Dr. Diandra: Turn to turn experts for speed and passing

0 Comments

I always encourage fans to listen to driver-crew chief communications. I think you appreciate a race more when you understand a team’s strategy and struggles. A lot of the discussion focuses on the turns.

Drivers and crew chiefs break turns into at least three parts: entry, middle and exit. Some break the corners down even further, but let’s start simple.

Rule one: Grip is proportional to the force pushing down on the tire.

The total force pushing down on a car is the car’s weight plus the aerodynamic downforce. I’ll ignore aerodynamics to simplify the explanation.

That leaves just the car’s weight; however, the total weight isn’t the relevant factor. We’re interested in the weight pushing down on each tire. That’s why weighing a racecar doesn’t involve a giant car-sized scale, but rather four smaller scales, one for each tire.

In the absolute simplest case, equal weight pushes down on each tire. Each tire thus has the same grip.

Rule two: You can only go as fast as the least grippy tire.

Anyone who has driven on ice or snow knows this rule. If the rear tires of a rear-wheel-drive car are on an ice patch, the car won’t go. If one drive tire is on a slick surface, the car may move, but probably not the way you’d prefer it move.

That’s an extreme case, but you get the idea. The least-grippy tire limits a car’s speed. You can have lots of grip in your rear tires, but without grip in the front, you won’t be able to turn.

I’ve posited a perfectly balanced car, with the same force on all four tires. But even then, the forces are equal only when the car is sitting still.

Imagine yourself driving. You engage the brakes as you approach a stop sign. What happens?

Your body shifts slightly forward as the car stops.

So does some of your car.

Everything supported by a vehicle’s suspension (the chassis, body, engine, driver, etc.) can move relative to the wheels. Engineers refer to this as sprung mass because it’s attached to the wheels with flexible components like springs and shocks.

When you brake, the car’s sprung mass shifts from the rear toward the front. That means:

  • More force pushes down on the front wheels
  • Less force pushes down on the rear wheels.

Rule one tells us that the car now has more grip on its front wheels than its rear wheels. Rule two tells us that the car will be slower because, while the front wheels have more grip, the rear wheels have less grip. The rear wheels limit the car’s speed.

The opposite happens when you step on the gas. The sprung mass shifts from the front toward the back, and the car now has more rear grip than front grip.

Since a driver brakes coming into a turn and accelerates coming out of the turn, this shift in grip has a major effect on speed and handling.

And there’s more. There’s also load transfer when a car turns. You’ve no doubt seen the tippy truck sign, right?The highway sign showing load transfer

A truck turning left could tip because of how its sprung mass shifts. Intuition might suggest that the truck should tip in the direction it’s turning, but that’s not how it works. In a left turn, load transfers from the left wheels to the right wheels.

And if you’re performing some combination of turning and braking or accelerating, load transfer happens in all directions.

Rule three: All the effects of load transfer add up.

Let’s combine all three of the phenomena to understand what happens when a driver turns a racecar.

  • She brakes as she approaches the turn.
  • While still braking, she starts to turn.
  • The car rolls through the corner at constant speed, with all the load transfer from left to right having taken place.
  • She accelerates as she starts to complete the turn.
  • As she leaves the turn, she accelerates while going straight.

The table below summarizes how the loading of the wheels changes during this process.

A table showing how the load changes as a car turns

The magnitude of the shift in force on the tires is proportional to the height of the car’s center of gravity. Semis and SUVs have a high center of gravity. That’s why they’re more likely to tip on a turn than a low-to-the-ground sports car.

One of the Car of Tomorrow’s vexing points was that its center of gravity was quite high for a race car. That made load transfer a much bigger effect. The video below shows the then-brand-new Car of Tomorrow at Martinsville Speedway. You can see as Robby Gordon comes out of the turn and gets on the gas that there isn’t even enough force on the left-front tire to keep it on the ground.

A video showing how significant load transfer can be

Because teams have access to detailed data about how their drivers — and all the other drivers  — navigate corners, they can analyze a turn in exquisite detail. That’s why they don’t stop at entry, middle, exit, but specialize to late entry or early exit, for example.

William Byron’s crew chief Rudy Fugle explained how teams use this data on NASCAR America Motormouths.

“We break the track down into segments,” Fugle said, “and say, entry, early entry, middle… wherever, these parts of the corner make the lap time. All the fast cars that are making laps make it here.”

Making a fast lap is important for qualifying, but there’s more to racing than speed. You have to be able to pass other cars, and that frequently happens in the turns as well.

“And then we also have some analysis on the most passes are made in this part of the corner,” Fugle said. “So you kind of know, like, OK, to go fast I need to be good here and to make passes, I need to be good here, because sometimes they’re in different spots.”

The challenge of dealing with a car whose grip constantly changes is, in my opinion, one of the most underappreciated aspects of racing.

