The gyro monorail, gyroscopic monorail, gyro-stabilized monorail, or gyrocar are terms for a single rail land vehicle that uses the gyroscopic action of a spinning wheel to overcome the inherent instability of balancing on top of a single rail. The monorail is associated with the names Louis Brennan, August Scherl and Pyotr Shilovsky, who each built full-scale working prototypes during the early part of the twentieth century. A version was developed by Ernest F. Swinney, Harry Ferreira and Louis E. Swinney in the US in 1962. The gyro monorail was never developed beyond the prototype stage. The principal advantage of the monorail cited by Shilovsky is the suppression of hunting oscillation, a speed limitation encountered by conventional railways at the time. Also, sharper turns are possible compared to the 7 km radius of turn typical of modern high-speed trains such as the TGV, because the vehicle will bank automatically on bends, like an aircraft, so that no lateral centrifugal acceleration is experienced on board. A major drawback is that many cars – including passenger and freight cars, not just the locomotive – would require a powered gyroscope to stay upright. Unlike other means of maintaining balance, such as lateral shifting of the centre of gravity or the use of reaction wheels, the gyroscopic balancing system is statically stable, so that the control system serves only to impart dynamic stability. The active part of the balancing system is therefore more accurately described as a roll damper. Historical background Brennan's monorail The image in the leader section depicts the 22 tonne (unladen weight) prototype vehicle developed by Louis Philip Brennan. Brennan filed his first monorail patent in 1903. His first demonstration model was just a box containing the balancing system. However, this was sufficient for the Army Council to recommend a sum of for the development of a full-size vehicle. This was vetoed by their Financial Department. However, the Army found from various sources to fund Brennan's work. Within this budget Brennan produced a larger model, , kept in balance by two diameter gyroscope rotors. This model is still in existence in the London Science Museum. The track for the vehicle was laid in the grounds of Brennan's house in Gillingham, Kent. It consisted of ordinary gas piping laid on wooden sleepers, with a wire rope bridge, sharp corners and slopes up to one in five. Brennan demonstrated his model in a