Working the Draft

There are few forces of nature more closely studied than the air we breathe every day of our lives. The air is responsible for so many things, yet you can’t see it. It, along with water and food, is one of only three substances required by human beings for survival.

Air is the giver of life to us all, and the reason we can walk about on two legs, sucking in the mixture of gasses with nary a second thought. There are people, however, who can “see” the air and make it do their bidding. They make their living running close together at speeds approaching 200 mph, using bits and pieces of atmosphere to propel themselves a little faster, a little harder, around great banked-oval racetracks on the weekends. That, my friends, is The Draft.

The draft is one aspect of air race fans have heard on TV for most of the last 30 years, and it has become part of the lexicon of the sport. Everyone talks about it, but how many really understand what it is? How does it work? Who invented it, and why does everyone on the track talk about it incessantly when the NASCAR series stops at Daytona or Talladega? Does it happen anywhere else? Who is the best at it? Can you really see the air? These are questions to which you will find answers as you read on.

Sounds Simple

The premise of drafting itself is simple. Two or more cars racing along on a track of any size will follow each other around the speedway as if one is tied to the rear bumper. Why? The draft. The car in front punches a hole in the air as it moves, roiling the air as it passes over, around, and through the car in front of it. The second car in line, by staying directly behind the leader, can use a principle of fluid dynamics—the vacuum—to “suck” along behind the lead car, thus saving fuel and wear and tear on the engine and other components.

Despite that relatively straightforward explanation, NASCAR Winston Cup driver Ricky Rudd put it in plainer terms: “Basically, you take two cars that can run 190 mph by themselves, but nose-to-tail they can run 200 mph,” Rudd says. “It’s sort of cheating the air. When you put two cars together, you reduce the drag tremendously, therefore the cars will run quicker together.”

Benny Parsons, the ’73 NASCAR Winston Cup champion, went nautical to explain what drafting means to him. “An old analogy is probably the best,” Parsons says. “A boat goes through the water, and the water spreads. You have a wake behind it, and I think air does exactly the same thing. You go through that air, and it splits and leaves that wake behind it. Before the air can re-form, there isn’t as much resistance, so when you ride back in that wake, it makes running easier; it takes less horsepower to maintain the same speed.”

Louis Duncan, the aerodynamics master who runs RAD, an aerodynamic partnership among Dale Earnhardt Inc., Andy Petree Racing, and Richard Childress Racing, has a slightly more academic description of what drafting is all about.

“Let’s begin with a solo car,” Duncan says. “If a car is on the track by itself, there’s pressure on the front because of the air flowing over the front of the car. There’s air pressure over the top, bottom, and back, which is caused by the flow of air over the car. If you have two cars nose to tail, then it changes the airflow and the resulting pressure on both of them. Visually, you can imagine the turbulent wake of air coming off the first car, and that changes the airflow on the car behind dramatically. There is no longer the smooth streamline of high-speed air over the nose of the car behind. The airflow still pretty much goes over the top of the second car and down to hit the spoiler, so the rear downforce is not a lot different, but the front downforce and drag are very different on the car that’s behind. There’s much, much less drag.

“The car that’s in front also has a different airflow—it is still about the same. The airflow over the back is very different because of the car behind. It backpressures the airflow over the roof of the front car so it may or may not hit the spoiler. Both cars have less drag, the front car has less rear downforce, and in the rear car, the front downforce is much more variable. Both cars have a lot less drag, and the downforce—the downforce balance front to back—is very different.”

Stay In Line

Winston Cup driver Rick Mast offered this explanation of drafting, up close and personal: “If I had to explain drafting, the first thing I would say is that what you see on the in-car cameras on television doesn’t do it justice. None whatsoever. In lay terms, the car in front opens a big hole in the air. The car behind him is in a void, so it has no resistance to the front end of the car, and that makes the car feel like it’ll run faster. It will run faster until you pull out and hit the air.”

OK, now that we have a working definition of drafting, how is it used? Why is it important? Duncan offers the famed “slingshot” move, born of many a thrilling race at Daytona and Talladega, as an example.

