Image credit: Nick Holland.
The 4th round of the WEC kicked off at the Nurburgring, after a commanding victory from Porsche at Le Mans. Porsche continued from where they left off, with another 1, 2 in the six hours of the Nurburgring.
All top three LMP1-H teams brought upgrades to their challengers, but no one could stop the second generation Porsche 919 in its tracks. The German outfit brought a revised front nose cone, lower chassis elements and new side impact structure aerodynamics, the total package leaving Audi and Toyota in its wake, with the lots of head scratching.
Porsche has moved to a more rounded front surface which maximises splitter performance up front. Without the double curvature this low load version increases the volume of air introduced under the car, thereby increasing the pressure gradient generated, for consequential downforce. In this the headlights are relocated to the new surface and new baffles try to increase and optimise the pressure differential that the splitter adds. There is a lot of performance to be gained from the splitter, and Porsche did just that with a well-earned 1, 2 at Nurburgring.
Also new on the 919 is the new alterations to the lower chassis. Turning vanes play a pivotal role in guiding the airflow up and around the frontal section of the chassis. These new turning vanes are not very complex, making up a newly designed cascade unit on the inner section of the car’s front wheel.
The cascading vanes help the car in several ways: brake cooling and flow management. Porsche has brought a new configuration for the Nurburgring race, which sees high downforce philosophy injected into the top category racers.
Below the front control arms you can note the new vanes, on the sideways “T” shape on the central section of the vanes is a new vane on the lower section of it, and this will help brake cooling. The air fill is guided straight into the ducts which cool the brakes. With much demand on brakes around the circuit, this looks to be a way to help control brake temperature rather than help deal with a cooling issue.
Also new to this advanced turning vane is a new vane placed on the inner section, right by the bulkhead of the 919. This is a much bigger vane and so will help take the tyre wake and vortex away from the under chassis splitter and diffuser as well as other elements. By this process, less turbulence will be carried to the rear of the car, so the underfloor elements have a cleaner flow to work with, thus more downforce to work with.
Furthermore, Porsche also ran its high downforce side impact structure louvers, which worked to great effect at the Nurburgring. Their high downforce design sees two curved louvres as well as new lower sill elements. By this, Porsche will be attaching the air flow to the chassis, to then be worked hard by the rear wing. The curves in the louvres will keep the flow very close to the chassis, without making it turbulent.
Finally the 919 sees a heavily revised rear deck configuration. The rear deck sees two inner extensions to the rear wheel pods, with a rear Gurney flap lining them. This is 100% a downforce generator. The extended pods with the gurney will draw low pressure towards it which will be used to push the gurney into the road.
The rear wing upper main plane was also updated for the Nurburgring round. There was a much higher angle of attack to help produce more downforce but with more drag.
The R18 saw two updates at the Nurburgring: the rear deck and the rear wing. Firstly to be on par with Porsche, Audi seems to have to used its low drag nose, which sees less surface area to help get air under the chassis as well as reduce drag on top of it. This proved a good move by Audi, but still it wasn’t enough to beat its sister company on the day.
At the rear of the car, Audi had increased the angle of attack of the rear wing’s main planes. This allows lift on the main plane to be reduced and used as a downforce benefit; this ‘inverse lift’ effect is the opposite of that used in an airplane’s wing, thus instead of taking off it helps keep the car on the track.
The higher the angle of attack the more lift is generated until the point of separation which is called a stall. When a stall happens, air-flow separates and the pressure becomes turbulent, which is bad for downforce.
Lastly, Audi had mini cut out section on the rear deck. It’s unknown what this does, but looks to be a way to slim the drag levels that little bit more.
As far as I’m aware Toyota only put up the angle of attack on the rear wing, which is pretty standard stuff. But as we know now, Toyota have stopped development on its 2015 car to concentrate on its all-new 2016 challenger which will have no V8 and heavily revised hybrid unit onboard.