There have been countless leaps in the evolution of car performance throughout Formula 1’s almost 70-year history. The innovative designs of Colin Chapman’s Lotus Cars’ harnessing of the area underneath the car to create downforce through ground effects was one of the primary evolutionary leaps that pushed the sport forward.
The idea behind ground effects took advantage of the concept of downforce. Inverted wings above the car, for example, facilitate downforce, which pushes the vehicle down towards the track to improve grip during cornering. The evolution of ground effects began when designers realized creating a similar low-pressure area between the car and the ground would produce the same result.
Colin Chapman: Ground Effects Pioneer
The man responsible for translating this idea into reality was Colin Chapman, the late founder of Lotus. Motor racing historians will note that he was not the first person to use the suction generated by ground effects to make cars corner quicker: Jim Hall’s Chaparral 2J used this principle to great effect in the Can-Am sportscar series as far back as 1970.
Hall’s design created a low-pressure area underneath the car by removing the air from beneath the vehicle with a pair of gigantic fans. Rival teams were not pleased and claimed that the fans used constituted as moveable aerodynamic devices and thus were breaches of regulation. Can-Am’s organizing body agreed with this appraisal and had Hall’s cars banned at the end of the season.
Around the same time that this was occurring, the BRM F1 team worked on a car whose unique broad shape was an inverted wing. Chief designer Tony Rudd oversaw this innovation. It provided Peter Wright, an aerodynamicist, complete freedom in developing this secret project. Ultimately, however, it never saw the light of day: management decided that the BRM F1’s project was detracting from their work on the P139 chassis.
Bringing Ground Effects Into F1
The first to make underbody aerodynamics work for F1 was Chapman, whose inspiration was sparked while on vacation in 1975. After his epiphany, he put Wright on the job, setting into motion the project that would eventually become the first ground effects Lotus: the legendary Lotus 78, developed in 1977.
Little was made evident from merely looking at the vehicle. It took opposing teams a large portion of the 1977 season to understand what made these cars driven by Mario Andretti and Gunnar Nilsson, reach such impressive speeds. Andretti and Nilsson took one and four wins, respectively, during the season. If the Lotus 78 was more reliable overall, Andretti could have potentially been champion rather than Niki Lauda of Ferrari.
Chapman’s goal with the Lotus 78 was to accelerate the outward airflow through the vehicle’s rear using the venturi effect. The venturi effect dictates that if a flow of air is constricted, it will speed up, and its pressure will consequently decrease. This phenomenon reduces the air pressure beneath the car and creates downforce, also known as negative lift.
The Lotus 78’s side pods were sculpted like inverted wings, with their profile rising towards the vehicle’s rear to create the venture shape, which accelerated airflow underneath the car out towards the back. Air could escape from the car’s sides, which reduced the venturi effect without a clear solution for this design aspect. Chapman, along with designers Rudd, Wright, and Ralph Bellamy, designed the 78 with longer side pods than the competitors’ vehicles to prevent the venturi effect’s diminishing. To this end, they ran curtains–first made of bristles, and later on, solid sliding units–to create a seal between the track and the side pod bases.
The design team had a eureka moment when, during an experiment in a wind tunnel, the tunnel’s movable floor had risen and attached itself to the car’s underside. This impressive suction capability was proof enough of the design’s effectiveness. However, one significant drawback to sculpting the vehicle to capitalize on ground effects became apparent: it could not reach its high speeds while driving in a straight line. However, the Lotus 78 more than made up for this shortcoming in unmatched maneuverability while navigating turns.
If the iconic Lotus 78 was the car that introduced ground effects to Formula 1, then its spiritual successor, the 79, was the car that optimized its use. Data released many years later revealed that what made the 79’s ground effects so effective was that it created 200 pounds of downforce from its rear wings, coupled with 100 pounds from the front wings when the vehicle was traveling at 150 miles per hour. A whopping 400 pounds of force was applied from underneath the car to facilitate unmatched ground effects. This figure rose to 600 pounds the next year, with the grounds effects downforce eventually peaking at an unthinkable 2,400 pounds.
Thanks to Andretti and teammate Ronnie Peterson’s skilled handling, Lotus took home two races in 1978 and six in 1979. Andretti enjoyed the honor of becoming a world champion, with Peterson following close behind as a runner-up despite his unfortunate passing at Monza two rounds before the race’s end.
Competing teams, including McLaren, did not see the same level of immediate success as Lotus did with their first ground-effects vehicles. Others, like Brabham, retooled the idea, taking on a design philosophy closer to that of the Chapparal 2J, which inspired the creation of the BT46B for the Swedish GP. What made this design noteworthy was the gargantuan rear fan made to pull air up from underneath the vehicle. While this novel design was successful, its life on the track lasted only one race, in which Niki Lauda piloted it and won. Shortly after Lauda’s victory, the BT46B was prohibited from competitions due to questions about its legality.
Despite these hurdles, however, ground effects vehicles coupled with overwhelming horsepower were a mainstay until the end of the 1982 F1 season. From 1983 onward, the FIA adjusted its regulations so that all Formula 1 vehicles would have flat undercarriages, which spelt the end of the ground effects era. F1 has not seen such a massive leap forward since that bygone era of innovation and curiosity. Despite that, designers continue to innovate with each new design…