Speed trap
Racecar Engineering|February 2021
Making the current IndyCar both look fast and hit its performance targets was a delicate balance of engineering and aesthetics

There had been several runners in the race to land the 2012 IndyCar chassis supplier contract, including concepts from Reynard, Lola and Swift. The extraordinary looking Delta Wing was also in the mix for a while, but was perhaps a step too far out of the traditional comfort zone for some. But in July of 2010, IndyCar announced that Italian racecar manufacturer, Dallara, had been awarded the contract to replace the series’ ageing IR-5 chassis with a new vehicle titled the IR-12.

Dallara had been sole supplier of chassis to IndyCar since 2007 with the IR-5, which was a development of the IR-3 and had become the weapon of choice for teams, pushing out Panoz at the end of the 2006 season.

The IR-5 served the series well but, as always in motorsport, there was a need to progress and further enhance driver safety. IndyCar’s intent was to produce a next-generation safety cell, drawing on Dallara’s extensive experience in the series, and the wider racing industry. The chassis was designed to allow the upper surfaces of the car to be swapped for updated parts as both Dallara and IndyCar refined the aero package.

Dallara worked with IndyCar legend, Dan Wheldon, while testing the IR-12, with Wheldon providing invaluable feedback to the engineers and designers refining the car ready for manufacture and customer delivery. Such was Wheldon’s contribution, it was named the DW12 in his honour following the Las Vegas accident that cost Wheldon his life and rocked the sport to its core.

For 2012, the car was to run in a specformat Aerokit, with power coming from Lotus, Honda and Chevrolet. Initially, the intention was to open up development of the attached aerodynamic surfaces to multiple manufactures such as Lockheed Martin, GE, Lotus and Chevy for 2013, but this was rejected unanimously by the teams on the grounds of increased cost. However, in 2014-2016 the regulations were changed to allow the development of manufacturer Aerokits in an effort by series’ bosses to open up the engineering innovation of the car’s development, and add another competitive facet for series’ engine manufacturers, Chevy and Honda, to generate individual aerodynamic packages.

The dawn of DW12

In March of 2012, the DW12 made its debut on the streets of St. Petersburg. The car met with a mixed reception, many fans taking a particular dislike to the new bumpers behind the rear wheels. The intention there was to stop following cars ‘climbing’ over the rear wheels of the lead car in the event of tyre-to-tyre, or nose-to-tyre contact. However, when combined with the DW12’s larger tyre ramps, it created a visual effect more akin to a Sportscar, and was one of the critical areas in which the DW12 took a step away from the traditional IndyCar aesthetic.

The design looked stretched, and seemed to lose part of the personality that had been key to American open-wheel racing for so long. Add to this forward-tapered sidepods, a roll hoop cover that leant back in a submissive manner and a high airbox and engine cover, and the result just looked awkward.

That awkwardness didn’t stop with the visual either, the weight distribution was biased to the rear, mainly a side effect of the rearward position of the radiators, combined with the new rear wheel pods. The result was tail-happy cars that were prone to reaching the point of no return with even the slightest amount of oversteer.

Add to this the car’s initial failure to reach the qualifying target speed of 225mph+ for that year’s Indy 500, Dallara and IndyCar found themselves having to play catch up over the month of May. Eventually, with significant Superspeedway bodywork changes and a 0.1bar boost increase, Hélio Castroneves touched 227mph in practice, with Ryan Briscoe taking the pole at 226mph.

In 2015, the regulations were opened back up to allow manufacturers, Honda and Chevrolet, to design and build their own Aerokits. The idea was to give the two marques individual identities by dressing the Dallara chassis with their bodywork within specified ‘boxes’, or volumes. However, rather than generating compelling personalities for their cars, the designers borrowed heavily from Formula 1’s playbook by adding aerodynamic devices wherever they were allowed. The cars went from awkward to ridiculous in their appearance. The road course kits had enormous multi-element front wings, with rear wings that resembled garden fence panels. Additional winglets on top of the now aerodynamically focussed rear wheel pods only added to the cluttered look.

