READY FOR INDY.(News; Indy Racing League makes aerodynamic changes to vehicles)

The Indy Racing League has settled on a package of aerodynamic changes in time for May at the Indianapolis Motor Speedway. Given a successful test at Indy in early April, there aren't likely to be further changes before the Indy 500, according to Brian Barnhart, IRL senior vice president for racing operations. Barnhart gave AutoWeek the blow-by-blow on three specific aero changes intended to do two things. The first objective is reducing both downforce and drag to trim the cars out for the reduction in horsepower that will accompany a reduction in engine displacement from 3.5 liters to 3.0 liters for Indy. The second is improving what Barnhart calls "in-yaw, off-axis stability.''

How's that?

"In light of the way the season ended last year, we have endeavored to improve the stability of the car when it is yaw,'' said Barnhart.

The first change is a quarter-inch vertical wicker running down the middle of the car, from the nose to the cockpit and the cockpit to the rear wing. The long wicker is supposed to disrupt airflow over the car if it gets sideways, and prevent low pressure from building up on one side. "Its sole purpose is increased stability in yaw,'' Barnhart said.

The second change is another quarter-inch wicker under the bottom of the rear-wing main plate, 1.75 inches from the trailing edge of the wing. This wicker is intended to equalize downforce for the reduction in horsepower.

Finally, the skid plate under the chassis has been revised. The plate will now curve from its center up toward the wheels on each side, so that the outside edges are 10 mm higher than the center. The curved skid plate effectively raises ride height 10 mm, and serves two purposes, according to Barnhart: It reduces downforce and improves yaw stability. It does that by channeling air out the other side of the bottom of the car if it skids, rather than allowing the air to build up and thus create lift.

The IRL settled on these changes after intensive study and discussion among series officials, team engineers, engine suppliers and chassis manufacturers. The league also hired two independent engineering firms that signed confidentiality agreements, according to Barnhart. One has extensive experience in racing and the other has none, so that league officials might compare their conclusions. "I'm not sure anyone has done such an exhaustive analysis in a five-month period,'' Barnhart said. "It was a very complicated process. We could not have done it without the cooperation of everyone involved.''