Racing aerodynamics
IN my previous column, I talked about the importance of car aerodynamics. As I’ve mentioned before, the XJ220 was originally going to be a Group B racing car and was initially designed as such. Although the principles are the same, the objectives for aerodynamics in motorsport are very different to that of road cars.
I was reminded of this long after the XJ220 was finished when watching the 1999 Le Mans 24 hours on television and saw the Mercedes-Benz CLK GTR of Peter Dumbreck take off and fly through the air. I remember thinking that shouldn’t have happened because all cars need less front lift than rear lift so that aerodynamically the car is always being pushed nose down. If not, it could take off just like the Mercedes did.
Obviously most road cars don’t have the speed to take off but front lift still results in less weight on the front tyres therefore affecting cornering and handling.
Sometime later I was discussing the flipping Mercedes with a manager from another Le Mans team, Richard Lloyd, who knew all about it. Because the CLK GTR wasn’t competitive, the Mercedes designers kept backing off the mechanisms that cause downforce in order to improve speed, more so to the front than the rear. Therefore once the nose was up, it forced more air underneath allowing the car to fly.
The mechanics of designing a racing car is also very different from those for the road. Whereas road car aerodynamics is about reducing lift and drag plus adding stability and cooling, racing cars need downforce which can only be measured with a rolling road in a wind tunnel. Plus the aerodynamics need to be adjustable depending on the circuit. That’s why I designed movable front and rear wings for the XJ220 so the downforce could be fine-tuned.
ALL CARS NEED LESS FRONT LIFT THAN REAR LIFT
While road cars need constant cooling through the radiators even at slow speeds, rac
