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The art of the draft

October 02, 2012, Mark Aumann, NASCAR.com



The art of the draft
Junior Johnson first took advantage of the phenomenon at the 1960 Daytona 500

European sports car drivers had described the effects of "slipstreaming" since the 1920s, but it wasn't until the construction of Daytona International Speedway in 1959 that NASCAR drivers began to understand the notion that a trailing car gets a significant aerodynamic advantage at high speeds.

You've felt the sensation if you've ever gotten close in behind a tractor-trailer rig at freeway speeds. The 18-wheeler "punches a hole in the air," or creates a miniature low pressure area directly behind it, according to race engineer Travis Geisler.

"There's that area behind it where you'll feel where you have to get out of the gas a little bit, because there's no air force on the front of your car," Geisler said. "You go through that little buffer zone when the car gets buffeted because the air's not smooth and then you get to where there's just a vacuum beyond the back of it and the air can't fill that void quick enough."

UPS... Game Changing Moments

Junior Johnson was the first driver to take advantage of what has since been called "drafting." During practice and qualifying for the 1960 Daytona 500, it was evident that Johnson's Chevrolet didn't have the horsepower to keep up with the Pontiacs and Fords on its own. But when Johnson tucked in behind one of the faster cars, he was able to be pulled along in its wake.

Johnson used that strategy to win the race, and ever since, drafting has been a key factor at high-speed, high-banked ovals.

And when Bill France envisioned and built a track in central Alabama longer, wider and with more banking than Daytona -- now known as Talladega Superspeedway -- the effects of drafting were even more pronounced. It was evident early on that the cars were pushing the boundaries of racing safety, given the technology of the time.

For decades, racing had always been about going faster. But now racing officials were grappling with the question of "how fast is too fast?" It all came to a head at Talladega in 1987, after Bill Elliott qualified his Ford on the pole at nearly 213 mph -- the fastest lap ever turned under official timing.

Just 21 laps into the race, Bobby Allison ran over some debris coming into the tri-oval and cut a right rear tire, sending his car spinning backwards and lifting it several feet off the ground -- and into the catchfence separating the fans from the action.

Thankfully, the fence did its job, keeping Allison's car from reaching the stands and creating a tragedy of enormous proportions. There were no serious injuries, but it was an incident which forced NASCAR officials to finally come to grips with escalating speeds.

From that point on, the sanctioning body has attempted to manipulate the maximum speeds attained on superspeedways through mechanical means -- whether by the use of carburetor restrictor plates or with spoiler angles and sizes -- in an effort to keep the cars planted firmly on the ground in the event of a crash.

That's generally accepted as being around 200 mph, although as drivers like Carl Edwards and Ryan Newman can attest, that's not necessarily a guarantee.

The use of restrictor plates created a different set of issues. With engines straining to run at maximum efficiency, the cars began to run in large packs, sometimes three- or four-wide. That created the potential for massive multi-car accidents, and both superspeedways have seen their share over the years.

"There's that area behind it where you'll feel where you have to get out of the gas a little bit, because there's no air force on the front of your car. "

--TRAVIS GEISLER

But two major factors led to the next evolution in drafting: the tandem draft. First, Talladega was repaved in 2006, making it nearly billiard-table smooth and allowing cars to run even closer together. A year later, NASCAR mandated the Car of Tomorrow, with its bigger "greenhouse" and more upright front windshield -- which meant more aerodynamic drag.

"The cars have a ton more drag than a typical old-style speedway car," Geisler said. "We were really able to change the shapes on things and really make a big difference on the amount of drag, to where an intermediate car would have a lot more drag, I mean double if not a little more than would a speedway car.

"Now, you can trim things and make them a little smoother and do some little things here and there to try and trim the car out. But you can't make a big step change on the amount of drag that they have, just because you're locked in on your shape so much more."

And perhaps even more important, the front and rear bumpers lined up nearly perfectly. As they are wont to do, drivers began to experiment with tandem drafting, finding out that two cars locked together in a continuous bump draft were significantly quicker than running in a regular draft.

With the switch back to the rear spoiler from the wing, the effect was even more pronounced. It radically changed the look and feel of superspeedway racing, as instead of a large pack of cars, now cars were pairing up and pushing each other around the track.

The novelty wore off quickly with fans, and last winter, NASCAR once again went to the rule book in an effort to minimize tandem drafting, mandating smaller radiators, changing the location of the grille openings, requiring softer rear springs and a smaller rear spoiler.

The new rules package did limit tandem drafting when the series returned to Talladega this spring, but some drivers had cooling system issues for much of the day, including Jeff Gordon.

"This temp thing is kind of a joke," Gordon said. "They are going to have to fix that. We all knew that was going to be a big issue, but when you can't really even race because the temps, even in a regular pack are an issue, we have to address that."

There were fewer overheating problems at Daytona in July, and NASCAR vice president of competition Robin Pemberton said those concerns are continuing to be addressed, specifically heading into this week's test of the 2013 chassis at Talladega.

"When we go to Talladega, we're going to concentrate on the cooling package, the drafting package," Pemberton said. "The handling is really the least of the issues down there. ... It's about working on the drafting package for Talladega -- and Daytona."

It's impossible to guess what form it may take in the future, but it's safe to say drafting will continue to be critical when it comes to getting to Victory Lane at a superspeedway. It worked for Junior Johnson in 1960, and Sunday's winning driver will reap the benefits.