and

Electrically conducting sheet guideways for levitation offer potential advantages over discrete coil guideways in construction cost and ride quality. Sheet configurations, however, have lower electromagnetic lift to drag ratios than some coil-based EDS (eg- null-flux systems). Sheet guideways can have a large operational clearance capability if superconducting coils are used, and they are sufficiently “soft ” so that a secondary suspension is not necessary on the vehicle. To compensate for the low damping constant of the suspension, however, feedback control using the propulsion system, aerodynamic control sufaces or other means are required. The lift and drag forces are essentially constant at a given velocity for a sheet guideway as opposed to coil based EDS guideways in which the discrete nature of the coils necessarily results in time varying forces and, in turn, induced vibrations. Parametric results for sheet guideway levitation are presented for lift, drag, and minimum lift-off velocity, together with estimated spring constants for guidance in sample configurations. Design examples are presented and the potential advantages discussed. The latter includes lift per unit weight and drag per unit weight estimates for superconducting and permanent magnet levitation systems