It's a very special day at the cocktail party, because we're featuring an extensive Q&A interview with Diandra Leslie-Pelecky, mediagenic condensed matter physicist extraordinaire and author of a terrific brand-new book: The Physics of NASCAR: How To Make Steel + Gas + Rubber = Speed. It's so extensive, in fact, and so substantive, that we're splitting it into two parts: Part I (this post) focuses on some of the actual science behind the sport and her adventures hobnobbing with the NASCAR crowd. Part II will be posted tomorrow and will focus on the broader issues of gender dynamics, effective communication of science to diverse audiences, and making NASCAR vehicles of the future more energy efficient.
This book's publication is particularly gratifying because I've known Diandra for years. We met at an academic/industrial workshop sponsored by the American Institute of Physics sometime in the 1990s, hit it off -- it helped being two young women of roughly the same age in what was usually a roomful of men -- and over the years became good friends, despite living in completely different parts of the country. And it's always gratifying when one's friends do well.
We've had lots of long dinner conversations over the years about physics, and communicating physics to broader audiences, but I distinctly remember one in particular, just after my first book came out. Diandra mentioned that she'd been thinking a lot about the underlying physics of NASCAR racing, and thought it might make a decent book. "You should totally write that book!" I exclaimed, recognizing (as did she) that it could potentially reach people who would never otherwise have any exposure to physics. I say that a lot to people who have ideas for books; it rarely translates into concrete action. (People have lives, after all, and writing a book is an enormous time- and energy-suck. It can literally consume you.) Blessed with an unusual degree of decisiveness, discipline, and drive, Diandra promptly went out and wrote it.
And she wrote a damned good book, too, packed with fascinating science illustrated by real-world crashes, wins and losses, and colorful anecdotes gleaned from all her backstage visits and interviews with the mechanics, drivers, car designers and so on. She gives a rare peek at how much effort, ingenuity, and just plain good science goes into this seemingly inane sport. I used to catch bits of NASCAR races on TV while flipping through channels, and marvel at how so many people could be so enthralled by a bunch of cars going around a track really, really fast. I get it now. At least a little. There's a lot more to NASCAR than circling around a track. Don't believe me? Buy the book and see for yourself; I suspect you'll get sucked in, just as I did. Check out her Website, and her schedule for speaking engagements. And join me in welcoming Diandra to the cocktail party!
Q: What is it that sparked your interest in writing a book about NASCAR physics? Were you just a really big fan of auto racing?
DLP: I was flipping through channels one Sunday and happened upon a race. Nothing exciting, just a pack of five or six cars going around a turn. I was ready to click to the next channel, but before I could, one of the cars in the pack -- all of a sudden, and for absolutely no apparent reason -- hit the outside wall. I'm a physicist. I know that things don't happen without a reason, so this bothered me a little.
No one was hurt but the car that hit the wall took out a bunch of other cars, so they had a bit of cleanup to do. That gave me time to watch the replays. I saw no tire problems, no engine problems, no contact with other cars. The announcers said something about the car "getting loose" and the other car "took the air off his spoiler." I felt the way I suspect my students feel when I start using physics jargon.
I got on the web, thinking I'd have an answer in 10 minutes. Two years later, here's a book about it. I've always liked writing and I've always liked teaching, but over the last few years, I had really gotten down about teaching. It is very frustrating teaching students who don't want to be there. That's partially our own fault because we do a pretty lousy job showing people that physics has to do with things they care about. When I explained things in class using NASCAR, or even cars in general, the students were more engaged because they could see the connection between what they were supposed to be learning and what was actually happening around them. There are very few other sports in which the link between science and winning is as strong.
The moment of conception for the book goes back to a conversation you and I had at an American Institute of Physics Industrial Affiliates meeting in Bethesda, Maryland in 2005. [Jen-Luc Piquant observes that Diandra has a far clearer, detailed memory of date, time and place than I do.] I mention this because we often forget that what we say to other people has great power. Sometimes a word of encouragement is enough to turn a wild dream into a plan.
I had been thinking about NASCAR and using it to teach physics all summer and mentioned it to you because I'd always harbored this abstract dream of being a writer someday. We are the same age, and I think we had been talking at our table about milestone birthdays. You told me to "Just do it" and sent me one of your book proposals and a referral to an agent. I sat on it for six months, then contacted the agent and figured that it would take a year or two to sell -- if it sold at all. Much to my surprise, it sold rather quickly. Then I actually had to write it!
Q: So what caused that crash you saw on TV?
