Mar 262015
 

Joel asks:

Can racetracks work together to make interchangeable/transportable SAFER barriers? To clarify – could SMI or ISC tracks (politics, blah) standardize wall heights, angles, etc. so that they could use barriers at Michigan to fill in the critical areas and then move the necessary walls to Darlington or Homestead? Or even simpler – could the existing walls be setup to install barriers that could be moved from track to track? In the long term I know this is probably not the most cost effective solution. But in the short-term if there are supply problems or significant cost barriers, I thought this could help?

Thanks for the question, Joel. (And apologies for taking so long to get to answering it.)

Installing SAFER barriers is a little more complex than installing a fence in your yard. SAFER barriers are custom manufactured for each section of the track taking into account the wall height, width and condition, the track banking and width. Even putting aside track politics, having a system of barriers versatile enough that they could move from Michigan to Darlington and be equally effective in both places would probably be cost and time prohibitive. You’d need a dedicated crew of people moving from track to track, trucks to transport the barriers and a procedure in place to inspect and qualify each piece after each race.

Standardizing wall heights could be more expensive and time consuming that it’s worth. Each track has its unique geometry and trying to make a one-size-fits-all barrier might be more trouble than it’s worth — and not as effective as just installing barriers.

Plus, if an area of the track is dangerous, it’s not just dangerous during NASCAR races. No track is going to claim they can’t afford to put more barriers in – especially after Kyle Busch’s accident. And although they do take time to manufacture, there are a growing number of companies certified to fabricate, install and maintain the barriers.

But you’d think there would be a better temporary alternative than a bunch of tires, right?

One of the things the SAFER group was thinking about last time I talked to them was a transportable version of the barrier that could be used for street courses. It’s a formidable challenge. The current barriers are fastened to the track wall, which is pretty firmly in place. How would you anchor something to a street in such a way that it would stay in place, but could be removed without significant damage to the road/sidewalk/parking lot?

Another problem that I haven’t really heard talked about is that it’s impossible to line a track with SAFER barriers inside and out. Emergency vehicles must have free and immediate access to the track (and a way out) when needed. The SAFER group also has investigated hinged barrier that could open and close, but developing a hinge that can take a direct hit from a 200-mph racecar and still open easily is a pretty stout challenge as well.

It all goes back to what I tell Moody (it seems) every week. If it were simple, they’d have already done it.

Thanks again for the question!

Mar 042015
 

A couple observations about history at Las Vegas…

Pole Speeds

BSPEED_LasVegasCumData_PoleSpeed

 

Pole speeds hovered inthe 170-175 mph until 2007. After the 2006 race, LVMS changed over to progressive banking, which increased the banking overall and changed the amount of banking in different lanes of the track. This added about 10 mph to the pole speed and it’s been on an uphill trajectory ever since. With the lighter car, it will be interesting to see what type of speeds they reach this year.

Cautions

BSPEED_LasVegasCumData_Cautions

 

The maximum number of cautions we’ve seen was in 2009, with 14, but recent years have averaged around four to six.

Best Drivers

It’s tempting to note who has the most wins – but the important thing is really how many times they won relative to how many times they’ve raced. In this case, Jimmie Johnson wins both categories – 4 wins, which means he wins approximately 30 percent of the time he races there. Keselowski, KyBu, Stewart and Gordon all have one win, but the percentage win rate ranges from about 15% (Keselowski) to 5% (Gordon).  Get well Kyle!

BSPEED_LasVegasCumData_DriverWinsPercentAbsandPercent_LGQualifying

After last week’s embarrassment at Atlanta, there will be extra emphasis on qualifying. Like most 1.5-mile tracks, where you start does have some influence on where you finish, so a good qualifying spot is sort of important.

BSPEED_LasVegasCumData_2014StartFinish

Here’s a graph of starting position vs. finishing position for last year’s race. I’ve highlighted the cars that finished 10 or more laps down. Those cars are usually in an accident or have a major parts failure, so they should be noted in case they skew the result.

You’ll notice there’s a general trend that suggests where you start influences where you finish, although the correlation seems stronger at the lower positions. The first 10-15 starting positions seem pretty random.  (Compare this to what you find at a plate track like Daytona, where staring position is pretty much entirely irrelevant. There’s also a more thorough discussion of how to analyze these types of plots in that blog). I made the graph for 2013, but it looks pretty much the same as for 2014, not I’m not posting it here.

Will be on SiriusXM NASCAR radio this Friday (March 6th) sometime between 3 and 7 East to talk about aging and the effect it has on drivers.

 

Feb 252015
 

TL;DR:  No.

