Known as the fan car, the Brabham BT46B has only raced once in F1.
The Brabham BT46B is one of the most extraordinary cars in the history of F1. Gordon Murray made possible an elegant solution to the problems posed by the success of the Lotus 79 and the limitations he had to deal with.
Most F1 fans know the basic story of Gordon Murray’s car that won the 1978 Swedish F1 Grand Prix in Niki Lauda’s only race appearance. In response to Team Lotus’ Ground Effect innovation, Brabham’s rear-mounted fan draws air from the car’s underfloor, while side skirts seal the sides of the floorpan and pull it to the ground for a similar effect.
However, there is more to the story and some legends are less accurate. So we’ve rounded up some fun facts about cars that you might not know.
The Alfa Romeo engine needed a fan car
Team Lotus first launched ground effects cars in 1977, but it wasn’t until the Lotus 79 came out in 1978 that everyone realized the potential of the concept. This caused a scramble for rivals to create their own ground effect designs.
But Brabham had a problem. The car had a big flat 12 Alfa Romeo “Boxer” engine. This architecture meant that attempts to create traditional ground effect venturi tunnels were fundamentally flawed. This led to consideration of a twin-frame design which proved too heavy, and the idea of a fun car was born.
Carlo Chiti, engine manager at Alfa Romeo, said: “Gordon Murray was, and still is, a very good engineer. It was impossible to create a ground effect vehicle because of the boxer engine. He had the idea of rear ventilation, which afforded the same physical advantage as the Lotus, and fitted a skirt.”
The fan was hidden by the garbage can lid
Word of the fan car had been circulating long before it appeared, but Brabham have been testing behind closed doors at Brands Hatch and at Alfa Romeo’s Barocco Proving Grounds, and the project even after arriving at the Anderstorp circuit for the Swedish Grand Prix in Formula 1. hide the details of
As a result, the fans were covered. While the team produced their own bespoke covers, the Brabham mechanics came up with a much simpler solution and came up with a dustbin cover that fit the fan perfectly.
The fan sacrificed about 30 horsepower
Unlike the 1970 Chaparral 2J “sucker machine” that pioneered the fan car concept in Can-Am racing, the fan was not powered by its own engine. Instead, it was powered by the Alfa Romeo engine through a complex system of four or more clutches that connected the fan to the lower gearbox shaft.
This meant about 30 horsepower went to the impeller rather than the wheels. But the gains in downforce and cornering speed were worth the lap times, so it was an acceptable compromise.
The fan was mainly for cooling
It was clear that the fans drew air from the subfloor sealed by the side skirts to create downforce, but regulations prevented this from being their primary purpose. The reason was the wording of the regulation.
A 1978 change included a caveat to the rule banning mobile aerodynamic devices. This stated that mobile aerodynamic devices would be permitted if the primary purpose was not aerodynamic.
Fans have had two influences on Brabham. One was to help suck the car into the ground, while the other was to increase the efficiency of the horizontally mounted water radiators above Alfa Romeo’s F1 engines.
To meet the regulations, all Brabham needed to do was demonstrate that over 50% of the effect was cooling.
As expected, five teams (Williams, McLaren, Lotus, Tyrrell and Surtees) launched protests even before the start of the race in Sweden. The basis of these protests concerned not only the primary function, but also whether the skirt was not fully attached to the sprung part of the car as required by the regulation.
The International Sporting Commission (CSI) declared the car legal before the event. After this protest, they decided it was legal again and discovered that the skirt was attached to the elastic part of the bodywork. And crucially for the fans, their main function was cooling, even if there were aerodynamic effects.
Measurements taken by CSI during a visit to Brabham HQ confirmed that over 55% of the fans’ power is used for cooling. Clearly Brabham’s main motivation for introducing the fan was aerodynamics, but some of the cars produced it in a way that satisfied this regulation through how it affected cooling.
tank parts included
The impeller itself has seven blades and required a lot of work to get it right. The car was originally intended to be ready for the Monaco Grand Prix in early May, rather than in Sweden six weeks later.
