INSIGHT: Engineering the aeroscreen

Image by Barry Cantrell/Motorsport Images

INSIGHT: Engineering the aeroscreen

Insights & Analysis

INSIGHT: Engineering the aeroscreen

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The biggest change for the NTT IndyCar Series in 2020 is mounted atop the cockpit as the new aeroscreen from Red Bull Advanced Technologies has brought driver protection to great heights.

Beyond the adjustments IndyCar’s drivers have made with racing behind a ballistic laminate created by PPG and a titanium halo supplied by Pankl, the race engineers associated with each entry have also faced new challenges to overcome.

Namely, it’s in tuning the 20-plus cars set to race at each round to deliver the handling characteristics needed by their drivers, and the outright speed that enables winning. Chief among the performance problems to solve is the newfound weight bolted up high on the front half of the cars. At approximately 60 pounds, the aeroscreen is not light or flimsy; keeping a flying car at bay requires a solid design.

The weight is a necessary evil in that regard; in exchange for the improved safety it offers, most race engineers have begrudgingly accepted the drawbacks in physics where the aeroscreen is akin to a runner carrying 30-pound dog food bags over each shoulder and asking them to sprint, stop, sprint again and make hard cuts left and right without tipping over.

On the surface, adding 60 pounds to an Indy car that hits the scales in the 1700-pound range sounds insignificant, but with its highly precise aerodynamic and mechanical tuning in mind, the heft and its pendulum-like influence on the racetrack has taken IndyCar’s finest engineering minds back to new starting points.

Alexander Rossi tests Andretti Autosport’s answers to the aeroscreen engineering challenge during February testing at Circuit of The Americas. Image by Phillip Abbott/Motorsport Images

“The tradeoff is the car has more drag and less downforce than before; the less downforce is obviously the biggest handling difference,” Alexander Rossi’s engineer Jeremy Milless told RACER. “The weight distribution also moves 0.8 percent forward. About the maximum we can adjust on the car to move weight distribution is half of that, 0.4 percent. Even if we do all of the weight distribution changes we’re allowed, we only get halfway back last year. And the center of gravity is 27 millimeters higher.

“It’s pretty big. It’s almost as big of a change as going to a new car. When IndyCar went from the Dallara IR3 to the [current] DW12, one of the big changes they made was with the weight distribution; it was 1.2 percent, and that was a massive change. We’ve got a change close to that number again with the aeroscreen coming in, so engineers have their work cut out for them.”

Mike Colliver, who rejoined A.J. Foyt Racing to engineer the No. 14 Chevy shared by the trio of Tony Kanaan, Sebastien Bourdais, and Dalton Kellett, walked through the problem-solving approach most people in his position applied to minimizing the performance deficits brought by the aeroscreen.

“To start with, we have not done a ton of testing with it, and I think that’s the story for the majority of teams in the pre-season,” he said. “We’re still learning a lot about the engineering side with every lap we turn. Basically, you’re going to first go with the fundamental physics changes. You’ve got almost 60 pounds of mass that’s further forward and much higher than you have in the past. So you ask what kind of problems do you think that’s going to present, and the first thing you come up with is that it’s probably going to create some understeer in steady-state corners and create some additional weight transfer, and an issue probably with saturating the front tire.

“Then we’ve got to figure out how do we counteract some of those changes, whether that’s from moving some ballast around to help us to the best of our abilities to minimize that change. And then secondly, what can we do from a weight-transfer standpoint to keep from wearing that right-front tire out. So those are the two issues. One, you’ve got the lateral transfer to the outside tire and then secondly the pure front-to-rear center of gravity change. And we have some new tires to figure out. It’s the usual race engineer fun; you’ve got way more than one variable you’re trying to resolve here.

“So the thing I would initially, as a fan, be looking to see is if the car is going towards understeer as the race goes on, and whether you get additional tire wear on the front more than the rear then you have in past years. That would be my outsider looking in, from a technical standpoint.”

Prior to the delay in starting the 2020 season, IndyCar teams had two rain-affected days of open testing at Circuit of The Americas, some private testing at Sebring, and a number of teams managed to turn some laps at Texas Motor Speedway, site of Saturday night’s championship opener.

Of the total testing time accumulated by each team, oval running was at the bottom for most. It should make the Genesys 300 rather unpredictable as some teams chase optimal chassis setups throughout the race as they find out how their cars, tires, and aeroscreens interact with the 1.5-mile high-speed TMS circuit.

“We were easily getting rid of understeer with no entry issues all day long in the couple hours we had of clean running at COTA,” Milless said. “It was pretty easy fixing there. It was like, ‘OK, got it.’ We went to Sebring, started really aggressive, thinking what we learned at COTA was going to transfer and it didn’t. I spent all day going back on everything I did. So I would say I don’t have a clear picture of exactly what it’s going to do yet. We’ve done about nine hours of on-track of testing before the first race. There’s a good chance for setup mistakes.”

Colliver is hoping the limited testing across the IndyCar field will play into his team’s hands.

“I think it levels the field, and I think it allows the smaller teams to catch up a little bit,” he said. And then, as always, the more races you do and the more data you collect, as you get down the road, the bigger teams are going to figure out how to gap the smaller teams. But in the beginning, it wouldn’t surprise me to see some of the smaller teams up at the front and some of the bigger teams maybe back a little bit further than you normally see them. That’s what I’m hoping anyway. I hope we’re one of the smaller ones that are up at the front!”

AJ Foyt Racing is counting on the limited track time for all teams with the aeroscreen will help to level the playing field. Image by Phillip Abbott/Motorsport Images

Although it isn’t related to race engineering, there are performance gains and losses expected once pit stops begin Saturday night as teams are required to change tires every 35 laps. IndyCar has allowed a seventh crew member to go over the wall and clean the front of the aeroscreen — which, as Milless says, will be another learning experience for teams.

“I don’t think anybody’s done an actual live pit stop,” he added. “We’ve all done static stops and things like that, but there could be some things none of us are expecting to handle.”

If, by chance, a team struggles to get the aeroscreen clean before its car leaves the pit box, Milless has visions of IndyCar drivers taking a page from a NASCAR legend to solve the problem.

“Have you ever seen the video of Dale Earnhardt getting out of his car under caution and sitting on the door and cleaning the windshield? It’s on YouTube. It’s awesome,” he said. “I think he’s leading the race and he’s completely outside of the car cleaning his own windshield under caution. It’s the best thing.”

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