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dalek (15489)
I know many people here don't care about sports, but I'm betting there are a lot of people here who know way more about engineering race cars than I do.
This weekend, Kurt Busch is missing his fourth consecutive race due to a concussion he sustained from a crash during qualifying at Pocono. As Busch drove through the final turn, he spun the car, and hit the wall hard in the right rear quarter panel. The right front of the car also hit the wall after the initial impact. It's a hard hit, for sure. But I've seen other impacts in recent years that looked just as hard and didn't injure the driver.
NASCAR switched to the next gen car this year, which features many changes over the gen 6 cars of the past decade. I believe that Ryan Newman's crash at the end of the 2020 Daytona 500 influenced the design of the next gen car. I watched that wreck on live TV and really thought I'd just seen a driver get killed. The tone of the broadcast, the way Mike Joy and Jeff Gordon talked about Newman's wreck was far too reminiscent of Dale Earnhardt's crash on the final lap of the 2001 Daytona 500.
Much like Earnhardt's crash, Newman's car got turned and hit the wall head on. Two decades ago, that impact might have been fatal. Now, drivers are required to wear a HANS device, which prevents their head from snapping forward in a crash and causing a basilar skull fracture, which is often a fatal injury. There is also a SAFER barrier that absorbs some of the impact. After the initial impact, Newman's car flipped and spun around in front of Corey Lajoie's car, which collided directly with Newman's driver's side window. Newman's head hit the roll cage, knocked him unconscious, and he sustained a brain bruise. Despite all of the safety improvements since Earnhardt's death, Newman was lucky to survive.
As I understand it, NASCAR designed the next gen car to have a stiffer chassis so that wrecks like Newman's wouldn't be fatal. However, a lot of drivers have complained that impacts to the rear of the next gen car are more violent than with the gen 6 car. Measurements of the forces experienced are not more severe than with the gen 6 car, but drivers say the impacts feel more violent.
It makes complete sense that the roll cage should be as strong as possible to protect the driver. If it's possible, strengthening the roll cage seems like an obviously good decision. Moving the driver toward the center of the car could also provide more protection. However, it's not clear to me that making the front or rear of the car stiffer would be beneficial in a wreck like Newman's. And if the front and rear of the car don't crumple as much, it seems like impacts in those areas would be more violent for drivers.
In a crash like Busch's, I expect the damage would be significant enough to require going to a backup car for the race, but not to injure the driver. Crashes like this are relatively common, particularly compared to Newman's crash. NASCAR is going to be a lot more dangerous if crashes like Busch's frequently injure drivers.
Am I missing something here? Shouldn't it be possible to strengthen the roll cage to protect against crashes like Newman's while also allowing the front and rear of the car to crumple enough to dissipate the forces from impacts? I'm not understanding why this is described as a tradeoff between providing more protection in a crash like Newman's but causing more violent impacts in crashes like Busch's. That said, I don't know a whole lot about the design and engineering of race cars, so perhaps I'm missing something.
(Score: 1, Interesting) by Anonymous Coward on Saturday August 13 2022, @01:04PM (5 children)
Isn't this one of those energy problems in physics? $e = \frac{mv^2}{2}$. If you're going 200 MPH, that exponential term is a bitch. Also why truck drivers need to be so careful about controlling speed on those steep descents, since that exponential term goes straight to brake heat. Could the idea with stiffer frames be that at those speeds, you're better getting the wall to absorb the energy?
Maybe they're also talking about rear-end collisions where the relative $v$ is small, so for those it's feasible for the car body to absorb $e$. I'm not an expert though.
If you're worried about safety, get one of those steering wheel + peddle + shifter kits and race in VR. Physics have greatly improved, especially with for example Gran Turismo (pre-VR) and Project Cars. But I get the appeal. I like to get a little reckless on mountain roads. Kirk figured it out in Star Trek Generations.
I need to find a shifter that has a range selector to flip between high and low for my truck simulator needs.
(Score: 1, Insightful) by Anonymous Coward on Saturday August 13 2022, @01:13PM
https://www.amazon.com/Shifter-Replacement-Logitech-Thrustmaster-EasyJakeBrake-Windows/dp/B07DVW2WYK [amazon.com]
(Score: 3, Interesting) by dalek on Saturday August 13 2022, @03:14PM
I believe you're correct about the nature of the problem and the math involved. That's also why Dale Earnhardt's wreck was so dangerous (see https://www.youtube.com/watch?v=8l3eNMhrRhU [youtube.com] around 4:44:00 for the crash), because there was just the single head-on impact with the outside wall instead of a lot of smaller impacts. There's another impact when Ken Schraeder gets caught in the wreck and hits the side of Earnhardt's car, but the head-on impact is what killed Earnhardt. It's the same reason Austin Dillon's crash at Daytona [youtube.com] a few years ago was so scary. He went airborne and had a sudden stop as the car was caught in the catch fence around the tri-oval. A lot of cars got wrecked there, but with a series of smaller impacts instead of coming to a sudden stop.
