Lotus 78/79 - John Player Special Mk III/IV | Formula 1 | 1977-1978 | Introduction of Ground Effects to Formula 1
After an unsatisfactory F1 season for Lotus in 1976, designer Colin Chapman started exploring low drag downforce solutions. Chapmans ideas were based on a de Havilland Mosquito fighter, particularly the wing mounted radiators and the hot air outlets that were designed to produce lift. Chapman realized an inverted version of the wing of the aircraft could be used on a Formula 1 car, and wrote a 27-page report which he gave to head engineer Tony Rudd who assembled a team to implement the ideas.
Design was based around the the idea of ground effects after some successful tests with models and prototypes in wind tunnels. The underside of the sidepods were designed as stout, massively inverted wings (shown above in pictures 3, 4, and 5 which is a photo of the sidepod from rear). It was discovered that by shaping the floor of the car in this manner, the air passing underneath would accelerate. This accelerated air caused a drop in air pressure under the car, creating a partial vacuum, thereby sucking the car to the track and providing more grip. Even the Mosquito’s radiator design was copied with the Lotus 78’s radiators positioned in such a manner that the hot air escaping would pass over the upper bodywork of the car, creating even more downforce. The great advantage of using ground effects to create downforce was that they do not create drag like traditional wings and spoilers, meaning straight line performance is not compromised. It was also found that air moving sideways under the car reduced the ground effects and side skirts were employed to avoid this, with great results. The ground effects were perfected in the Lotus 79 which featured upgrades that produced around 30% more downforce than the Lotus 78, so much in fact that the chassis of the car had to be strengthened to compensate for the downforce, g-forces, and grip.
The Lotus 78 did well in 1977 with driver Mario Andretti placing 3rd in the Drivers Championship and Lotus placing 2nd in the Constructors Championship who were kept out of first place by a high number of retirements on the season. The Lotus 78 won on it’s first race in the 1978 Formula 1 season and went on to do well in the next 4 races with teammate Ronnie Peterson taking another win before the Lotus 79 was used. The Lotus 79 went on to compete in 11 more races for Lotus to finish the season, taking four 1-2 finishes for Andretti and Peterson, respectively. Andretti also took first in a race that Peterson retired from, and Peterson took 3rd in a race that Andretti had retired from. Lotus won the Constructors Championship in 1978, Mario Andretti took the Drivers Championship and teammate Ronnie Peterson placed 2nd in the points, showing the absolute dominance of the ground effect cars.
The Lotus 78 and 79 featured one of the most significant vehicle designs in all of racing history. Rivals scrambled to design something to compete with the successful Lotus cars and ground effects remain a huge part of automotive design to this day, from Formula 1 cars to road cars.
(Sources: Wikipedia, “The Secret Life of F1,” ultimatecarpage.com)