|Audi R18 e-tron quattro|
A significant reduction of the displacement limits put additional emphasis on (aerodynamic) efficiency ahead of the 2011 season and prompted Audi to develop the first closed cockpit sports racer for over a decade. Dubbed the R18 TDI, the new machine featured an equally new engine with an innovative single turbo layout. The engineers left room in the design for future developments, including the adoption of a hybrid drive system.
While the R18 TDI proved a winner at Le Mans first time out, it was deemed too heavy and for 2012 a lighter version was developed. One of the main reasons additional weight had to be shed was for the additional mechanicals required for the hybrid system. Hedging their bets, two versions of the evolution were readied; the 'conventional' R18 Ultra and the R18 e-tron quattro, equipped with two additional electric motors and a flywheel to store and distribute the generated energy.
Both versions sport a gearbox that features a complete carbon-fibre casing and has been the source of much of the weight saving. This is mated to the same wide-angle V6 with the turbo-charger wedged between the cylinder banks. The single turbo featured variable turbine geometry to ensure it is effective throughout the rev-band. In an effort to increase the parity between the diesel and petrol powered machines, further restrictions were imposed on the diesel engines, lowering the V6's output to a claimed 510 bhp.
Changes have also been made to the front of the chassis to accommodate two electric motors, which also double as generators. The energy is stored in an electric flywheel that is mounted alongside the driver. Supplied by Williams Hybrid Power, the flywheel spins in a vacuum at speeds of up to 45,000 rpm. Compared to conventional batteries, a flywheel can be charged and de-charged quickly and also does not suffer from degradation. As per the regulations, the storage capacity is restricted to just 500 kJ.
The kinetic energy is generated and used by two MGUs or Motor Generator Units, connected to the front wheels. Following protests from a rivalling team, it was decided that front motors could only be used at speeds of over 120 km/h. This removes most of the all-wheel drive benefits provided by the driven front wheels. To cool the motors and the flywheel an additional cooling system is fitted, which is responsible for a slight increase in weight and drag compared to the conventional R18 Ultra.
The modifications made to the front crash-structure in order to accommodate for the MGUs are also incorporated in the Ultra, and Audi have stated that if needed one could be converted in the other version without much effort. Suspension is more conventional with double wishbones all around. Push-rods are used at the front while the new rear-end features pull-rod actuated springs and dampers. Another novelty is a rear-view camera that is connected to a small screen in the cockpit and improves the drivers' rearward visibility.
Opting to run the 2011-specification in the FIA World Endurance Championship season-opener at Sebring, the R18 e-tron quattro and Ultra did not debut until round two at Spa. Unfortunately there was no serious opposition as Peugeot had suddenly left the sport earlier in the year and Toyota was not quite ready yet. Audi scored a 1-2-3-4 victory with the two e-tron quattros sandwiched by the pair of Ultras. The hybrids had run particularly strong early in the race when the track was still quite wet.
At the official Le Mans Test a month later, the new Audis were subjected to the first serious test as Toyota joined the fray with their all-new, petrol-hybrid powered TS030. The six works cars were surprisingly close with the R18 e-tron quattros leading the way. Allan McNish's quickest time of 3:25.927 was nearly two seconds faster than his best lap in the R18 TDI at the 2011 Test. In qualifying nearly a fortnight later, the e-tron quattro once again set the pace, only this time it was André Lotterer in the #1, who was fastest of all with a lap of 3:23.787.
Early in the 24 Hours of Le Mans, the Audis looked to walk away with the race but as the evening fell the two Toyotas clawed back the deficit and one even briefly grabbed the lead. Sadly for the race, it all went horribly wrong for the Japanese team as one car crashed out and the other was hit by mechanical issues. The four remaining Audis did make a genuine effort to race for the win, resulting in some exciting moments. In the end it was the #1 e-tron quattro that grabbed the first ever win for a hybrid at Le Mans.
In the first two of the remaining five rounds of the FIA WEC, Audi fielded one each of the R18 variants, while the last three were disputed by two e-tron quattros. Toyota bounced back from Le Mans and despite running just a single car, they scored three victories. The other two wins and the World Championship were for the Le Mans wining squad of Fassler, Tréluyer and Lotterer. So in its first season of racing, the innovative R18 e-tron quattro won both the 24 Hours of Le Mans and all of the silverware at the end of the year.
Article by Wouter Melissen, last updated on December 31, 2012
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