When I lived in Nebraska, I put bags of sand in my pickup truck’s bed to increase its rear grip. That additional force made the truck less likely to get loose. Racing is like having a bag of sand on each corner of the car, but the weight of each sandbag changes when you speed up, slow down or turn. The best drivers are those with an expert feel for how far they can push their car without exceeding its traction limit.

Hailie Deegan to make Xfinity debut at Las Vegas

0 Comments

Hailie Deegan announced Tuesday that she will make her Xfinity Series debut Oct. 15 Las Vegas Motor Speedway on NBC and Peacock.

The 21-year-old Deegan is in her second full-time season in the Camping World Truck Series. She finished a career-high sixth in that series last weekend at Talladega Superspeedway.

She will drive the No. 07 car for SS Green Light Racing with Jeff Lefcourt.

 

 

Alex Bowman to miss Charlotte Roval race

0 Comments

Alex Bowman announced Tuesday night on social media that he will sit out this weekend’s Cup playoff race at the Charlotte Roval.

Bowman said on social media: “I am continuing to make strides in my recovery to make sure I can return to competition at 100%.”

This will be the second consecutive race he will have missed because of concussion-like symptoms after his crash at Texas Motor Speedway.

Noah Gragson will drive the No. 48 car this weekend for Bowman.

“Alex’s health is our first priority,” said Jeff Andrews, president and general manager of Hendrick Motorsports, in a statement. “We’re focused on supporting his recovery and seeing him back in his race car when the time is right. Alex has a long career ahead of him, so we will invest the necessary time and take our guidance from medical experts. We’re putting no pressure on him to return before he’s 100% ready.”

Bowman will be one of the four drivers eliminated from title contention Sunday.

Also Tuesday, Cody Ware announced that he will sit out this weekend’s Cup race at the Charlotte Roval, as he continues to recover from the ankle injury he suffered at Texas.

NASCAR Power Rankings: Chase Elliott leaps to the front

0 Comments

A slick late-race move by Chase Elliott carried him to Victory Lane Sunday at Talladega Superspeedway — and back to the top of the NBC Sports NASCAR Power Rankings.

Elliott is the only driver with five victories this season. No one else in the playoffs has more than two (Tyler Reddick, eliminated from the championship hunt, has won three times).

Elliott, already qualified for the Round of 8 with his Talladega win, will be among the favorites in Sunday’s race at the Charlotte Motor Speedway Roval (2 p.m. ET, NBC).

Here’s how the rankings look approaching the end of the Round of 12:

NBC Sports NASCAR Power Rankings

1. Chase Elliott (No. 3 last week) — Elliott’s power move to win at Talladega was quite impressive and gave him four top-five finishes in the past 10 races. Clearly, he has re-established himself as the championship favorite.

2. Denny Hamlin (No. 1 last week) — Hamlin drops a spot despite a strong run (20 laps led and finishing fifth) at Talladega. Count him in the hunt for an elusive first championship.

3. Ryan Blaney (No. 8 last week) — Blaney simply will not go away despite continuing as the playoffs’ only winless driver (not including the Texas All-Star Race). He was victimized by Chase Elliott on Sunday at Talladega, finishing .046 seconds short of victory and a push into the next round.

4. Kyle Larson (No. 2 last week) — Superspeedway racing generally is not Larson’s strong point. He finished 18th Sunday despite leading eight laps and being in the front group much of the day.

5. Joey Logano (No. 4 last week) — Logano had an unusually poor performance at Talladega. He was involved in an early-race accident and struggled much of the rest of the day, finishing 27th.

MORE: Elliott celebrates, Logano laments

6. Ross Chastain (No. 7 last week) — Chastain tied Aric Almirola for most laps led (36) at Talladega and has been consistent as of late with three finishes of seventh or better in the past four races.

7. William Byron (No. 5 last week) — Byron’s worst news last week came off the track as he was penalized by NASCAR for dumping Denny Hamlin under caution at Texas. He finished 12th at Talladega.

8. Chase Briscoe (No. 9 last week) — Briscoe is quietly making the case that he could make the Round of 8 and challenge for the title.

MORE: Winners and losers at Talladega

9. Daniel Suarez (unranked last week) — Suarez maneuvered through the Talladega draft with style and came home eighth. He has three top 10s in the past seven races.

10. Christopher Bell (No. 6 last week) — Bell had a rough day at Talladega and will be looking to Sunday’s race at the Roval for redemption.

Dropped out: Tyler Reddick (No. 10 last week).

Talladega’s tale of two drivers: One celebrates, one laments

0 Comments

TALLADEGA, Ala. — It’s dangerous to forecast what is going to happen next in these playoffs in a Cup season unlike any other. 

