Industrial Equipment Noise

Engineering NASCAR: Part II — The Season

By Mark Devlin, IEN Staff

February 14, 2008 -- Born in 1931, Robert Glen “Junior” Johnson ran ‘moonshine’ as a young man—delivering illegal liquor to customers. Modifying cars to be faster and handle better than those of the pursuing authorities during Prohibition, he also learned to drive better than those officers. Considering the alternative, outrunning them seemed the better deal, and outrun them he (usually) did. He’s credited with devising the bootleg turn: downshifting, turning the vehicle in the direction of the opposite lane, fishtailing the car in a controlled manner and turning it completely around—all in the blink of an eye—ready to speed off past the pursuing vehicle in the opposite direction. Talk about some interesting physics; weight, intense velocity changes, and wildly shifting mass in the precisely controlled acceleration/deceleration of a 3,000+ lb object—along with a healthy knowledge of how the car’s powertrain, braking systems, and suspension were engineered to function (and modified to function better). Here’s a (very) basic illustration (courtesy of Wikipedia) of how it works...

 Translating his driving skills to the fledgling, more lucrative, and legal NASCAR series in 1955, he won five races and finished sixth in that season’s point standings. Practicing for the Daytona 500 in 1960, Johnson discovered something. While many years later, people said that the late Dale Earnhardt Sr. could “see the air” moving around a car at speed, it was Johnson who keenly discovered that driving (very) close to the lead car gave his car more speed—an advantage that led to his win of the Daytona 500 in the same year. This quiet, unassuming man from the backwoods of North Carolina was actually an intuitive, engineering- and physics-minded genius whom—among other accomplishments—discovered the aerodynamics of “drafting” in which the lead car (or, today, even a bicyclist and its rider in competitive cycling) pushes air out the way, creating less drag on the following object.

Fast-forwarding to the present, Assistant Professor of Physics at the University of Nebraska, Diandra Leslie-Pelecky, author of the new book The Physics of NASCAR, reflectively calls Johnson an “intuitive physicist” since, as he put it, “the air was creating a situation, a slipstream type of a thing.” An excellent review of the book is available here from The New York Times. According to that article, the advantage isn’t only for the trailing car...

Junior Johnson and his successors discovered that drafting could help not just the trailing car, but also the leading car by reducing the amount of turbulence at its rear. Two cars drafting together can go 3 to 5 miles an hour faster than a solo car, and extra trailing cars add a little more speed, which is why the drivers spend so much time in single-file bumper-to-bumper traffic.

At no point in the sport’s history has that “slipstream situation” of aerodynamics played such a critical role in NASCAR racing as it does today.

Last year, NASCAR’s Car of Tomorrow (COT) was introduced, and put into limited service by NASCAR race teams at certain events. Quoting from our own article about the COT last year here on The Blog...

It's that safety element that drove NASCAR to develop something completely different. Something that cheats the wind better than ever before. Something so different that it's subtle--so subtle that even many fans don't notice much of a difference: The "Car of Tomorrow."

The first thing one notices about the COT is the rear wing. Compared to the previous spoilers of the still raced car of yesterday, the wing looks more like something off of the neighbor kid's fart-mufflered Honda. In fact, the wing is but one element of the COT, an element that not only creates a safer level of critical aerodynamic downforce but also smoothes airflow behind the car so that it flows in a less chaotic (and accident-causing) way over the next competitor's car. Just the new wing makes it more difficult to "take the air off" of the car in front of you by following right on the guy's bumper.

Here’s a look at the previous Cup car, next to the COT on the right...

Has the COT been a success? Drivers are mixed; some say it works well, others hate it—the latter, because the new design doesn’t create as much frontal downforce. The COT isn’t limited anymore—it’s on for the full 2008 season. Joining the legions of unsung heroes behind NASCAR—more so this year than ever—are more, better, and even brighter engineers. Let the Computational Fluid Dynamics begin...

This year, Ph.D’s like Eric Warren, technical director and aeronautical engineer for Michael Waltrip racing, uses CFD simulations, according to the NYT article, to “calculate the airflow at 100 million points on the vehicle.” (...about 5 million points of which change in a minor confrontation, er, “racing deal.”)

