At first glance, the R10 looks very similar to its R8 predecessor. However, the innovations in the new car go far beyond its V12 turbo-diesel powerplant.
There are significant changes and innovations throughout the car, including
chassis and bodywork
dimensions
aerodynamics
electronics
cockpit
transmission
cooling
chassis dynamics
brakes
Chassis and bodywork: The R8 had a traditional chassis with separate bodywork design. This has been replaced in the R10 with a Formula 1-like integration of the carbon fiber monocoque with the body - eliminating the need for separate bodywork to smooth the aerodynamics of the car. The result is a significant weight saving, which partly makes up for the weight of the 5.5-liter diesel compared to the 3.8-liter V8 it replaces.
The modular design of the R8 chassis, which allowed lightning-fast repair of the rear end of the R8, has been extended on the R10 to include the front of the car and access to the front suspension.
Dimensions: The V12 is considerably longer than the V8 it replaces, which necessitates a longer wheelbase for the R10.
Aerodynamics: The new Le Mans regulations for LMP1 cars were intended to slow the speed of the cars, in part by reducing downforce by about 15 percent, through restrictions on front splitter design, ride height, wings, etc. Audi says they have been able to recover ?the majority? of the new car?s aero efficiency through an extensive wind tunnel program. Despite the demands of the larger engine and cooling system, the new car?s profile is 5 cm lower than the R8?s.
Looking at the car, a number of aero features are evident. The high, ?stepped? front splitter is a response to the regulations. Moving rearward, it?s evident that the car is much more dramatically ?waisted? than the R8, with a narrower, more pointed nose and an even more pronounced gap between the sidepods and the nose and cockpit areas. The car now has even more of a ?formula car with pontoons? appearance.
The 2-seat cockpit required by the requlations now has to accomodate the HANS driver safety system, as well as separate rollover structures for the driver and the hypothetical passenger - the latter intended by the rulesmakers to reduce aero efficiency and slow the cars. In an interesting interpretation of the rules, Audi has adopted an innovative ?rollover pylon? design to replace the traditional roll-hoop - undoubtedly with aero benefits.
Following current F1 practice, the rear bodywork is now the minimum required to wrap around the engine and transmission, and seems, visually at least, to be dramatically lower than the R8. Certainly, from the cockpit rearward a tremendous amount has been done to get the regulation rear wing in clean air, to derive the maximum possible efficiency. The rear view shows the clever use of the wing endplates, which kick in to merge with the rear bodywork behind the wheels, thus creating with the tail of the sidepods what is in effect a downforce-creating plane parallel to the wing.
Electronics: The R10 makes greater use of onboard computers to control its major systems than did the R8, with all important functions computer-controlled over a CAN-bus network. This simplifies cockpit design, with fewer function-specific switches (for headlights, as an example).
Cockpit: The need to keep the cockpit area as narrow as possible for aerodynamics, while still allowing the driver to work at peak efficiency for long periods, puts considerable emphasis on cockpit design. With a relatively high pedal box, similar to an F1 car, plus the low profile of the bodywork, there is little room for the steering wheel. Audi?s minimalist interpretation of a drag-racer?s ?butterfly? wheel is the result. The wheel integrates a multifunction display and control system, and the shift paddles for the electro-pneumatic gear shift. Electric power steering replaces the R8?s hydraulic system.
Note the large row of shift lights placed as high on the wheel as possible. The diesel engine is said to be so quiet that the driver is unable to hear it at speed. Coupled with the engine?s much lower powerband than a gasoline V8, the driver will rely much more on the shift lights to tell him when to shift.
Transmission: The X-trac gearbox manages to accomodate the tremendous torque of the diesel while still being lighter than its R8 counterpart. No word on the number of gears - perhaps the wide powerband and low-end torque of the diesel allowed X-trac to save a gear? That would help account for the weight saving. A special ceramic clutch was developed to accomodate the engine, along with stronger rear axles.
Cooling: The V12 diesel requires greater cooling than the V8, resulting in larger radiators mounted inside higher sidepods, for a weight and aero penalty.
Chassis dynamics: The long wheelbase, coupled with the huge thrust of the diesel engine, would tend to make the understeering tendencies of a sports prototype almost unmanageable. Audi is dealing with this problem with specially-commissioned wide tread front tires, giving more front-end grip, although with an aerodynamic penalty through wider sidepods. Braking performance should benefit as well.
The huge torque of the engine would make it very difficult for the driver to modulate the throttle in low grip situations (rain, debris on the track), a problem which Audi manages with a traction control system.
Brakes: As in a modern F1 car, the carbon fiber brake disks are completely enclosed in an aerodynamic shroud, fed with cooling air by carbon-fiber ducting mounted on the suspension. (No more dramatic night-time views of glowing brake disks?)
As you can see, the design of a state-of-the-art sports car is a challenging system engineering problem, balancing conflicting requirements to come up with an integrated ?system of systems.? In the recent past, nobody has been better at this than Audi. It should be interesting to see the R10 perform! Sebring is 3 months away?
[Source: Audi]
