The Brabham BT46 was a car designed for the Bernie Ecclestone owned Brabham Formula 1 team for the 1978 season. The B version of the car was introduced at the 1978 Swedish Grand Prix (third round of the season) as a counter to the dominant ground-effect Lotus 79 and immediately made headlines. The ‘fan car’ as it became known had arrived, however its’ future was short lived.
The initial T46 for the 78′ season featured several radical design elements, one of which was the use of flat panel heat exchangers on the bodywork to replace conventional water and oil radiators. Engineer David Cox, upon seeing pictures of the car, calculated that the BT46 had only around 30% of the cooling surface area required. He contacted Brabham to express his concerns.
Eventually the BT46 raced competitively with nose-mounted radiators similar to the previous BT45 for most of the year,. Drivers by Niki Lauda and John Watson were able to win one race in this form and scored enough points for the team to finish third in the constructors championship.
The BT46B Fan Car generated an enormous amount of downforce using it’s gearbox mounted fan, which the team claimed to be for increased cooling, but which also extracted air from beneath the car. The car raced in this configuration in the Formula One World Championship for a single race — the 1978 Swedish Grand Prix at Anderstorp, which was duly won by Niki Lauda. The B specification BT46 was withdrawn by Brabham after one race even though the FIA had ruled it could be used for the remainder of that season. Gordon Murray, designer of the car, later said that the car was withdrawn by Brabham due to concerns from Bernie Ecclestone, the team owner.
The BT46 was an aluminium alloy monocoque featuring the trapezoidal cross section common to many of Gordon Murray’s 1970s designs. It featured inbuilt pneumatic jacks fed from an external supply of compressed air to lift it off the ground for tyre changes during practice. It employed a very early version of the carbon brakes that were in universal use by the mid-1980s—a concept taken from the aircraft industry. The system, which Brabham had been developing since 1976, combined carbon composite brake pads with a steel disc faced with carbon composite ‘pucks’.
Cox produced the overall layout for the car, utilising the cooling properties of the fan to be able to argue that this was its primary purpose, thus satisfying the regulations. Gordon Murray designed a version driven by a complex series of clutches running from the engine to a large single fan at the back of the car, anticipating problems caused by the momentum of the fan during gear changes, although in practice these were not required. Therefore, the faster the engine ran, the stronger the suction effect. Like the Lotus, it had sliding “skirts” that sealed the gap between the sides of the cars and the ground. These prevented excessive air from being sucked into the low pressure area under the car and dissipating the ground effect. There was a rule banning “moveable aerodynamic devices”, but the fan also drew air through a horizontally mounted radiator over the engine. Using a fan to assist cooling was legal—Brabham had used a small electric fan to this effect on the BT45Cs at the South American races at the start of the year—and Brabham claimed that this was the primary effect of the new device. These claims were lent some legitimacy by the cooling system issues that had affected the original design at the start of the year.
Brabham’s lead driver, Niki Lauda, realised he had to adjust his driving style, mostly for cornering. He found that if he accelerated around corners, the car would “stick” to the road as if it were on rails. two modified cars were prepared for the Swedish Grand Prix at Anderstorp on 17 June 1978, for Niki Lauda and John Watson. When not in use, the fan was covered by a dustbin lid, but it soon became clear what the modified Brabham was intended to achieve: when the drivers blipped the throttle, the car could be seen to squat down on its suspension as the downforce increased. Lotus driver Mario Andretti said
“It is like a bloody great vacuum cleaner. It throws muck and rubbish at you at a hell of a rate”.
There was uproar from rival teams, who saw the “fan car” as a threat to their competitiveness. Although the car was not considered illegal, it was withdrawn and would never race again.
Chassis: Aluminium Monocoque
Suspension (front): Pullrod double wishbone
Suspension (rear): Pullrod double wishbone
Axle track: Front: 1,549 mm (61.0 in)
Rear: 1,626 mm (64.0 in)
Wheelbase: 2,590 mm (102 in)
Engine: Alfa Romeo, 2,995 cc (182.8 cu in), Flat-12, NA, Mid-engine, longitudinally mounted
Transmission: Brabham / Alfa Romeo 5/6-speed manual, Alfa Romeo Differential
Fuel: Fina Agip