Lotus 78: The revolutionary car that changed Formula 1 forever

Uros Radovanovic
The iconic Lotus 78 Formula 1 car.

The iconic Lotus 78 Formula 1 car.

The new FIA technical regulations came into effect in 2022 with the aim of providing viewers with more exciting racing in Formula 1. That’s when all the cars switched to the ground effect concept, which allows for effective generation of downforce while creating less dirty air in their wake.

However, not everybody knows the true origins of ground effect cars in Formula 1…and it goes back further than you may initially think.

Let us tell you the story of the incredible Lotus 78, the car that changed this sport forever.

It all started quite by accident

Engineers Peter Wright and Tony Rudd were studying car aerodynamics in the 1960s and trying to find ways to give the cars additional performance.

They were the first to attempt to apply the principles of Bernoulli’s Equation [a vital principle in fluid dynamics relating to how speed, pressure and height interact] to cars, but without much success. They deemed the idea unsuccessful and continued their research.

Several years later, Peter and Tony were engineers for the Lotus F1 team when their team boss at the time, Colin Chapman, ordered them to reevaluate the fundamental principles of their cars. Lotus was in a tough spot and was looking for a way to build a car that would bring them victories again.

The engineers went to a wind tunnel to reexamine the philosophy they had worked on several years earlier. The results were now better but still far from desired.

After hours of testing in the tunnel, there was a failure in the sidepods, causing their edges to drop to the car’s floor. Although it wasn’t planned, they noticed a significant increase in downforce and knew they had discovered something new. It was the beginning of a successful ground effect.

Lotus had to get back to basics

To better understand the basics of ground effect, it’s necessary to familiarise yourself with the behaviour of fluids. Let’s take, for example, the flow of air through a closed tunnel that narrows at one point. All fluids, including air, tend to maintain a constant mass flow rate in this scenario.

This means that the air velocity through the narrow part of the tunnel increases, leading to a decrease in pressure in that area. Such tunnels are also known as Venturi tunnels. But how does this relate to a car?

Engineers tried to shape the car’s underbody in a way that it resembled a Venturi tunnel. In other words, air would flow beneath the car, and the tunnels would start to narrow, reducing pressure.

Afterwards, the tunnels gradually widened to equalise the pressure with the outside – these are called diffusers.

Following this discovery, Lotus engineers actively worked to transfer this effect to the car as efficiently as possible.

Lotus had significant challenges to overcome

The biggest drawback of this idea was that Venturi tunnels had to be completely sealed off from the outside to work successfully. Therefore, Lotus focused on designing skirts because the edges of the floor were the main problem.

They had to find a way to bring the floor’s edge as close to the ground as possible to isolate the tunnels below and prevent outside air from entering. Since the car’s height changes during a race depending on its speed, position, and track bumps, this task became even more challenging.

Despite achieving some victories, Lotus experimented with various solutions throughout the 1977 season, constantly testing their idea.

The first skirt idea was nylon brushes placed on the edge of the floor. Their advantage was flexibility and adaptability to the car’s varying height, but they wore out quickly and became too short, allowing air to enter under the floor.

After trying different materials, the team finally settled on a sliding skirt mechanism. Engineers designed a carbon panel that could adjust its height with the help of a spring. This proved to be a better solution, but the results were not the most successful.

Another problem Lotus faced was aerodynamic balance. To have an efficient car, you needed to ensure that the front and rear axles received the equal force of downforce. To achieve this, Lotus had a large and draggy rear wing that posed a problem on straights.

However, this actually helped Lotus because other teams didn’t recognise the potential of ground effect due to the team’s 1977 season results. As a result, Lotus remained the only team that continued to develop this philosophy, which paid off in the following season.

Lotus 79 – The car that catapulted the team to Formula 1 success once more

The 1978 season was historic – six wins and a further podium securing the Drivers’ Championship for Lotus and Mario Andretti.

After four races running the 78 – with a win apiece for Andretti and Ronnie Peterson respectively in Argentina and South Africa, Monaco saw the arrival of a new Lotus chassis: The 79.

Engineers narrowed the cockpit, moved the fuel tanks behind the driver, and created an incredibly fast car. Ground effect was maximally utilised, and the performance gap between Lotus and the rest of the field was enormous.

Furthermore, the aerodynamic balance problem was solved, and the large rear wing was replaced with a much smaller one, allowing Lotus to achieve high speeds on the straights. Simply put, the car performed exceptionally well in all conditions and track configurations.

The 1978 season will not only be remembered for victories; unfortunately, Lotus’ driver at the time, Ronnie Peterson, tragically passed away after injuries sustained in a race at Monza. Peterson was the team’s second driver that season and assisted his teammate Andretti in winning the championship.

During practice for the Italian Grand Prix, Peterson damaged the car, and it wasn’t possible to repair it before the main race.

Lotus had only the previous year’s car, designed for the smaller-framed Andretti, available. The team managed to prepare the car, and Peterson participated in the race until the incident that occurred. He suffered a severe leg injury and was urgently transported to a hospital in Milan. Unfortunately, his condition worsened, and Peterson passed away the following day.


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The continuation of ground effect in Formula 1

In the early 1980s, ground effect became very popular, and many teams attempted to implement it in their cars. However, the fact was that this effect was very dangerous at the time. Even a minor problem could lead to a significant loss of downforce and, consequently, control over the car. Driver safety was at a very low level during those years, so the FIA decided to ban this effect. They introduced a rule requiring all teams to have completely flat floors, marking the end of the ground effect era.

Now, with driver safety at a much higher level, ground effect is back in the spotlight. Along with this effect, overtaking is easier, and more exciting Formula 1 races are possible.

However, we should not forget the legendary cars and the Lotus engineers who forever changed this sport.

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