Thermodynamicist David Cox worked on the properties of fans. The fan component itself originally came from the tank. Originally made of plastic, then glass-reinforced nylon, these had to be heavily reinforced with cast magnesium blades.
As Gordon Murray explains in his book One Formula, 50 Years of Car Design, even the fan hub was recreated in solid aluminum at the last minute after another catastrophic failure.
“During initial testing, we had a catastrophic fan failure and tried various materials that seemed to work. But a few weeks later we had another fan blade failure and it was cast in magnesium. This made the fan much heavier Another catastrophic fan hub failure occurred a week early as far as Sweden. Enough time to machine two solid aluminum hubs, the final assembly was sent to Sweden without testing,” said Murray.
Despite the fact that the final version of the fan was not tested, it proved reliable enough for Niki Lauda to win the Anderstorp circuit.
Lauda and Watson qualify with full tanks
Brabham drivers Niki Lauda and John Watson have been given strict instructions not to reveal the strength of their fan car. This also included being advised on engine revs as the engine was visibly sucked into the pit soil.
But also, under the direction of Brabham team owner Bernie Ecclestone, he had a large number of qualifying cars to stabilize what Niki Lauda called a ‘vacuum cleaner’ in his famous book To Hell and Back.
“The vacuum cleaner was ready in time for the Swedish Grand Prix in Anderstorp. Our biggest concern was to show its undeniable superiority and get out of the game,” said Lauda.
“John Watson and I rode the qualifying lap with a full tank and did our best to avoid pole position.
This explains why Lotus’ Mario Andretti took pole position, around 0.7 seconds ahead of the two Brabhams.
During the race, Niki Lauda said he passed him easily after “playing cat and mouse” with Mario Andretti and won “embarrassingly easy”.
it was not banned in 1978
The fan car is often said to have been banned after its one race, but this is not entirely true, despite Brabham having withdrawn it from competition.
A CSI analysis of the car concluded that it is legal under the regulations. Only in 1979 was a change in the wording made. CSI tried to frame it as a ban, but there was more to the story.
Brabham team owner Bernie Ecclestone understood that his position within his Formula One Constructors’ Association, FOCA, was the basis of his growth potential in F1. Hampered by the dominant performance of the fan car and the potential cost implications of rivals being beaten hard and having to fight back.
So Bernie Ecclestone was persuaded to abandon it and to what could be presented as a ban for the rest of 1978, even though the car remained legal for the rest of 1978. It was created.
There was a second generation fan car design
The Brabham BT46B was only Gordon Murray’s first attempt at a fan car. To make the most of the concept, it was a modification of the current BT46.
But Gordon Murray was already working on a bespoke fan car, the Brabham BT47. However, due to a rule change in 1979 which prohibited such a design, the car was never raced and never actually built.
The initial design featured two important modifications. First, the fan speed was variable, as Gordon Murray explains in his book One Formula 50years of Car Design.
“We were looking at a variable pitch fan that was driven by the speed of the car. It was basically moving on straightaways and even though the cooling was reduced in that short amount of time, the car didn’t get hot enough,” Gordon said Murray said.
“Then when we got to the corner, the fan kicked back on. The car was boxy the whole time, so with the same intake we would have had a lot more downforce.”
This allows it to generate ground effect downforce when cornering, but does not absorb as much power on the straights.
Second, the subfloor area has been enlarged to maximize downforce. Gordon Murray wrote Brabham BT48 instead. Brabham, unreliable and compromised by their big Alfa Romeo engine, finished eighth in the Constructors’ Championship despite Chiti producing a new V12.
The fan car participates twice
Fanker raced only once but also took part in a time trial at Donington Park on 3 June 1978.
It was one of only five cars entered in the non-championship Gunnar Nilsson Memorial Trophy. It wasn’t good enough for the race, but the car pretty much had a glorious qualifying session.
Nelson Piquet drove the car and finished fourth in the event won by Williams driver Alan Jones. James Hunt (Wolf), Mario Andretti (Lotus) and Rupert Keegan (Arrows) were the other contestants.
