When you come right down to it, auto racing is applied physics. At roughly 200 mph down the straight at Daytona International Speedway, a Winston Cup car is a melding of thermodynamics and aerodynamics, each science in conflict and concert with the other.
For decades, thermodynamics ruled. Success on a racetrack could be predicted by whichever driver had the most power under the hood. But today, thanks to NASCAR's restrictions and rules tending, there is less horsepower difference from one engine to another, from the pole to the 43rd starting spot, on any given Sunday, no matter what it may say on the valve covers.
Faced with not being able to build a dominating engine, teams began experimenting with how to build a better package around it. Starting with what were once stock cars, the factories began to massage bodywork or build special editions such as the Ford Talladega and the winged Dodge Daytona and Plymouth Superbird to gain an aerodynamic edge. Those cars marked the first skirmishes in what was to become the aero wars of today.
"I was among the first crew chiefs to take a car to a wind tunnel," recalls Gary Nelson, now head of NASCAR's technical development team. "We didn't know what to look for. We weren't even sure what aerodynamics were. We just knew they were important.
"One of the things we recognized was that if a car could go 100 mph with the engine it was allowed, that in order to make it go 200 mph we needed four times the power. We worked all season long to gain five or six horsepower, so we figured that in order to go faster we had to reduce aerodynamic drag," Nelson says. "But it was all such a mystery. You couldn't see air, so it was hard to figure out what to do with it."
When NASCAR began to allow full tube frame cars, the aero battle was joined in full and the giant fans on wind tunnels from coast to coast began spinning. The result was a nip here, a tuck there, maybe just a tad of a curve someplace else. Speeds went up, but handling on big tracks became lethal.
Then, teams discovered they could also use air to help plant the nose. Soon the shape of cars--refined in $2,000-an-hour wind tunnels built for the aircraft industry--became just as important as horsepower.
"I was among the first crew chiefs to take a car to a wind tunnel. We didn't know what to
NASCAR asks manufacturers to design racing bodies that look uniquely different while, under the paint job and decals, are almost identical. And just like you should have learned in high school physics, for every action there is an equal and opposite reaction.
Ask the fans how they compare today's racing to the pre-aero era, and many will say they love the close on-track competition, but feel parity has left the cars circling speedways like a long string of colored pearls. Drivers feel much the same way. The term "aero push" is part of every driver's vocabulary. It's the loss of downforce on the nose of the car. It lightens the force on the front tires and allows them to head for the outside wall in a turn.
Aero push isn't anything new; it is just that today there is a name for it. Now NASCAR apparently is stuck with it.
Geoff Gray has spent time both in the grandstands and the driver's seat, racing everything from delicate sports cars to hefty trucks.
"As a fan, I think the aerodynamic parity has created much closer racing," he says. "The quality of the entertainment keeps fans on the edge of their seats. Twenty years ago you might see two or three drivers together on the track. Now, most of the field is in the same pack."
Still, the Midwest race fan says he would like to see NASCAR find a way to bring more passing to the sport.
"From the fans' standpoint, racing isn't as good as it used to be," says Terry Rabone, who has gone to every race at California Speedway since Winston Cup first began using it as a West Coast stop. "All you hear from the stands is 'aero push, aero push.'"
Gray says NASCAR needs to do less tinkering with the rules once it waves the first green flag of the season. "I know they want tight racing, but NASCAR should set the rules before Daytona and stick with them," he says. "If a manufacturer made a mistake and built a car that isn't as good as the rest, well they have a year to figure it out and make it right for next season," Gray says.
The winged Plymouth Superbird and Dodge Daytona marked the first skirmishes in what was to
NASCAR got itself into the aerodynamics business because of parity and manufacturer politics. It wanted to find a way to make the on-track performance of each brand of car near equal.
"One of the problems we had was that as cars evolved, they began to change an awful lot," NASCAR's Nelson says. "They each had about the same size engine, but one may have had a much longer hood over it and another had a longer wheelbase. There was so much difference between a Chevy and Ford that we had to keep adjusting the specifications. Then, when they went to front-wheel-drive cars, it became a moving target. It was almost impossible to keep up."
NASCAR increased its control over the shape of its cars and began to get serious about aerodynamics just about the time its teams discovered the advantages of hours spent in wind tunnels coming up with even a tiny improvement.
"NASCAR calls what it has today 'aerodynamic parity,'" says an industry insider. Teams, drivers, and knowing fans call it "common body templates." "The new Dodge was built using the 2000 Taurus body templates," the insider says. Changes were allowed in the front and rear bumpers and enough variation was allowed on the hood to make it look like a Dodge and not a Ford. The bodies are so close that Ford supplied Taurus sheetmetal to Dodge teams during Chrysler Corp.'s first year back in Winston Cup. Like the Dodge, the next generation Pontiac is based off the Taurus templates.
