The Lotus 78 was setting the way for Formula One. It showed the potential of ground effects in 1977. The Lotus was, for all intents and purposes, the first real attempt at ground effects. Chapman and the Lotus developers realized they could gain some advantage of downforce without the heavier drag caused by more conventional wings. They were refining their ideas with the Lotus 79 for the 1978 season.
Gordon Murray - yes, the same Gordon Murray that designed the McLaren F1- was designing for Brabham at the time. He had a sense of what Lotus was developing, and knew the potential of ground effects. But even if he wanted to replicate their Venturi tunnels, the flat-12 Alfa engine the Brabham team was using at the time was not a good fit. It was too wide, and wouldn't allow them to gain enough space to take advantage through the use of tunnels. Yet he knew he wanted to lower pressure under the car. He recalled the success Jim Hall had in 1970 with his Chaparral 2J 'sucker car' in the Can Am series, prior to being banned from that series.
In Hall's Chaparral, the two fans were driven by a dedicated two-stroke engine. Murray utilized a complex series of clutches running from the engine to one large fan at the back of the car. The advantage of the Murray design versus Hall's was that the faster the engine ran, the more suction was created.
Niki Lauda was Brabham's lead driver at the time. In his autobiography, louder described the car as unpleasant to drive due to the heavy lateral loads. He was on the leading edge of the transition from pure mechanical grip and driver skill to one of larger driver physical effort and aerodynamic g- loading.
The two Brabham fan cars, which were essentially heavily modified BT46s, debuted at the Swedish Grand Prix at Anderstorp in 1978, driven by Niki Lauda and John Watson. The secretive tech was concealed until the last possible minute, including covers over the fan openings.
The BT46B qualified in both second and third place behind Andretti in the ground effects Lotus. Based on this unanticipated success, the car was protested before the race even began. At the time, there was a rule in F1 prohibiting "movable aerodynamic devices", but since the fan also drew air over a radiator it was able to be classified as a cooling fan. They were allowed to continue for the race pending a more formal ruling.
While Watson spun in a back-marker car's oil, Lauda passed Andretti, going on to win the race by over half a minute. This only exacerbated the quantity and intensity of the protests. The owner of the Brabham team at the time, Bernie Ecclestone - yes, that Bernie Ecclestone - had just transitioned from the secretary of the Formula One Constructors Association (FOCA) to its president. Colin Chapman of Lotus and the other heads of the FOCA teams threatened to withdraw any support of Ecclestone as president unless he discontinued racing the BT46B. Ecclestone crafted an agreement with the FOCA in which the car would have been discontinued after three more races. That agreement was nullified, as the Commission Sportive Internationale intervened and declared definitively that fan cars would not be allowed in Formula One. The ruling did not overturn the Swedish Grand Prix victory, though.
In light of the ruling, the cars were returned to their standard configuration. Brabham finished the 1978 season third in constructor's championship points. In the 14 races of the 1978 season the various Brabham BT46 models raced, they only completed five, retiring from all other races. In those five races completed, Lauda was always on the podium, including two overall victories, one of them coming from the 'fan car'.
Just like the Tyrrell P34 'Six-wheeler' discussed in a previous article, the Brabham BT46B is just another large and successful attempt at innovation that got lost in the shadow of the paradigm shifting Lotus 78 and 79.