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29/08/2012
A BAT-MOBILE AT LE MANS

NISSAN DELTAWING PROTOTYPE AND TYRES
Positive results for the Nissan DeltaWing prototype, the “Garage 56” car at the 24 Hours of Le Mans. A car with aerodynamics and tyres taken to extremes and a small 300 horsepower, 1.6 litre engine capable of competing with the much more powerful V8s

Fabio Quinto

THIS YEAR'S 24 HOURS of Le Mans wasn’t just about LMP1s and LMP2s. Or even about the usual GTE class GTs. Taking part in the pit lane for experimental vehicles was a car with the number 0 on its side, a racing car that is pure science fiction: the Nissan DeltaWing. The designers of this experimental racing car took weight reduction and aerodynamic resistance to the extreme so that they could use a smaller engine, but with enough power to compete against the V8s. The Nissan prototype weighs only 575 kg with a full load (driver and fuel) and 475 kg empty. Practically half that of an LMP1 which weighs a minimum of 900 kg. To achieve this, the designers have put all the weight of the cockpit, engine, wings and aerodynamic profiles on the rear wheels.
The result is a tendency to oversteer, as described by its designer Ben Bowlby: “When you reach the threshold of grip, the tendency is to oversteer. This is unusual in a rear-engine racing car which, particular conditions excepted, is normally an understeer limited vehicle. In our case, we will have progressively increasing oversteer to allow the driver to counter steer and maintain control of the vehicle, something you can’t do in a car that understeers. From the driver’s standpoint, understeer is an unstable condition that can be corrected only by slowing down and starting again, but with controlled oversteer, the vehicle is must easier to handle”.
The engine is an example of extreme downsizing. A Nissan four-cylinder, 1.6 litre Dig-T generating 300 HP at 7,400 rpm. It is a turbo petrol engine with direct injection and constant torque of 310 Nm between 4,000 and 6,750 rpm, not very different from the Nissan Juke. A choice that also halved fuel consumption, given that its tank capacity is only 40 litres.
Also important was the choice of tyres. Those in the front, in particular, had to be adapted for a front track that is only 60 cm wide. So Michelin created a new tyre with a diameter of 58 cm and tread width of just 10 cm. And it weighs only 5 kg. By contrast, a “normal” LMP1 is 71 cm in diameter and 36 cm wide. However, the rear tyres are less extreme at 31 cm wide and 62 cm tall, dimensions that are very similar to those of an LMP2. On 3 June 2012, the day of the 24 Hours tests, the Nissan DeltaWing used only one set of slick tyres over almost 722 km: a record for racing tyres.
The DeltaWing was in 29th position at the starting grid. After a regular start, an increase in temperature (a plastic bag was blocking the radiator) and a gear problem forced the single-seat Nissan to make a pit stop. After the sixth hour of the race, the car driven by Satoshi Motoyama was unintentionally sent into the wall by the LMP1 Toyota TS030 Hybrid driven by Kazuki Nakajima.
Despite the accident, the technicians said they were satisfied with the outcome of the race because they were able to see the result of a project that began in 2008, when Bowlby decided to design a new standard chassis for the 2012 IndyCar championship. According to the British designer “motor racing, especially in the United States, is dominated by strict rules that stifle design and innovation. The rules are so tight that the cars are basically all the same”.
This was the start of the DeltaWing project. But in 2010 the organizers again chose Dallara for the construction of the chassis. So Bowlby agreed with entrepreneur Don Panoz and All American Racers founder Dan Gurney to debut the prototype at the 24 Hours of Le Mans and Nissan agreed to provide the engine and develop the prototype. Following Le Mans, the DeltaWing experiment is now preparing to bear fruit for sports and production cars. The aim that the designers have declared several times is to take motor racing back to its origins, which means a “training ground” for technologies that will then be applied to mass produced cars. A 30-year process that now appears to be completely reversed.

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