“The slingshot procedure at Daytona is a good example of how drafting can affect your performance,” he says. “The slingshot is when the second car is higher on the track than the lead car and gets a lot of momentum and speed. It then gains more momentum and speed by gradually making a left turn and going through the wake of the first car and has even less drag. He then pulls to the bottom of the track and passes the lead car. What’s going on there aerodynamically is that the slingshot car is acting like a solo car when it’s up high. It has much less drag, and it’s also going downhill. This is almost always done in the corners so that it has a lot less drag when it passes the wake of the first car. It also has enough momentum to go ahead and pass the first car.”

Got all that? The slingshot is simply a matter of taking the air and using it to your advantage. That’s the essence of drafting—using every scrap of air to get past the guy in front of you. Horsepower becomes a slave to physics, and using the draft well can mean as much as a whole tank full of nitrous oxide when it comes to short bursts of speed.

Any Secrets?

OK, now that we’ve established what the draft is and how it can be applied, let’s ask another question: Is there a big secret to it?

Rudd says there isn’t. “It’s sort of like catching a wave in the ocean if you’re bodysurfing or riding a surfboard,” the Virginia native explains. “It’s an invisible wave. It’s not just riding that wave and taking advantage of it; it’s knowing how to use it to your advantage, knowing how to change the handling on your car. If you ride on the inside or outside of the guy in front of you, you change the handling on your car. You also change the way the guy in front of you handles.”

A.J. Foyt, one of the true masters of his craft in any type of car, has seen the draft and used it both in stock cars and open-wheel Indy cars, as well as sports cars. The four-time Indianapolis 500 winner—who also won the ’72 Daytona 500 for the Wood Brothers—says there is a secret.

“Well, actually, it’s just knowing where to set yourself, how to draft, and how to work people,” Foyt says. “The closer you can run to somebody, the better off you are. When I used to draft, when I went in the corner, I used to like to drop the left front kind of underneath him. If I couldn’t get by then, that way it holds him tight and you tight. Some people try drafting and they’ll swing to the outside, which jerks him loose and screws you up. That to me is one of the big secrets of drafting.”

Parsons says drafting was more a process of feel than anything else. “I think that Buddy Baker and Earnhardt were the guys that were just absolute masters at it. They were able to feel, when they pulled out, something that told them to pull back in or go ahead. When they decided to make that pass, it seemed to be a lot easier for them to do it. When I was trying to make a pass, it was a struggle for me, and it seemed a lot easier for them.”

Baker, who along with Earnhardt is the man most often mentioned when talk turns to masters of the aero game, says drafting is a learned skill like anything else. “It’s procedure, just like a guy who learns to land an airplane on an aircraft carrier,” Baker says. “It seems impossible to some, and to those who understand it, it’s almost formality.”

Baker says the key to drafting is to watch and learn. “To race well at Daytona and Talladega, you have to learn to read the car in front of you or what the air is doing—if there is such a thing as the vision of air. You can’t see air—that’s the first thing—but it’s there. You can feel it, and you can feel what it does to the car. You can watch the tachometer and see an improvement. What you do is pay attention to what your car is doing and what the other car is doing, and you do it to your advantage.”

Baker also says the draft is used nearly everywhere NASCAR cars race, just not to the same degree as it is at Daytona and Talladega. The science of it stays the same, whether you’re at Atlanta or Michigan.

Early Discovery

The draft itself is a product of the laws of physics and fluid dynamics. It is not a new thing, either in nature or in racing. In 1959 nobody knew what the draft was or what it could do. That happens to be the same year that Daytona International Speedway held its first race, and it is the same year that Baker started racing. Baker says it didn’t take long for the stock car pioneers to figure out there was something in the wind.

“A couple of people found it by mistake, I guess,” Baker says. “Junior Johnson was talking on TV the other day and said he was going down the back straightaway in the first Daytona race. He was fixing to pass a car, and as he got up close to it, it jerked him forward. He looked down and said, ‘Whoa! Look it here! Well, if it does that, then these slower cars have air coming off the back of them.’ So he’d run at them, and it doesn’t take very long when you see one guy do that and somebody else sees it. ‘Wow, look what two cars do together, and then three, and a whole train of them.’ Then you start experimenting with what you need to do.”

p>Much of Baker’s reputation as a draftmeister came from his time in the super-slick Dodges of the early ’70s. They were fast; they cheated the air with their swoopy noses and towering winglike spoilers.

