The balancing act required for improving racing at Indy

IndyCar's re-introduction of a universal aerokit in 2018 saw the aesthetic appeal of the series take a monumental leap forward, and also brought an end to the days of countless meaningless passes in the Indianapolis 500.

All the 500s staged in the DW12 era - between 2012 and 2014 with its standard aerokit, and 2015-2017 with the ugly manufacturer kits - were entertaining, without question. But the cars ran in packs, and the passes looked too easy: the guy in front - providing he didn't throw a vicious block - pretty much had to give way to his challenger.

This was an ironic twist on what went before. The previous generation of IndyCars had promoted undemanding throttle-pinned-to-the-bulkhead racing at any other ovals of 1.5 miles or more, but at Indy they were tricky, finicky beasts, the kind that could give even three-time Indy 500 winner Dario Franchitti the yips during a qualifying run. They were great.

The introduction of the DW12 in 2012 changed that. Despite Franchitti and Chip Ganassi Racing team-mate Scott Dixon being clearly the fastest on race day that year, they couldn't break the tow to their challengers.

As 2018 Indy 500 winner Will Power recalled: "The new car had sorted all the other ovals out, made them into proper drivers tracks with separation between the cars. But Indy had been turned into something of a pack race where you could not get away, even if you were faster."

The handsome universal aerokit of 2018 largely removed that issue, and four-time Indy winner Rick Mears welcomed the change after witnessing it in action that year, reasoning that it "put the performance back into the drivers' hands" by giving them more feel for what the car is doing, overall grip levels and tyre life.

That said, there were complaints in 2018 that it was now too hard to make a pass. The new superspeedway aerokit had less downforce than its predecessor but also more drag having eliminated the rear wheel guards. Consequently, the lead car created a much longer tow than before, but the shape of the draft changed too. As team owner Dale Coyne observed, the tow was "more intense, but narrower".

"You tow up real fast, faster than with the last car, but when you move out to pass, you just don't pull past at a great rate of knots," he said. "The passes you have seen are coming at the end of the straights, where you come up the inside and just steal the line of the guy on the outside."

"There's too much understeer in the cars when they got close to the cars in front. In 2019, that was improved a lot with Firestone's help but then the understeer crept back in this year because of extra weight on the front of the car from the aeroscreen" Tino Belli

Before 2012, a driver closely following the car in front would stagger their approach to the turns, running half a lane higher - or lower - to get some downforce onto one front wing, one sidepod and one half of his rear wing. That didn't work so well in 2018 nor this year, the first with the new aeroscreen, according to many drivers.

PLUS: How the aeroscreen will change the Indianapolis 500

"There's too much disturbance coming off the rear of the guy ahead," said one of the aces, who didn't wish to be named. "We're just understeering. If you go half a lane lower, obviously that's less effective because that's the unloaded side of the car.

"Go half a lane higher and you're still understeering but you're a lot closer to going into the grey, the marbles, and then probably the wall. I think it was pretty decent last year, but the aeroscreen has given the right-front [tyre] too much work again. You just have too much push for the tools [in-cockpit adjustment] to help."

This goes some way to explaining the testing at Indianapolis Motor Speedway this week, trialling wing configurations that will allow the cars to run closer together on the superspeedway while still meeting safety requirements.

The superspeedways have seen IndyCar retain the holes in the underwing - which have been filled in for short ovals and road/street courses - to comply with its effort to reduce lift in nose-up or high yaw situations, such are seen during a spin. Work was conducted in the background on a solution that involved only partially filling in the hole, with a test at Indy provisionally planned for April canned due to coronavirus.

But the COVID-19 restrictions gave IndyCar sufficient time to keep working at the underwing solution to better understand how airflow quality is affected, and now Tino Belli, IndyCar's director of aerodynamic development, says it has improved "to the point where we're quite happy with it".

"The basic idea with the parts we're evaluating this week is to shift the front aero downforce back onto the leading edge of the underwing," he says, "so that teams can run less front wing angle, and the underwing is more in ground-effect mode."

Belli said this would not limit the number of options open to an engineer when tailoring the car's handling balance to the taste of the driver, with all the front wing options that teams have currently left unchanged.

"One of the problems you have when you have several options is that they all have to be mapped in the windtunnel and they need to be mapped in combination with everything else," he says. "You can't just map all the options of the front wing in isolation - they need to be assessed with the various underwing options because they all interact with each other.

"You could spend millions of dollars in a windtunnel getting it all mapped out, trying every permutation. What we have to balance is giving the teams enough options that they can tune the car to what the driver needs, but not enough options that they bankrupt themselves in a windtunnel!"

Belli, VP of competition Bill Pappas and IndyCar president Jay Frye have the job of ensuring the field is tight but that excellence from drivers, engineers and teams is rewarded. The purist will be pleased to hear there is no intention of getting back to an aerodynamic package that allows a driver to be towed around the Speedway without consequence in the wake of a car that is 3mph faster - as Belli (pictured below in 2018) puts it, "'after you' racing, nobody wanted to lead".

"Although the fans probably thought all the passing was very exciting, it was not challenging for the drivers," says Belli. "The driver in front would often let the guy behind pass so he could sit behind and save fuel. It was what I call peloton racing, like in the Tour de France.

"Since 2018 we've had real racing, so that the drivers with the best set-ups and who tune their cars best during the race are the guys who ended up at the front. It also creates a little bit of separation, so that you don't have the cars running endlessly in a pack with the possibility of a massive Daytona 500-like crash.

"What we've also seen, though, is too much understeer in the cars when they got close to the cars in front. In 2019, that was improved a lot with Firestone's help [a new right-front tyre], but then the understeer crept back in this year because of extra weight on the front of the car from the aeroscreen, so we're aiming to get it back to how it was in 2019.

"It's not easy, otherwise we'd have done it already. For [chassis supplier] Dallara this was almost a year's work in CFD and the windtunnel, checking airflow patterns, and stability and so on at the various degrees of yaw and nose-up. Any new part you come up with for the Indianapolis Motor Speedway requires six CFD cases for stability as well as the one case for straight ahead.

"Ultimately, we want the best drivers and the best teams to win the races, but not to have everyone so strung out that they can't run close" Tino Belli

"It's six times the amount of work for every part you want to consider putting on a car, compared with four years ago. As you can imagine, it slows down your rate of development to 17% of what it used to be."

IndyCar's ethos going forward is clear. As Belli puts it: "Our responsibility to the drivers is to make each change as safe as possible and our responsibility to the fans and the teams is to keep the racing entertaining. And then within the teams, we want to still give the engineers enough latitude so that they can still make a difference.

"Ultimately, we want the best drivers and the best teams to win the races, but not to have everyone so strung out that they can't run close," he says. "We don't want the passes to be easy because then anyone can do it. We had that era.

"Passing should be possible but challenging, and I think we got the balance of that at Indy correct in 2019. I think a lot of people appreciate that a pass that isn't completed can be as exciting as a successful pass."

It's a fair point and one that is often forgotten - that being able to defend (within the rules) is as important a racing skill as the ability to attack. It rarely earns the same praise, just as a great tackle in football won't earn the same plaudits as the guy who scores a great goal. IndyCar isn't aiming to make passing easy nor defense impossible.

It's a fine balance.