Speed Trap - RaceCar Engineering - Part Two
Late in 2020, RaceCar Engineering, one of the world's leading technology magazines for the MotorSport industry, invited Chris Beatty to tell the story of how the critically acclaimed 2018 Universal Aero Kit was developed for IndyCar.
Making the current IndyCar both look fast and hit its performance targets was a delicate balance of engineering and aesthetics
By CHRIS BEATTY
It was Christmas of 2016 at this point. Dallara shut down for the holidays, but Beatty and Belli continued to work on the wings and tyre ramps over the festive period to make up lost time. To look fast, Beatty wanted the rear wing as low as possible. They experimented with numerous vertical and longitudinal positions and worked up countless end plate concepts. Tino’s wife, artist Marina Belli, added a fresh pair of eyes at this point, helping Belli feed back on the various images Beatty was presenting, looking for that all-important ‘tension’ the car needed.
At last, a developed concept morphed out of these efforts that ticked both aesthetic and performance boxes. The end plate swept back from the car, giving a feeling of speed while maintaining the functional aerodynamic requirements. The rear wing concept was ready for Dallara to test in CFD when the company returned to work in the New Year.
Attention then turned to the road course tyre ramps. The Superspeedway version
had not changed much from the original Andrea Guerri concept. The lines continued
to gain definition as sidepod development progressed, but Guerri’s original intent was
still very much there, as it is today. However, Belli wanted to try something different for
the road course versions. These needed to be more about downforce production, rather than high-speed streamlining. Other than that, the brief was open.
Subsequent designs varied from simple winglets and ‘ski’ ramps to more advanced
modular systems that could function on both speedway and road courses via a removable streamline element exposing a more aggressive slope beneath it. In the end, the solution was right in front of them.
Finally, Beatty suggested utilising a modified version of Guerri’s Superspeedway
ramp, but with a sculpted concave top to produce the required downward pressure.
‘We were chasing a design we already had,’ Beatty recalls. ‘The speedway ramp was such an iconic element of the oval car by now, everything else we produced just didn’t look right. In the end, we used the same lower geometry but re-worked the top.’
Together with the work Dallara had put in on the front wing, the team finally had what
looked like a complete road and short oval concept to move forward.
In parallel, Belli had been working with Dallara to develop the floor of the car. The
intent was to reduce the dependence of top-surface downforce, instead of shifting
the emphasis to floor-generated ground effect. The reason for this was to improve the
downforce drop off often experienced when cars are racing close to each other.
Dallara had by now worked up the initial CAD model for the Superspeedway kit so
could initiate wind tunnel testing to see how the CFD numbers stacked up with reality.
With Belli in attendance, the aerodynamics department, headed up by Dialma Zinelli and Marco Milanetti, began working through how the progressed design behaved in terms of outright performance but also compromised orientations such as a high-speed spin. Would a spinning car liftoff, for example? Perhaps motorsport’s biggest dread is an airborne car clearing a debris fence, and IndyCar and Dallara go to great pains to prevent this.
The new, larger side pods had also gone through additional development. Dallara
had extended the leading edge of its initial concept further forward than on the DW12
but Beatty, who came to the project via his push for greater cockpit safety and through
an introduction by Stefan Wilson, wanted the leading edge extended further still.
With the spectre of Alex Zanardi’s terrible accident at Lausitz still at the forefront of his
mind, the view taken was that drivers can never have enough side protection, especially with the high levels of impact frequently suffered on Superspeedways.
As a result, Belli worked with Dallara to turn the front portion of the sidepod into a
full safety structure manufactured in a carbon / Dyneema fibre hybrid cloth.
Back to the future
IndyCar’s president, Jay Frye, took to the stage at the Detroit Motor Show in January
2017 and gave the world its first teaser of what the future of IndyCar could look like
by sharing Andrea Guerri’s initial sketches with the media. Later, in a meeting with
team personnel, drivers and a select group of media, Frye presented the most up-to-date renderings of the car.
It was the first real litmus test of how the car was developing, and feedback was
overwhelmingly positive. IndyCar was heading back to a future that echoed its
1980’s heyday. Finally, it looked like the fans, and the series would get the car it needed to move forward to bigger and better things.
Perhaps the only ‘negative’ comment came from Penske’s Will Power, who didn’t like the
road course rear wing endplate, which he felt reminded him of the now-defunct A1 Grand Prix series car. He was perhaps right. The endplate had gone through so many iterations it had become a compromise of mixed ideas.
But time was now in very short supply and, late on a Friday afternoon, Belli asked
Beatty to take another swing at it, based on some pointers seen in other formulae.
Within an hour, Belli, Papis and Frye received a selection of screengrabs showing the 3D outline of a new, swept-back, road course endplate, featuring a horizontal reflex. A 3D turntable animation combined the wing with the rest of the car, giving the team a fuller view of the overall design, empowering them to go ahead and green light the idea.
The following week, Beatty and Belli worked the new concept up and sent a 3D
file to Dallara for CFD testing. It was then a creative direction exercise between Beatty
and Dallara to make sure the part also realised the aesthetic design intent. Aside from some minor aero tuning to the angle of reflex, this is the rear wing you see racing today.