As the extent of Kyle Busch’s injury Saturday evening at Daytona became evident, Twitter erupted in angry calls for SAFER barriers to be put up on every wall at every track. An interesting division of sides appeared. A small number of people cautioned that simply plastering every track with SAFER barriers was likely to not only not prevent driver injuries, but might actually introduce new problems. Other people accused this group of being insensitive and “stupid”.

Interestingly, the small number of cautionary voices were people like the folks who write Racecar Engineering magazine, people who have been involved with motorsports safety research and people with advanced engineering degrees.

So let’s be really clear here. While I appreciate the passion with which people responded to the accident, opinion has absolutely no place in science and engineering. We work with facts, realizing that oftentimes, we don’t have all the facts we need. In an ideal world, we would have data from collisions at every track in the world, from every angle, with every type of racecar. But we don’t.

It’s fine for fans (and especially for drivers and their teams) to raise their voices and demand more attention to safety, but the average fan (or the average driver) has zero business specifying what those safety measures ought to be. The average NASCAR executive or track administrator doesn’t, either.  Motorsports safety is a constantly evolving research field and luckily, NASCAR recognizes that and works with the top people in the field.

Daytona

Let’s start with the obvious. A bare concrete wall at a track where speeds reach 200 mph is indefensible. To their credit, NASCAR and the Daytona folks promised to rectify that right away. Tire barriers – which are not ideal, but are definitely better than nothing – were up for the next day’s race.

Racetracks originally put up concrete walls to contain the cars and protect the fans. They weren’t there for driver safety. People don’t question the status quo.  It wasn’t until a number of serious accidents in both IndyCar and NASCAR prompted an effort to develop a better wall. I detail the origin and development of the SAFER barriers in my book, The Physics of NASCAR, based on my interviews with the barrier developers. The effort was initiated by IndyCar, but gained momentum when NASCAR threw their support (and money) behind it.

Once the technology was developed and proven, NASCAR mandated SAFER barriers on the outside walls of all tracks. It was a long road to development because it was a brand new (and frankly, counterintuitive) idea and everyone wanted to make sure it would work under as many conditions as possible.

How SAFER Barriers Work

For an overview of NASCAR safety, check out this video I made with the National Science Foundation. Here’s the brief version.

BSPEED_SAFERBarrier_Schematic

The SAFER barrier works by extending the time of impact. It’s much more comfortable to fall on a mattress than a floor because the mattress gives. The mattress absorbs and dissipates energy, so that the energy isn’t dissipated through you.

BSPEED_SAFERBarrier_HitA NASCAR stock car going 180 mph has approximately the same kinetic energy as stored in 2 pounds of T.N.T. When the car comes to a stop, all that energy has to go somewhere. Energy can be dissipated by skidding (friction between wheels and asphalt), light and sound (it takes energy to make that screeching noise and to produce sparks), spinning (energy is used to rotate the car) and deformation (energy is used to crunch or break things).  The key is that you want to dissipate energy any way except through your driver.

A mattress won’t make much difference to a speeding stock car. You need something much stiffer, and that’s the purpose of the SAFER barriers. They’re like mattresses for race cars. They use the energy of the car to deform the barriers and spread out the impact over a longer time. This directs energy away from the driver.

Why SAFER Barriers Aren’t the Only Answer

SAFER barriers save lives and this analysis is meant in no way to diminish their importance. But the inventors of the SAFER barriers would be the first folks to remind us that it takes multiple safety devices, working in unison, to protect the drivers (and the crowds). HANS or hybrid devices, helmets, restraints and the car itself are all part of the equation. You can’t address any one of those elements without considering the others. So here, briefly, are some things to think about.

Kinetic Energy Ranges

SAFER barriers work best in a specific kinetic energy range. I was surprised when interviewing drivers for my book to find that more than one mentioned that hitting a SAFER barrier at low speed actually hurt worse than hitting a concrete wall. But it’s true. The wall works by giving. If you don’t hit it hard enough, it doesn’t give and then it is just like hitting a concrete wall. This is relevant for a couple reasons.
1.  Most tracks host more than one kind of racing series. The kinetic energy scales of those series can vary widely. Any solution has to make the track safer for everyone who races there, not just stock cars.
2. Different tracks have different speeds, so even just within a single racing series, this means different kinetic energies. Compare Martinsville and Daytona, where the maximum speeds are a factor of 1.5-2 different. That means the kinetic energy scales differ by a factor of 2.25-4. That’s a big range. The response of the SAFER barriers can be tuned by using different strength foams and different types of steel tubing – but again, it has to work for all series racing there, not just NASCAR.

