Lotus 78: the car that started F1's ground-effect revolution

This is what rivals didn’t see until it was too late – an invisible revolution which made their cars redundant overnight. With the 78, Lotus brought ground effect to racing 

Mario Andretti Lotus 1977 French GP Zolder

Lotus took off with 78 ground-effect design

Bernard Cahier/Getty Images

Thirty years ago, the motor sport world tilted on its axis. In one of the rare instances of technological step change, Team Lotus developed ground effect aerodynamics and with the Type 78 ‘wing car’ jolted itself from the arctic latitudes of the previous two seasons to the equatorial sunshine of five wins, second in the constructors’ championship and third in the drivers’ championship for Mario Andretti. From that moment forward, motor racing was changed forever as first Formula 1 and then other formulae began to harness the downforce created by artful airflow management beneath the car.

Despite its pivotal role in realigning racing car design priorities, making efficient aero design the sine qua non, the 78 is not as fondly remembered as the following season’s 79, for one principal reason: the 79 carried Andretti and Lotus to the world championship double. But was it really the better car? The designer of the 78, Ralph Bellamy, thinks not and begins below his story of its development with the wind tunnel session that was to redirect motor sport history.

 

Lift-off

2 Gunnar Nilsson Lotus 1977 Belgian GP Zolder

Gunnar Nilsson at Zolder – where he would take his only F1 win, at the wheel of a 78

“Peter [Wright] and I went down to the Imperial College wind tunnel one Monday morning, bright-eyed and bushy-tailed, ready to start the aerodynamic programme. But there was a technical problem with the tunnel so we weren’t able to start until the Wednesday. By the end of that week we’d achieved the surprising result that when you placed an inverted aerofoil section close to the moving belt, it was sucked up. We hadn’t anticipated that because conventional wisdom was that ground effect was bad. If you look at F1 cars of that period, their front wings were always mounted quite high, clear of the ground. Suddenly we were finding that if you put them lower they worked better.

From the archive

“Peter and I returned to Imperial on the following Monday and concentrated our efforts on trying inverted wing sections ahead of the rear wheels. Peter ran the tunnel and collected the data, while I made changes to the model – which was just a block of wood down the middle, representing the monocoque, with bits screwed on the side. When we started to get inconsistent results Peter suggested that this might be because the wing sections were being screwed on at slightly varying heights each time. So we put a piece of cardboard on the end of the wing to close off the gap to the belt, to allow us to set the height more consistently. When we ran that, the downforce figures just went off the scale. We realised then that what we had to do was seal off the gap between the wing edge and the road. On the 78 we initially used brushes, which provided only a partial seal but allowed the car to run over kerbs. Later Peter developed the more effective sliding skirt system.

“When we’d finished the testing, Colin asked me whether I wanted to build a car along these lines. I said yes, and to his credit he said OK, let’s do it. We could have run the 78 in late 1976 but one reason we didn’t was that we all thought as soon as other designers saw it, they’d understand it straight away and copy it. But in 1977 the team was actually able to con people that the improved performance came from a clever differential. There was a campaign of disinformation and it was amazingly successful. Even when new cars appeared for 1978 it was clear that many other designers hadn’t an inkling what the 78 was about.”

 

Structure

1977 Dutch GP Mario Andretti Lotus 78

The successful ground effect machine started a sea change in F1 car design

Grand Prix Photo

“Because the technical regulations limited the size of each fuel tank, you needed three tanks to get through a race. So the 78’s chassis comprised a central section with seat tank, plus two side tanks on either side of the seat tank. The side panels of the monocoque were all of aluminium honeycomb sandwich material, so all told the tub was quite stiff. All that was inherited from the 77 was the rear suspension.

“I’m convinced that for the 1978 season, rather than introducing the 79, Team Lotus should have stuck with the 78 and put the 79’s rear end on it. That would have been a better car than the 79 because the 78 was a lot stiffer and stronger as a result of its full-width chassis. Colin had got the rules changed to allow one big fuel tank, which meant that the 79 could have a thin central monocoque with composite wings hung on either side. It was lighter but not stiff enough.”

 

Exiled

3 Gunnar Nilsson Lotus 1978 Argentinian GP Zolder

Airflow harnessed beneath the car proved to be a powerful performance advantage – but could the car have won F1 titles?

“The launch of the 78 was deliberately low-key. Previous JPS launches had been spectacular affairs in London but the 78 launch took place in Norfolk a few days before Christmas when most people were more interested in other things. Peter Windsor came up and we had a chat about the car.

From the archive

I’m reliably informed that when Colin read the resulting article he was hopping mad, even though I’d been careful to ensure that he got the glory. He said nothing to me about it – didn’t blow his top, call me into his office and dress me down. Instead I was told that there were problems in the road car factory, and I was to sort them out. That was me out of the race team, so I never went racing with the 78.”

 

A step too far

“The 78 should have won the championship in 1977 but Colin stuffed it. Not content with having aerodynamically the best car on the track – and a structurally sound one at that – he had to go off to Cosworth and do a deal to get development engines. But development engines blow up. Races were lost due to engine failure when the car should really have won every race once the skirts were fixed – it was so much faster than anything else. As a result, people don’t remember the 78 for the great car it was.”

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