We don’t really hear much about ground effect any more, but jump back to the 1970s and it dominated motorsport.
So what exactly is it? Basically, air travelling over the top of the car is of a higher pressure than air travelling underneath it. Mimicking the principles of Bernoulli’s principle (which states that water travels faster in a constricted environment), teams would seal the exposed sides of the car with skirts, channelling the low pressure air beneath the car, which speeds up the underside airflow. This greatly increases downforce and decreases aerodynamic drag.
Ground effect was originally used by Chaparral in 1970 with the 2J. Looking more like a washing machine than a car, the 2J had its corners covered by small side skirts to seal the low-pressure air underneath the car.
The back of the car had two huge fans, taken from a military tank, that would pull air from underneath and throw it out the back, creating a low pressure area beneath the car that would suck it into the tarmac. It wasn’t entirely successful and was banned at the end of the season.
In Formula 1, Colin Chapman (father of Clive in the video above, and founder of Lotus Engineering LTD), introduced ground effect to the sport with the Lotus 78 in 1977. This was later improved the next year with the 79, and 1978 also saw the return of fan cars with Brabham’s BT46B.
Brabham’s fan car only competed in the 1978 Swedish Grand Prix, which it dominated. The cars were so quick they were ordered to run on full fuel tanks to not raise the suspicion of other teams. While it won the race, the fan was banned for the next round, which was followed by mandatory flat floors in 1983 due to the dangerous cornering speeds that ground effect cars could achieve.