Static Downforce Systems Suck To Generate More Grip


Chaparral 2J at the Goodwood Festival of Speed by Hugh Lunnon

Chaparral 2J at the Goodwood Festival of Speed by Hugh Lunnon

More often than not, new technology for cars is usually implemented in racing first. Sometimes the technology is a major step like fuel injection or independent suspension. Other times it’s making an existing technology better like carbon ceramic brakes. After proving its worth, this technology will make to production cars.

It is very rare for an idea that works not to make it into production, but it does happen. Static downforce systems are a good example of this.

Downforce generated by spoilers produce increased pressure between the road and the tire, thus creating more grip and increasing cornering speed. However spoilers are only effective above a certain speed, lower speed require a larger spoiler. The spoiler also generates drag that will ultimately reduce the top speed of a vehicle. Static downforce is a kind of an “artificial” downforce generated when a vehicle is not moving; all cars create this downforce through its weight.

Chaparral Cars, a producer of Can-Am cars created by Jim Hall, was the first to design race cars effective aerodynamic devices like air dams or spoilers. Some spoilers implemented were controlled by the driver to provide downforce in a turn and reduce drag during a straightaway.

Chaparral’s most innovative car came in 1970 as the 2J, which used a snowmobile engine to turn two fans mounted in the back. The car used a lexan skirt around the bottom of the car create a seal for the fans to create suction. The suction system only produced .18 psi of suction, but that equaled 900 pounds of downforce whether the car was moving or standing still. This gave the 2J a .5 lateral-g advantage in 30-90mph turns. In qualifying it would beat the next fastest car by several seconds, but ultimately the snowmobile engine proved to be unreliable during the actual races. After its debut season it was banned from the Can-Am series.

Later in 1978, the same technology came was used in Formula 1 Brabham BT46B “fan car.” The Fédération Internationale de l'Automobile (FIA) which oversaw Formula 1 had already banned moveable downforce generating devices. Brabham used a loophole in this ruling that allowed downforce to be generated as a secondary effect, and claimed that the fan’s main purpose was to cool the engine. The car’s first and last race was the 1978 Swedish Grand Prix. During the race, a car lost oil on the track that forced the other cars in the race to slow down when driving over the slick surface. The Brabham using its static downforce system would actually accelerate through this area, allowing for the car to dominate the race by 34.6 seconds. The BT46B was never banned from racing again, but was retired.

It is unlikely for a static downforce system to work on public roads due to uneven surfaces, weather conditions and debris. But the idea of generating an additional .5 lateral-gs in a turn is a very compelling one.

 
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