Other Applications: Launching Rockets?
|
|
INDUCTRACK LAUNCHER could provide the initial boost for future spacecraft. The craft could be mounted on a levitation "launch cradle" that would glide up a sloping one-kilometer-long track. Unimpeded by wheel friction, the cradle could accelerate the spacecraft to 950 kilometers per hour. The craft's engines would then ignite and propel it into orbit. |
After the construction of the test track at Livermore, officials at the National Aeronautics and Space Administration became aware of our work. As a result, the space agency awarded the laboratory a contract to build another model, aimed at demonstrating a very different application of the Inductrack concept. Studies by NASA have shown that if their rockets could be accelerated up a sloping track to speeds on the order of Mach 0.8 (950 kilometers per hour) before the rocket engines were fired up, it could substantially cut the cost of launching satellites. Such a system could reduce the required rocket fuel by 30 to 40 percent, thereby making it easier for a single-stage vehicle to boost a payload into orbit. Our Inductrack model, which will have a track about 100 meters long, will be designed to accelerate a 10-kilogram "launch cradle"-the rocket's platform-to speeds of about Mach 0.5 (600 kilometers per hour). Because of the shortness of the test track (compared with the kilometer-or-so length of a full-scale system), the electrical drive circuits for the NASA model must achieve 10-g acceleration levels. In a full-scale system the acceleration levels, limited by the strength and weight of the rocket itself, would be more modest, on the order of 3 g's.
Another possible application of the Inductrack was conceived by California inventor and entrepreneur Douglas J. Malewicki. His proposed maglev system, known as SkyTran, would transport small, two-passenger cars at up to 160 kilometers per hour. The podlike cars would be suspended from a monorail-type track that would support the levitating circuits. The cars would be available, on call, at each station in the system. After the passengers board a car, it would glide up to the main track and merge with the traffic speeding by the station. As a car approached its destination, it would switch to an exit track, dropping down to the station to allow the passengers to disembark.
As with any new technology aimed at improving or supplanting an older one, only time will tell how the Inductrack will be employed. In making the transition from theory and models to a fullscale system, several technological issues will have to be addressed. For example, to make the Inductrack's ride more comfortable, the system must damp out motions caused by aerodynamic forces. Another challenge would be clearing the track of any metallic junk that might be attracted to the Halbach arrays. (To accomplish this, the train's lead car could conceivably be equipped with the magnetic equivalent of a cowcatcher.)
In addition, the Inductrack's designers face the economic challenge of keeping costs low enough to provide a compelling advantage over conventional railways. I believe, however, that the essential simplicity and flexibility of the concept will ensure that it finds many applications-not only for high-speed rail systems but also for uses that we have not even imagined.
_______________________________________________
The Author
RICHARD E POST is a senior scientist in the energy division of Lawrence Livermore National Laboratory in Livermore, Calif. He is also professor emeritus at the University of California, Davis. He received his Ph.D. in physics from Stanford University in 1951 and was involved in controlled fusion research at the Livermore laboratory for four decades. His other research interests have included electron physics, traveling wave linear accelerators and energy storage. He gratefully acknowledges the contributions of J. Ray Smith, project leader, and William H. Kent, lead technician, in the construction and operation of the Inductrack model, and of Louann S. Tung, project leader for the NASA Inductrack model.
Further Information
More information on the Inductrack system is available at www.llnl.gov/str/Post.html
on the World Wide Web.
The home page of the Railway Technical Research Institute, developer of the
Japanese maglev, is at www.rtri.or.jp/index.html
on the World Wide Web.
The home page of the Transrapid System, the German maglev, is at www.maglev.com/english/index.htm
on the World Wide Web.
_______________________________________________