I don't know the physics and engineering well enough to know if a stiffer frame would better transfer energy into the SAFER barrier. If it did, there's still the problem of what happens when two cars collide with each other. It's typical on restarts for cars to drive into the back of other cars and push them. The driver at the front of a line on a restart wants to be pushed from behind, otherwise the other line is going to have an advantage. With the new cars, even common collisions like those are causing the HANS device to be fully extended, meaning that there's a lot of force pushing the driver's head forward even in that situation. I don't believe that happened with the car of tomorrow or the gen 6 cars.
With respect to your last point, there's always going to be some danger driving race cars, particularly at tracks like Daytona and Talladega. You're never going to completely get rid of the risk that comes from pack racing at speeds of nearly 200 mph, or from some of the relatively high speed collisions at smaller tracks. Even so, you don't want drivers getting seriously injured or killed somewhat frequently, like what happened in NASCAR back in the 90s. It seems like the safety of the next gen cars has regressed somewhat for the majority of impacts, which isn't a good thing. I also think concussions are taken a lot more seriously now in sports (not just NASCAR) than 20 or 30 years ago. You're not going to completely eliminate the danger in NASCAR without destroying the sport. There are always going to be tradeoffs, like the window net being a somewhat vulnerable part of the car, but necessary because drivers need to be able to get out of the car quickly if it's on fire. It's just about keeping the risk to a reasonable level.
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest just whinge about SN.
(Score: 1, Informative) by Anonymous Coward on Saturday August 13 2022, @10:30PM (2 children)
Yes, at top level I'd agree that it is an energy problem. However, once you dig deeper, there are a lot of details that can make a large difference. Put another way, energy absorption as structures deform and crush is a wildly non-linear problem. A small difference in impact angle, or head position relative to the seat, (for a couple of examples) could results in a large difference in the driver's head accel/decel.
NASCAR runs actual crash tests (with instrumentation) but these are expensive and I doubt they cover much of the range of different impacts that might occur. One test I remember reading about used up a car twice--once with a front crash and then with a rear crash. After that I don't think you can also use it for a side impact like a T-bone...
They may have done some sim work and possibly also some near-static crush testing--watch the structure collapse in slow motion, with load cells all over. Both of these are widely done for production cars, but I don't have any references for that.
If you followed the development of the new car, you may remember that the original plans called for a carbon-epoxy central "tub" which makes for a very rigid "safety cell" for the driver. This is the way that most cars are built for other pro race series. At some point in the NASCAR development process (I don't remember reading any details) the carbon tub was exchanged for a welded roll cage, similar to previous 'Cup cars.
Part of the problem with NASCAR (in this context) is that they tend to hold detailed information close. While I can't see how releasing more details would be a problem, they obviously feel that way. Other race series (like IndyCar and F1) have a lot more instrumentation in the cars during races and they learn from crash data, technical papers are published. Here's a press release about Indy Car--they started using a crash data recorder in 1993(!)
https://www.nhtsa.gov/sites/nhtsa.gov/files/indy_race_cars_are_equipped_with_crash_data_recorders-safety.pdf [nhtsa.gov]
Does NASCAR do this? I don't believe they do.
(Score: 2) by dalek on Sunday August 14 2022, @03:50AM
Great post; thank you!
NASCAR was late to add crash recorders to their cars. I believe that happened starting in 2002, in response to Dale Earnhardt's fatal crash. That also led to the development of the car of tomorrow. Here's an article that discusses some of the data that NASCAR collects about crashes: https://nascar.nbcsports.com/2022/07/15/friday-5-hard-hits-have-cup-drivers-wondering-whats-happening/ [nbcsports.com]. While they do collect some data, I'm wondering how much data they're actually collecting about how energy gets transferred through cars during crashes, as in how many sensors they have around the cars and where they're placed.
