The slots were added to allow the beam to crush on a side impact. It was decided thru FEA that the beam was too stiff, and once the floor crushed to the point of reaching the end of the beam, it acted as a fulcrum to lift the car up.
By cutting the slots in the beam, it is hoped that the beam will deform enough to prevent this from happening.
05/23/12 Carbon dust permeated a section of the Dallara Auomobili facility in Speedway, Ind., as personnel cut three slots in underwing supports of the new IZOD IndyCar Series cars to lessen lateral and maintain vertical stiffness.
While it might seem contrary to safety objectives, testing by Dallara earlier this week found that the stiffness of the underwing supports could be a contributing factor to the car slightly lifting off the racetrack in three instances over the Indianapolis 500 qualifying weekend when it impacted the SAFER Barrier with the car's centerline parallel to the wall.
"Dallara's response has been immediate to try and make sure all improvements possible could be implemented in time for the race – all credit to them," said Will Phillips, vice president of technology for INDYCAR, sanctioning body of the IZOD IndyCar Series. "Feedback from observers, safety officials and drivers enabled Dallara to have the data very quickly, and their solution and response is a great example of how safety comes first."
The simple modification will be complete for Miller Lite Carb Day on May 25 on all 33 cars in the starting lineup.
Through the nine days of practice and qualifications, five crashes were recorded. All competitors – Josef Newgarden, Bryan Clauson, Oriol Servia, Ed Carpenter and Charlie Kimball — were checked at the infield medical center and cleared to drive.
The 2.5-mile racetrack is the first oval test for the new car that was designed and manufactured with safety features not incorporated in the car that had been in use from 2003-11.
Crash computer modeling and sled testing of the monocoque, roll hoop, attenuator, side and bottom intrusion panels and nose box was part of the design and development process at the company's Italy headquarters.
[Editor's Note: The wide flat underbody is like a big sail. Once a car turns sideways and gets tilted so the air gets under the car, we will have liftoff. So now they are cutting slits in the sail to relieve the air pressure and hopefully cause the sail to stall. Without that the car will reach new heights and one day clear the catch fencing.]