Souping Up Indy Cars - for Safety
Carbon-fiber frames and high-tech tires help protect drivers traveling at 200-plus m.p.h.
INDIANAPOLIS-TYPE racing cars go faster each year, but the tracks themselves don't change. They are still just circular roadways surrounded by concrete walls. If the cars go faster and the tracks stay the same, why aren't more and more drivers injured?
The answer is in the cars. This past May's Indianapolis 500 provided an example: Fifteen accidents (a crash every 33 miles) took the spotlight that afternoon. Despite speeds approaching 230 miles per hour, no one was killed, and the only serious injuries involved ankles and feet.
Nigel Bennett, chief car designer for the Penske racing team, attributes some of this to "luck." But he and other race-car designers, such as Alan Mertens, the designer of the Galmer chassis, are helping improve the safety of Indianapolis-style cars, the kind used in high-speed, "Indy class" races like the New England 200 in New Hampshire this summer.
"The real breakthrough," explains Mr. Mertens, "was carbon fiber. It has a phenomenal strength-to-weight ratio; it absorbs a tremendous amount of energy; and it is a laminate, so it can be sculpted into complex geometric aerodynamic designs." Carbon fiber began replacing aluminum on Indy cars in 1983. Last year, Bennett and Penske began forming the entire cockpit and chassis from carbon fiber. This year, Galmer followed suit.
While carbon fiber has clearly saved lives, it has not eliminated injuries, particularly to drivers' feet and ankles. For that reason, Bennett, Mertens, and others suggested some design changes to the Indy-car sanctioning bodies. Their suggestions were accepted: Next year, the snouts of Indy cars will be longer, rounder, and wider. The cars will be heavier, less aerodynamic - and safer.
Designers face a constant struggle between performance and safety. They want to keep their drivers safe, but not at the expense of losing races. By having the rules changed, all drivers will be at the same disadvantage.
Bennett, in particular, would like to see this trend continue. He says that speeds at the super-speedways are excessive. Because of the tremendous gravitational forces on the driver when a vehicle traveling at 200-plus m.p.h. hits a concrete barrier, Bennett does not think that any amount of engineering will make the drivers completely safe. He would rather see shorter tracks and slower speeds, changes he says are unlikely.
`ENERGY," Bennett explains, "is directly proportional to speed squared, so dropping the speeds by 50 or 60 m.p.h. would lessen the chances of serious injury. In fact," he concludes, "I can't remember the last time someone was seriously injured at a short oval or road course."
Tire technology also helps Indy cars run safer at high speeds. Tires enable all cars to stop when they are supposed to and stay on the road in a curve. But family driving and race driving are completely different. Few people exceed speeds of 65 m.p.h., and they arrive at that speed gradually. Indy cars race at 220 m.p.h., and they arrive at that speed very quickly.
"The hard part for us is the transition," explains Pete Sheppler, an Indy-tire developer for Goodyear. "As tires get hot, they get softer and stick to the track better. Indy cars are often racing at full speed before the tires have a chance to warm up. That was the main problem at Indianapolis this year.
"Being in Goodyear's racing division gives us a lot of flexibility," he continues. "To maximize safety and performance, we can really fine-tune changes in rubber compounds, construction techniques, and tire pressure to fit the car, the driver, and the track conditions, and cost does not usually have to be a major concern.
"To build a street tire, on the other hand, the parameters are different," he says. "The tire must be affordable and it must perform consistently under a wide variety of conditions."
So there is little linkage between the testing labs in Indianapolis and Detroit. While carbon fiber may be flexible, strong, and safe, it is also very expensive. It requires a great deal of hand labor, and it does not mass-produce well. As a result, the most significant advance in Indy-car safety will not find its way into our garages any time soon. And when it does, Mertens believes it will be used in a few critical areas, and only in cars made almost entirely of molded plastic.