“The first time I saw a wind tunnel, I said, ‘What do we need that for? We work in 200-mph air all the time,’” Baker says. “We started making the car slicker, and all of a sudden you’d go to the track and say, ‘Wow, this thing drives so much better. It actually feels like it’s going to stay down on the ground.’ Spoilers were more important than drag and aerodynamics. A good example is going to a test nowadays and getting in one of these cars. It’s pretty effortless when you’re out there by yourself. They drive so well. The first time I tested for Rusty Wallace, I went, ‘Wow, I can’t believe anything could be that easy to drive.’ We were running quick, too, still in the 194- to 195-mph bracket.”

Today, the cars are, overall, much cleaner and more aerodynamic than even the old Dodge Superbird and Daytona models. In fact, Duncan says the single biggest change in the use of air as a tool came when the single-piece Kevlar noses were adapted in the early ’80s.

“The cars had a steel front bumper and a 4-inch blade spoiler tucked up underneath the front bumper,” Duncan says. “Then NASCAR and the manufacturers made the switch to a one-piece Kevlar nose. Before that time, they were lucky to get any front downforce on the car at all, and the Daytona cars had lift. The faster you’d go, the more the nose would lift.”

Lift is a bad thing, by the way. Lift is the opposite of downforce, and it tends to make cars act like airplanes. It was this characteristic—exhibited by Bobby Allison at Talladega in 1987—which led to the introduction of restrictor plates in NASCAR today.

A Few Restrictions

The outgrowth of aerodynamics has led to larger spoilers at steeper angles, and the plates mean there’s not enough power to pull the hat off your head when dropping out of line to pass. That has sort of ended the days of “working” fellow drivers in the draft, says Rudd.

“Now, in this day and age, they’ve got them slowed down so much, and we have so much spoiler on these cars that you can’t really work a guy like you used to,” he says. “Used to be you could drive up under his fuel cell if you wanted to pass him and basically lift the rear tires off the ground just by affecting how much air he has on his rear spoiler. Those days are sort of gone at Daytona, but they still apply at Charlotte and places like that. If you want to pass a guy, you don’t necessarily have to outrace him; you just drive up underneath him so close, and he’ll want you to pass him.”

The key to figuring out the draft, according to Foyt, is feeling where your car was most comfortable and staying there. “You can just feel your car, how it’s drafting off the other car, and moving you around, and so on. That’s how I did it. Wherever it feels real comfortable is where you try to draft the other guy and still let the two of you draft and not slow down when he’s comfortable. In other words, if he’s a little bit loose, you’ll drop down a little more on the inside to keep his back end under him,” he says.

The restrictor plate has been both a boon and an albatross for racers at high-speed tracks. While it does limit speeds by choking off the amount of fuel-air mixture that can be ingested by the engine, it also leaves everyone more or less equal. This means the draft is crucial to success at Daytona and Talladega.

“The scary part is the restrictor plate,” Mast says. “We’re all bunched together because of the draft. The scariest part of it is, you can’t get away from each other. Everywhere we race, we get away from guys we might not want to race with at that particular time, or there’s a situation where a couple of guys are racing that you don’t want to be around. With the draft and restrictor-plate racing, we’re all the same now; you can’t get away from those situations. You’re thrown in there, and that’s the worst thing about it.”

While drafting is the only means by which drivers can pass while running with restrictor plates, the advent of the plates has made the whole process more difficult. “The more aerodynamic the cars get, the less drafting means,” Parsons says. “Fortunately, through the late ’70s and early ’80s, we were unrestricted, so you had the power to use the draft and go by. Since they started using the restrictor plates in 1987, it’s made drafting much more difficult.”

So that’s the draft, ladies and gentlemen. It’s air as a tool to win races, and it is both simple and complex. Remember, two cars together have less drag than one alone, and it’s all a project of making the wind work for you, not against.