NOW THAT WAS A CAR
The story of the controversial but successful Brabham BT46B
Fans attending the Gunnar Nilsson Memorial Trophy at the recently reopened Donington Park on 3 June 1979 might have gone home disgruntled at the complete lack of a Formula 1 race – Silverstone and Brands Hatch’s owners had lobbied the FIA to nix it – but in future years they would come to cherish having witnessed two historic final outings. In the five-lap time-trial event which replaced the planned Race Of Champions-style non-championship F1 thrash, James Hunt essayed his final competitive laps in an F1 car (he announced his retirement four days later) while British F3 champion and F1 rookie Nelson Piquet intrigued the crowd with a car making only its second ever appearance in front of a paying audience, and its last for the better part of three decades: the Brabham BT46B, better known as the ‘Fan Car’.
Hampered by unfamiliarity with Brabham’s superseded Alfa Romeo flat-12 engine, Piquet was also rolling on higherprofile 1979-spec rear tyres which impaired the effectiveness of the car’s signature feature. Neither was he au fait with the counter-intuitive driving style it required: more revs equalled more grip. Piquet’s best time of 63.61s put him fourth, behind the 61.37s clocked a few minutes later by future world champion Alan Jones in a Williams FW07. It was an underwhelming coda to the radical Brabham’s short but meteoric competition history.
The genesis of the BT46B underlines a fundamental truism of motor racing: for all that the competitors publicly advocate a level playing field, in private all but the most naïve are digging relentlessly to uncover an ‘unfair advantage’. By the late 1970s the Ford Cosworth V8 engine’s ubiquity was driving the better-resourced competitors to look for an edge elsewhere via advances in chassis, tyre and aerodynamic technology. When Lotus unlocked the advantages of ‘ground effect’ aero, rivals had to copy it or find alternative innovations.
Brabham and its chief engineer Gordon Murray occupied the latter camp, having partnered with Alfa Romeo from 1976 as a means of getting an edge on a field largely populated by Cossie V8s. Alfa’s flat-12 had more grunt than the DFV but this was offset by its greater weight, higher cooling demands and slightly patchier reliability, along with the company’s slightly chaotic nature – or, as Murray put it, “delightfully unstructured way of working”. Durability improved over the course of Brabham’s first two seasons with Alfa but, as the BT46 took shape on Murray’s drawing board in the winter of 1977, Brabham’s last victory (Carlos Reutemann in a Cosworth-powered BT44 in ’75) was a receding memory. Team owner Bernie Ecclestone was growing impatient.
Murray’s first blue-sky notion with the BT46 was to cool the car an entirely different way, via surface-mounted heat exchangers. This enabled him to pare back the chassis to the minimalist trapezoidal shape he had achieved on the BT42 and BT44. In practice, though, the heat exchangers offered insufficient cooling and distorted the chassis through cycles of expansion and contraction as their temperatures fluctuated.
One individual who could divine the lack of cooling by eye as he studied images of the cars during testing was David Cox, a consultant engineer with a passion for motor racing and an eclectic CV which included a stint in the aerospace industry. Cox contacted Brabham to suggest there was a problem and this led to a consultancy arrangement which would have significant influence on the B-spec BT46.
Murray was already in the process of junking the surface cooling in favour of conventional radiators, which had to be mounted at the front owing to lack of space elsewhere. It was an imperfect arrangement, but the car was
“IF THEY COULD PROVE THE FAN’S “PRIMARY PURPOSE” WAS COOLING, IT HAD A COMPELLING ARGUMENT FOR LEGALITY ”
competitively quick in the hands of Lauda and John Watson – competitive, that is, with everyone bar Lotus.
While working for other teams, a number of the engineers at Lotus had tried without great success to influence the speed of the airflow around and under the car to create negative pressure and, through that, downforce and extra grip. It was while windtunnel-testing the Lotus 78, in which inverted side-mounted wings were packaged within bodywork along with the radiators, that Lotus’s Peter Wright had the eureka moment… when the model began to sag. Sealing the underfloor, preventing air from being sucked in from the sides, was the key to activating the concept’s potential.
Flaws in the early design – the aerodynamic centre of pressure was too far forward, creating understeer which required an oversized rear wing for balance – meant the 78 didn’t quite fulfil its potential during its maiden season in 1977 and rivals were slow on the uptake. Lotus improved the concept for the following year’s 79, including sliding rubber skirts rather than brushes, and a chassis optimised for more airflow through the sidepods (at some cost to rigidity). Others now had to react or be left behind but, at Brabham, Murray had a problem he shared with Ferrari: a flat-12 engine layout which ruled out a direct copy of Lotus, because the cylinder heads would impede air flow through the sidepods.