It seems like it would be important to test the forces from collisions at a variety of angles, but I definitely see why it would be quite expensive. Kurt Busch's crash was a hard crash, for sure, but not something that really looked unusual or that it should be particularly dangerous. He got loose coming out of the final turn, spun, and backed hard into the wall. That's a pretty common type of crash. The same type of impact could also happen if a tire goes down. As I recall, there were quite a few crashes in practice and qualifying at Fontana where drivers got loose in the turns, spun, and smacked the wall in turn 1 and turn 4. I also remember quite a few cars having tires go down and spinning out at the spring Atlanta race. Does NASCAR just not have enough sensors on the cars to know how the forces are being transferred through the car and what the driver is experiencing?
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest just whinge about SN.
(Score: 0) by Anonymous Coward on Sunday August 14 2022, @06:28AM
I think one difference that is making a real difference (as you suggested) is that the next gen car has a completely redesigned rear. For starters, the rear suspension is fully independent and that can drastically affect the force vectors in a crash. As for the body, they reduced the rear crumple zones, added a larger and softer bumper, and stiffened the frame, which probably means that a lot of smaller hits are dampened (or even go undetected by the drivers) but the large ones are felt more firmly and at a more obtuse angle.
To answer your other question, from what I have seen and heard from others NASCAR does provide public and private data. However, even their private data is nowhere close to what FIA provides privately.
(Score: 3, Interesting) by RS3 on Saturday August 13 2022, @06:24PM
I don't know the physics and physiology of concussion, but I'm fairly certain it varies person to person. That seems intuitive largely from watching sports, including boxing. Some people seem to easily withstand huge cranial impacts, and other people are severely injured from a seemingly minor impact.
I'm pretty certain the severity is largely dependent on the peak force (impulse) that results from a deceleration. (kinda stating the obvious, but just to define it)
Stated another way in physics: the peak force (impulse) is dependent on the initial kinetic energy and the distance over which the deceleration occurs. The shorter the distance, the higher the peak impulse.
My intuition (hunch) is that it's quite difficult to decelerate a human from 200+ MPH to zero in a short distance and not cause concussion, no matter how much you try to absorb the deceleration energy.
I've wondered if the crumple zones are the problem. They're not adaptive, although they're probably progressive. But once you've absorbed some energy and the crumple zone is used up, you now have a sharp increase in impact force (deceleration) - frame hitting frame or engine block. That remaining impact energy will vary (wildly) depending on the speed, angle, geometry, car's construction, etc.
(Score: 3, Interesting) by fliptop on Saturday August 13 2022, @08:49PM (1 child)
Newman's wreck is considered to be an example of how far safety improvements have come [businessinsider.com].
One rule my Dad always had about buying cars is never to buy in the 1st year of a new model. A car that's been redesigned needs time to shake out any bugs. Perhaps what's happening right now in NASCAR is the same thing. Quote [usatoday.com]:
The engine size and HP rating has not changed w/ the gen 7 cars [autoweek.com]. Faster collapse of the crumple zone in a wreck could also mean less time for the brain to slow down from crashing into someone's skull. Not sure a stronger roll cage would help w/ that.
What I'd like to know is how they balance driver safety (in a wreck) and changing the car so it handles better therefore there's not a wreck in the first place. I think the drivers have not had time to shake out the bugs.
To be oneself, and unafraid whether right or wrong, is more admirable than the easy cowardice of surrender to conformity
(Score: 2) by dalek on Sunday August 14 2022, @04:36AM
One of the purposes of the roll cage is to protect a driver during a crash like Ryan Newman's. As much as NASCAR tries to prevent cars from becoming airborne, it still happens, particularly at the high speeds that are reached on superspeedways. You don't want the roof of the car collapsing inward if the car flips and lands upside down. You don't want the car being completely torn apart if it goes airborne into the catch fence, leaving the driver exposed. The roll cage should also provide some protection from the second impact in Newman's crash, where the front of Corey Lajoie's car is colliding directly with Newman's driver's side window. The bars should be sturdy enough to prevent Lajoie's car from directly making contact with Newman. I do give a lot of credit for NASCAR for making the cars safer. As I noted, even the initial impact that Newman experienced might well have been fatal during the gen 4 era. I don't think the crash would have been survivable then. NASCAR did make the cars and the tracks much safer.
As I understand it, Newman's head hit the roll cage during that crash. I also believe Joey Logano's head hit one of the bars in the roll cage in a crash [youtube.com] where he went airborne at Talladega last year. If you watch that video long enough, you'll also see the in-car view from Bubba Wallace's car, where Logano was airborne right in front of him. If Logano's car had ended up on top of Wallace's car, you definitely want the roll cage to prevent the roof of the car from collapsing on Wallace. Thankfully, that didn't happen. In either case, though, if the driver's head is hitting bars in the roll cage, there's a risk of a head injury.