DLP: The grip of each tire is proportional to how much force is pushing down on that tire. You can get grip two ways: mechanical grip, which is the interaction of the tire and the track, and aerogrip, which is due to air molecules rushing past the body and pushing down on the car, which again pushes the tire into the track. Without aerogrip, you have to slow down around the turns. The amount of aerogrip depends on how fast you're going and how other cars disrupt the airflow around you. If a car comes up behind you just right, they can decrease the amount of air hitting the rear of your car, which decreases how much grip your rear tires have. The car I saw crash lost rear grip and couldn't slow down enough to make the turn.
Q: You had the opportunity to go behind the scenes and interact with the drivers, owners, mechanics, and various others who make NASCAR happen. What were some of the highlights of researching the book?
DLP: The book turned out much differently than I expected because I went into it thinking that I'd talk to the technical people to get background and then write up chapters explaining different topics. I thought the technical people were just in the race shops, but the race track garage is filled with science.
I went to a meeting of the Society of Automotive Engineers Motorsports Conference -- at this point, I didn't know a suspension from a carburetor -- and I met people from F1, Indy racing, drag racing and NASCAR. They were more than happy to answer my questions and they were very welcoming of a total outsider into their group. Not all professional societies are like that.
Josh Browne, who was the No. 19's Crew Chief at the time, was at the conference and I invited myself to "embed" with their team for a couple of races. Josh understands the potential power of using motorsports to get people interested in math, science, and engineering, and he has been (and continues to be) incredibly supportive. The guys on the No. 19 team let me follow them everywhere, ask a lot of questions, and made sure that I didn't get run over in the garage.
I was surprised by the access I was given, both at the track and in the shops. I was upfront with each team that my goal wasn't to spill their secrets, and I got a lot of great stories that ended with, "Oh, please don't publish that!"
Q: You also got to drive one of the race cars, thereby earning the envy of teenaged speed demons everywhere. Inquiring minds want to know: how cool was that?
DLP: The Team Texas High Performance Driving School at Texas Motor Speedway made that a great experience. You have to understand that I'm afraid of basically everything, especially things that I've never done before. Team Texas puts ten cars on the track at a time and each car has an instructor in the passenger seat. I picked Team Texas because I liked the idea of having someone right there, and because they offered the opportunity to do a driving experience and then a ride-along with one of their instructors. I figured if I didn't get the car over 100 MPH myself, I'd at least get the feeling of speed from the ride-along.
I was surprised because I wasn't that nervous waiting for my turn. It's because I was focusing so much on how I was going to capture that experience and all the subtleties for the book. I was concentrating on the track and the signals from the instructor, and I was a little disappointed when we finished and pulled into the pit road because I didn't think we had gone very fast. Paul, my instructor, told me I did a pretty good job for a first tie, and that we had hit the max speed: about 150 MPH. I have a videotape taken from the car, and when I went back and watched, we had passed just about all the other cars on the track. There is an ignition chip that limits the engine rpms, which limits the speed. When I went back to the in-car tape, I could hear when the chip kicked in, which is called "hitting the chip."
I rode with Mike Starr, who owns the Team Texas Performance Driving School. For anyone thinking about doing a ride-along at Team Texas, let me note that when you own the school you get to run in the lead most of the time. The difference between my driving and his driving is that I was doing 150 MPH down the straightaway. Mike was doing 150 MPH around the turns. I thought my head was going to go right out the passenger window -- we were pulling about 2g! While we were driving, they kept the cars pretty far apart, but when we were passengers with the professional drivers, we were going 150 MPH and I could literally have reached out and touched the car next to us. Way cool.
When I got out, I was fine, but after about a minute, I felt like I had drank a whole pot of coffee. My legs were wobbly and my heart was racing. My hands were actually shaking. I thought that maybe my body had finally caught up with my brain and was appropriately afraid.
When I was with the No. 19 team at Atlanta for qualifying, our driver (Elliott Sadler) was one of the last to go out, and he ended up with the second fastest time. While we were waiting for the other cars to finish, I noticed that Elliott was shaking the same way. Josh told me it's adrenaline. It's like winning in Vegas: you get a rush and you want to do it again.
Q: Was there anything that surprised you about the world of NASCAR?
DLP: Almost everything surprised me about NASCAR. In academia, we talk a lot about how open-minded we are, but we all have stereotypes, especially about things that are outside our immediate experience. I had my own stereotypes of NASCAR and most of them were totally wrong.
I was pleasantly surprised by how helpful everyone I worked with has been. I started talking with people like Eric Warren and Andy Randolph, both of whom are PhDs (in aeronautical and chemical engineering, respectively), so we had the common background of having been through the hazing experience known as graduate school. (In both interviews, we ended up talking about funding. Put any two PhDs in a room and they talk about funding.) At my first race, I spent most of my time with Josh and Chad Johnston, who are both formally trained engineers. By my second race at Martinsville, I had screwed up enough courage to pester the mechanics in the garage. That sounds like an upside-down approach, but that's the way it felt most comfortable to me.
