1978 Brabham BT46B ‘fan car’

Controversial? Yes, but only because it was so brilliantly clever. Gordon Murray’s marvel would have changed the game, which is why his boss – with one eye already trained on Formula 1’s bigger picture – diplomatically withdrew it after a single race. Colin Chapman’s ground-effect coup was left in the dust when Niki Lauda won the 1978 Swedish GP by more than half a minute. This is that chassis. It subsequently finished second at the British GP as a non-fan car, but today it’s presented in the spec Murray intended – and in running condition. Perhaps more than any car in the collection, we’re intrigued by what it will go for at its first sale.

Brabham-Alfa Romeo win under a cloud, Anderstorp, June 17

The superiority of the Lotus 79 ‘ground effects’ car was severely challenged in the Swedish Grand Prix by the B–version of the BT46 Brabham-Alfa Romeo, a brilliantly conceived design even though there was considerable doubt as to its legality according to rules agreed upon by the Formula One Constructors’ Association and the CSI. The bone of contention was item 5 in Article 1 which, under the heading Aerodynamic Devices, the definition states: “Any part of the car whose primary function is to influence aerodynamic performance” is considered to be an Aerodynamic Device, and therefore according to Article 3, Item 7 “Aerodynamic devices must comply with the rules relating to coachwork (i.e. heights, widths etc) and must be firmly fixed while the car is in motion. It is permissible to bridge the gap between the coachwork and ground by means of flexible structures subject to the coachwork measurements”.

The Brabham team made experiments with BT46/2, one of their earlier tests cars, and arrived in Sweden with BT46/6 (Lauda) and BT46/4 (Watson) modified in a similar manner. They had a large single water radiator lying flat on top of the Alfa Romeo flat-12 engine with the whole of the rear of the car between the wheels, totally enclosed and sealed off, with the exception of the upper surface of the radiator. At the back a very large fan was driven off the rear of the gearbox and this sucked all the air out from around the engine/gearbox area, which naturally caused cooling air to flow down through the horizontal radiator. So far so good.

If the path from the underside of the radiator to the fan had been ducted and sealed there would have been no further discussion, but it was not. The fan could also suck away all the air around, and under the engine and also under the car. Flexible skirts under the car at the front, sides and rear, effectively sealed off the underside of the car so that the fan was creating a low pressure area under the car, causing a down load to be applied to the car (in effect, the reverse of a hovercraft). Now the important factor was that the Brabham team said that the primary function of the device was to draw air through the radiator and cool the engine. That was what they said. The arguments arose because some, principally Lotus, McLaren, Tyrrell, Surtees and Williams, did not accept what the Brabham team said. They maintained that the primary function influenced aerodynamic performance and therefore by Art. 3 It. 7 it had to be fixed while the car was in motion.

Before the race the Swedish organisers received five official protests, but turned them down and allowed the Brabhams to take part. Niki Lauda really pressed Andretti’s Lotus 79 throughout the first 37 laps of the 70 lap race, and we saw a piece of real motor racing demonstrated by two hard drivers, and they left the rest of the field far behind. On lap 38 Lauda went by into the lead and eight laps later there was an almighty bang as the Cosworth DFV in the Lotus destroyed itself, leaving the controversial Brabham to cruise to an easy victory. Putting aside aerodynamics and rules and regulations, it was a superb demonstration of motor racing. DSJ

Taken from Motor Sport, July 1978

Brabham BT46B

Year 1978
Designer Gordon Murray
Races 1
Wins 1
Poles 0
Fastest laps 1