Get Off Your Grass

Get rid of the grass. Grass has no business being anywhere in a racetrack that cars could possible end up in.

a. Remember how I mentioned that you can dissipate energy by friction between the tires and the ground? The higher the coefficient of friction between the two materials, the more energy you dissipate. You know what the coefficient of friction is between grass and rubber? Very small. It’s even smaller when the grass is wet. This is why road courses have gravel traps. Huge friction that slows down the cars and hopefully stops them before they hit. (Gravel traps have their problems, notably that it’s near impossible to get out of one once you get in one, and that flying gravel is dangerous and difficult to clean up.)

b. Second, there is a drop off between the asphalt and the grass – a lip on which the car can catch, creating a torque. Check out Elliott Sadler’s crash at Talladega.

When he comes from the grass back onto the track, the roof of the car catches on that lip and starts the car rolling again. If I were a driver or an owner, I would be after every track to get rid of any grass near the track.

The Car Itself

NASCAR has done an amazing job engineering a much safer car than we had fifteen years ago. But the job isn’t done. There hasn’t been a career-ending injury (including death) during a race in any of NASCAR’s three major series since 2001. (Note added. It was pointed out to me that Jerry Nadeau‘s career ended after a very hard hit in 2003 during practice for a race at Richmond.) The injuries we have seen have all been below the knee. Dario Franchitti broke an ankle at Talladega. Brad Keselowski hit a wall testing at Road Atlanta and broke an ankle. Kyle Busch’s injuries from the Daytona crash were to his left foot and right lower leg.

The pedal box and the front of the car need some attention. Can the idea of collapsible steering columns be worked into the pedals? The front of the car is designed to crush (thus dissipating energy) in a crash, but maybe there is a way to refine how the crushing happens and reinforce the driver’s cockpit near the legs. I’m sure the folks at the NASCAR R&D Center are already thinking about this side of the problem.

Perhaps there are driver safety devices than could be developed as well, similar to the HANS device that prevents the head from slamming forward in  a wreck. Maybe there’s a carbon fiber leg brace or similar piece that could provide some extra protection for the driver’s legs in a crash. Of course, anything developed can’t interfere with the driver’s ability to control the car after a crash.

The Fallacy of Safe Racing

Motorsports is dangerous. People are killed participating in motorsports – especially at the lower levels, where the safety requirements are much lower than in the high-dollar, high-visibility series. But even in NASCAR, even in F1, even in Indy, there will be serious injuries and – I’m sorry to say – we haven’t lost our last driver to an on-track incident. All you need is that one in a thousand, one in ten-thousand confluence of events.

What Should Fans and Drivers Be Demanding?

Don’t tell NASCAR and the tracks that they should cover every conceivable wall with SAFER barriers and then sit back and congratulate yourself for a job well done.

Consider for a moment the ratio of people whose job it is to make cars fast to people whose job it is to make racing safer.

NASCAR has become so much more proactive about safety in the last years. If I were a driver, I would be lobbying NASCAR to hire more people at their R&D Center focused on safety, and to support more motorsports safety research at universities and industry.

The FIA has an Institute for Motorsports Safety.  It’s a non-profit foundation that centralizes safety initiatives and testing and works to get safety innovations on the track quickly.

Maybe it’s time for NASCAR to team up with IndyCar and the Tudor United Sports Car series and form something similar in the U.S. This isn’t an issue that should come up only after a serious wreck. It’s an issue that needs long-term, on-going commitment and attention. As a fan, I’d pay an extra buck or two on top of a race ticket if that ‘tax’ were earmarked for safety research.

For More:

 

Feb 202015
 

Okay, it obviously does if you’re one of the cars that fails to make the race. But beyond that- given the huge amount of attention that’s been given to the ’embarrassment’ that was this year’s qualifying – does where you start make any different as to where you finish?

To investigate, I plotted the starting positions against the finishing positions for each race at Daytona. I wanted to do both the July and the February race to see if there was any difference given the different formats of the qualifying (regular qualifying+ duels vs. regular qualifying).

If there were a trend, you would expect a pattern to emerge on the graph. For example, starting position tends to be very important at mile-and-a-half tracks. Although there’s some scatter in the data, there’s a pretty clear trend that the people who start toward the front tend to finish toward the front. Same for the folks who start in the back.

BSPEED_StartingPositionDaytona500

It’s always interesting to look at the points that don’t follow the trend. For example, the point in the upper right circled in red is a car that had engine problems and didn’t finish the race.

