NASCAR Rule Changes Leave Teams Scrambling For Wind Tunnel Time

In one respect, the racecars being developed for the 2013 NASCAR Sprint Cup season will be on the racetrack next week -- in the form of ideas that will be incorporated into the new models.
On Tuesday, NASCAR sent a technical bulletin to all Cup owners, crew chiefs and drivers, listing rule changes that will take effect as of May 16, in time for the Sprint All-Star Race.

Typically, NASCAR’s technical bulletins are more about housekeeping items and less about major changes to the competition package, but Tuesday’s bulletin, which contained a laundry list of rule changes in eight areas, was significant enough that crew chiefs immediately began booking wind tunnel time.
Of greatest interest was the shortening of the side skirts on the Cup cars, designed to create greater ground clearance. NASCAR also has mandated use of superspeedway-sized stationary air deflectors (commonly known as “shark fins”) on all tracks of two miles or more.
According to Robin Pemberton, NASCAR’s vice president of competition, the rule changes were inspired by work on the 2013 car, with an eye toward raising the speeds at which a car will lift off and become airborne.
“In working on our 2013 car, there were some things that we worked on that we can apply to help with liftoff speeds, and one of them was the Daytona and Talladega back glass and (rear) deck fins for the two-mile and above tracks,” Pemberton said Saturday at Darlington Raceway.
“The other one was raising the clearance on the skirts an inch on the right and an inch and a half on the left. The majority of that was for safety.”
One byproduct of the shortening of the side skirts will be a loss of downforce and a possible decrease in the stability of the cars in traffic.
“In some places where they don’t get the (suspension) travel, it’ll reduce the downforce just a little bit,” Pemberton said. “It’s not a bad thing. It’s a marginal thing, but it does take some of the downforce off the cars.”
Just how much downforce the Cup cars will lose is an open question, and there’s no firm consensus among crew chiefs as to what the number will be, even though several teams already have tested the changes in wind tunnels and during a Goodyear tire test at New Hampshire earlier this week.
Most agree, however, that the cars will be somewhat more difficult to handle and that the changes might make it marginally easier for one car to pass another.
There’s also a consensus that the changes to the side skirts will force changes to the suspensions of the cars -- particularly to the rear suspensions -- as crew chiefs try to recreate the “seal” (or close proximity) between the side skirts and the pavement as a method to recover downforce.
As one crew chief told the NASCAR Wire Service on Saturday, “We’ve been working all year to keep the back of the car up; now we’ll have to work to get it down.”
Even if the loss of downforce is a corollary effect of a larger safety goal, it will be well received by many drivers.
“Hopefully that’s part of an evolution away from downforce and away from aerodynamic devices and toward the roots of what we’re doing here,” said Roush Fenway Racing driver Carl Edwards, an outspoken proponent of taking downforce away from the Cup cars and putting more control in the drivers’ hands.
“I think it’s really cool of them to do that.”