The Brabham BT-46B ‘fan car’ was a car designed by the Brabham Team in 1978, to complete with the all-dominant Lotus 79 car, which can be found here. It was highly successful in terms of pace, beating the Lotus in its only race.

Design

The concept was radical in itself - using two dedicated fans to suck the air from underneath the car, reducing the pressure beneath the car and producing additional downforce.

This design choice over the sidepod venturi tunnels was due to the fact that the engine package, the Alfa Flat-12 engine at the time, was too bulky for an effective implementation of the concept.

To maximise the effect of the fan, which reduced the air pressure from within the skirts, the skirts had to be sealed quite well, and the driver had an altimeter to check whether the skirt was damaged or not.

Fun Facts

1. The legality of the fan was questioned, but was deemed to be legal after the fan was allegedly for ‘cooling purposes’. When cornerning, the drivers had the additional task of reading the altimeter - they can continue at their normal pace if it was at the green; slow down when it was in the red (ie the skirt was damaged)
2. With one win in Sweden in 1978, the BT-46B is the only Formula One car with a 100% win record.
3. Contrary to what many media outlets say, the BT-46B wasn’t actually banned, according to its chief engineer, Gordon Murray

References

https://www.motorsport.com/f1/news/banned-tech-brabham-bt46b-fan/4808234/

https://www.motorsportmagazine.com/articles/single-seaters/f1/gordon-murray-looks-back-notorious-brabham-fan-car