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THE SCIENCE AND SKILL OF DRAFTING<br />
Gone with the<br />
Aerodynamics plays a huge part in motorsports. Regardless of the type of race<br />
machine, airflow will influence its top speed, acceleration, deceleration, handling<br />
and cooling. So it’s no surprise that racers try to manipulate it to their<br />
advantage. They design bodies and aerodynamic devices to manage air. And<br />
when they’ve done all they can with design, they try to influence the air during<br />
the race. There’s no better example of this than drafting.<br />
Slip Sliding Away<br />
Drafting, or slipstreaming as it is also<br />
known, plays a role primarily in auto<br />
and motorcycle racing. As a race<br />
vehicle rushes through the air, its<br />
body design creates an air pressure<br />
bubble in front and a minor vacuum<br />
behind it. Together, the effects produce<br />
drag. Aerodynamic detailing<br />
can reduce drag, depending upon<br />
how much freedom designers are<br />
allowed. But by drafting, a driver can<br />
reduce drag on his own.<br />
Drafting occurs when a car tucks in<br />
closely behind another. The leading<br />
vehicle loses some of the drag at its<br />
rear. The following vehicle still has a<br />
vacuum at its rear but now has less air<br />
resistance in front. The result is that<br />
both machines go faster. In fact, the<br />
closer they are, the faster they go.<br />
As former NASCAR Winston<br />
Cup champion and NBC broadcaster<br />
Benny Parsons explains, “A<br />
boat goes through the water and<br />
the water spreads. You have a wake<br />
behind it. I think air does the same<br />
thing. You go through that air and<br />
it splits and leaves that wake<br />
behind it. Before the air can reform,<br />
there isn’t as much resistance,<br />
so when you ride back in that<br />
wake, it makes running easier.”<br />
Power to Pass<br />
Of course, the point of drafting is to<br />
make two or more racecars go faster<br />
and, at some point, to allow one of<br />
the machines to pass — to “slingshot.”<br />
Slingshotting occurs when one<br />
vehicle gains speed in the first vehicle’s<br />
wake and pops out to pass using<br />
Air pressure creates<br />
a drag on lead car.<br />
The wake of lead car<br />
creates an area of<br />
decreased pressure.<br />
26 www.uawdcx.<strong>com</strong>
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