Monday, January 04, 2010

Testing shows that the Bald Spot Sports Arpro headrest drops G forces

Rearward thinking

By Dave Lewandowski - Indycar.comSunday, January 3, 2010

Air bags in the cockpit?

The Indy Racing League isn't quite there, but the sanctioning body of the IZOD IndyCar Series and Firestone Indy Lights continues to research, test and develop innovative hardware and materials to better protect drivers in the current Dallara chassis while projecting applications for the new generation of race car due in 2012.

Indy Racing League director of engineering Jeff Horton recently tested a variety of headrest configurations at the Center for Advanced Product Evaluation in Westfield, Ind. Results will be presented at the annual Indy Racing League season preview meeting Jan. 12 and recommended for implementation by teams for the season that begins March 14 in São Paulo, Brazil.

"For the past several years we've seen higher head G forces in rearward accidents than we think we should," Horton says. "The car will hit at 50-70 Gs against the SAFER Barrier and with the centrifugal force pulling the driver's head forward they get a little bit of a run at the headrest. So it's not uncommon to see near 100 Gs or higher on the head when the Gs of the car are much lower. The goal was to tune the headrest system to allow the head Gs to be reduced in a rearward accident."

Horton developed a "floating back" to curb the disparity in G forces. The Kevlar skin of the headrest is attached to the front of the foam and the sides are allowed to float, "so the driver only feels the effect of the foam during impact," according to Horton.

"The skin is necessary to keep the helmet and HANS device from digging into the raw foam, which allows the driver to ramps because of the stretch of the seat belts in a rearward accident," Horton says.

They also have experimented with different foams that provide increased energy absorption. Expanded Polystyrene (EPS) - beads mixed with a two-part resin and harden - has been the standard.

"Through our own testing, we know the inconsistencies of the how glue affects the hardness of the foam," Horton says. "The material of the future is Expanded Polypropylene (EPP, engineered plastic foam). Its beads are steamed together, and all the material is made in blocks and then machined into the shape you want and it's 100 percent consistent.

"It's lighter (1.5 pound per cubic foot), which is the same technology as some of our seats. Teams are switching because of the weight difference. This should be less expensive because a team should be able to handle repairs in-house -- it's a simple machined piece of foam with a Kevlar skin that's been molded and all they have to do is glue it together. Before, it required body work so you needed a carbon shop to do the repairs and there was a specific process needed to pour the EPS foam."

Impact testing at CAPE consistently showed a drop in head G forces from 148 for the current headrest to 104 using the floating system and EPP foam.

"As better materials come along, it's easier to put them in," Horton says. "It gives you the flexibility to change materials; if something better comes along that attenuates the energy then it's no problem. Everything Dr. Trammel and I have done research-wise we're trying to make the current cars safer and collect data on everything that will help us make things safer and less expensive on the new car."

So air bags in the cars next? Horton and Trammel have looked into at least mini-air bags on the six-point driver harness. They'll do more research.