2008 in our sight: aerodynamics

The ING Renault F1 Team suffered from aerodynamic problems throughout the 2007 season. It is the team's aim to solve these, and it has great ambitions in this sector for the upcoming 2008 Formula One season.

The ING Renault F1Team’s mission in 2008

In 2007, the team suffered two kinds of problems. First of all, the change to Bridgestone tyres upset the aerodynamic efficiency at the front of the car. Secondly, the data calculated in the Enstone wind tunnel did not translate onto the track. The engineers understood and then solved these problems during the season. Today’s mission is to design bodywork that will enable the new R28 to pull back the time lost in 2007, and also to find the performance gain usually achieved from one season to the next. The aim is to be back at the front of the field and the first simulations are already very encouraging.

The theory

Aerodynamic downforce is generated by a pressure difference between the two faces of a wing or a part of the bodywork. At the origin of this phenomenon is the speed of the air molecules, which flow over the surfaces. When two of them arrive at the angle of attack of a wing at the same time, one flows over the upper surface of the wing while the other flows under its lower surface; they then join up again on the exit. But the trajectory of the former is shorter than that of the latter, and their speed is different: slower over the top of the wing than under the bottom. This variation in speed creates a difference in pressure, which, in turn, generates downforce. The higher the difference in speed the greater the downforce. But the formula does not work all the time. If the distance to be covered by the air molecules flowing under the wing is too long, they get lost before meeting up again with those that have gone over the upper part, which leads to a spectacular reduction in downforce. This is why the engineers superpose several wings with small surfaces and almost never mount single elements. This solution enables the molecules crossing the lower surface to be speeded up by the faster ones flowing across the upper surface of the wing below. Of course, downforce is always accompanied by drag (air resistance to the car’s forward motion). The aim of the aerodynamicists is to pinpoint the load and minimise its consequences. Indeed, they consider the car as a huge wing: the diffuser accelerates the flow under the floor and creates a maximum difference in pressure between the upper and lower surfaces of the car.

Which part has the greatest influence?

It is difficult to divide up the different parts of the overall downforce and to attribute it to a specific element of the car. However, it would be true to say that the diffuser generates 40% of the total downforce while the front wing gives 25% (10% only when the front end of the car is running in turbulence), and the rear wing 35%. Aerodynamics are still the cheapest means of improving performance. The teams invest almost 20% of their budget in this area knowing that there is a direct proportional relationship between the number of elements tested in the wind tunnel and the gains on the track. This is why ING Renault F1 Team began running its wind tunnel 7 days out of 7, 24 hours a day, 2 years ago.