The decision of the F1 de reuse the concept of the ground effect from 2021 caused a lot of talk about the Lotus 78 y 79, the vehicles that with this aerodynamic solution as a base revolutionized the category in the late 1970s.
The idea for these cars arose in 1976 with a technical study that Colin chapman, owner of Lotus, performed on the bomber Havilland Mosquito. Part of that essay by 27 pages was based on the radiators mounted on the wings and hot air vents that were designed to induce lift.
Chapman realized that such an inverted system could generate significant downforce on cars.. To confirm his hypothesis he relied on the principle of fluid dynamics of Bernoulli, according to which if the speed of a fluid is increased, its pressure decreases. To put it another way: by accelerating the flow of air that passes under the car, its pressure decreases and the car "sticks" against the ground.
The team-manager passed his idea on to his design team and that's how Tony rudd, head of engineering; Ralph bellamy, chief designer; Martin Ogilvie, vehicle engineer; Y Peter Wright, head of aerodynamics; they got down to work.
THE BIRTH OF THE FLOOR EFFECT
Rudd and Wright, who had come to Lotus from BRM, they had already analyzed this concept in their previous team. But the lack of the correct testing methods and the debacle of the British Racing Motors they made the possibility of installing an inverted wing profile in a car forgotten.
Wright dusted off that project and began testing at the Imperial College wind tunnel. His test model was an F.1 scaled to the who stuck pieces of cardboard on the sides of the car body. This confirmed that as speed increased, the underside of the car got closer and closer to the ground.
The results were presented to Chapman, who immediately ordered construction of the car to begin. It was given the code name John Player Special MK III in honor of the main sponsor of the team.
For the construction of the new car, solutions applied in the previous models were used. Of Lotus 72 it inherited its basic shape and internal design, but with better weight distribution and a longer wheelbase. Of Lotus 77 took the monocoque made of aluminum and honeycomb. The body, meanwhile, was made with fiberglass and aluminum panels to reinforce the points of the chassis.
By July 1976 there were already five finished Lotus 78 vehicles, such the official name of the new car. The American Mario Andretti, the team's first driver, got tired of testing it on the Lotus test track in Hethel and tried to convince Chapman to make him debut at the Dutch GP that year, but the Englishman preferred to leave the premiere for the 1977 season. His idea was to take by surprise the rest of the teams that were still fascinated by him. Tyrrell P34 six-wheeler. And so it happened.
In that tournament Lotus achieved five victories, one more than those achieved between 1974 and 1976. Andretti won in Long Beach (United States), Jarama (Spain), Dijon-Prenois (France) and Monza (Italy). While the Swede Gunnar nilsson celebrated in Zolder (Belgium) in what was his only victory in the category.
Andretti, who did not score on nine of the 17 dates, finished third in the tournament behind the Austrian champion Niki Lauda (Ferrari) and the runner-up South African Jody Scheckter (Tyrrell).
In 1978 nobody could with Lotus, that began the year with the model 78 and from the sixth date, in the Belgian circuit of Zolder, it replaced it with the 79. This new vehicle took full advantage of the benefits of the ground effect.
Thanks to additional design work on the Venturi tunnels Under the car, the low pressure area was kept uniform throughout the entire lower part. This was achieved by extending the body towards the rear wheels rather than ending abruptly before the rear axle as in the 78
This evolution also required a redesign of the rear suspension to allow the air to come out cleaner and the use of a smaller rear wing for less drag.
The Lotus 79 was secretly tested in late 1977 by Peterson and proved to be extremely fast, although the chassis suffered early fatigue due to severe suction and G-forces generated by ground effect. In fact, the 79 produced 30% more downforce than the 78. The problem was solved with reinforcements on the chassis and the monocoque.
Andretti won the '78 title in a campaign that included victories at the GP's in Argentina, Belgium, Spain, France, Germany and the Netherlands. His Swedish teammate Ronnie Peterson won in South Africa and Austria. It was a resounding 1-2 for Lotus in the championship, although there were no celebrations for Peterson's tragic death at the start of the Italian GP with two dates remaining on the calendar ...
The ground effect concept applied by Lotus was replicated by other teams until the International Automobile Federation he banned it in late 1982. The reason? The increase in cornering speed and lateral force that made cars very dangerous.
Instead the flat bottom -with different variants it remains to this day- which causes the car to stick to the ground, although minimizing the air flow.
The Lotus 78 and 79 were revolutionary cars. So much so that this concept applied in the past is the path that Formula 1 chose for its future.