With safety in mind, IndyCar debated the necessity for the rear beam wing. The beam
served a purpose of providing a location for IndyCar’s spin flaps – two devices that pop
up when the airflow switches to a rearward bias, forcing the car into the ground and also acting as a form of air brake in the same way NASCAR’s roof flaps operate.
Other than locating the flaps, the beam was not serving a significant purpose from
either safety or aerodynamic performance perspectives, and a cleaner back end to the
car was more in keeping with the brief. With the beam removed, the safety flaps needed
a new home, so Belli integrated them into the top surface of the rear diffuser instead,
providing a tidy solution and maintaining these vital safety innovations.
The time came to reveal the car to the wider world. Autodesk, a technical partner
of IndyCar, took on the role of rendering the car for both road course and Superspeedway Aerokits and the reception was again overwhelmingly positive. Fans immediately started dropping fantasy liveries onto the renderings all over social media and the media was full of praise for the new direction the series was heading in. For the design and aerodynamic teams, however, the race against the clock was still very much on.
Rear wing ‘lite’
Wind tunnel testing had shown the proposed Superspeedway rear wing was generating too much drag. If the car was to reach the 230mph qualifying target at the following year’s Indy 500, it needed a re-think.
Belli and Dallara now turned to the known performance of Honda’s Aerokit and
cannibalised a rear wing mainplane to test in the tunnel. The numbers improved, so it
was decided to proceed with the new wing.
The problem was the Honda wing was very narrow, its chord, or depth front to back, was
around half that of the original concept and very straight. Suddenly, the Superspeedway car went from looking visually strong to appearing weak. Not what IndyCar wanted.
Part of the issue was the Honda wing had no endplates. Devoid of its rear tyre pod mounted winglets, it resembled a narrow plank of wood. Aerodynamically, it was on the
money, but work was needed to claw back some of the aesthetic points its predecessor had scored. The challenge was on to try and make a skinny wing appear fuller. Dallara tried out traditional flat endplates, but they just exacerbated the issue. Beatty, meanwhile, pushed for the continuation of the swept-back concept, with smaller endplates.
The team worked up a concept using swept-back end plates that extended
rearward to give the impression of volume when viewed from the side. But these made
the wing look like it had lost an element. Beatty then illustrated the mainplane with
swept-back edges and endplates. This was closer to the original aesthetic goal but
meant the Honda mainplane would need to be set aside and a new central plane
developed. Dallara worked the new concept up in CFD and wind tunnel testing, and the
Superspeedway car was now back looking clean and fast, even with its new ‘diet’ wing.
Less is more
A further late development was the removal of the barge boards, or ‘sponsor blockers’ as they had become known. Sitting forward of the sidepods, these devices were intended to prevent wheels interlocking and tyre-to-tyre contact. However, with the sidepods now wider when compared to the DW12, the scope for wheel intrusion was significantly reduced.
Again, to reduce potential accident debris, IndyCar made the decision to remove them
entirely, which had the added benefit of further cleaning up the lines and the leading
edge of the floor, as it no longer needed to support the outboard device.
There was some initial concern that the removal of the engine cover fin, tyre pods and bargeboards would reduce the amount of advertising space on the cars, making it
hard for teams and drivers to raise funds, but IndyCar had Neilson calculate a ‘heat map’ for the new race car. It showed that a reduction in clutter actually improved the car’s overall score, the larger surfaces having more clarity. It was the age-old adage, less is more.
The development team were now down to the finishing touches, with Dallara’s Guerri
penning concepts for the front damper cover ‘brows’ that replaced the pushrod and rocker blisters. Working with Belli and Beatty, he also came up with new concepts for the mirrors that IndyCar was happy with.
Dallara then turned its attention to the manufacture of the prototype bodywork,
that was to make its debut at Indianapolis Motor Speedway in the hands of Juan Pablo
Montoya and Oriol Servia.
Testing was a success, with both drivers proclaiming the new configuration made the
car more challenging, but fun to drive, giving driver talent the opportunity to shine. The
road course set-up allowed for close running, and a car drivers were able to hustle to gain lap time and position. Raceability was back and, combined with the new, aggressive look, the drivers and fans loved it.
The car performed as anticipated in the opening races of 2018, with the road course
Aerokit having an immediate effect on the quality of on-track competition. At the
season-opening race at St. Petersburg, there were 110 passes between the top 10, with 11 of those becoming lead changes.
Following that year’s Indy 500, held in abnormally high temperatures, it was apparent drivers were struggling with understeer in traffic. IndyCar and Dallara traced the issue to a small radius between the wing and end plate that was causing flow separation at certain conditions, resulting in a loss of downforce. Modifications to the wing overcame the issue for the following year, together with optional wickers and wing chord extensions for Pococono and the next year’s Indy 500.
Beatty continues to work with IndyCar, Dallara and, more recently, Red Bull Advanced
Technologies as the 2018 car evolved. We will cover how IndyCar teamed up with Red Bull to produce perhaps the sports biggest safety development for decades in the next blog installment, coming soon...
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