The point that is the furthest from the line (furthest defined as the perpendicular distance between the point and the line) is the one circled in crimson and labeled “Harvick”. Despite leading 23 laps, Harvick had axle/hub trouble and spent 30 laps in the garage. His 41st place finish didn’t reflect how good his car was – at least until it broke.

Similarly, the other crimson-circled data points represent cars that ran more than 3 laps down due to problems in the pits, mechanical difficulties, or accidents that didn’t result in the car leaving the race, but did enough damage to require time in the garage or pits fixing the car.

Here’s similar data for Phoenix – it shows the trend even more strongly. If you started well and your name wasn’t Kurt Busch (engine failure), you finished pretty well. If you started in the back, that’s pretty much where you stayed.

BSPEED_StartingPositionDaytona500_2014Phoenix

So if this post is about Daytona, why am I going on and on about Las Vegas and Phoenix?  Well…

I wanted to show you what you were looking for first. And the analogous plot for Daytona is a mess. You might not realize that it means there isn’t a trend if you hadn’t seen data where there was a trend first. So here’s last year’s Daytona 500.

BSPEED_StartingPositionDaytona500_2014Daytona500

 

Again, plotting starting spot on the horizontal axis and finishing position on the vertical axis. I got clever this time – the red shading represents finishing positions that were six laps or more down relative to the winner. The red circles represent DNFs, due either to engine problems or crashes. (Just for comparison – at Las Vegas in 2014, only the last nine positions were six or more laps down.

There’s no discernible trend in this plot. Now you see why I showed you the other one first, right?

But maybe it’s one of those anomalous years, right? Let’s look at the data for the last three Daytona 500s.

BSPEED_StartingPositionDaytona500_CumDaytona

<sarcasm> Oh, yeah. Much clearer.</sarcasm>.

The trend (or rather, the lack of a trend) holds for the last three Daytona 500s and, in fact, for the July races as well.

Drivers and media types tend to talk about Daytona being a ‘crap shoot’. That’s reflected by the fact that where you finish has very little to do with where you start when you’re talking Daytona.

Why? Well, one big factor is that the close proximity of the racing means that you are much more affected by everyone else on the track. You can be the perfect driver, but it you happen to be behind Donny Dangerous and he spins, you have little chance of avoiding being caught up in it yourself. Remember at 190mph, you’re talking traveling a football field in the blink of an eye.

 

 

 

 

Dec 122014
 

The primary motivation for all the changes to the Chase format was to up the excitement factor – the “game seven moments” as NASCAR brass put it. While the fact of the matter is that you can’t guarantee excitement, all the machinations put in place definitely increased the stakes of the chase races.

I’ve heard a lot of people say that the increased stakes spurred the drivers to be more aggressive and that resulted in better racing.  To be sure, we had a couple notable off-track incidents. It’s pretty surprising when Matt Kenseth loses his cool. But what about on-track?

Lead Changes

I started thinking about how you would measure that.  My first inclination was to look at lead changes. If drivers are being more aggressive, there ought to be more lead changes in Chase races than in other races. Now, comparing this is a little tricky.  You can’t compare a Talladega (where the ever-shifting lanes of cars trade the lead, resulting in hundreds of lead changes) to a Martinsville or a Charlotte.

But there are eight tracks in the Chase that have races earlier in the season.  What about them? I looked at how many lead changes there were at each track in the Fall, then compared that to the Spring. Kudos, as always to racing-reference.info for putting all this data at my fingertips. I took the difference, so that a negative number means that there were more lead changes in the Spring and a positive number means there were more lead changes in the Fall.

For example, At Loudon, there were 18 lead changes in the Spring race, but only 10 lead changes in the Fall race, so you get a bar going down of magnitude (18-10=) 8. Surprisingly, For all races except Texas, there were the same or MORE lead changes in the Spring race.

BSPEED_ChasePlayoffFormat_2014

This, of course, led me to wondering. Could it be that perhaps drivers were being less aggressive during the Chase? So I looked at tracks with two races but neither one of them in The Chase. I added them (and made the graph 3D because it looks cooler that way). The last five races (the ones on the right) are non-Chase races.

BSPEED_ChasePlayoffFormat_SFALL

 

So regardless of the race being in or out of the Chase, the first race at a track routinely (with one exception) has an average of seven more lead changes than their latter-season counterpart races. The only difference (and it’s very minor) is that there are an average of 4.75 fewer lead changes Fall vs. Spring in Chase races and an average of 10.4 fewer lead changes in non-chase races.

Finally, I thought it might be helpful to look at the same data for the year before, where we didn’t have the playoff format.