The industry source says manufacturers at first lobbied against adopting similar body shapes but eventually realized NASCAR wasn't going to back down on the issue.
"Each template is unique," Nelson says. "You can still tell a Dodge from a Pontiac. But yes, they are all very similar."
Right now the quarter-windows are still free for teams to tinker with, but NASCAR is developing its own "greenhouse" specifications that may curb even that bit of variation. The larger greenhouse is being developed chiefly in response to drivers who say the downsizing of today's cars--coupled with more safety gear inside the race cars--makes it difficult to get out in an emergency. But just like a thicker wing on an airplane produces more lift, a larger greenhouse on a race chassis reduces downforce going to the tires. Late-season testing of cars with the new greenhouse showed them the need for more work before the 2003 season begins.
Elliot Sadler (front) says aero push "is like somebody has two jacks under the car and is
Just like the engines for each track require a unique camshaft and intake and exhaust configuration, the aerodynamic needs also differ.
"At Martinsville you are looking more for mechanical grip. It doesn't matter if the car is rolled over or if the left-front valance is on the ground," says Elliott Sadler, who drove the Motorcraft Ford for Wood Brothers Racing in 2002. "But at places like Michigan, Indy, and Charlotte, you need to keep the attitude of the car right, to not only get mechanical grip but to get aero grip to try to take care of the push that you hear so much about," Sadler explains. "You want to keep the left-front fender on the ground ... and keep the car as flat as you can."
Sadler says it's tough to describe what "aero push" feels like. "It's nothing that you will feel on an ordinary car. It is like somebody has two jacks under the car and is lifting it off the ground and making it push. No matter which way you turn, it doesn't matter. It's just going to slide."
Kurt Busch, who drives the No. 97 Rubbermaid car for Roush Racing, says the effects of aerodynamics on passing are compounded by tires that last so long cars can run the low groove lap after lap, eliminating one of the chief areas for passing on many ovals.
Says Sadler, "It is a tough situation, but I think aerodynamic parity has been good for the sport. It allows us to race closer together."
But that close racing also contributes to what's become known simply as "the big one," the almost signature wreck at superspeedways that can take out a third of the field in one crash.
"I think drivers become frustrated, not because they are not able to pass, but because we are in a tight pack all day long ... You feel like you are glued to each other ... 43 cars are glued to each other," Sadler says.
Busch's NASCAR debut as a professional was in the 2000 Craftsman Truck Series race at Daytona. Compared to the sleek bodies on a Winston Cup car, the trucks look like they have all the aerodynamic refinements of a trackside war wagon. But around Daytona, the trucks will turn faster qualifying times and races usually include many more on-track passes than a Cup race.
"It's all horsepower," Busch says. "Sure the trucks don't have the aerodynamics of a car, but with 650 horsepower compared to what's available in a restrictor plate Cup engine (approximately 400-plus) the trucks just produce a more exciting racing environment on that track. The trucks are slowed down because of all that drag, but they have the horsepower to overcome it.
Aerodynamics, packaged with engine restrictor plates, virtually glue cars together at supe
Some drivers have suggested that NASCAR should find a way to reproduce the truck aero figures on Winston Cup cars and turn them loose without restrictor plates. Nelson counters that each time you add more drag to the cars, you will end up with more downforce. "You can't just change one thing," he says.
Don't expect to see any radical change in the next year that will alter the level of competition. Look, instead, for a gradual reduction in aerodynamic downforce.
Nelson said by reducing total downforce, he hopes to lessen the impact of taking air off the front or rear of the car. "If you have 400 pounds of force on the nose and you lose half of it, it will be a more severe change than if you have only 200 pounds or 100 pounds and lose half of that number," he says.
If you reduce the aero downforce, the cornering speeds should get slower, which should mean there is more power available coming out of the corners (right now on big ovals cars are cornering at nearly full power) and that will create opportunities to pass.
Some of the reduced downforce could be generated by the proposed taller greenhouse, which not only may create more lift by accelerating the air as it goes over it but also divert air that now goes to the rear deck spoiler.
Other things will have to change also. Today's Goodyears work so well at the current levels of downforce that the tire maker may have to create one that will work as well at reduced loads.
"The thing is that when you look at the three elements--engines, aero, and tires--when you bring those things under control, then races are won by things we can't control," Nelson says. "That puts the emphasis on the drivers and the teams willing to work harder. It becomes the human element that wins races. That's really how races should be won."