RS Q eTron E2 ready for assault on Dakar

IN CONJUNCTION with Audi’s announcement last week that it will start to building F1 engines comes a commitment from them to continue in other forms of motorsport including international desert rally ‘raids’ like the Dakar.

The German car-maker has turned its back on LeMans style sports car racing to free up resources for the F1 effort and to concentrate more on desert rally raids. As such, they have redeveloped the successful RS Q e-tron E2 making it lighter, more aerodynamic and more efficient.

This is the second evolution of the car that won the recent desert rally in Abu Dhabi and is set to compete for the first time next month at the 2022 Morocco Rally then in the 2023 Dakar Rally.

It’s a fast turn-around for the German race outfit that uses the desert rally program to fine tune new technologies that can be eventually implemented on mainstream Audi passenger vehicles. The innovative second evolution prototype presents itself as significantly improved for the Morocco Dakar Rallies.

Technicians and engineers started at the ground and worked upwards on the second-generation prototype conjuring a completely new body that features significantly enhanced aerodynamics. It helps move the vehicle’s weight lower for a lower centre of gravity and handling improvements there from.

New operating strategies further improve the efficiency of the electric drivetrain.

In the interior and when changing wheels, the driver and co-driver benefit from easier operation. These changes bring with them the E2 nomenclature attached to the second evolution car. Audi says the name channels the legendary Audi Sport quattro in its final development stage for Group B rallying in the 1980s.

“We’ve managed a good debut at the Dakar earlier this year with the Audi RS Q e-tron and even managed first stage victories in a motorsport discipline that is new to us,” said Audi Sport GmbH motorsport managing director Rolf Michl.

“The entire team is working brilliantly together and pulling in the same direction. As is usual at such an early stage, the drivers, co-drivers and technicians quickly agreed on the next development targets. We have summarised the result in a new evolution package – the RS Q e-tron E2.”

This marks the beginning of the second phase of Audi’s development program in desert rally vehicles which starts preparation for the 2023 Dakar Rally in October after the new prototype has a run in Morocco.

“The Audi RS Q e-tron E2 does not adopt a single body part from its predecessor,” said Audi Sport GmbH chief designer Axel Löffler.

To comply with the prescribed interior dimensions, the cockpit, which was previously narrowly recessed towards the roof, is now significantly wider. The front and rear covers have also been redesigned.

“We are now doing away with the underflow of the rear bonnet to the left and right of the B-pillars. In conjunction with modified lay-ups, like optimised fabric layers of the composite materials, this solution reduces weight,” said Mr Löffler.

The so-called T1U prototypes will have to weigh 2100 instead of 2000kg in the future. Given that the first generation of the RS Q e-tron was overweight, it was still necessary to save several dozen kilograms. This is accompanied by the lowering of the vehicle’s centre of gravity.

The aerodynamic area of the body below the front and rear covers is completely new. Its widest point is at the height of the cockpit while the body tapers significantly towards the front and the rear. Audi has now dispensed with the part of the guards that was behind the front wheels and formed the transition to the door.

Internally, this structure was called the elephant foot. As a result, the designers saved more weight and optimized the air flow.

“The aerodynamic aspect should not be underestimated in desert rallying either,” explained Mr Löffler.

The new cockpit dimensions mean that the body has a larger and therefore less favourable cross-section. However, it was possible to reduce the overall aerodynamic drag by around 15 per cent. This does not change the top speed. It remains limited to 170km/h in the regulations.

The improved air flow offers one major advantage.

“It further reduces the energy requirements of the electrically powered car,” said Mr Löffler.

“We implemented the aerodynamic calculations entirely using computational fluid dynamics (CFD).”

These computer simulations replace the time-consuming work in the wind tunnel and still deliver precise results.

The E2’s electric drivetrain comprises an energy converter consisting of an internal combustion engine and a generator, as well as a high-voltage battery and two electric motors on the front and rear axles.

Energy management plays a crucial role here. The electronic control system of the complex electric drivetrain proved its worth in the first rally events. Challenges only arose in extreme cases. At the 2022 Dakar Rally, for example, Audi noted short-term surpluses of power in situations where the wheels made less contact with the ground while jumping or on uneven terrain.

The officials of the FIA, the world automobile federation, intervene at a threshold of two kilojoules of excess energy and impose sporting penalties.

“By way of comparison, more than one hundred times the amount of energy flows to the motors per second within the permissible limits,” said Audi Sport GmbH development engineer for embedded software, application and test bench Florian Semlinger.

“We could have made it easy on ourselves and set our threshold several kilowatts lower, but that would have meant performance disadvantages. Instead, we put a lot of fine-tuning into the power controllers.”

Two individual limits – one for each motor – are now recalculated by the software within milliseconds. As a result, it operates precisely along the permissible limit.

The so-called auxiliary consumers also benefit from optimised control. The servo pump, the air-conditioning cooling pump and the fans have a measurable impact on the energy balance. During the debut season in 2022, the Audi and Q Motorsport rally team gained valuable experience that enables better assessment.

The air-conditioning system for example works so aggressively that it could cause the coolant to freeze when constantly running at its maximum output. In the future, the system will run in an intermittent mode. This saves energy, yet the interior temperatures only fluctuate slightly, even over longer periods.

The operating strategy for the fans and the servo pump has also been optimized. The systems can now be regulated differently for the lower loads on the liaison stages than on the special stages.

Audi desert rally drivers Mattias Ekström and Emil Bergkvist, Stéphane Peterhansel and Edouard Boulanger, and Carlos Sainz and Lucas Cruz can look forward to their new workplaces. The displays are still in the driver's field of view and located in the centre console in the usual style, and the central switch panel with its 24 fields has also been retained.

However, engineers have restructured the displays and controls.

“The totality of all the functions quickly creates confusion,” said Mr Semlinger.

“That's why, for the first time, the driver and co-driver can now select from four system areas using a rotary switch.”

The Stage theme contains all the functions that are important while driving competitively – such as the speed limiter in sections with speed limits or the air jack. The Road part contains turn signals and the rear-view camera, functions that are often in demand on the liaison stages. The Error option is used to detect, categorise and catalogue errors. The Settings section includes everything that is useful for the engineering team during testing or after the car arrives at the bivouac.

Crews can now work much more easily after a puncture. Simple, flat and easily removable body components replace the previous bulky covers for the spare wheels in the flanks. The new ten-spoke rims from partner Rotiform are much easier to handle. Drivers and co-drivers can grip them more easily and complete the change more safely.

“We have combined all the important lessons in a very short time. The result of our ideas is the E2 evolution,” said Audi Sport GmbH head of vehicle operations Uwe Breuling.

“Our development team’s determined and cost-efficient work has prepared us perfectly for our second Dakar Rally.”