I don't think it would necessarily provide much protection in Kurt Busch's crash, though I don't know a whole lot about how the forces from the impact get transferred throughout the car. But you definitely want the roll cage to be stiff and strong to protect the driver in other types of crashes. One difference between the gen 6 cars and the next gen car is that the rear quarter panels are a lot smaller. I'm wondering if the size of the crumple zone has changed, and if that is a factor.
As for handling, that's complicated. One of the main complaints about the last few years of the gen 6 car was that the cars were too easy to drive, and it decreased the quality of the racing. A lot of people, including many of the drivers, say that the cars should be hard to drive, and that it results in better racing. In the Fontana race this spring, a lot of cars spun in practice and qualifying, and people noted that the next gen car was harder to drive than the gen 6 car. The Fontana race was excellent and provided the best racing at that track in many years. Drivers say that the cars in the Xfinity series, which functions largely as a developmental series for young drivers, are harder to drive than the cup cars or the trucks. The quality of racing in the Xfinity series has been really good in recent years, probably better than in the cup series. Obviously you want to prevent certain types of impacts, like putting flaps on the cars to prevent them from becoming airborne. But I think the poor handling is somewhat of a feature, not a bug.
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest just whinge about SN.
(Score: 0) by Anonymous Coward on Sunday August 14 2022, @11:34AM (1 child)
American Football causes traumatic brain injuries that lead to increased suicides and homocides. NASCAR crashes are obviously horrible for the human body even if you don't burn to a crisp.
Sports like golf and tennis? Not very deadly.
(Score: 1, Funny) by Anonymous Coward on Monday August 15 2022, @12:43AM
> Sports ...
don't include golf and tennis.
https://www.goodreads.com/quotes/42427-there-are-only-three-sports-bullfighting-motor-racing-and-mountaineering [goodreads.com]
(Score: 1, Informative) by Anonymous Coward on Wednesday February 01, @04:34PM (2 children)
Turns out that the NASCAR crash test program for the current "next gen" car included a lot of simulation and correlation work. Nice, fairly technical, overview at this link, https://www.automotivetestingtechnologyinternational.com/features/crash-testing-nascars-next-gen.html [automotivetestingtechnologyinternational.com] Here's a sample from the article,
Also includes an overview of the whole-car crash test that was done at 'Dega...using a steering robot to drive the car into the wall (Safer Barrier).
(Score: 2) by dalek on Thursday February 02, @01:55AM (1 child)
Thank you! That's a really interesting article, and it goes into a lot more technical detail than I've heard before. If they tested it out at the high speeds cars run at Talladega, it seems like they got it right. Despite the issues with slower speed crashes into the rear of the car, this car does perform really well in the biggest crashes at Daytona and Talladega. The article provides a lot more detail about how the crash testing was done and was really informative.
I am curious what they're referring to in their simulations when they talk about boundary conditions. Some of my work involves fluid dynamics simulations, though on a different scale from what would be used to simulate the aerodynamics of a car. In that context, it typically refers to lateral boundary conditions. We simulate what happens on a finite three-dimensional grid, and the lateral boundary conditions are define what happens at the edges of the grid. I'm assuming they're referring to something different here when they talk about boundary conditions.
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest just whinge about SN.
(Score: 1, Interesting) by Anonymous Coward on Thursday February 02, @04:29AM
Sounds like you are asking about this paragraph?
> Once the model was prepared for simulations, NASCAR tapped into its historical crash database, examining real-world crash speeds, angles and trajectories to establish the boundary conditions for the right-frontal impacts, T-bones, rear impacts, roof crush cases and more, that would be used to assess and optimize the design. In all, more than 5,000 crash simulations were run.
Looks to me like the author did some creative "terminology escalation" here. I would call that determining load cases (basic structural engineering), but don't hold me to that... A quick search for:
determining crash load cases
turned up some possibly interesting papers (I didn't look in depth).
What I found interesting was the very careful development of the programming of the driving/steering robot for the eventual live crash test -- starting out at lower speeds and making sure that the path following worked, including the last-second turn away from the wall. AB Dynamics is probably the leading supplier of robot driving systems, their stuff has been developed for many years and is used at proving grounds by most/all of the big car companies. ABD has also been doing good business with many of the ADAS and autonomous driving suppliers, supplying moving targets of various kinds (dummy pedestrians/cyclists/cars) to use when testing a self-driving system.