thumb|right|A remaining section of the Aérotrain track near [[Saran, Loiret, 2006]]

The Aérotrain () was an experimental Tracked Air Cushion Vehicle

(TACV), or hovertrain, developed in France from 1965 to 1977 under the engineering leadership of Jean Bertin (1917–1975) – and intended to bring the French rail network to the cutting edge of land-based public transport.

Though similar to a maglev design, which levitates a train car over a complex electromagnetic track to eliminate all resistance other than aerodynamic drag, the Aérotrain – also a "train without wheels" The final prototype, the Aérotrain I80, set a world speed record in 1974 for overland air cushion vehicles, reaching a speed of and a peak speed of . The prototypes, which ultimately used twin turbine engines through a ducted propeller with seven blades, demonstrated they could accelerate and decelerate quickly, which offered a huge advantage of enabling effective service between tightly spaced stops. Prototypes used gas turbines with giant propellers, which created tremendous noise both inside and outside the train car itself – and thus required reduced speeds in urban areas. SNCF felt they already had trains that could run at those reduced speeds. Proponents pointed out electric linear induction motors could make the TACV silent. Eventually SNCF simply opposed the project, citing a broad litany of concerns. and SNCF formally shifted support to the TGV as its high-speed ground-transport solution. Notably, D'Estaing's wife was the granddaughter of Eugène Schneider, founder of what became an international syndicate, Schneider Group. Noted Belgian journalist Karel Vereycken pointed out: "the Schneider dynasty have been and are still a pillar of the history of the French railroad and steel industry. Hence, the innovation of the Aérotrain (to be built by the aircraft industry) would not, in the short run, have made them more wealthy and one can easily imagine that a train without wheels does not get much enthusiastic approval of the feudal wheel producers." Rohr abandoned the technology in 1975.

Test tracks

thumb|right|Aérotrain prototype #02

thumb|right|Prototype 02 of the aérotrain at an exhibition at Saran, 2009; rear view

thumb|right|Aérotrain I80 upon delivery in 1969

thumb|right|Artist's impression of a Rohr UTACV

thumb|right|A remaining section of the Aérotrain track in the forest of Orléans near Saran, 2006

thumb|right|Saran Aérotrain rail

thumb|right|Aérotrain guideway at Chevilly

Most of the track for the Aérotrain was constructed of ferroconcrete to provide an inverted "T" shape for the monorail, with the tracks ultimately used only for experimental purposes.

  • The first test track was long and was built in February 1966 in Gometz-le-Châtel, Essonne, France, for Aérotrains 01 and 02, re-using an abandoned railway formation. The track is visible today, partially demolished for urban expansion, with most of the remaining track in ruins. A section was kept and restored as a memorial at a roundabout in Gometz.
  • A second track made of aluminium and asphalt was built in 1969 for Aérotrain prototype S44 in Gometz-le-Châtel, built metres away from and parallel to the first track. The aluminium guide rail was disposed of after the tests, the rest of the asphalt track was kept intact and converted into a pedestrian path in 2008 and 2009.
  • In 1969, a third, 18 km test track was built to test Aérotrain prototype I80. This test track was in Loiret, France, north from Orléans, stretching between Saran and Ruan, a location that would enable it to be used in a future Paris-Orléans line. The track was elevated 5 m above the ground, was supported by pillars and allowed speeds of . A platform stood at each end of the line to reverse the train, while a hangar on the central platform at Chevilly housed the test vehicle. This line, while abandoned, became a famous landmark subject to disputes over its visual condition after the end of the Aérotrain programme – and remains today, visible to the east of RN20 and the Paris-Orléans railway line.
  • Until 1974, a fourth, test track was to be found at the High Speed Ground Test Center near Pueblo, Colorado in the United States. This test track was built for the UTACV prototype. Due to its length, it was suited only for a top speed of 233 km/h (145 mph).

Prototypes

Five prototypes were built:

  • Aérotrain 01 was a 1/2 scale (10.11 m, 2.6 t) prototype. It was originally propelled by a three-bladed reversible-pitch propeller powered by a aircraft engine, which was later replaced by a Turbomeca Marboré jet engine. The air cushion is maintained by two compressors. It had places for four passengers and two crew.
  • Aérotrain 02 (shown in picture in test track section) was another sub-scale prototype, seating two crew. It was powered by a Pratt & Whitney JT12 turbojet.
  • Aérotrain S44 was a full-size passenger-carrying car intended for suburban commuter service at speeds of 200 km/h (in particular links between city centres and airports). It was equipped with a Linear Induction Motor (linear motor) propulsion system supplied by Merlin-Gérin.
  • Aérotrain I80 was a full-size passenger-carrying car for intercity service. It was 25.6 m long, 3.2 m wide, 3.3 m high, had a mass of 11.25 t empty, and had 80 passenger seats. In its original configuration (as I80-250 for 250 km/h), it was propelled by twin Turbomeca Turmo III E3 turboshaft ( each) powering a ducted propeller, 2.3 m in diameter, with seven blades of variable pitch. A Turbomeca Turmastazou 14 turboshaft engine powered the air compressors – six vertical for support and six horizontal for guidance. Braking was typically provided by reverse thrust of the propeller, and in emergencies by a friction brake on the central rail. External noise was 90–95 dBA at .

The Rohr prototype, officially called the Urban Tracked Air Cushion Vehicle (UTACV) and colloquially the Rohr Aerotrain, was propelled by linear motor and was designed to carry 60 passengers at 240 km/h (150 mph). The museum plans to open an Aérotrain exhibit within the test vehicle.

Timeline

  • 1963 — Jean Bertin presents a 1/12 scale model, 1.4 meters in length, to the public authorities and to SNCF.
  • 15 April 1965 — Creation of the Société d'étude de l'Aérotrain (Company for the study of the Aérotrain).
  • 16 December 1965 — Completion of the construction of the first prototype, Aérotrain 01.
  • 21 February 1966 — Official inauguration in Seine-et-Oise (but now in Essonne) of the 6.7 km trial track for Aérotrain 01 between Gometz-le-Châtel and Limours (on the abandoned easement of the Paris-Chartres via Gallardon line). That day, in front of the press, Aérotrain 01 reached 100 km/h. Days later it reached 200 km/h.
  • 23 December 1966 — An added rocket provides a combined power of , the Aérotrain 01 reached a speed of 303 km/h.
  • 1 November 1967 — Equipped with a jet engine, Aérotrain 01 reached a speed of 345 km/h.
  • 1967 — Construction of Aérotrain 02. Of the four prototypes that had been built, the last two remain stored in Versailles, France.

Jean Bertin's company, now , remains in business, focusing on the aerospace, defense, and transportation sectors. Outside Orléans, the remains of the abandoned and partially-demolished elevated concrete test track still stand to this day, easily visible from the parallel SNCF Paris-Orléans railway.