Lotus 78

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**Lotus 78**

Full name	Team Lotus
Base	United Kingdom
Team principal	Colin Chapman
Technical director	Tony Rudd
Race drivers	Mario Andretti Ronnie Peterson Gunnar Nilsson
Test drivers	{{{Test_drivers}}}
Chassis	Lotus 78
Engine	Ford-Cosworth DFV
Tyres	Goodyear
Debut	1977 Argentine Grand Prix
Final race	{{{Final}}}
Races competed	33
Constructors' Championships	1 (1978)
Drivers' Championships	1 (1978)
Race victories	7
Pole positions	9
Fastest laps	7
1978 position	1st (116 points)

Katsuake Kubota in a Lotus 78 at Brands Hatch in 2005

The Lotus 78 'wing car' designed by Peter Wright, Colin Chapman, Martin Ogilvie and Tony Rudd, was the car that started the ground effect revolution in Formula 1.

1 Concept
2 Development
3 Racing history
4 Bibliography
5 External links

[edit] Concept

In early 1976, spurred on by the disappointing performance of the ageing Lotus 72 the previous season, Chapman wrote a 27 page document detailing his ideas on low drag air penetration. After careful examination of Bernoulli's principle of fluid dynamics, he had thoughts on the effects of an upturned aeroplane wing profile fitted to the car, and gave the document to his head of engineering Peter Wright.

Wright then set about experimenting with F1 car body shapes using a wind tunnel and a rolling road, when by happy accident he began to get remarkable results in one of the models. Closer inspection found that as the rolling road's speed increased, the shaped underbody was being drawn closer to the surface of the road. Wright experimented with pieces of cardboard attached to the side of the model car body, and the level of perceived downforce produced was phenomenal. The results were presented to Colin Chapman, who gave Wright, aerodynamicist Martin Ogilvie and designer Tony Rudd free reign to come up with an F1 chassis design. The result was the Lotus 78 which appeared in July of 1976. Mario Andretti wanted to introduce the car early, possibly at the Dutch Grand Prix that year but was overruled by Chapman, as he didn't want other teams discovering what Lotus had achieved. The 78 was introduced at the first race of 1977, and proved to be the class car of the field that season, winning five races.

[edit] Development

The 78 was loosely based on the Lotus 72, sharing the same basic wedge shape and internal layout, but featuring detailed aerodynamic improvements, better weight distribution and a longer wheelbase. The car created quite a stir when it first appeared, and outwardly seemed ahead of its time. Internally of course, it was a quantum leap ahead.

Based on Bernoulli's discoveries, the underside of the sidepods were shaped as inverted aerofoils, in the same vein as conventional wings but on a much larger scale. Wright and Chapman had discovered that by shaping the floor of the car in this way, they could accelerate the air passing through the gap between the ground and the underside, thereby reducing the air pressure under the car relative to that over it. This created a partial vacuum, effectively sucking the vehicle down which forced the tyres harder onto the track. The greater force downwards on the tyres gave more grip and thus higher cornering speeds. To make the suction effect as great as possible, the monocoque was much slimmer, thereby making the area of low pressure cover as much area under the car as possible. Ground effect had the great advantage of being a low drag solution, unlike conventional wings, meaning that the increased cornering ability was not compromised by a decrease in straight line speed. If anything, because of the decreased air resistance, the top speed of the car also increased accordingly.

To begin with, brushes were fitted to the base of each sidepod to keep the low pressure area under the car. When these proved insufficient, Lotus tried plastic skirts, but these abraded very quickly, until finally moveable rubber skirts were developed which proved very effective. The sliding "skirts" sealed the gap between the sides of the cars and the ground and prevented excessive air being sucked into the low pressure area under the car and dissipating the ground effect. Andretti described driving the 78 as if it was 'painted to the road.'

The fuel tanks were three separate cells, with one behind the driver and one each in the mid-section of each sidepod. The sidepod tanks could be controlled from the cockpit by the driver and could be used to fuel the engine separately or together, improving performance and weight bias in cornering. The suspension set up from the previous Lotus 77 was used, with the suspension designed for quick changes in geometry. This helped set the car up for a specific circuit when required.

[edit] Racing history

Unfortunately, the low pressure area under the car was too far forward, requiring a very large rear wing resulting in a lot of drag at high speeds. This was especially noticeable on fast tracks such as Hockenheim and the Österreichring, where the Ferraris and McLarens were much faster than the 78. To compensate, Ford provided development versions of the DFV, increasing the car's speed but also sacrificing reliability. Andretti had no less than five engine failures in 1977, costing him the world championship to Niki Lauda, even though he had won four races and taken six pole positions to Lauda's three wins. Eventually a smaller wing was designed in time for the Italian Grand Prix (see above picture), which cut the drag factor significantly, and allowed Andretti to take a popular 'home' victory. Another problem was with the rear suspension, which although slightly modified to allow clearer airflow from the rear of the sidepods, it was still directly in the path of the exiting air, which affected the stability of the back of the car, causing oversteer.

It was obvious that the 78 was something special, as proved by Andretti and Gunnar Nilsson who won once in Belgium. Other teams started scrambling to design their own version for 1978. The problem they had was that they didn't know exactly what was so special about the car, as Chapman and other members of Lotus came up with any number of excuses to hide the real reason. That as well as the skirts, which hid any view of the underside of the car.

The 78 was good enough to still be a winner in early 1978, with Andretti and Ronnie Peterson scoring a win each and another 3 pole positions before it was replaced by the Lotus 79, which was as far ahead of the 78 as the 78 had admittedly been ahead of the rest of the field in 1977.

In all, the Lotus 78 took seven wins, nine pole positions and scored 106 points in its career.

[edit] Bibliography

Lotus 78 and 79: The Ground Effects Cars by Johnny Tipler
Mario Andretti: World Champion by Mario Andretti and Nigel Roebuck

[edit] External links

Lotus 78 - season results; race photograph
78 - race and pit photographs
1/20 scale model and pit photograph of actual car
Aerodynamic Illustration - Explanation of Side Pod Aerodynamics

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