With the likes of Leslie-Pelecky and Warren, this ain’t just the Good Ol’ Boys sport anymore.

So, how exactly does a physics professor become interested in NASCAR?

“It started when six cars were going around the turn, and one of them suddenly started wiggling and went into the wall for no apparent reason,” she recalled. “It was like spontaneous combustion. As a scientist, you look at that and say, ‘There has to be a reason.’ It drove me nuts because I couldn’t explain it. I felt as if I was in a different universe.”

(Isn’t it heartening when even extremely smart people are extremely confused?)

The "aerodynamics arms race" continues, and is but one of the elements covered in Leslie-Pelecky's book. According to the NYT, the author "...explains everything from the mechanics of racing engines to the molecular properties of the drivers' fire-retardant suits, paying special attention to the endless battle against that great, evil force, drag." Sounds like a must-read, even if one's just curious about how things work and not so much about the sport itself.

To some, NASCAR—especially on television—isn’t very exciting. Just a bunch of cars making lefts, right? Seems that way at a glance. Watch things closely, though. Forget about the constant left turns. Watch the drivers. Watch the speeds. Watch how very easily the cars lose traction and skid into a pit stall as though they’re on ice, but cling to the track at insane speeds. Watch how close to the edge everything is, from following distances (sometimes a foot, sometimes inches, sometimes no space at all with bump-drafting or today’s “slam-drafting”). Think of the forces at work, and how the drivers (usually) control those forces and harness them in their favor. If that doesn’t give you more respect for the sport—not only NASCAR, but any form of motorsports—go to a race. If that doesn’t work, don a fireproof suit and helmet and just drive one (such as in the Richard Petty Driving Experience, at tracks around the country, or in other such programs in the lighter, higher G-force forms of open-wheeled racing). If I can do it, you certainly can. It’s worth every penny just for the fun of it, and you’ll climb out of the car giggling like a kid on Christmas morning.

Beyond adult appreciation of the sport is a relatively new element for NASCAR: according to this source, 36% of those under age 18 in the U.S. are NASCAR fans. Getting young people involved in science and engineering is one of Leslie-Peleky’s goals, certainly a worthy and admirable endeavor. Prior to The Physics of NASCAR, her career has included, for instance, teaching Matter and Motion: The Physics of Cars.

Leslie-Pelecky’s speaking schedule includes...

March 10, 2008: American Physical Society March Meeting. Technical presentation: Materials at 200 mph, New Orleans LA.

April 11, 2008: American Physical Society Teachers Day. Presentation: Stock Car Science: The Physics of Going Fast. Adams Mark Hotel, St. Louis, MO. 

Maybe I’ll see you there.

Check out the New York Times article. Enjoy the Daytona 500 this Sunday, and remember the legends like Junior Johnson (He'll be driving the 2008 Corvette Z06 pace car.). Remember that it’s not about making lefts. It’s about the drivers, teams, fans—as well as the science and engineering.

Update, Feb. 21, 2008...

Driving for racing legend and industrialist Roger Penske, Ryan Newman won the 2008 Daytona 500 in a nail biting sprint to the checkered flag, following a caution. With a "push from heaven," Newman grabbed the lead on the final lap.

The Daytona 500 win was a first for both. As a team owner, Penske's won the Indianapolis 500 a record 14 times, and has been trying for a Daytona 500 trophy for 24 years. The win also broke an 81-race, 2-year drought for Newman.

Engineers rejoice, as Newman is one of your own. According to an article at the Star-Telegram, Here's Some Sound Advice: Stay In School, and Shut Up...

Race winner Ryan Newman and crew chief Roy McCauley are an odd couple of sorts in NASCAR's Sprint Cup Series garage, in that both are college graduates. Newman, 30, earned a bachelor of science degree in vehicle structural engineering from Purdue University in 2001. McCauley, 37, graduated from the University of Maryland with a degree in mechanical engineering in 1992. The real-world value of Newman's diploma?

"In general, I always said my engineering degree helped with two things, more everyday life things, and that was time management and problem-solving," Newman said. "Those two things definitely helped me be a better person. I would suggest that anybody that has the opportunity, whether you're 5 years old or 15 years old, to think about college."

Congratulations to the drivers, teams, and especially the unsung heroes of the sport: the engineers and scientists who make it all work.