The Daytona 500 is NASCAR’s season-opener, and also the series’ biggest race. Held at the track just a little way from the beach in Florida where the series got its start, it’s a 200-lap, 500-mile test of endurance for car, driver, and team. (And depending when they started partying, for the fans.) I’ve been to quite a few endurance races at this point, and although there are some differences between a NASCAR race and your average long-distance sportscar event I figured the basics would still apply. Like driver preparation, for example.

“It’s a tough challenge, especially because it’s the first race of the year; it’s easy not to be in the best shape coming off the holidays. Being a race car driver on an easy day, when it’s not too hot, when the tires work, when everything is smooth—it’s not over the top challenging. But there are very few easy days,” explained Brad Keselowski, who races for Team Penske in the #2 car. “Daytona is a long race, usually in weather that’s much warmer than anywhere else so you’re not acclimated. And it’s a restrictor plate race so the cars are grouped up, you can’t just drive off into the distance. And there’s a lot of anxiety because it’s like the first day of school.”

Car setup for Daytona is all about optimizing aerodynamics. “It’s about how much stability you build in the car, and where you have your attitude. If you have the back of the car really trimmed out, it has no inherent stability because there isn’t any downforce. Once you start bringing the back of the car up, now you’ve got some stability, the car has some aero load and can stay planted a little better,” said Travis Geisler, Team Penske’s NASCAR competition director. With every car limited to same 400 horsepower (300kW), the trade-off between air working for you as downforce and air working against you as drag is critical, and where teams can find the edge over their rivals.

“For here, where it’s wide-open and the track’s pretty smooth, you can get pretty aggressive,” said Geisler. Back at the race shop, engineers will “replay” a lap of the track on a car mounted to a seven-post rig measure the actual variation of the tires’ contact patches. “It’s the load the tire experiences on the track. If you get too stiff on everything, the tire loses contact and you start washing up the race track [understeering]. That becomes your limit in a lot of places. If it’s not bouncing out of the groove then the driver just has to deal with it,” Geisler explained.

For as much as there are similarities, the Daytona 500 is very different to an event like the Rolex 24 or Petit Le Mans, or even the Indy 500, particularly on race weekend. “There’s a big difference between our IMSA teams and IndyCar teams, and our NASCAR teams at that point. They all have full telemetry data on the cars during a race weekend; they can measure everything that’s happening, they can run it through their simulations and so on. We basically have a human for feedback” said Geisler “At that point, you have to listen to them, and simulation is close but it’s not reality.”

“That’s what separates a lot of NASCAR drivers from a lot of other styles of racing, where you really have to be in tune with your car and have feedback that makes the car faster,” Geisler told us. “It’s one thing for a driver to say “hey, I’m too loose on the exit of turn four, you need to work on that.” But if we fix that and you go slower, you weren’t understanding what the limit of your speed is, you were going off your comfort level. Drivers have to learn to disassociate those things, because their comfort level and the speed of the car may not be the same thing. Ideally they are—that’s a perfect car, when they’re happy and fast—but in a place like this that’s unlikely to be the case. That’s why they get the extra comma on their paycheck.”

Even though it’s a long race, driver comfort plays second fiddle to the lap time. “There’s “I need a mouthguard” territory, and there’s “I can’t drive this” territory, and you can tell by their voice when it gets to a certain point,” Geisler explained. “Eventually the ride quality starts to really degrade the performance of the car 10, 15, 20 laps into a run because the tire grip is just so bad [by then].”

That’s not to say driver comfort isn’t important in this current era of NASCAR. Keselowski thinks this is the area where he’s seen the most change as a driver over the past decade. “One of the biggest changes as a driver has been the seat and how you’re positioned in the car. We now have lightweight carbon fiber seats; my body is scanned, and then special moulded foam pads are made from the scans. All that stuff is very light, very nice,” he told me. Even the seatbelts are custom-made for each driver. “Now they’re sewn and made perfectly for my body—I even have a different set for when I’m 4-5lbs heavier than right now,” Keselowski said.

The extent of this preparation even extends to the weather. “The key is to understand what’s coming this way. A lot goes into the cars and a lot goes into the race preparation. Cars have to be ready two weeks before; the more the teams can understand about track conditions and weather conditions, the better they can race,” said Pat Suhy, manager for General Motors’ NASCAR activities.

GM’s been working with IBM’s The Weather Company to provide its racing teams (in IndyCar and IMSA as well as NASCAR) with as accurate forecasting as possible. “In the lead up to the event you start getting an idea of the weather patterns to prepare the cars, the playbook. At the track, the key is having confidence in the tools we provided to the teams. Until they develop confidence in them it’s hard for the teams to commit to using them. As our teams got hold of the data and it kept getting refined—we’re in the middle of a journey—as we get to race weekend they see the data is good and they pay attention.”

“We share learnings across the core Chevrolet teams. No one gives away speed secrets but when one team develops confidence it helps uptake with the others,” added Byron McMichael, a meteorologist and senior accounts leader at IBM. The data come from over 100,000 weather stations, before being fed into one of IBM’s AI systems, with new forecasts pushed out about every 15 minutes or so. “There’s a lot of AI and machine learning built into the forecast. It was a pretty fun journey because you don’t realize how much weather impacts racing—you always think about precipitation but not all the other aspects of weather that affects racing. We’re the only ones out there able to produce the forecasts with this much accuracy because of the amount of data we can feed the AI with,” McMichael said.

What counts as perfect weather for a cup car, I wondered? “A cool sunny day with some heat in the track from solar load and cold air for the engine. Overall a nice bright sunny day is ideal. A super-hot, super-sunny day generates better racing as the cars begin to slide,” Suhy explained.

Sadly for most of the competitors, this level of preparation often counts for naught. The 61st running of the Daytona 500 was for the first 190 laps a measured, even boring affair, the most drama being a three-car crash as some of the field was entering pit lane. Then, with 95 percent of the distance completed, it appeared to be brains and not tires that were fading. As the race restarted from a caution period (brought out by Keselowski suffering a puncture), a massive 21-car pileup ensued, kicked off by Matt DiBenedetto’s #95. The race was red flagged to allow the carnage to be cleared—this was all just broken car bits, for the current Gen6 car is a remarkably safe racer.

After a lengthy delay, the race was restarted, with a couple of laps under the safety car to get everyone settled before the green flag. When the green was waved with six laps to go, we got another wreck—this one involving six more cars. Cue the safety car, then another restart and… yep, another big wreck, this time sufficient to bring out the red flag for a second time. (Perhaps the Daytona 500 was jealous of the Rolex 24, which also saw an unprecedented two red flags this year?) When things finally got going for the last time, Denny Hamlin’s #11 managed to avoid hitting anything for two laps and he took the win. In fact, at the checkered flag, just five cars—out of a field of 40, mind—were undamaged.

I suppose the moral of this story is that if you want to be at the front, you need to put in all that time and effort in preparation. But that’s all for nothing if you get caught up in someone else’s wreck with 20 miles to go.

https://arstechnica.com/?p=1463463