When it comes to the aerodynamics, every millimetre counts
The technical DTM regulations comprise some 200 pages and 23 paragraphs. The biggest chapter of these regulations deal with the aerodynamics and is packed with specifications defining minimum and maximum dimensions. There’s nearly nothing as complex and as difficult to describe as the three-dimensional body parts that are touched by the head wind and more difficult to describe. At the same time, the wind streaming around the car is a fundamental performance factor. After all, it’s about reducing the drag and the contact surface to the max while using the air streaming around the car for generating maximum downforce at the same time. Consequently, it won’t come as a surprise that the engineers try to use even the last fraction of a millimetre of the maxim body dimensions defined by the regulations.
The forces generated by the aerodynamics are illustrated by the fact that the downforce produced by a DTM car driving at 260kph would be that massive that it would enable it to easily race on a ceiling. But even some 120 years after the invention of the automobile, the secrets of the air haven’t been explored completely. Therefore, the aerodynamicists would love to spend 365 days a year in the wind tunnel to use every imaginable trick for searching for the ideal shape for the allowed add-on parts. In this area, every single millimetre counts as even the slightest area possibly can make a huge impact on the performance of a car. At the DTM cars’ rear wing, for instance, you will find an edge that is standing – depending on the profile’s adjustment angle – upright or bent slightly to the front. That’s the so-called Gurney Flap. If you believe the drivers, their cars would be undriveable without this component.
But those responsible have to be extremely careful while designing their components as DMSB (the German Motor Racing Association) and Dekra closely check if the stipulated dimensions are met – particularly after a race. And therefore, those who moved too close to the stipulated limits run the risk of getting disqualified, after having crossed the finish line.
But although this is easy to read, realising it is extremely elaborate and cost-intensive at the same time. Only if the moulds for the body components made of compound materials have been manufactured absolutely precisely, the teams can be sure that the components produced meet the stipulated tolerances. And attaching the parts correctly to the cars is just as important. After all, the dimensions only are controlled when the parts are mounted on the car.
For quite a while, now, the constructors have moved that close to the limits of what is allowed and what isn’t, with their designs, that checking the parts with the naked eye or classical measuring tools is just impossible. Therefore, highly precise measuring arms are used to day – that are operated by trained engineers. But although they can rely on these devices, a scrutineer arguably would need several days if he wanted to check all the dimensions defined on the 69 pages of the DTM aero regulations.