The NTT IndyCar Series has a new rear attenuator in the works that will be implemented heading into 2023.
Together, IndyCar and its official chassis supplier Dallara have developed a redesigned unit that has been commissioned to improve crushability and further reduce the forces transmitted into the cockpit in rearward impacts.
“Our current attenuator has evolved slightly over time, so when I joined IndyCar, the original DW12 attenuator became the source of development after a few drivers complained of having headaches after backing the car into the wall on street courses,” IndyCar director of aerodynamic development and veteran chassis designer Tino Belli told RACER.
Image via IndyCar/Dallara
“So the steps taken on the old attenuator were to change the backface, which was originally solid and all molded in. We cut that backface out to allow it to be more tubular rather than a closed end, to aid in its crushing. And then we thinned this section out and basically went from a core with two skins to having one skin so that on a rearward impact, the attenuator had some softness before it started really crushing and taking out a lot of energy.
“That’s been successful in removing the street course headaches. But we’ve wanted to make it even more progressive and the plan was to introduce a new attenuator with the 2.4 HY . But we’ve brought it forward.”
Rather than wait for the new 2.4-liter twin-turbo hybrid V6 formula change, IndyCar will spend 2023 learning how the revised attenuator, which is made from the same composites used to form an IndyCar chassis, performs and if any additional changes are needed, it will have time to make those design adjustments prior to 2024.
“The key thing about the new attenuator is, it’s longer and the shape has changed,” Belli said. “The ability to model these layouts in FEA (finite element analysis software) is a lot better now, and from that, you will see that we don’t have the flat top and bottom anymore. This new profile helps the attenuator retain its shape while it’s being crushed in a rearward impact, and that allows it to crush in a much more predictable way.
“The whole idea here, because it’s longer, is to use the extra distance to reduce the peak Gs and the average G in a rearward impact, to better slow and soften the hit. It is also lighter. Even though it’s longer and bigger, it’s lighter. And all of the wing mounts are exactly the same with the same bracketry.”
Larger, stronger mounting studs will also be introduced in an effort to hold the attenuator onto the back of the transmission when a driver hits a wall at an angle from behind. The last new item to complement the revised attenuator is a larger rain light.
“When it’s raining, we’re trying to make it easier for the driver to see through the aeroscreen,” Belli said. “If we can create more light, there’s more chance of them being able to see the car in front, so we’ve gone to a bigger rain light than we currently have. And for 2024, we will probably have rain lights in the rear wing endplates as well.”