alloy carbon vented brakes and discs.
On the Aerodynamics side Audi discovered their 2014 e-tron created too much drag, so spent the winter developing a new front nose, side bodywork and rear end. This allowed a cleaner flow over the entire surface of the car, with additional brake inlets on the front bodywork to help cool the braking system. Audi will run with twin louvres on the side section, allowing for a cleaner exit of air entering at the front. Audi has also mounted its heat exchangers such to R18 e-tron quattroassist the overall aerodynamic concept.
Furthermore Audi’s low-drag Le Mans bodywork features a much flatter nose with cut out sections of the front bodywork opposite the nose cone on either side. This allows a greater amount of airflow to enter through the car and exit via the louvres after the front wheel arches. Like Porsche, Audi have re-
designed this section for a smoother air flow to the back of the car where the diffuser and rear wing will benefit.
The back of the car features its Fuji style single exhaust surrounding that Audi believes the air will pass over lot more efficiently than before. Audi use them on circuits that require less downforce as they create less drag, but also stop hot gases from the tail pipe interfering with the rear wing mainplane. The cleaner the flow the rear wing gets, the more downforce it will
produce. This is different to Porsche, who use the gases primarily as a downforce gain.
A neat trick Audi applied to the low-drag spec R18, was to hide its wing mirrors in the front fenders of the car. The created less surface R18 e-tron quattroarea than the conventional wing mirror layout. Along with the rest of the new aerodynamic parts, this feature meant enabled Audi to keep up with the Porsche 919 at Spa – later winning due to Porsche stretching their tyres and recovery capacity.
At the back of the Audi R18, the new bumper has much bigger air exit vents, thus allowing more air to escape. It’s a similar concept that Nissan have applied to the GT-R LM, although the Audi concept remains standard LMP (Le Mans Prototype) technology.
As air enters via the front vents (opposite the nose cone) it travels outwards of the car – likewise through the side bodywork. This makes an ultra-Aerodynamic profile for air to escape and also creates very little drag in the process. It’s a very good idea to help aid in speed as well keeping downforce levels high.
The R18’s smaller surface area will aid in creating smaller coefficient drag levels and reducing the overall the wake of the car, meaning the R18 car is going to be much faster in a straight line.
For the rear wing the two main-plane’s follow each other in a step; 24h Le Mans 2015feeding the rear wing in a very clean fashion as to gain more downforce on the back of the car. This tells us that Audi are still going for a higher downforce spec car, which unlike Porsche, have a very slippery shaped bodywork.
Porsche
With substantially increased straight line speed and down-force, the 2015 919-Hybrid showed just how big a stride Porsche has made from their 2014 car at both the Silverstone and Spa rounds.
M15_0847Beginning with the chassis, Porsche carried over its two-piece bonded chassis from the 2014 WEC season. The design was fairly outdated and allowed the car too much movement; flexing an estimated 0.01 of a millimetre.
For 2015, Porsche knew performance could be gained here, so consequently switched to a one-piece monocoque. This therefore meant Porsche saved a lot in weight, with additional help from Capricorn Composite GmbH (of which Porsche bought a 25% stake this year) who changed the weave of the Carbon for added stiffness with less being used up in the process.
For the Suspension, Porsche had much discussion on where to go given Audi went for Front-rear interconnected system. It’s still unsure what Porsche run now, although it’s a well-adapted FRIC system (to minimise pitch and roll) is in development for the car. The most recent monocoque has led to the new design which Porsche Technical Director Alex Hitzinger was very pleased about.
Image: Audi Motorsport