Flying low with Maglev

Abstract

A new transportation system is on the horizon-the comfort and safety could lead to public acceptance of first in the history of man in which electrical and this new mode of transportation. electronics engineering seems destined to play the dominant role. Successful magnetic-levitation (Ma-A decade of search glev) high-speed ground transportation now appears When the need for high-speed ground transportaalmost certain for a variety of reasons. There is no tion was recognized some ten years ago, a worldwide fundamental flaw in using magnetic forces for both effort evolved to find suitable methods for reliable suspension and propulsion, and various technological suspension and propulsion. The early efforts concenoptions are available for optimizing system design. trated on improvements in conventional rail technolo-The system can operate with a relatively "soft" largegy, with attempts to adapt air-cushion suspension for clearance suspension that has no contact with the operation over a guideway. The magnetic system was ground, not even for power pickup.recognized as a theoretical possibility, but was never Energy consumption can be less than that for jet given the attention it deserved. Although today it has aircraft, even at Maglev speeds of 500 km/h (311 mi/ greater credibility than air-cushion suspension, it was h). Overall system economics are potentially superior only about six years ago that modern Maglev was to short-range aviation, if the Maglev system can at-born. tract a large number of users. When compared with a Recent approaches to achieving stable suspension railroad system operating at much lower speeds, the and guidance have developed along two rather dissystem clearly has cost disadvantages. However, there tinct lines, with many lesser variations of each of is no indication that railroads operating even at the these lines. One approach, the ferromagnetic attrachighest speeds they can sustain can satisfy man's tive system, and the first to be tested in an experiground transportation needs. If costs per kilometer mental vehicle, uses high-power solid-state control were the primary consideration, only railroads and systems to vary the current in an electromagnet and ships would be-on the scene today! achieves stability by means of feedback control. The The evolution of new Maglev concepts is proceeding vehicle magnet rides below a ferromagnetic rail and rapidly with no indication that the ideal compromise uses attraction forces for suspension. The second aphas been reached that will satisfy the many conflictproach-the superconductive inductive system-takes ing requirements. Because of Maglev's exciting possiadvantage of new high-field superconductors, and bilities, international competition is building up in uses motion of a dc magnetic field to create an ac the development of an operational passenger-carrying field in a conducting guideway. This approach prosystem. Activity is strong in Japan and Germany, duces suspension by a repulsive-force interaction bewith lesser efforts in the United States, Can...