BSPEED_ChasePlayoffFormat_2013vs2014

And it’s pretty much the same story. There are fewer lead changes in fall races than spring races in 2013 as well.  Recall that the races where cuts were made were Dover, Talladega and Phoenix, and there’s no big standouts there either.

So if you want to quantify racing quality by lead changes, you can’t really make a case that the new format led to more aggressive or better quality racing to any great extent.

I looked at a couple of other parameters as well. I tallied up the number of accidents in each race, counting true accidents as well as spins, but not debris, competition or drunk-people-sitting-on-catchfence cautions. I then compared those Spring vs. Fall. In chase races, there was an average of one more accident in the Fall than the Spring and in non-chase races, there was an average of just about one more accident in the Spring than the Fall. Over the course of the season it average to just about zero, but remember that these are very small numbers of races, so you can’t read too much into the statistics. There would have to be some overwhelming difference in numbers to be convincing.

Next up – looking at Driver Finishes to see if they’re driving more or less aggressively.

Nov 072014
 

Flared side skirts became an issue when social media started noticing them somewhere around Kansas. The fact that the most obvious example of this was on the 2 car and Brad Keselowski is rapidly taking over from Kyle Busch as most-love-to-hate driver in NASCAR may have brought the issue to the fore faster.

The side skirts (or ‘vertical extension panels’) help seal the bottom of the car to the track. This picture, of the 2013 Toyota Camry, shows the clearest example of the side skirt because you can see the line where the side skirt joins onto the side of the body. The cutout is for the jack – if there were no pit stops, there’d be no reason for the cutout. The side skirts help funnel the air that does get under the car smoothly out, and they keep air from coming on on the sides.

2013_Camry_Side

Side skirts are made of a durable rigid plastic — except for one spot on the right side of the car near the tail pipe area. The rationale for this is that exhaust pipes get very hot. Although plastics are indeed the material of the future, plastics that are really, really heat resistant also tend to be expensive and harder to work with.

The plastic from which the side skirts are made is pretty rigid. You can cut it and bend it a little, but you really can’t monkey with it too much.  Except for that metal part, near the right rear wheel.  You know… this part:

NASCAR_2014_FlaredSideSkirts

Flaring out the right rear of the side skirt started out being done by a couple of teams and now you can find most all of the teams doing it.  So now for the burning questions.

Is it illegal?

Nope. NASCAR hasn’t fined or taken points from anyone for doing it.

Is it happening accidentally?

A lot of internet pundits initially claimed that this was the result of hard racing, no ride-height rule, and drivers racing on the apron, where the possibility of banging the car on the track is maximum. But not when it’s happening to so many cars and happening every week.

And then video appeared that showed jackmen pulling out the skirt during pit stops – right in front of the NASCAR officials overseeing the pitstop.  So no, it’s not happening by accident.

Is it really an advantage?

There have been a number of times in the garage where a team started doing something goofy just to see how many other teams would copy them. There are some cases I know about where teams made a modification they’d seen other teams make without understanding it — but they also had their engineers figuring out whether it was doing anything. If one of the backmarker teams had started doing this, I doubt anyone else would have noticed, unless that team all-of-a-sudden improved.

NASCAR does have a history of allowing something and then cracking down on it when it becomes too blatant, so the first teams doing this knew they might get their hand slapped.

The argument people have made is that it changes the balance of aerodynamic force. you’re providing a couple more square inches for air molecules to slam into. In this case, I doubt there’s much of an effect down the straightaway (especially with the rear-end skew), but it probably does help a little in the corners.

It certainly isn’t hurting the cars, or teams wouldn’t be doing it.

Why are they only doing it on the right? If it increases downforce, wouldn’t you do it on both sides?

They can’t do it on the left. The left-side skirt is entirely plastic and you can’t bend it. Plus, the issue here is really in helping the car turn, so you wouldn’t want to make the same change on both sides.

Should NASCAR prohibit it?

BenHur

First, let’s note that this has been going on for much longer than most people realize.  Like most things in NASCAR, it starts with one team sticking their nose out a little (or their skirt out a little) and escalates until it’s a big enough effect that those of us sitting at home notice.

It’s not like NASCAR hasn’t been aware of what’s going on.

The main reason I can see for NASCAR stepping in is that a sharp piece of metal sticking out at wheel height has the potential to turn Phoenix and Homestead into the Roman Colosseum.

Not that anyone would purposely try to cut someone’s tire down, but it makes bumpin’ and bangin’ a very different proposition.

Here’s the problem. It’s going to be tough to police. And I don’t say that just because Jeff Burton said it and he’s almost always right. It is possible for the skirt to get bent and banged by (for example) a tire being pulled off at an angle, or contact on the track.

