Throttle-Back Thursday: Lauda was untouchable in the notorious Brabham BT46B ‘fan car’

It was hard enough to keep up with Lauda even when he wasn’t piloting skunkworks machinery like the BT46B, but the so-called fan car’s performance edge made him untouchable — until it was banned, at least.

One relatively short but engrossing chapter in the late Niki Lauda’s celebrated Formula 1 career is the Brabham BT46B, the infamous, rules-skirting “fan car.” It dominated the sole race in which it participated, demonstrating its effectiveness so stunningly that it was quickly banned. It’s such a novel, bold machine that it’s worth revisiting today.

The BT46B’s was Brabham’s quickly improvised attempt to harness the power of ground effect. The idea was to reduce pressure beneath the car, essentially sucking it to the track (in addition using airflow over aerodynamic surfaces, like wings, to generate more conventional downforce). While Colin Chapman induced ground effect by modifying the underside of the Lotus 78 to lower pressure by aerodynamic means, packaging issues with the BT46 prevented the Brabham team from carving out underbody channels. Instead, designer Gordon Murray hit upon another way of accomplishing the same end, one that’s so obvious it almost hurts in retrospect: Use a fan to simply suck all the air out from beneath the car. Well, duh!

Unlike the earlier Chaparral 2J, the fan at the back of the car that was eventually dubbed the BT46B was driven by the Alfa Romeo flat-12 (rather than a separate engine — a small two-stroke in the case of the 2J). The way the team was able to skirt regulations banning movable aerodynamic features was mounting the fan alongside a radiator, calling it a cooling device and basically daring other teams to prove otherwise. That allowed it to adhere, more or less, to the letter of the law … and that’s what racing is all about, right?

To help keep things under wraps, a garbage can cover was strapped over the fan ducting when it wasn’t on the track. These days an F1 team would probably use a custom-made carbon fiber assembly costing more than new Miata.

The BT46B’s shining moment — and sole race because it was quickly banned — was the 1978 Swedish Grand Prix. Though behind the wheel of the so-called sucker car, Lauda was able to best Mario Andretti’s Lotus 79, stopping the Italo-American’s winning streak in spectacular, buzz-worthy fashion. 

Yet despite offering the coveted unfair advantage, Lauda reportedly did not particularly like the BT46B: He saw it as a fundamentally artless way to achieve superiority, one that relied more on fancy, complicated machinery than driver skill. Plus, the harder you drove it, the harder it sucked down to the track; it cornered so well (what a problem to have!) that it apparently subjected drivers to exhausting lateral g loads, making it punishing to drive for long stints.

In any case, it’s a Formula 1 footnote that’s still fascinating to learn about today. We covered the ’78 Swedish Grand Prix in the June 30, 1978, issue of Autoweek; check it out below.

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