This week’s Richmond short track package test session — NASCAR’s latest attempt to remedy the Next Gen’s short track shortfall — fell short of expectations. Although progress was made in moving toward a softer tire with more grip and more wear, the aerodynamic experiments yielded little to no difference.
The wake from a race car — any race car — creates turbulence or ‘dirty air’. A car running in another car’s wake loses downforce. That means the closer you get to the car you’re trying to pass, the less grip you’ve got. That makes passing difficult.
The diagram below (courtesy of Ford Racing) is a 2013 computational fluid dynamics calculation that contrasts the nice, smooth airflow in the front of the car with the turbulent, unruly patterns behind the car.
Eric Jacuzzi, NASCAR’s Vice President of Vehicle Performance, told NASCAR.com before the test that this was “a problem as old as time in racing and physics”. Some of motor sports’ best minds, in NASCAR, in IndyCar and in F1, have tried to solve this problem.
No one has.
NASCAR’s approach is turning lemons into lemonade via a splitter that would invert the passing problem. The new ‘lift splitter’:
- Creates lift (rather than downforce) when a car runs by itself.
- Creates downforce when a car runs in the wake of another car.
In other words, clean air would be a disadvantage and passing would be easier.
The composite photo below compares the testing splitter (top) with the current splitter (bottom). The sides of the splitters are similar. When mounted on the car, you can’t tell the difference between the two without getting underneath the car. (And they didn’t let us do that, unfortunately.)
The most obvious difference is that the testing splitter is missing a huge chunk in the middle. But that’s not the most important difference.
The top of the cutout on the new splitter has a lip: a gradual curve downward and away from the front of the car when it’s mounted. The sides of the cutout resemble the strakes on the car’s diffuser. That’s the part that is supposed to work the magic.
NASCAR tested this splitter as shown, and with a panel covering the missing part.
Did It Work?
We had not access to any data, like lap times, during or after the test. But it was clear just watching the three multi-car runs on the first day that there wasn’t much difference between the race package from Sunday and the package on Monday.
The drivers made three six-car testing runs of 30 laps/caution laps/30 laps to simulate race conditions. In each case, there were a few passes in the early laps — a sort of shuffling out. Then they spread out single file.
In the afternoon runs, NASCAR re-racked the drivers after the first 15 laps of each segment, putting the cars in different order to see if stronger cars could come from the back. The last run of the afternoon was rained out with two dozen or so laps remaining.
The Drivers’ View
Drivers spoke to the media after debriefing with NASCAR. They unanimously confirmed our observations.
“I couldn’t tell much of a difference from my car yesterday to today,” Ryan Preece said, “so not what we were all hoping for.”
I didn’t stay for the second day: I refer you to Kelly Crandall’s excellent summary for a first-hand report. In brief, the second day of testing focused on tires; however, NASCAR removed the rear diffuser and went to a four-inch spoiler instead of the usual two-inch spoiler. They also added pieces to elongate the lip on the ‘lift splitter’ to see if that might help.
The upshot was that NASCAR (and the drivers) felt a little more optimistic about the softer tires, and the alternate set-up.
But at the end of the first day, Jacuzzi said NASCAR would have to do off-season testing to pursue a stronger short-track package. He mentioned that they would investigate a broader range of options, including shifting and braking.
Oh, and I didn’t use strong enough sunblock and came home looking like Louden the lobster from New Hampshire.
Questions & Answers
If NASCAR finds things that work, why wait for 2024 to make changes?
Fabricating enough new splitters for every team would take until at least October. Plus, NASCAR doesn’t want to change rules in the middle of the playoffs. Therefore, waiting until 2024 is the best option — especially if off-season testing yields some advances.
Who gets to test and why?
Manufacturers picked three cars: Christopher Bell (Toyota), William Byron (Chevrolet) and Ryan Preece (Ford). The cars NASCAR added to ensure that smaller teams get information are Kaulig Racing’s Justin Haley (Chevy), Wood Brothers’ Harrison Burton (Ford) and Legacy Motor Club’s Noah Gragson (Chevy.) There are only two Toyota teams to choose from, so both of those teams get to do tire tests during the year. Some of the smaller teams never get to tire test, which is why NASCAR invited them.
Who comes to tests?
We weren’t allowed to take pictures in the garage, but I would have loved to show you the row upon row of data geeks in front of laptops sitting in garage stalls. NASCAR runs a lot of instrumentation that teams aren’t allowed to use during races, so this is a rare chance to get really detailed information. Manufacturers sent their representatives, too.
With all the advance work NASCAR did, how come the splitter didn’t work?
The short answer is because the real world is complicated. NASCAR extensively modeled the aerodynamics using computational fluid dynamics simulations. They tested single cars in a rolling-road wind tunnel and went so far as to test two cars in the wind tunnel at the same time. And that’s not an easy experiment to do.
It’s not surprising that everyone involved was pretty deflated at the end of the first day. It’s equivalent to a SpaceX launch where the rocket fails to lift off. The only thing worse than a failed experiment for a scientist or engineer is a failed experiment you then have to explain to the media.
A race car is complex mixture of many, many variables: aerodynamics, tires, vehicle dynamics, engines, transmissions, and more. It’s not like NASCAR has separate dials for each one of these elements. If a car generates more downforce, the tires wear faster. Less downforce and the lap time falloffs are smaller. When a driver brakes, the attitude of the car changes. That changes the aerodynamics. Not to mention the range of tracks the car must handle.
So the test was a waste of time?
Not hardly. NASCAR went to great lengths to get the same measurements they got in the wind tunnels. The data they collected will help them refine their modeling and what data they gather in future experiments. You frequently learn more when things don’t work than when they do.
As Jacuzzi said, this problem has existed since the start of racing. If it were simple, they would have solved it by now.
Then we shouldn’t expect to hear anything more about this splitter?
Don’t expect the splitter to go anywhere, at least not yet. Here’s the one big problem with this test: It was originally scheduled for New Hampshire, a high-grip flat track. But the New Hampshire race weekend suffered from heavy rain. That forced NASCAR to move the test to Richmond, a low-grip, moderately-banked track.
Drivers were very happy that the testing was done after a race weekend, when the track was fully rubbered up. But they all felt that Richmond wasn’t the best place to run.
“Just the track is so slick that you are naturally going to get spread out because the you’re sliding around like crazy,” Christopher Bell said, “I mean, all six of us are just complaining about being sideways loose.”
Just because the splitter didn’t show any difference at the Richmond short track package test doesn’t mean it won’t make a difference at other tracks. Richmond and New Hampshire may be only a quarter mile different in length, but they are worlds apart from each other in terms of tire loads and speeds.
Why not test after Martinsville, then?
No one — not NASCAR, not the teams — wants to be testing the week before the championship race. We’re at the end of a grueling schedule and there’s a lot on the line. The manufacturers will be entirely focused on the cars that have made the final race.