Lotus 91

After several uncompetitive seasons with experimental or uncompetitive cars, Colin Chapman went back to basics and designed the Lotus 91, based in part on the Williams FW07 and Lotus' own 88 design. Powered by the Ford Cosworth DFV and using a standard Hewland gearbox, the 91 was uncomplicated and easy to maintain. Following Brabham's lead, the new car was the first Lotus chassis to use carbon brakes, improving braking performance considerably.

After a design study by Chapman into new composite materials, the decision was taken to build the car in carbon fibre and Kevlar, making it, after the McLaren MP4/1 and Lotus 87, the third F1 car to race to be built from the material - the Lotus 88 not having raced before it was banned.^[4]

Under the direction of Peter Warr, the team worked hard to make the car as competitive as possible. The lightweight chassis gave the 91 a fighting chance against the far more powerful turbo engined cars and Cosworth worked on a short stroke version of the DFV purely for Lotus' use.^[5] The sidepods were full length units, extending to the very back of the car to take full advantage of the ground effect aerodynamics. However the 91 was quite pitch sensitive, making it tricky to drive.^[6] The Lotus 91 was the basis for the Lotus 92 - which pioneered active suspension in Formula 1. This suspension was revolutionary, using an on-board system to control the ride height and behaviour of the suspension, thus the Lotus 92 was the first car to be fitted with active suspension. The system was partially controlled by computers but at this early stage was mostly operated by hydro-pneumatic valves.^[7]

Elio de Angelis used the car well but found the 91 was mostly competitive on ultra fast tracks like Hockenheim, Monza and the Österreichring. The latter track provided a thrilling final lap win for de Angelis against Keke Rosberg in the Williams.^[8] That win, as well as several other consistent results by de Angelis and a podium place by Mansell, helped the team to fifth in the final standings in 1982, before ground effects were banned for the 1983 Formula One season and the 91 was replaced by the first Lotus turbo car.

The 91 was the last Lotus F1 car to win a race under Colin Chapman's rule before he died of a heart attack on 16 December 1982.^[9]

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