Today is the anniversary of the car's first appearance at the 1978 Belgian GP, a race it duly won and whose appearance prompted a development war in F1 as rivals realised they too needed to follow its ground effect concept.

However, the Lotus 79 was not the team's first foray into 'ground effect', but rather a refinement of a solution it had introduced a year earlier with the 78.

A happy accident

Lotus 78 overview

Photo by: Giorgio Piola

The key advantage of the Lotus 79 was a discovery that almost happened by mistake, as continuous running with a wind tunnel model had led to some fatigue, leading to the floor of the sidepods drooping at their edges. Although not planned, this instantly showed a sharp increase in downforce.

Lotus was initially confused by this, but set about replicating the results and it found that closing off the sides of the floor increased downforce dramatically.

Now though it had to find a way to make that work out on track, as extending the sidepod down to the floor wouldn't work. It needed something flexible, otherwise it would wear or break, with something as simple as an uneven track surface likely to cause issues.

The team could have started its experiments and run the skirt design towards the end of 1976, but opted to wait, fearing that other teams would catch on too quickly and work the solution into their designs for the following year.

Even though the 78 had seven wins in its own right, it acted as a moving laboratory for Lotus, as it took what it had learned during wind tunnel experiments and figured out how to bring things to life in the real world.

Mario Andretti, Lotus 78 survived an exploding fire extinguisher

Photo by: David Phipps

In search of a way of using skirts, it turned to nylon brushes in the first instance. But these rubbed away on the track surface too easily, meaning that the ground effect it were searching for disappeared as the car put down the laps.

The issue was that as downforce grew, the car was sucked to ground even further, meaning it had to find a solution that not only meant the skirts touched the ground when static, but could ascend when forces acted on the car.

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It tried numerous materials and methods in which to maintain the seal, before finally settling on the sliding skirt method. This was effectively a carbon honeycomb panel with a ceramic rubbing strip sandwiched between the sidepod walls.

Furthermore, a sprung mechanism inside the sidepod helped to control how much travel the skirt would have.

The Lotus 79 Ford sidepod with the famous ground effect aerofoil

Photo by: Motorsport Images

The 78 was clearly a leap forward for Lotus but not enough to vault it right back to the front of the pile, with a large wing at the rear of the car needed to improve its balance. This resulted in an unwanted drag penalty, meaning it was often slower than its rivals on the straights.

Fortunately for Lotus, this masked the potential of its solution from the other teams and, when the heavily refined concept, in the form of the 79 appeared, it was too late for the other teams. Rivals now had to play catch up and work out all the pitfalls of ground effect that Lotus had encountered already.

Black beauty

Lotus 79 1978 detailed overview

Photo by: Giorgio Piola

Debugged, the 79 was the class of the field, bringing six victories and four podiums during the 1978 season, leading to championships for both Lotus and Andretti.

The car had moved the needle, maximizing the size of the ground effect tunnels by not only utilizing a narrow cockpit but also by moving the fuel tank behind the driver, rather than having side tanks like its predecessor.

Lotus 78 and 79 comparison

Photo by: Giorgio Piola

This obviously lengthened the car, but it played into the team's hands by allowing longer tunnels that had also been widened to the maximum width possible within the regulations.

As a string of good results headed its way and the other teams began to try to follow in their footsteps, Lotus set its sights on the next machine…

The Lotus 80

The 80 was a typical example of Chapman's desire to continually innovate and take giant leaps forward, simply unsatisfied by the notion of refining what had worked before.

The 80 was an extreme ground effect car, designed to maximise the ground effect advantage, using a long skirt, right from the nose to the curved sidepods that pared in alongside the rear wheels.

One of its major problems was maintaining the seal between it and the race track, an issue that was only magnified by the curvature of the bodywork.

The team failed to make the car work and would have to return to the 79. But by then it was too late, the others had caught up and Lotus' big advantage had gone.