be considerably simpler than the surface needed to support the same vehicle on wheels; hovertrains could be supported on surfaces similar to existing light-duty roadways, instead of the much more complex and expensive railbeds needed to support the weight on two rails. This could greatly reduce infrastructure capital costs. In 1960 several engineers at Christopher Cockerell's Hovercraft Development Ltd. in Hythe, Hampshire, began early studies on the hovertrain concept. At the time, a major problem was selecting a suitable power source. As the hovercraft had no strong contact with a running surface, propulsion was normally provided by an aircraft-like solution, typically a large propeller. This limits the acceleration, as well as the efficiency of the system, a major limitation for a design concept that would compete with aircraft on the same routes. Introducing the LIM Through the same period, Eric Laithwaite had been developing the linear induction motor (LIM) at the University of Manchester. By 1961 he had built a small demonstration system consisting of a LIM reaction plate and a four-wheeled cart with a seat on top. In 1962 he started consulting with British Rail (BR) on the idea of using LIMs for high-speed trains. A November 1961 Popular Science article shows his Hovertrain concept using a LIM, the accompanying illustration shows small lift pads like those from the Ford Levapad concept, running on top of conventional rails. After moving to Imperial College London in 1964, Laithwaite was able to devote more time to this work and perfect the first working examples of large LIMs suitable for transport systems. LIMs provide traction through the interaction of magnetic fields generated on the vehicle and a fixed external conductor. The external conductor was normally made of plates of aluminium, chosen due to its high conductivity in relation to its price. The active portion of the motor consists of a conventional electric motor winding stretched out under the vehicle. When the motor windings are energised, an opposing magnetic field is induced in the nearby reaction plate, which causes the two to repel each other. By moving the fields down the windings, the motor pushes itself along the plate with the same force that is normally used to create rotation in a conventional motor. A LIM eliminates the need for strong physical contact with the track, requiring instead a strong reaction plate. It has no moving parts, a major advantage over conventional traction.