehow incorporate the technology into a large commuter rail system called the Aero Train, which is depicted above.
Obviously, it'll probably take a while -- if it ever does happen.
Test footage of robotic ground effects prototypes:
(via IEEE Spectrum)
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May 12, 2011
Look up "caspian sea monster" sometime. Admittedly this is a more restricted use which might actually have practical value. Past flying train tech has included monorail hovercraft in the UK. That didn't end up commercially viable and the track was dismantled 50 years ago
The article says Maglev trains are "susceptible to the slowing effects of wind drag". Meanwhile, this ground-effect train "...eliminates the problem of railway friction...it accomplishes this by floating on a cushion of air that propels it forward instead of the strong force of an electromagnetic field, which contributes to the drag effect whenever a Meglev is moving at slower speeds." Newton tells us that "Every body remains in a state of constant velocity unless acted upon by an external unbalanced force." This means that a body remains at rest in the absence of a non-zero net force and continues to move at constant velocity I suggest they consider building a base-limit roof for the train, enclosing it in full area so that the train resists any opposing wind movements or other weather interruptions. Plus, it creates less noise (if you're outside).
Maglev is exactly why the Calif High Speed Rail project is such terrible, money-wasting idea. 19th century fixed rail was the thing 50 to 150 years ago but we've got to move on. The money designated for this boondoggle should go to R&D and new forms of public transportation. By the time HSR is finished in 2023 the "Big One" (9.0 earthquake) will hit and the whole system will be swallowed by the San Andreas Fault.
Why build trillion dollar 20 year plan infrastructure for a flying train when aircaft already do this and can change destinations at the drop of a hat. The energy saved by the train would be small compared the energy consumed by the construction of the infrastructure to support it. Unless you are looking for a jobs program for a political candidate. If you can improve the efficency of systems that use existing infrastructure-IE: low friction or electromagnetic berings or superior high efficent propulsion systems for aircraft and cars etc. then you have something.
Since it's still in the concept stage there's no info on how loud it will be. The existing forced air types of transport are extremely noisy. (Hovercraft, STOVL aircraft etc.) It will surely set off the NIMBY folks who don't want a jet screaming through their areas.
The two examples definitely point out the advantages of a ground-effects vehicle, but that technology is anything but new; the only difference is by offering a 'hard' track for it to fly in. A simple search in Google Images for Ground Effect Aircraft displays numerous prototypes and operational GEA that have been around for decades. That said, those same video examples point out the disadvantages of stability that could make the passengers seasick (or airsick) at best. Without some form of physical stabilization, an airborne vehicle in a channel is more at risk of crashing into the sides or deck of the channel than it is of flying comfortably or smoothly within that channel. A much more efficient method would be a cylindrical vehicle in a tube since the air would be forced to move equally around all sides--though again you would fight compression drag which is what this concept is supposedly trying to eliminate. Secondly, a "train" is a number of vehicles/wagons physically linked to each other, and neither of these concepts begins to demonstrate this definition. Most monorails and current maglev trains exemplify this definition through an articulated vehicle able to bend through curves, something the current ground-effects vehicles seem unable to perform. Rigidity is needed to help maintain a 'wings-level' attitude on the straight stretches yet flexibility is needed to allow each segment to bank into a turn smoothly and independently. In essence, the two requirements are mutually incompatible. This isn't to say such a concept is impossible, but gyroscopic precession is about the only reliable method I can imagine with each 'car' independently equipped. Said gyroscopic precession could also stabilize the combined vehicle better than any rail or guide system. The drawback to this concept is that the gyroscopes would have to be comparatively massive to overcome the inertia of the vehicle itself at speed.
This is an interesting concept but possibly old stuff... The videos are dated 2001 and 2002 and second phase. Then there are the already mentioned issues... walls, stability, stop, go and emergencies. Lets not also forget where, and how... I would think the walls really limit the potential as to where such transportation can be installed along with increased costs to install and maintain over a rail...
I see the guide wall system and starting and stopping (take off and landing) will be the hard parts of this design. Also making sure the train can handle sudden emergency decelerations without plowing into the ground will be a key issue. Do they even need rails for this or can tires handle the take off and landing? Again that could further simplify the design and lower the cost to build both the train and the guide walls. The major upside over maglev is that in theory it should be far less costly to build and operate.
Japan suffered a 9.0 earthquake in March and its high speed rail system is still there; it took about a couple of months to fix up the Tohoku high speed rail line. (More ordinary trains and railways have a bigger problem, as a tsunami swept away the slower trains' tracks). Furthermore, CaHSR will not be swallowed up by San Andreas. It might get broken along the line of the fault wherever it crosses the fault, though, but San Andreas is a strike-slip fault, basically meaning that one side of the fault will move to the left and the other side to the right. http://www.yomiuri.co.jp/dy/editorial/T110430002784.htm Actual effect of 9.0 earthquake on HSR system.
