Flying low may help solve transportation problems
By Joe Kleinsasser
 Glen Zumwalt, distinguished professor emeritus of aerospace engineering, looks at a piece of the Airtrain scale model, which would be a high-speed ground transportation system that would "fly" passengers to their destinations. |
It has wings, but it’s not a plane. It needs rails, but it doesn’t stay on them. What is it?
If Glen Zumwalt is right, the Airtrain, an alternative method of transportation, will dramatically change the way Americans travel.
The Airtrain, designed to run on electricity, would use a fixed rail system and an aerodynamic vehicle to carry 60-72 passengers at speeds up to 200 mph. At lower speeds, for travel in a city, it would run along an overhead rail strung along towers that are at 100-foot intervals. At higher speeds, it would lift off the railing and "fly."
Proximity sensors would measure the position of the craft from the rail. Once the Airtrain is airborne, the rails would serve primarily as a guide. In case of an emergency, they would become a landing place.
Zumwalt believes the Airtrain can help meet the transportation needs of America. Unlike trains, the Airtrain would not require bridge-type structures all along the route, and it wouldn’t divide up property, towns and farmland.
The Airtrain also can provide relief from the crowded skies and multi-lane highways.
After working as a Wichita State aerospace engineering professor for 24 years and retiring in 1992, Zumwalt teamed with retired Boeing engineer Elvest Lehl to develop Airtrain.
Zumwalt credits Lehl for being ahead of the times and having the idea nearly 30 years ago. Neither had time to actively pursue the dream, so they put it on the back burner.
"It wasn’t until we both retired that we got very serious about this," says Zumwalt. "We got some investors to help us do the first expensive thing, and that was to get a very good computer simulation.
"Boeing-Seattle does this better than anyone so we contracted with them to take our geometry, our design and run a series of tests on it."
The results confirmed their belief that the idea was basically sound.
Designing the Airtrain required some ingenuity. "You can’t use airplane engines," says Zumwalt. "Nobody is going to put up with the noise and pollution. At low speeds we will have motors that drive the wheels.
"Very quickly we go to the propellers driven by electric motors for efficiency and less noise.
"Of course this is the first electric airplane. Nobody has ever had a long enough extension cord."
The wingspan of the Airtrain must be kept below 65 feet to permit travel between city buildings and to keep right-of-way requirements low in the countryside.
 Mark Murrell, a research machinist, readies the model of a possible new mode of transportation for testing in WSU's wind tunnel. |
"The idea is beautiful, but it is also aerodynamically difficult," says Zumwalt. "When you have side winds, airplanes always turn into the wind. This causes them problems only in landing. But the Airtrain always has to be parallel to the track. So this will be the first aircraft that cannot crab (turn) into the wind."
To combat the problem of crosswinds, the inventors created independently tilting wings and four hinged wing tips.
The wings also are different, since flying is naturally more efficient when the wings are long and thin. Zumwalt says because the wingspan of the Airtrain has to be limited, they put two wings in the design.
The Airtrain will feature tandem wings, a low front wing and a high back wing.
After some final tests in the WSU wind tunnel this month, Zumwalt says they will have gone as far as they can with the model. The next step is to try and sell the design to an aircraft company or a consortium.
Finding a home for the invention has been difficult from the beginning for Zumwalt and Lehl. It has perplexed government agencies as well.
In the late 1970s and early 1980s the inventors made some preliminary proposals to the Department of Transportation.
The DOT sent it to the railroad commission, but it said it wasn’t a railroad.
The DOT sent the idea to the Federal Aviation Administration, but it said it wasn’t an airplane.
Nevertheless, Zumwalt says they weren’t discouraged. "A lot of people find this intriguing. A lot of investors are people with aircraft background.
"Our motivation is that this is an affordable system if it can be made to work. The market is transportation between cities 100 to 300 miles apart where both the roads and skies are overcrowded."
Even if the Airtrain becomes a reality, you probably won’t find it in Kansas. The Airtrain would have a better chance for success on the heavily populated coasts with possible routes from Los Angeles to San Francisco, Portland to Seattle, or New York to Washington, D.C.
In order for the Airtrain to become a viable travel alternative, the cost of a trip will have to be comparable to airline travel. Zumwalt says that’s possible by Airtrain, but not by any other available transportation system.
"Remember, all of our transportation systems are tax subsidized," says Zumwalt. "The airlines do not build the airports or maintain the flight control systems.
"We pay for the highways with our taxes. So realistically this would probably require a subsidy, but it cannot be exorbitant.
"If we don’t go that direction (electric power) then the air pollution problem becomes worse and worse in the cities."
Whether American drivers can be lured from their cars remains to be seen. Some transportation authorities believe that the early 21st century will be the era of high-speed trains. Higher fuel costs along with crowded highways and skies may be the ticket to make the Airtrain an appealing travel alternative.
"While challenging, the prospects for succeeding are believed to be excellent," says Zumwalt. "This or something very much like it will happen."
More on the Airtrain can be found online at Airtrainnow.com.
