Coming off an Indy 500 where passing proved to be a greater challenge than in recent years, the NTT IndyCar Series is working on a plan to test new aerodynamic configurations at the Indianapolis Motor Speedway that would allow for an increase in overtaking.
October 29 has been penciled in for the date of the test on the 2.5-mile oval, and six cars – three apiece from Chevy- and Honda-affiliated teams – have been asked to keep the date open to try various aero changes designed to improve the quality of the show.
“We always do something at the Speedway, usually in the fall; last year was the aeroscreen with the 9 and the 12 car, and the year before that, we did a six-car tire test, so we’re working on some things, possibly at the end of October. Nothing solid we’ve confirmed; I would say it’s very likely, though,” IndyCar president Jay Frye told RACER.
“Usually when we’ve done this, it would have been being done now, but with the season going on as long as it is with COVID, the testing window is now the end of October when teams are done with the season.”
Multiple items will be sampled during the test; use of the downforce-reducing openings in the outer regions of the underwing being the primary area of interest.
“Of the pieces depicted in the image, we call the red, the upper filler, the green, the lower filler, the blue, a wing, and yellow, a bargeboard,” said Tino Belli, IndyCar’s director of aerodynamic development. “We’ve been working on this with Dallara going on almost 11 months to get to this point. COVID slowed us down a little bit. Our target was originally to test something like this prior to the 500, somewhere around about the open test, but it also helped us because that extra time allowed us to refine this part as such that we’re pretty confident that it’s going to work.”
IndyCar’s new-for-2020 aeroscreen driver protection devices have served their intended purpose, but the height and forward placement of the the 58-pound units have also created some adverse performance traits the series is hoping to overcome prior to the next Indy 500. The goal for the test is to find the right combination among the four new components that will deliver an increase in front-end stability by adding more downforce without placing more demand on the front wings.
“So because of the extra weight in the front of the car, the amount of front wing being used and all the add-ons have increased, the front wing angles are much higher than were originally intended,” Belli said. “When you put forward weight on the car, you now tax the front tires harder, so you have to add front wing, and you tend to make it less happy in traffic.
“We did talk about making a new front wing. The problem with the new front wing is, if you want to get more front downforce out of the front wing, there’s a couple of problems. One of them is the front wing is the first thing to get into the wake of a car in front. A wing is quite high off the ground, so it’s not really in ground effect. So it’s air-speed dependent. You would probably have to increase the cord, which is really bad for a five-degree nose-up configuration. So if the front of the car went up in the air, it significantly increases the chances of it doing a backflip.
“So now we want to take the load out of the front wing, but still create enough on downforce, and the front part of the floor is one of the most effective places to do that. It’s very close to the ground. So it’s in ground effects, and it’s basically more car-speed dependent than air-speed dependent. The actual road moving under the car is helping to create the downforce. And so it should help reduce the amount of understeer of when you’re following the car in front. A nice addition to this is it’s more efficient than doing it with front wings, so we get a nice chunk of total downforce at the same time for a given center of pressure.”
Belli, whose resume includes numerous IndyCar chassis designs and decades of race engineering experience, expects some, but not all of the four test pieces to receive the stamp of approval for superspeedway use.
“The bargeboard is a test piece we’ll try, but in all likelihood, our 2021 solution will be the green, the red and the blue, without the yellow,” he said.
“We want to test the yellow, but we have to be careful that we don’t end up creating too much front downforce because we have to have the front wing in the range where it can be backed out far enough for qualifying when you’ve got the rear wing at minimum. And then we have to create enough front downforce with a wing when it goes into the positive side for the race, where we put the rear wing up at two degrees with a wicker on it.
“So we have to keep that front wing in the range that it will work. And it does have a large range, but we just want to test it with the bargeboard in position to see what we learn.”
Provided the October 29 date is confirmed, Belli expects to have a tight window to run through the various aero options. The test will be limited to aerodynamics as Firestone is not planning to make any changes to its Indy 500 tires.
“So the other thing is testing on October the 29th, we’re likely to have a very short day because we can’t get running until we get air temp plus track temp up to 100 degrees Fahrenheit,” he said. “And right now, we have about 180 to 200 laps at our disposal, because when we do the six-car test, we send all six cars out together. The guy at the front does five laps rotates to the back. So you end up with 30 laps per run, which is pretty much full fuel to empty on every configuration that we do the test on.
“We always like to begin and end on the same configuration. So the first one will be the 2020 setup. Then we’ll step through, with the first step will be the red and green only. There’ll be red, green, and blue. When we do green and red and no blue, there is a 10-millimeter wicker on the trailing edge.
“The blue one has a wicker built in integrally, but when we test it without the blue piece, we do have a wicker that goes on that little green trailing edge. It won’t be like a super-fine trailing edge. Wickers are really nice at forcing air to stay attached. That blue wing has taper and twist. Dallara did a really, really good job studying this piece. And it has actually made all of our stability numbers better.
“Then it’s going to be testing red, green, blue, and yellow, and go back to 2020 just to make sure that the track rubbering in and air conditions and stuff like that don’t spoil the read.”