An aircraft burns more than 75% of its trip allotment of fuel just getting to altitude on shorter trips (500 miles or less). With a plane using on average 500 gallons of jet juice on that trip, if you saved 375 gallons by simply not climbing that high, on each trip, won't the savings overcome the initial setup costs in pretty short order? Example: At an estimated 500 gallons used by a single flight, the cost in fuel alone is over $2000 using today's prices. In ten years, the cost could be double or triple that amount for the same trip. A Ground Effect aircraft that stays near ground level doesn't need to climb once it lifts off, riding a cushion of air. This is NOT a "Forced Air" system like hovercraft or the STVL aircraft nosacredcow describes, quite literally it's no different from any other aircraft but with shorter, deeper wings that are only effective in that ground effect domain possibly long enough to provide enough lift to 'jump' an unexpected obstacle for a limited distance. The cost savings from a conventional aircraft would be around 75% or $1500 off of that single flight. Multiply this by even one trip per day for a month and you've saved $45,000. Two trips a day over that same route or one round trip saves $90,000 or more. Eleven months of just that one route with one round trip per day saves $1,000,000 in fuel costs alone, almost totally disregarding other cost savings by not having to pressurize the cabin for high altitude or maintain expensive high-altitude life-saving equipment on board. It may even be possible that the rolling gear could be fixed in a partially-exposed manner which eliminates expensive and troublesome hydraulics for lifting and lowering that gear and offer a safety factor even beyond what conventional aircraft have to do in the event of engine failure. In other words, the cost of the vehicle itself could be significantly reduced over conventional aircraft. When you consider that Amtrak runs dozens of trips a day on the NEC and additional dozens on other heavy-use corridors, if they used a concept like this, not only would they significantly undercut the costs and prices of the airlines on the same runs, they could conceivably be faster as they have less intersecting traffic to worry about at starting and ending points. At, say, 36 trips per day over the NEC, the cost saving could add up to $19,440,000 in one year. This is the GEV's biggest advantage.
My biggest question is how it would be less costly to build and operate. Consider that the maglev uses electricity to power the vehicle, I agree that you have the costs of installing and maintaining the electrical components. That said, to be a "Zero Emissions" transport, the ground effects train would also need electrical power supplied, relying either on inductive/capacitive power or a physical connection--little different from maglev. Honestly I see no significant cost differences between the two methods. On the other hand, using a form of gas-turbine engine to provide both thrust and electrical power, the trackage would become much less expensive but we retain our reliance on fossil fuels when we really need to find ways to eliminate it. The advantage would be that less fuel is needed to attain airspeed because the vehicle doesn't climb out of ground effect and doesn't have to burn additional fuel to achieve flight altitude--the greatest fuel cost in aviation today. At no point can we rely on battery power today due to the weight and cost of any battery pack powerful enough to offer any significant range.
They do not say how they intend to power what is essentially a low flying plane so I was making the assumption of a turbine. Electrified rails or an overhead wire did not seem practical for something intended to fly. With a turbine you eliminate the need for a route long power source and theoretically you reduce the maintenance costs to maintaining the train its self and the containment walls and not hundreds of miles of electrified wire or track. A turbine engine also eliminates the problem Japan saw where the March earthquake knocked out power and trains were stranded. Only to be hit by the tsunami minutes later. Bio fuels instead of oil products, as demonstrated by the US Air Force and several airlines, can also fuel turbines so it becomes sustainable. Potentially they could grow some of their own fuel in the railroad rights of way while providing a barrier for people concerned about the noise from trains running in excess of 200 mph close to their homes. With this design if you do not eliminate the electric power infrastructure you would be looking at higher maintenance / operating costs because you would have to maintain the containment walls and the power grid. Keep in mind that Europes long praised train system built its reputation around diesel electric trains running affordably at speeds up to 120 mph. I am not sure when the obsession with electric HSR began, but ever since the Europeans went electric their rail systems have been bleeding money and requiring subsidies to operate. Beyond their use in flying trains, turbines might be the natural evolution from diesel electric engines. Another potential design / safety feature of this is putting the train in trenches to limit noise and improve access control. Beyond being sturdier than walls, they would make it easier to run the train under road crossings and limit other types of unintended access. The trench option would allow for simple roof structures to be put in place over the trenches to manage most weather situations. I say trenches because you really do not need to spend the money on tunnels when covered surface trenches will do the trick at a fraction of the costs.