Giorgio Piola's F1 technical analysis
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Giorgio Piola's F1 technical analysis

Banned: The full story behind Brabham's F1 'fan car'

Few cars in Formula 1 history made such an immediate impact, and been such a long-lasting talking point, as the famous Brabham 'fan car' that won on its debut at the Swedish Grand Prix in 1978.

That season had been dominated by the Lotus 79, which introduced the world to 'ground effect' and led to championship glory for Mario Andretti.

However, it was this other machine that captured the hearts and minds of everyone involved in the sport that year too – the Brabham BT46B, or the fan car as it's more affectionately known.

Lotus had the jump on everyone when it came to ground effect, as it had introduced its first car to utilise it a year earlier. But the Lotus 78 wasn't as successful as anticipated as the secret sauce needed to make the sidepod wings work – the skirts – needed development.

The team took five victories in 1977 but it wasn't enough for them to challenge Ferrari, and it only finished two points ahead of McLaren. Owing to this, most of the grid hadn't realised the 78's potential so, when the 79 arrived, they were all too late to respond.

Brabham BT46, the brainchild of Gordon Murray, Brabham Designer

Brabham BT46, the brainchild of Gordon Murray, Brabham Designer

Photo by: David Phipps

Meanwhile, over at Brabham, it was set to introduce the BT46 for the 1978 season. This was a car that was set to use a revolutionary heat exchanger setup, rather than conventional water and oil radiators, in a bid to save a considerable amount of weight.

Having tested the new car, Brabham and its chief designer Gordon Murray had to concede that the panels laid out on the slanted sidepod bodywork didn't provide sufficient cooling and the BT46 would have to be redesigned.

Brabham BT 46

Brabham BT 46

Photo by: Giorgio Piola

The BT46 was unveiled for the second time at the third round of the championship, in South Africa and featured the front mounted radiator arrangement that the car's predecessors had all utilised.

This was a design the team was hoping to ditch in favour of improved aerodynamics, and the aforementioned weight reduction. Meanwhile, stacked atop the engine, more radiators littered the '46's previously untarnished rear end.

Murray continued to ponder the design rationale behind the Lotus 78 throughout, which now, in its second season, was proving to be more reliable and thus relatively more successful.

Both he and McLaren had toyed with V-shaped air dams on their cars in previous seasons to create a localised low pressure region. But he soon worked out that the 78 appeared to be using these full length skirts with the sidepod underwings to create a combined effect.

Lotus 79 1978 detailed overview

Lotus 79 1978 detailed overview

Photo by: Giorgio Piola

The problem for Brabham and Gordon Murray was that he knew only too well that its car couldn't accommodate the wing-shaped sidepod tunnels that were necessary, owing to the team's use of a flat-12 Alfa Romeo engine.

Instead he'd have to think laterally and decided upon a controversial method to equip his B-Spec Brabham with even more downforce.

Chaparral 2J

Chaparral 2J

Photo by: Mike Stucker

It's unclear if the inspiration for the BT46B came directly from the Chaparral 2J, but the boxy sportscar, eight years its junior, had also employed skirts and fans to create negative pressure under the car. However, where Chaparral had been able to use a separate engine to power the rear fans, the BT46B would not only need to run off the Alfa engine, it would also need to be seen to be cooling it.

After all, having studied the rulebook and consulted with various parties, it was widely accepted that so long as cooling was the primary purpose for the fan being on the car it would be considered legal.

The team immediately set about making sure that was the case, with over 50% of the fan's duty to be considered as cooling for the radiators. This would leave plenty of margin for the fan to create the necessary negative pressure beneath the car.

Brabham BT46B 1978 fan car detail view

Brabham BT46B 1978 fan car detail view

Photo by: Giorgio Piola

Just as Lotus had issues with the skirts on the 78, Brabham knew it too would face a similar challenge to keep the edge of the floor sealed. Upon doing so, its cars would be visibly sucked to the floor, even when stationary.

As such, the car needed to be driven counter intuitively, with the driver having to add throttle to counter the understeer he'd normally get on corner entry, rather than lift out of the throttle. This paired, with the potential for a failure of a skirt, led to a pitot tube being mounted on the car's nose whilst an altimeter was rigged-up in the 46B's cockpit.

On corner entry, the driver would monitor the gauge and accelerate if the gauge was in the green and would know he had to slow, as a skirt had failed, if it was in the red.

The car was rushed into action as the team saw how dominant Lotus was becoming, and it was finally unveiled at the Swedish GP, amidst a furore of consternation from the rest of the teams.

Rivals were suitably outraged by the BT46B and immediately lobbied for its removal from the event. But, having done his due diligence with the governing body ahead of time, Murray was certain it would uphold its inclusion.

It's a pretty widely known fact that Bernie Ecclestone, then owner of the Brabham team and executive of FOCA had a rather difficult balancing act on his hands. Worried about the sheer speed of the BT46B compared with the Lotus 79, which at the time was noticeably quicker than anything else, he ordered the drivers to qualify on full tanks and use the hardest compound of tyre.

He even went as far as to speak to his drivers - Niki Lauda and John Watson - asking them to deliberately under drive their cars, so as not to show their true pace.

The car was still remarkably quick though and seeing as rivals had failed to win the battle to get the car banned on a technical front, other drivers began to voice their concerns over safety. Mario Andretti, cajoled by team boss Colin Chapman, was the most vocal and claimed the car was throwing dirt and stones out the back of the car.

It's the same tactic that was used to have the Chaparral 2J removed from competition in sports cars, so a worthwhile venture.

But, it would be Ecclestone who'd have the last say. With Lauda winning the race, Ecclestone knew he had to placate FOCA, so agreed to withdraw the car from use after the Swedish GP. But that was not before trying to negotiate being able to use it for three races...

The BT46B 'fan car' still holds a mythical status in F1 to this day, owing to the 'What if' scenarios that could have unfolded had Brabham continued to use the car. It also remains the only F1 entrant with a 100 percent win record.

Mario Andretti, Lotus 79 Ford, leads John Watson and Niki Lauda, both Brabham BT46B Alfa Romeos, at the start
Mario Andretti, Lotus 79 Ford, leads John Watson and Niki Lauda, both Brabham BT46B Alfa Romeos, at the start
1/6

Photo by: Motorsport Images

Niki Lauda, Brabham BT46B
Niki Lauda, Brabham BT46B
2/6

Photo by: Sutton Images

Brabham BT46 "Fan Car"
Brabham BT46 "Fan Car"
3/6

Photo by: Sutton Images

The rear end of Niki Lauda's Brabham BT46B Alfa Romeo fan car.
The rear end of Niki Lauda's Brabham BT46B Alfa Romeo fan car.
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Photo by: Motorsport Images

The rear end of Niki Lauda's Brabham BT46B Alfa Romeo fan car.
The rear end of Niki Lauda's Brabham BT46B Alfa Romeo fan car.
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Photo by: Motorsport Images

The controversial Brabham Alfa Fan car made its debut in Anderstorp.
The controversial Brabham Alfa Fan car made its debut in Anderstorp.
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Photo by: Motorsport Images

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