The NASCAR pit officials can’t see everything. Their primary job during pit stops is to make sure the wheels aren’t going to come off again. Do you want them to take their eyes off the tires so they can check what the jackman is doing? Maybe with the electronic pit officiating coming next year, that will be possible.  Not this year.

NASCAR’s Sprint Cup Series Director Richard Buck told popularspeed.com

“I will say the garage is comfortable with how we’re managing it right now.  It’s the same for everyone. That’s how we try to manage everything — that it’s the same for the big teams as it is for the little teams.”

NASCAR has done a really good job not knee-jerk reacting to things. They tend to wait and see how things evolve. When they threaten to get out of hand, NASCAR makes a rule. This happened with the skewed-out rear ends a few years ago. It got to a certain point and then it got silly.  The cars couldn’t even get up on the rails for tech. When NASCAR made the rule, it had all the details – how much they would allow, how it would be measured.

I wouldn’t be surprised if they do something next year, but don’t expect anything to happen in the next two races – unless there’s a catastrophic accident that can be linked back to the flared side skirts.

And on a chemical note…

I always tried, as a teacher, to find analogies to help my students understand scientific concepts.  For example, my mental picture of “potential energy” is of a cat about to pounce or a sprinter on the blocks the second before the gun starts the race. You can see the energy ready to go in the tensed up muscles and once they move, you can see the kinetic energy (energy of motion).

Last Sunday at Texas, I got another one.

A catalyst is a chemical that initiates or speeds up a chemical reaction, without taking part in said reaction itself. All I need is a good video from Texas to make my point now.

That, or chemists everywhere should start referring to catalysis as “Harvicking”.

 

 

 

 

Oct 172014
 

Every year at this time, we hear that Talladega is a wild card because “Anyone can win”.  Which, of course, made me wonder — can anyone win?

Who Wins Races?

Let’s start by looking at who wins races in general. I analyzed the last three years and everything we have so far for this year and put it in a table. Why a table? Because tables help you see your way through all the numbers.  What I was interested in was trying to find a correlation between who wins and how “good” a driver they are, as determined by how high they finish in the standings at the end of the year.

The number in each box is the percent of all wins run by drivers in the top 5, top 10, top 15, top 20 and the Chase.  Note that I discarded some situations, like Brian Vickers, who won a race in 2013, but sat out much of the season due to illness and finished 78th in points. Same thing for Hamlin and Stewart, neither of whom ran all the races that year, but won a race.

Note that the new rule – that anyone who wins is automatically in the top 16 is going to invalidate this type of an analysis in the future because someone who would’ve finished lower in points gets boosted up by the win.

Year T5 T10 T15 T20 Chase
2011 44.4 63.9 83.3 91.7 77.8
2012 48.6 88.6 94.3 100 88.6
2013 61.8 70.6 91.2 94.1 85.3
2014 35.5 71.0 96.8 100 100

Here’s a gratuitously colorful graph of the same data, just for Moody:

BSPEED_PercentWinsByFinishingStatus

The take-away message:  It is very unusual for a driver who ends the season outside the top 15 to win a race. In fact, for the last three years, more than 70% of the races are won by the top ten drivers. (And I don’t know about the goofy perspective Excel uses in those graphs.  It makes it look like the numbers for 2013 and 2014 are less than 70% – but they’re not. I promise.)

But What About Talladega?

If Talladega really is an ‘equal opportunity racetrack’ in terms of winning, then the stats ought to look very different over the years. I analyzed Talladega races all the way back to 1990, which is almost 50 races. You know what? It’s not that different from the average.

Year T5 T10 T15 T20 Chase
2011 44.4 63.9 83.3 91.7 77.8
2012 48.6 88.6 94.3 100 88.6
2013 61.8 70.6 91.2 94.1 85.3
2014 35.5 71.0 96.8 100.0 100.0
Talladega 44.7 72.3 91.5 95.8

The stats are almost identical relative to every other race track out there. Out of the 47 races I included, only two were won by drivers outside the top twenty.

Jamie McMurray – 2009 Fall (22)

David Ragan – 2013 – Spring (28)

I omitted the Spring race in 2009 because the driver (some guy named Brad Keselowski (?)) only finished in 38th place – but only ran 15 out of the 36 races. So if you’re currently running below 20th place, you’ve got less than a 5% chance of winning.

Even the year Michael Waltrip – the patron saint of teams hoping for an upset at a plate track – won, he finished 15th.

Wait a Minute… That Can’t Be Right

We all remember David Ragan winning Talladega and Daytona and Trevor Bayne winning the Daytona 500.  Is it true that if you’re not in the top 15 and you’re going to win, it’s likely going to happen at a plate track?  Let’s look at the exceptions.

