GROUND EFFECTS ON THE LOTUS 79
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The law of diminishing returns isn’t kind to motorsport innovation – largely because it is such a competitive world that any single advance that hands one player a huge advantage will be protested and banned. So, if you wrote a book on how to win, you’d probably avoid big leaps in performance, and aim for many, smaller, incremental changes to out-fox the opposition. In other words, you’d say, “Don’t do what Lotus did with ground effect and the Lotus 79.” Because Colin Chapman and his team discovered something so advantageous they had to sandbag in qualifying to try to hide what they’d found.
What had they found? In a wind tunnel at Imperial College, using scale models, Lotus engineers had discovered that if you could seal the side of the car to the ground and accelerate the air underneath it, you created a low pressure zone, and the downforce generated was exponential. It was so simple a piece of physics that much of the time was spent working out how to make the skirts work that dropped down from the sidepods – you needed a very clever material that could withstand that much friction. They did this at Hethel, dragging stuff along the ground behind a Renault 4 van – which supports my theory that a Renault 4 or Citroen 2CV has been involved in every great post-war automotive discovery. But most of it appears to have been spent protecting this massive advantage. So, as rumours swirled around the paddock of trick differentials, Chapman had one mechanic leave the back of the garage after every test session with a large object under a towel. Everyone assumed it was a diff
– it was, in fact, a kettle.
The 79 was dominant from the very beginning, helped by the fact that the basic mechanical package of Ford DFV and Hewland transmission were well proven and therefore reliable.
Ground effect is a strange feeling from behind the wheel. I’ve experienced it twice. The second time was in this very car, the Lotus 79 that gave Mario Andretti his world championship. It was so profoundly ‘right’ from the moment he did that first testing lap, I’m pretty sure Mario knew the championship was his. But the car is now a piece of history, and the skirts still have the original friction surfaces, so Clive Chapman would only allow one lap with them down. And I genuinely did feel a difference – a stability and level of high-speed grip that felt almost artificial.
But I did get to push another famous exponent of ground effect much harder – a Porsche 956. Wow. The grip increased the faster you went. It was bonkers. Back in 1978, with a 450bhp DFV strapped to your back and a total weight of 610kg, it must have felt like an alien racing car. But Chapman’s secret didn’t remain one for long. Everyone had ground effect soon, and everyone went way faster – meaning the crashes were more violent and, inevitably, ground effect was banned.