But aesthetics was not the main issue with the 2015-’17 manufacturer Aerokits. The resulting development race produced an alarming cost escalation that forced IndyCar to step in and freeze and further iterations throughout 2017.

Universal Aerokit

In 2016, IndyCar’s president of competition, Jay Frye, instructed VP of competition, Bill Pappas, and director of aerodynamics, Tino Belli, to initiate work on the next generation of Aerokit. IndyCar presented a list of guidelines and an aggressive timeline to racecar design and manufacturing companies highlighting the main requirements of the new ’kit, inviting them to tender for the design and production elements of the job.

IndyCar had conducted tests trying different aerodynamic parts on the DW12 car. The criteria included running the cars without the rear tyre pods and experimenting with the floor to generate more ground effect. These tests intended to assess the impact on vehicle dynamics and formulate aerodynamic and engineering targets for the 2018 package.

The new Aerokit also needed to be more robust in the case of contact than previous versions, and was intended to replace all the current parts, other than the road course rear wheel pods. At this stage, minimal wheel guards were to be retained for the Superspeedway kit to satisfy stability requirements, while the underwing and road course front wing main planes could be changed to achieve the stability and performance targets.

For the Indy 500, where aero stability in a spin is critical, stability was to be at least as good as the 2016 manufacturer designs, but without the domed skid. Initially, the beam wing and beam wing anti-lift flaps were to remain for the Superspeedway races.

A performance target of 230mph was set for the Indy 500 qualifying speed, although available turbo boost could increase to achieve this target, should cornering speed be reduced too much.

A modern look

This time, the aesthetic was essential, with IndyCar stipulating a modern look to a classic IndyCar and reduced reliance on top surface aerodynamic downforce, shifting the balance to underbody-generated downforce to both increase raceability and reduce clutter, in turn, minimising potential accident debris.

The engine architecture from the DW12 was to be retained from the plenum down, allowing a new, low-slung engine cover to regain a more classic IndyCar silhouette. The turbo inlet was to be repositioned, along with the radiators in new, Coke bottle-shaped sidepods that were to include enhanced side impact structures beside the driver.

The basic premise was to strip the DW12 down to its tub, nosecone, roll hoop, engine, underwing, running gear and suspension, before then re-designing everything to fit around the bare assembly.

By November of 2016, IndyCar had made the decision to stick with long-term chassis partner, Dallara. With the tender phase of the project now complete, IndyCar could focus on the design of the new Aerokit. Dallara’s in-house stylist, Andrea Guerri, had sketched several concept ideas for the original pitch, and the constructor begin to refine the concept for presentation to IndyCar.

Just prior to this, in October 2016, designer, Chris Beatty, who had worked with IndyCar on the early concept for the PPG Aeroscreen project, approached Belli about collaborating on the 2018 design. The timing was perfect as IndyCar and Dallara had reached a sticking point. The car, while ticking many of the technical and engineering boxes, had clearly been generated by an engineering team, with only a cursory nod to the design aesthetic.

This might not be an issue in some race series. After all, the saying ‘form follows function’ could have been written about racecar design engineers. However, IndyCar wanted to create a statement design, one that would re-establish the brand as the fastest racing series in the world.

At this point, there was still too much of the old DW12 design language on show. It was a competent racecar, designed by some of the best engineers in the world, but the car did not scream IndyCar, nor evoke the heritage and passion of the Indy 500. The car had to look fast, as Beatty reiterated in an early conversation with Belli: ‘It needs to look like it’s doing 230mph, even when it’s up on the jacks.’ It didn’t.

Belli sent designs for the Superspeedway Aerokit to UK-based Beatty for some initial feedback. Over a weekend, Beatty sketched out a newer, faster-looking silhouette with swept-back wings and jet fighter-style sidepod intakes, along with several other more detailed design ideas and comments.

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