Tech Center: NASCAR feels carbon fiber impact

February 11, 2014, Ron Lemasters Jr., NASCAR.com

Kasey Kahne

Adding carbon fiber makes it seem like space age for the race age

Video: Watch sledge-hammer test on carbon fiber hoods

When the new Generation-6 car made its on-track debut last year at Daytona, there was a lot of talk about the new lines and the fact that the new Ford, Chevrolet and Toyota resembled the actual production cars.

They weighed less, too, which is important. Less weight means a better power-to-weight ratio, and better power-to-weight means more speed -- theoretically, anyway. It definitely has helped lower the car’s center of gravity, which was higher when the Gen-5 was introduced.

A savings of 160 pounds -- 100 on the right side and 60 on the left -- might not sound like much, but it makes a huge difference in trying to get one of the cars through a corner.

Part of that weight savings came in the form of different materials in the body panels. Yes, NASCAR has entered the world of composites on the outside of the car instead of just inside the mainly sheet steel skin.

Carbon fiber? You mean that stuff you “microwave,” the stuff that all the open-wheel guys use, the stuff that turns into sharp little toothpicks when you hit something with it?

Yes -- and no.

The carbon fiber used on the Gen-6 outer shell is limited to the hood piece and the deck lid, in place of the sheet metal that has been part of the sport for the last 50 years. And they aren’t made in the microwave -- the specific equipment used to bake carbon fiber is called an autoclave.

The addition of a Kevlar coating means they won’t splinter, either. It’s the same kind of material used on the splitters to keep them from grinding away.

One advantage is the fabrication shops like carbon fiber better because builders don’t spend near as much time on an English wheel or with the grinders.

"It’s a consistent part so we can build stuff more in advance and the hoods and deck lids just kind of interchange," Kenny Francis, crew chief for Kasey Kahne, said. "It’s not as much a hand-built part and a much better quality-control part, so we feel like it will make car-building easier."

Early on in the testing process, there was a shortage of the new pieces because approvals stacked up at NASCAR. The hoods are aerodynamic enhancements, and as such must be supplied by the manufacturers.
In the first televised tests from Daytona, however, there was a decidedly new look to the hoods as the cars raced around the high-speed oval: the hoods were flapping like window shades in a thunderstorm.

Carbon fiber, while light and strong, is more flexible than sheet metal. That meant testing would have to be done to make sure that the pieces held up and were fireproof.

There was another reason NASCAR wanted to make the hood and deck lid a specific, one-size-fits-all component: the tendency of racers to … enhance pieces for aerodynamic advantage.

“The deck lid is an area that is very important to the car,” NASCAR VP of Competition Robin Pemberton said. “Over the past few years, it was becoming a science project, whereas if a deck lid can distort a certain way during a run, during the afternoon, it generates more downforce.

“It became a piece that was only made for a race or two races, then was thrown out. It was labor intensive, was not predictable and it wasn't fair for some teams that had more resources than others that could afford to do that week in and week out when other teams could not.”

Carbon fiber, once it is baked, is almost impossible to reshape. The process used to make it is absolute; therefore, it is easier to just scrap a piece that doesn’t work and bake up another one.

To guard against the urge to be creative, NASCAR mandated that all pieces would be limited to a single vendor, per manufacturer.

Five Star Race Car Bodies (Chevrolet), Roush Industries (Ford) and Crawford Composites (Toyota) are the vendors making the hoods for each manufacturer, and each had to overcome a shortage of finished products to teams early in the offseason.

As for deck lids, which were smaller than the previous versions, NASCAR turned to Composite Resources, a company based in Rock Hill, S.C. that builds pieces for the military and aerospace programs. Composite Resources also fields sports-car teams through Core Autosport.

Sports cars are nearly all carbon fiber in the bodies and tubs, so the expertise was a good fit.

With nine races in the books, we’ve seen the hoods and deck lids in crashes, and as expected, they will shatter on a stiff impact. That’s part of the beauty of carbon fiber: it comes apart and takes impact force away from other structures, including the driver.

The other beautiful part of it is if it isn’t damaged all that badly, it can be repaired. Steel hoods and deck lids can be beaten out, but they’ll never be right, aerodynamically.

Composite materials have been in NASCAR cars for many years, starting with the air scoops off the windshield that pushed air to the carburetors. Carbon fiber seats made a big splash in the aftermath of crashes with major frontal impacts, and now the teams are making overflow cans and other items from the material.

It’s space age for the race age in NASCAR, and it will only move forward from here.

Note: This story originally ran on May 7, 2013.

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