So keep that in mind, but Chase Elliott’s victory at Talladega moves him one step closer to returning to the championship race for a third consecutive season.

It’s easy to overlook that beyond earning a spot in the Round of 8 with his win Sunday, Elliott scored six playoff points. That gives him 46 playoff points. He has the opportunity to score seven more playoff points this weekend at the Charlotte Roval — an event he has won twice — before the next round begins.

Once the current round ends, the points will be reset to 4,000 for each of the remaining playoff drivers and they’ll have their playoff points added. 

At this point, Elliott would have a 21-point lead on his nearest competitor and a 31-point lead the first driver outside a transfer spot to the championship race.

The next round opens at Las Vegas, goes to Homestead and ends with Martinsville. 

A key for Elliott, though, is to avoid how he has started each of the first two rounds. A crash led to a 36th-place finish in the playoff opener at Darlington. He placed 32nd after a crash at Texas to begin this round.

The up-and-down nature of the playoffs, though, hasn’t taken a toll on the 2020 Cup champion.

“I feel like I’ve been doing this long enough now to understand the roller coaster that is racing,” said Elliott, who is advancing to the Round of 8 for the sixth consecutive season. “It’s going to roll on, right? You either learn to ride it during the good days, during the bad days, too, or you don’t. That’s just part of the deal.

“So, yeah, just try to ride the wave. Had a bad week last week, had a good week this week. Obviously great to move on into the next round, get six more bonus points. All those things are fantastic, we’re super proud of that.

“This deal can humble you. We can go to the Round of 8 and crash again like we did the first two rounds, or you can go in there and maybe have a really good first race. I don’t know. You show up prepared, do the best you can, figure it out from there.”

————————————————————————————————————————————————

Joey Logano has always been one who wants to race at the front in a superspeedway event instead of riding at the back.

When asked last month about the idea of Texas Motor Speedway being reconfigured to provide superspeedway-type racing — as Atlanta Motor Speedway was before this season — Logano questioned the value of that type of racing.

“Is that the type of racing fans want to see?” Logano said. “Because when you look at the way that people have finished up front in these superspeedways lately, (they) are the ones that are riding around in the back. 

“Do you believe that you should be rewarded for not working? Because that’s what they’re doing. They’re riding around in the back not working, not going up there to put a good race on. 

“They’re riding around in the back and capitalizing on other people’s misfortune for racing up front trying to win. I don’t think it’s right. That’s not racing. I can’t get behind that.”

Logano sought to race at the front as much as possible Sunday at Talladega, even after his car was damaged in an early incident, but he took a different tack on the final restart. He restarted 24th and dropped back, finishing 27th.

“We just wreck all the time, so we thought, ‘Boy, we’ve got a big points lead, let’s just be smart and don’t wreck and we’ll be able to get out of here with a top 10, assuming they would wreck because they always do,’” Logano said after the race. 

“That was the only time I’ve ever stayed in the back, ever, was today and they didn’t wreck. We gave up a bunch of our points lead. We’re still plus-18, which is a decent spot to be, but, the goal was to race for stage points and then drop to the back and wait for the crash. I hate racing that way. I’ve gotten beat many times from people that do that, then I tried it and it didn’t work.”

————————————————————————————————————————————————

Michael McDowell’s third-place finish continues his strong season. 

McDowell’s finish extended his career-high of top-10 finishes to 12. He has five finishes of 11th or better in the last seven races. 

“I’m proud of the season we’ve had and the run that we put together,” McDowell said. “Everyone did a great job on pit road executing and getting us track position when we needed it. It’s good to be there at the end and have a shot at it, just disappointed.”

Front Row Motorsports teammate Todd Gilliland finished seventh. 

“Race car drivers are greedy,” Gilliland said. “I wish I could have gotten a couple more there, but it was still a really good day. We ran up front most of the day and my car handled really well, so, overall, there are definitely a ton of positives to take out of this.”

Sunday marked the second time this season both Front Row Motorsports cars finished in the top 10. They also did it at the Indianapolis road course. 

————————————————————————————————————————————————

NASCAR confirms that the Hendrick Motorsports appeal of William Byron’s 25-point penalty from Texas will take place Thursday.

Should Hendrick lose that appeal, the team could then have a hearing before the Final Appeals Officer. That session would need to take place before Sunday’s elimination race at the Charlotte Roval (2 p.m. ET on NBC).

“Twenty-five points in the playoffs is a ton,” car owner Rick Hendrick said Sunday of Byron’s penalty. “I mean, in the regular season if you got a bunch of races, you can make it back up.

“I’ve seen other cars under caution hit each other. In that situation, (Byron) wasn’t trying to spin him, but they got a tower full of people, they could have put him in the back, could have done something right then rather than wait till Monday or Tuesday, then make a decision.”

Byron is 11 points below the cutline after Talladega.