This is the new Audi R18 that will claim the company’s 10 th victory in 2011 24heurs du Mans. Audi returns to a closed cockpit configuration since the R8C of 1999 and the related Bentley EXP Speed 8. The latest regulations with the engine displacement restrictions favor coupe racecars instead of open cockpits because with about 150hp less power drag is more important than ever. The new R18 follows the engine-downsizing trend of recent years and it is powered by a new V6 turbo diesel. The previous R15 had a V10 and both its predecessor the R10 (the first Diesel Le Mans winner) and the 2009 winner Peugeot 908 used a V12.---



As mentioned, the most obvious change is the closed cockpit. The monocoque according to the press release is constructed as a one piece instead of two halves for rigidy and weight optimization. The door openings follow the design of 908 that exploited the regulations to the extreme. Every aperture is comprised of two parts, the door and a adjacent body cover.



The large fin between the cockpit and the rear wing is mandatory for this year. Audi used it in conjunction to the central rear wing support. The wing is supported from the end plates as usual but only from one central pillar. It is also supported from the top where the airflow has a lower speed hence the disruption will be less. Acura was the pioneer of this design (called “swan-necked”) and I won’t be surprised if it finds its way to Formula 1 where the f-duct plays a similar role as this big fin. Driver operated f-duct is banned for 2011 but passive system will mostly be used.



A wind-tunnel image released from Audi intentionally or accidentally allowed some data to be seen. Even if for one reason or another the data isn’t very accurate it is worth noticing that more than half of the vertical force is produced at the front. It also showed a drag coefficient of around Cd0.47 but that is very closed coupled to wing configuration to extract any useful conclusions.



This lead to another Acura influence, the use of four identically sized wheels. Current regulations allow a evenly (or even fwd biased) aero balance and the previous R15 couldn’t take advantage of the large amounts of downforce produced at the front. The latest R15 iteration (R15+) had modified front fenders with additional fairings to accommodate larger tires if needed The R18 use rear tires also in the front and it is designed around the big front wheels thus the resulting huge front fenders.

Seeing the plan-view of R18 one can see the extensive aerodynamic and packaging effort of the team. The shape of the front fenders almost extends the diffuser in the vertical plane to improve its efficiency. Many openings and louvers behind and over the front wheel also release some of the pressure inside the wheel arch. In the rear of the car the rear fenders have big forward facing protrusions that shape a 3 dimensional tunnel that lead the airflow to the rear wing.



Another interesting aspect of R18 is the new V6TDi. There are rumors that the turbos (or possible its single turbo) is located between the two cylinder banks. The latest BMW twin turbo V8 used in road cars like the X5/6M and the next M5 has a similar configuration (above right). This design allows a very compact packaging, very important for this year’s aim to minimize drag. Also by locating the turbos very close to the exhaust the turbo lag is minimized. The R18 has a centrally mounted air scoop above the cockpit where the previous R8, R10 and R15 had two air-scoops located in front of the rear wheels. Those cars had conventionally mounted turbos beside the engine. The rear exhaust of the new car is also centrally mounted thus enhancing this scenario.



The windshield is of vital importance on a car with so limited view from inside that is also destined for night racing. Audi used its experience from the R8C and also from its DTM team and the closely related Bentley EXP. The drivers will also have the enormous all LED headlights at their disposal.

The R18 will be tested in April at the Le Mans official tests and its first race will be the 6h race at Spa-Francorchamps in 8 May. The big challenge is to preserve the Audi domination in Le Mans at the 24h race, which is to take place in 11 and 12 of June.

Additional links and images:

mulsannescorner.com
scarbsf1.wordpress.com
autoblog.com