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  Article Image gallery (60) Chassis (3) Specifications  
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Country of origin:Great Britain
Produced in:1968
Numbers built:4
Designed by:Maurice Phillippe and Colin Chapman
Successor:Lotus 64 Ford
Author:Wouter Melissen
Last updated:October 16, 2014
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Click here to download printer friendly versionOnly a few years earlier, the Indy 500 was dominated by the very conservative front-engined 'Roadsters' but by the second half of the 1960s, the cars racing at the 'Brickyard' represented the absolute cutting edge. Two of the men responsible for these rapid changes were Colin Chapman, who, in 1965, fielded the first mid-engined car to win the race and STP supremo Andy Granatelli, who backed the turbine-engined special for Parnelli Jones in 1967. For the 1968 race, the two joined forces to field a team of Pratt & Whitney powered Lotuses, rightly described at the time as the most sophisticated racing cars ever constructed.

Dubbed the Lotus 56, the all-new Indy racer was built around a full-length aluminium monocoque chassis. The fuel was stored in vast tanks in the two side-members of the chassis. Suspension was by double wishbones on all four corners, with the coil springs, dampers and disc brakes mounted in-board to reduce the unsprung weight. The rolling chassis was clothed in an altogether less conventional wedge-shape body. The body effectively formed a single line from the low and sharp nose to the tall, cut-off tail. As the turbine engine did not need a radiator, the clean lines were not disturbed by a large radiator opening. Carefully developed in the wind-tunnel, the design was deceivingly simple.

To power the new Lotus, Chapman and Granatelli had signed an exclusive deal for the use of a Pratt & Whitney industrial turbine that could be modified to meet the regulations. These restricted the amount of fuel and air fed into the turbine. The modified Pratt & Whitney engine featured a three-stage compressor and depending on ambient temperature and altitude produced around 430 bhp. The turbine was mated to a Ferguson all-wheel drive system with the transfer box mounted between the driver and the engine. This system had already been tried and tested in Ferguson's own cars that had run at Indianapolis between 1964 and 1967. Due to the engine's abundance of torque across the rev-range, no conventional gearbox was needed.

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  Article Image gallery (60) Chassis (3) Specifications