Thou shalt not pass

Did IndyCar get its sums wrong with its new aero kit? It’s a hot topic in the States

They call it the greatest race on earth, but after the 2018 Indianapolis 500 the fans — and the drivers — had a different view. The 102nd running of the event was criticised from both sides of the fence for being processional and devoid of overtaking.

It wasn’t perceived to be a humdinger and the finger of blame was pointed squarely at the new aerodynamics on the Dallara DW12 one-make Indycar.

Largely responsible for the record numbers of lead changes seen in 2015-17, the weird and wacky manufacturer bodykits have gone, to be replaced by a one-for-all aero package used across both the Chevrolet and Honda -powered versions of the car.

Overtaking wasn’t as easy as it had been, particularly for a car down in the pack. That goes a long way to explaining why there were fewer lead changes — a much touted number in the stat-heavy world of North American racing — in the IndyCar Series’ blue riband event. The lead changed 30 times on May 27, which compared with the all-time record of 54 in 2016.

The allegation was that it was now too difficult to slipstream past the car ahead.

“You could get in the draft, but you couldn’t stay in it,” says Dale Coyne Racing driver Sébastien Bourdais, a four-time Champ Car title winner prior to his short foray in F1 with Toro Rosso. “We were getting a lot of understeer and with the power levels we’ve got, you can’t hope to pass if you don’t stay full throttle through the corners. You really had to time it right.”

But then the so-called Universal Aero Kit 18, developed by Dallara in conjunction with IndyCar, was conceived to make passing harder.

“In the past the cars would pass and pass back on the straights,” explains Tino Belli, IndyCar’s director of aerodynamic development. “We don’t think that emphasises the skill of the driver. If you are a sitting duck, that’s like having a drag reduction system.

“The target was for drivers to really have to race. We don’t want passes to be easy – they should be difficult. The best team and driver combination should win the race.”

Not that Belli thinks everything was perfect on the first outing for the universal kit in superspeedway form. The expat Brit concedes that IndyCar didn’t have time to evaluate fully “the effects of slipstreaming” with the latest aero configuration.

A car that owes its DW nomenclature to the late Dan Wheldon, the first driver to try the Dallara in 2011, now has what Belli calls “a significantly different drag signature” from its manufacturer-bodied predecessors. It was this that caused the issues that made overtaking so difficult during the Indy 500.

“The front wing gets into the high-intensity wake and makes the car understeer more,” says Belli, who was Michael Andretti’s race engineer in CART back in the mid-1980s and subsequently worked as an aerodynamicist at the Leyton House Formula 1 team. “It was in traffic where the teams were having more problems than in the past.

“I don’t think they all got it right, but some did,” he adds, pointing to Alexander Rossi, who came from the back row to fourth in his Andretti Autosport entry. “I think in future years more teams will get it sorted out, but we will also be looking at how to make the car more benign in the wake of another car for next year.”

The problem was exacerbated by race-day temperatures well over 90 degrees Fahrenheit — into the mid-30s Celsius — that made it the second-hottest Indy 500 on record. This cost the cars downforce and the teams were not able to add more courtesy of the strict aerodynamic specifications laid down by IndyCar. They were, for example, not allowed to run more than two degrees of rear wing.

Bourdais reckons the problem can easily be overcome. “If the car feels fine with the wing at plus two at 75deg F, it isn’t going to feel fine at 90deg F,” says the Frenchman. “You suddenly lose something like 100lb of downforce, which was too little for those conditions. It’s easily fixable. There are plenty of tools in the box to give us more downforce.”

A NEW ERA

IndyCar abandoned the idea that manufacturers could develop their own aero packages for a multitude of reasons. Prominent among them was a desire to attract another car maker as an engine supplier to the series. It believes the expense of developing its own bodywork was an obstacle standing in the way of that.

“If a new manufacturer comes along and has to develop a new race car body, it adds a significant amount of cost,” says Belli. “They tended to look somewhat similar whereas the original idea had been to offer the manufacturers the chance to create visual differences between the cars.”

Aesthetics were also on the list. The bodykit cars weren’t pretty, and “IndyCar wanted to hark back to the days when the cars looked fast standing still,” says Belli. “We aimed for the cars to look sleek, rather than ending up with the boxy solutions we had previously.”

The intricate aerodynamics of the manufacturer cars caused another problem. They tended to shatter and fragment in the event of an accident, which resulted in longer safety-car periods for the clean-up operation.

“There were too many parts that tended to disintegrate in the event of an accident,” Belli says. “That’s not safe for the drivers or the spectators, and it had implications on the length of the yellow-flag periods. We’ve made the cars much more robust in the event of an accident with the new kit.”

The universal aero package had produced some cracking racing in its high-downforce configuration, used on the road and street courses and short ovals prior to the 500. IndyCar isn’t so sure that the jewel in its crown was the boring race many have alleged.

It has come up with some stats of its own to suggest the race wasn’t quite as processional as has been claimed. It says there were 633 race passes compared with 578 in 2017.

“We think,” says Belli, “this has all been blown a bit out of proportion.”