Unlike many other senior engineers up and down the grid, Murray understood what Lotus was doing – he simply couldn’t clone the idea because it was fundamentally incompatible with the BT46 chassis design and engine format.
Thus, the idea of adding downforce while solving the cooling issues with the same device was born. In 1970 Jackie Stewart had raced a Chaparral sportscar in Can-am which used a separate two-stroke motor to drive a pair of rear mounted fans which sucked air from under the car. Murray and Cox collaborated on a similar arrangement, albeit one which would be powered by the main engine – and cleverly arranged in order to circumvent rules banning moveable aerodynamic devices. If they could prove the fan’s “primary purpose” was cooling, it had a compelling argument for legality by the letter of the law, if not its spirit.
The origins of the idea are somewhat opaque. Cox is known to have seen the design for a fan concept on Maurice Phillippe’s drawing board late in 1977 when he went for a job at Tyrrell. He described the encounter in a subsequent interview with GP Racing’s sister title Autosport; having agreed to keep the concept confidential he discussed it with Phillippe in detail and opined that it wouldn’t work as sketched, providing insufficient cooling. The concept centred around radically downsizing the car’s radiators and having a crank-mounted fan pulling air from under the car via horizontal radiators mounted at floor level, thus serving a dual purpose while remaining virtually unseen.
In practice Tyrrell’s system didn’t work – the sides weren’t sealed and the engine overheated, so it failed on both counts – and was abandoned at the testing stage. For his part, Cox told Autosport that in his conversations with Murray he merely prompted his new associate to come up with the fan idea
independently, thereby enabling Cox to keep his promise to Phillippe. Historically, Murray has taken the credit, though in later years Gary Anderson – then a Brabham mechanic, later a designer in his own right – has said that he proposed a fan system similar to Tyrrell’s after the unsuccessful first test of the surface-cooled BT46. Pick a truth you like.
Cox’s and Murray’s final design involved sealing the entire engine bay using a leather bellows arrangement similar to a blacksmith’s forge, with a vertically mounted fan scavenging the air. A large radiator atop the engine provided the fundamentals for the claim this was an innovative new cooling system, though its true purpose was obvious when the car squatted as the driver blipped the throttle: the higher the revs, the faster the fan spun, generating more suction.
As a safety precaution Cox created a cockpit-mounted suction indicator using an altimeter from a scrapped aircraft. A pitot tube on the BT46B’S nose provided external static pressure readings which the meter could compare with those in the engine bay, warning the driver to back off if the rubber seals were damaged.
So fast was the BT46B that on its maiden race outing, at Anderstorp in Sweden, Lauda and Watson were repeatedly told to slow down in practice and Ecclestone made them qualify with the fuel tanks full. Nevertheless, they lined up second and third on the grid, much to the consternation of rival teams. Colin Chapman was the most vociferous, the Lotus chief
raising a veritable posse of fellow team owners to lodge formal objections. Besides claiming the car was illegal, they protested that the fan represented a safety hazard because it would scoop up and fire debris at following cars.
“It was never throwing dust or stones,” Murray wrote in his autobiography. “It was all led by Chapman. We would have won every race and he could see his championship flying out of the window.”
Baulked by Riccardo Patrese, Watson spun off in the race but Lauda picked off Mario Andretti’s Lotus to win at a canter. Representatives of the governing body then attended the Brabham workshop, tested the BT46B’S rear end with an anemometer, and certified that over 55% of the air was passing through the radiator. The car was legal – though Murray was informed the loophole would be closed come the end of the season.
So the BT46B, counter to myth, was never banned. Rather it fell victim to politics: Ecclestone’s business portfolio also included the Formula One Constructors’ Association, via which he was in effect unionising F1 and annexing the commercial rights by stealth. A long and bitter FOCA meeting the Thursday after the race signified the political temperature and, for once, Bernie elected to play the long game and yield to those allying themselves with Chapman. Ecclestone decreed the ‘Fan Car’ be withdrawn and set his eyes once more on the pot of gold on the commercial horizon.
Murray was so enraged that he ordered the third chassis being built up as a ‘Fan Car’ to be scrapped. Next time out, at Paul Ricard, Watson delivered a rather more productive riposte to Brabham’s rivals. “It gave me unlimited pleasure,” he said, “to put my car on pole position without a fan and stick it up those little shits.”
“ECCLESTONE DECREED THE ‘FAN CAR’ BE WITHDRAWN AND SET HIS EYES ONCE MORE ON THE POT OF GOLD ON THE COMMERCIAL HORIZON ”