SPECIAL: Won and done – the Brabham BT46B 'Fan Car'

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SPECIAL: Won and done – the Brabham BT46B 'Fan Car'

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SPECIAL: Won and done – the Brabham BT46B 'Fan Car'

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In 1978, Brabham’s Gordon Murray needed something big to beat the Lotus 79. His eureka moment came with the BT46B “Fan Car,” a Formula 1 legend that raced – and won – just once.

This story appears in the Oct./July 2021 ‘Great Cars Issue’ of RACER magazine alongside other great features including an interview with 2021 NTT IndyCar Series champ Alex Palou and a look back on the short, but memorable exploits of cars such as the Indy 500’s whispering turbines and Bentley’s Le Mans-winning Speed 8.

Click here to get your copy, or set yourself up for a full year of stellar motorsport writing and photography with a print or digital subscription.

Desperation. That’s what drove Gordon Murray to the most infamous eureka moment of his envelope-pushing career.

In early 1978, the South African designer was feeling the heat – much like his angular Brabham BT46. Its novel surface cooling that promised to do away with conventional radiators was an unmitigated flop, replaced by conventional radiators.

To make matters worse, as Brabham scrabbled to save its season, Lotus was sucking, too… in a far more effective sense. “Black Beauty,” the Type 79, was threatening to gallop away with the Formula 1 season thanks to the low-pressure alchemy brewing beneath its elegant full-length, sealed-skirt sidepods.

The “wing car” had landed, but Murray found himself grounded with little room for maneuver.

His problem was Carlo Chiti’s flat-12 Alfa Romeo, which was bigger and wider than the almost ubiquitous Cosworth DFV V8 and a hindrance in regard to the venturi tunnels he needed to generate ground-effect downforce. His first solution was a twin-monocoque design – a precursor to Colin Chapman’s 1981 Type 88, perhaps? – but the added weight and complexity made it a non-starter. Back to square one. Or at least the FIA rulebook.

Murray paused over the article on aerodynamics that would prove key: “Any device whose primary function is to have an aerodynamic influence on the performance of the car has to be firmly attached to the sprung mass.” There it was. Eureka! The key words were “primary function,” so Murray devised a plan: mount a conventional radiator horizontally over the engine and cool it with a fan hung out the back, driven via engine speed through the gearbox. The story he’d peddle was that a fortuitous side-effect created by fitting flexible skirts to seal the underfloor meant the fan also sucked the car to the ground.

After two private tests, the Brabham fan car went public at a Goodyear tire test at Brands Hatch. Not wishing to give away too many of the BT46B’s secrets, the car’s fan – key to producing suction – was covered with the lid of a trash can in the pits. Sutton/Motorsport Images

Even today, Murray still emphasizes the Brabham BT46 “Fan Car” was entirely legal, to the letter of the rulebook, because the primary function was cooling, not aerodynamic benefit. As he recently noted: “When the FIA measured the flow of air through the fan and through the radiator, they found that 60 percent of the air was for cooling and 40 percent for downforce, meaning that aerodynamics was not the primary function.”

Niki Lauda, the reigning world champion who’d quit Ferrari for Brabham in 1978, spelt out the reality in typically pithy terms. He nicknamed the car “the vacuum cleaner.”

The BT46B ran initially at Alfa’s Balocco test track in Italy, before Brabham boss Bernie Ecclestone booked a strictly private session back in England at Brands Hatch. The track was like Fort Knox according to those who got a whiff – but naturally a scoop photo was captured of the car with its giant fan standing proud below the rear wing.

Brabham then went public at a Brands F1 tire test, although every time the BT46B pitted it was wheeled into a garage and the shutter was pulled down. Still, prying eyes got a closer look when the car stopped out on the circuit. Brabham’s mechanics rushed to hide the device with the aid of a trash-can lid, the diameter of which happened to be a perfect fit.

Lauda’s teammate, John Watson, had his first taste at Brands. “My first thought was it’s a complicated bit of kit,” he tells RACER. “Is it going to work, or is it another surface cooling dream that Gordon’s come up with?”

In his book “To Hell and Back,” Lauda reckoned the fan car “unpleasant to drive. It understeered massively, all the more so when you took your foot off. The fan was powered by the engine, with the result that the suction effect fell off when the revs dropped.”

With Brabham careful not to show its full hand pre-race, Mario Andretti’s Lotus 79 started the Swedish GP from the pole. Niki Lauda’s BT46B (No. 1) tailed the Lotus in the early laps, before a small error by Mario was Niki’s cue to pass and pull away with “embarrassing ease.” Motorsport Images

Watson is more forgiving: “Downforce was always being generated, plus you still had front and rear wings. On full power in and out of a corner, you had the benefit of low-speed downforce that the Lotus didn’t get.”

All hell broke loose at Anderstorp when the fan car rolled out for its debut at June’s Swedish Grand Prix. According to Lauda, Ecclestone had been mindful to “apply to the sport’s governing body for an affidavit attesting the legality of the new design.” But Chapman immediately recognized the threat it represented, and he wasn’t alone.

“Tyrrell had a spitting fit and couldn’t get his words out,” says Watson. “Gordon needed to develop it and get a more refined sealing system, with Lexan skirting similar to what we used for ground-effect cars. There were still bleeds. Nevertheless, it generated a lot of suction.”

The key now was for Brabham not to give the game away on just how much suction… Lauda and Watson were under strict orders to take it easy in practice, but in the pitlane it was impossible to hide the effect of the fan. Each time the throttle blipped, the suction sank the car, which rose slightly again when the revs died.

“Bernie was leaning into the cockpit: ‘Don’t rev the engine when you’re sitting in the pits!’” recalls Watson. “But you had to keep the engine running and every time you gave it a blip, you could feel the car coming down. ‘Crude’ is an unkind word to use, but it was the first phase of what would have become a phenomenal amount of downforce.”

The campaign against Brabham went into overdrive, Chapman and Andretti stoking the fire on a safety angle. “That thing was an absolute goddam nightmare to follow,” insisted Mario. “You got right up behind it, and you just got showered with stones. Now suppose there was a bolt or something on the road, and that came back through the fan at you. I mean, it would be like a bullet! A visor wouldn’t help you.”

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