Year Driver Finishing Rank Track
2013 Martin Truex, Jr. 16 Sonoma
2013 David Ragan 28 Talladega
2012 Joey Logano 17 Pocono
2012 Marco Ambrose 18 Watkins Glen
2011 Trevor Bayne 53 Daytona
2010 Regan Smith 26 Darlington
2010 Paul Menard 17 Indy
2010 Marcos Ambrose 19 Watkins Glen

This year Aric Almirola won Daytona, and I’ve left that out because we don’t know where anyone is finishing yet. He could be 15th or better still.

But even if you counted him, not even half of the “upsets” take place at restrictor plate tracks.

But I swear I remember all these times…

I gotta tell you. I sweated this one out. I have looked at Dega Data for two straight days because I knew there had to be something interesting in there.

And I finally found it – but it runs counter to all my intuition. This is one of those things scientists have to be very, very careful about – not letting our expectations get in the way of reality. If you expect to see something, you’re more likely to see it.

So why does everyone think anyone can win Talladega?

It’s not at all surprising – it’s called the von Restorff or isolation effect. It’s named after a woman named Hedwig von Restorff (1906-1962), a psychiatrist and children’s doctor who conducted a set of memory experiments and found that an isolated dissimilar item surrounded by otherwise similar items would be better remembered.  In other words, it basically says that when something stands out as being very unusual, we tend to remember it.  For example, consider two lists

A B
9 TCE
21 GTS
3 JWN
16 PDY
QXK QXK
5 RWV
13 MTX
8 LEB
54 DVQ
3 PYN

The same three-letter sequence is in both lists. If I showed you the lists, then took them away and asked you what you remembered, you’d remember the letters better if I’d given you the A list than if I’d given you the B-list.  We tend to remember the unusual. And there’s a reverse effect, in that you may actually remember less about the things that don’t stand out.

Now if only I could wipe Michael Waltrip’s last dance (and 70’s mustache) out of my memory.

Oct 032014
 

@NASCARRealTime, @TheOrangeCone and @CircleTrackNerd had an interesting dialog when the 2015 rules were announced. They were debating whether the track records that are now standing are going to be essentially locked into history. The debate ended with an appeal to me and Goody’s Headache Powder. TwitterConvo_TrackRecords

When the Gen-6 car was introduced in 2013, new track speed records were established at 19 of 32 qualifying sessions. Yes, that’s more tracks than we run, but the record at Martinsville, for example, was broken in the spring and again in the fall. Another way to look at it is that out of 20 tracks where there was an opportunity to break a track record (meaning we exclude Dega and Daytona because their records are pre-restrictor plate, plus rainouts) – it happened at 16 places.

Why? The primary change was the much lighter car – they took 150 lbs off relative to the Gen-5 car while maintaining the same engine power and increasing downforce.

That changes in 2015, as one of the new rules NASCAR announced is a 1.170″ tapered spacer that will reduce power by about 125 hp. Gene Stefanyshyn (senior vice president of innovation and racing development for NASCAR) expects this is only going to decrease speeds by no more than 3-4 mph in most instances.

That seems like a weird trade off, right? 125 hp = 3-4 mph? Well, that’s because the engine isn’t the only place they’re making changes. They’re going to decrease the spoiler size to six inches, which will take away about 300 lbs of downforce, but will also reduce the drag on the car.

Here’s the theory: racing on ovals is won and lost in the corners. The primary impact of horsepower (all other things held equal) is determining maximum straightaway speed. In the corners, you’re not (except for plate tracks) using all the horsepower you have – you’re more limited by your lateral grip, which is determined by downforce.

Any driver can mash the gas coming down the frontstretch. What makes a difference is how soon they get off the gas/onto the brakes coming into the corner and how soon they get onto the throttle coming out of the corner. Let’s say you have to slow to 180mph to make a corner. It makes a difference when you start braking if you’re going 210 mph vs. going 200 mph.

You may actually be able to take the corner faster if you aren’t slowing the car down quite so much. A number of the drivers and NASCAR officials have stated that slowing down the cars a little (and remember, we’re talking 3-4 mph) should give drivers more options in the corners and thus make for more exciting racing.

But What About the Records?

Yes. A lot of records were broken in 2013. But a number of those records have been broken this year. The overall trend of pole qualifying times is up. Even when a rules change or a track change decreases the qualifying time, the next year, it starts creeping back up. I plotted qualifying times for a couple tracks to show this. Everyone’s been talking about these records being broken as if the speeds were stuck and then suddenly they jumped up. Not at all.

