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Cranfield Motorsport Simulation (CMS), in the 80’s known as Flight System and Measurement Laboratories (FSML), and Lotus started researching active suspension, originally intended to equip its Formula One racing cars. CMS developed the control laws and electronic hardware and Lotus the hydraulic system, integration with the host car and of course the Lotus name. The active F1 ran in Brazil and Long Beach '83 in the hands of Nigel Mansell. Despite lacking competitiveness, it proved that active suspension could withstand hard use at 180 mph and 3 g lateral acceleration. The development team went back to the drawing board and did more tests to improve the software. It was not raced again until 1987, when the Honda-powered 99T won 3 races in the hands of Ayrton Senna.
However, the active suspension did not offer sufficient advantage in F1 racing. Theoretically, it could raise cornering speed considerably ("Cornering at 200mph" used to Team Lotus's slogan), but on the down side, its hydraulic pump consumed too much horsepower. I don't have the exact figure, but years later Lotus told us the active suspension in its Excel development car consumed 4 - 4.5 hp on smooth road and up to 9 hp on rough road. Worst of all, Team Lotus did not get specially developed tyres to extract its potential. As the active suspension reduced the tyre's slip angle, the tyres generated insufficient heat to attain the necessary working temperature.
Just after the F1 debut in the 1983 season, CMS and Lotus Engineering started developing the active suspension technology for production car use. It used the Esprit as the development platform. Like the racing car CMS, used hardware - hydraulic actuators and control valve came from the aerospace industry, where active control was used in advanced jet aircraft. The most crucial element of the active suspension was the software rather than hardware. Hours of road testing was used to acquire the necessary data in order to write the program.
The first 2 generations were springless, but the Mk III and Mk IV system, which were equipped in the Excel development cars, had springs as back-up in case the active system broke. The software was gradually improved. British magazine Fastlane tested them twice, once in the '87 Mk III and then in the Mk IV two years later. In the latter it reported significant improvement in ride quality and body control. It also expressed full optimistic that the system would go into mass production within a few years, probably under the name Volvo, Chevrolet or Mercedes-Benz, as they all had been consulting Lotus.