NASCAR is largely a meritocracy. If you go to people unprepared, they'll let you know (just like in physics). If you ask intelligent questions and are upfront, they'll be exceedingly generous with their time. No one was ever condescending or rude.
I went into the project thinking this would be like an anthropological expedition: I would stand in the back and take notes and report what I saw. And I guess that's exactly what I started out doing, but what I saw were people passionate about their jobs who work 60-80 hour weeks because they are obsessed with figuring out how to make their car go faster. In other words, people like scientists, except they make better money than we do.
I remember standing on top of the hauler in Atlanta -- it was March, and very, very cold. It was my first time at the track and I hadn't yet gotten the nerve to venture into the garage per se. I could see the track from the top of the hauler, and if I ducked down, I could see into our garage stall. The team wasn't having a great practice, and I remember in particular one time they had rushed to make a change to try to make the car better. The entire crew was standing in the empty garage stall waiting. The driver (Elliott Sandler) came over the radio after a lap and said, "Nope. Not any better." I could hear the disappointment in Elliott's voice and I remember watching Kirk Almquist (the car chief) from the top of the hauler, and seeing his shoulders slump and his head hang when he heard that. You can't watch people who care so much about what they're doing and not be pulling for them to succeed.
Q: You've said that NASCAR drivers are "intuitive physicists." What do you mean by that?
DLP: Drivers can explain impulse and conservation of energy, but they don't use those words to do it. When it comes to racing, drivers are experimentalists and I'm a theorist. How many times have I calculated the centripetal acceleration around a banked curve? You get a number and it's mostly meaningless. You write it down and move onto the next problem. But I have a gut-level understanding of what 2gs feels like now.
Most drivers don't recognize that they are explaining "physics." I have a tape of Elliott explaining his 2003 Talladega accident (a quintuple somersault with two pirouettes and an upside down landing) that I used in my class. [Jen-Luc found a video clip of the accident here, as well as a clip of the all-time worst NASCAR crash to date, for all you morbid rubber-necking types... like her.] It looks like a very serious accident, but Elliott walked away with literally nothing more than the wind knocked out of him. Elliott explains on the tape that, because he slowed down over a period of time, each hit dissipated a little bit of energy, and he felt a little force, but nothing like he would have felt had he stopped all of a sudden. Well, that's F=dp/dt in physics language. Elliott was surprised to find out we were team-teaching physics.
Jeff Gordon did an ESPN Sports Figures episode in which he explained the difference between kinetic and static friction. When you're going around a turn, you want to slide a little in the radial direction, but you can't slide so much that the car loses grip and heads into the wall. When the car starts sliding up the track, you're in trouble. Jeff says in the tape that his job is to detect the change from static to kinetic friction. He may not have known the words prior to taping, but I guarantee you he can feel the difference between those two types of friction through the seat of his pants in a way that most of us who can write the Lagrangian equations of motion for a race car cannot.
Q: Were you ever tempted to just buy a junker and take apart the engine to see how it works?
DLP: I lucked out having met Dr. Andy Rudolph, who is the Engine Technical Director at Bill Davis Racing. I visited him just after the spring Fontana race, where their No. 22 car's engine had blown up. The engine was in pieces sitting on a cart. The oil pooling around reminded me of blood. Andy was looking at it like a doctor whose patient had left the hospital looking perfectly healthy and now here he was doing an autopsy.
Engine books often show an exploded view of the engine. I got the literal exploded view of the engine, which helped me understand the relationships between the pieces better. The first time I talked with Andy, I didn't even realize that they use pushed engines, but he is a really good teacher, so I think I've got a halfway decent understanding of the engine. [Jen-Luc sez check out this photo of Diandra lookin' all cool and mechanical in the garage with Andy Randolph. You can just hear them saying, "Assume a spherical tire..."]
One of the great things about the people I met is that I'm still in contact with many of them. When they changed the size of the restrictor plate at Daytona, I sent Andy an email that was essentially my understanding of the changes, followed by, "Is that right?" He replied, "Yes, but..." and proceeded to show me another level of science I hadn't thought about.
A NASCAR engine works pretty much like a standard internal combustion engine. What really made me crazy was trying to understand the suspension -- the shocks, springs, weight distributions, etc. The suspension geometry is unique to stock car racing. NASCAR just changed car models, so the old cars, which can't be used anymore, were being sold off "pretty cheap" (meaning tens of kilobucks). I pondered getting one just to be able to understand the suspension a little better, but I'm sure there's a zoning regulation about having a car body without an engine in it sitting in your front yard. I could probably swing buying a chassis, but an engine is likely beyond the budget of an academic.