TrackPoleSpeeds_Charlotte2

So here’s Charlotte.  There are year-to-year oscillations, but the overall qualifying times have ben nothing but increasing.  On average, over the last twenty years, they’ve increased by about 0.7 mph each year.  So let’s assume that speeds are down across the board by 3 mph. In four or five years, they will likely be right back where they were before. You see a big jump in the slope of the curve (how fast it’s getting larger) from Gen 1 to Gen 2, but after Gen 2, it’s been pretty consistent.

I put each of the car generations on the graph to see how much difference changing car models actually made, but the track condition also makes a huge difference. Let’s blow up the last twenty years.

TrackPoleSpeeds_CharlotteRecent2

So there was a big jump after the 1994 repave. Then remember 2005 when we all learned a new word: levigation? They diamond ground the track, which made it very rough. Pole speeds jumped and the fall race that year was an unmitigated disaster, with tires blowing left and right. They did a formal repave in 2006.

And if you really want to see what a different track surfaces make, take a look at Kansas.

TrackPoleSpeeds_Kansas

After the re-pave, the pole speed jumped from 176 mph to 191 mph. There’s almost no history to rely on, but the following year, the fall speed was 4.3 mph slower than the spring speed.

In addition to major changes in the track, you get year-to-year oscillations due to things like weather and the tires Goodyear provides. One of the goals for the new set up is to allow Goodyear to make grippier tires that wear out faster, which could have a big impact on qualifying and (more importantly) racing.

So are the track records safe?  Probably for a couple of years.  But I’m not betting for much beyond that. The guys designing the race cars are just too clever to let little things like rules keep them down. The impressive thing is going to be if they figure out how to make the cars faster while also making the engines more reliable and longer lasting.

A final note. In the end, we judge drivers on race wins and championships. Poles may help you win a race, but I guarantee you if you give a driver a choice between a win and a pole, they’re going to choose the win.

Aug 222014
 

TurbulentSmokeA persistent motorsports issue (and not only with stock cars) is the aerodynamic passing problem. You can’t pass without grip. Grip is a direct result of downforce. Downforce comes from two places: the weight of the car (mechanical grip) and the billions and billions of air molecules hitting the car (a.k.a aerogrip).

Racecars are designed to take advantage of aerodynamic downforce. Everything from their shape to the aerodynamic appendages added to the car are all optimized to produce downforce. You can play around with mechanical grip some by adjusting the weight on each corner of the car and trying to control how the weight changes as the car turns, brakes and accelerates. Aerodynamic grip is even more subtle.

And complicated.

Aerodynamicists think about fluid flow (fluid meaning liquid or gas) in terms of two extremes. Laminar flow is when the air (or water) moves predictably over a surface in nice, uniform sheets with relatively little variation from sheet to sheet.  In the diagram below explaining how a wing works (an airplane wing; turn your computer upside down if you want to see how a car wing works) the air is represented by nice, neat lines that very politely crowd each other as they work their way around the wing. Changes in pressure and velocity happen gradually.LaminarFlowOveraWing

The other extreme is turbulence – when the air (or water) flows in swirls that are not at all well behaved.  Turbulence is chaotic – large differences in pressure and velocity that change quickly. Turbulence is very difficult to describe mathematically because it’s just so darn complicated.

It’s easier to see experimentally. Pour some cream into your morning coffee and stir it with the back of your spoon. The spoon moves the cream out of the way, creating a gap. The cream swirls around the back of the spoon and fills the gap, forming a lovely swirling pattern.  You can see the same thing in the wake of boat – the water flows back in to fill the gap the front of the boat made. Smoke rising from a cigarette is turbulent as it mixes with the air.  Breaking waves are turbulent.

In turbulent flow, the air molecules end up going in all different directions.  If you’ve ever driven very close to the back of a semi on the expressway, you’ll feel your car buffeted from different directions – that’s the turbulence.

Laminar and turbulent flow are both evident in the aerodynamics of racecars. The front of the car is smooth and sloped.  The cross section of the car (what you’d get if you took a slide of the car perpendicular to the direction the car’s traveling) gets larger and larger as you get further from the front fascia. The car keeps pushing a bigger and bigger hole in the air.

Things change when you reach the B-post.  Now the car needs to push away less air because it’s sloping down. Its cross section is getting smaller. The air starts swirling in around the rear window, becoming turbulent. The wake of a racecar is similar to the wake of a boat. The water’s going in all directions, trying to fill the hole made by the front part of the boat.

A technique called computational fluid dynamics lets engineers visualize the airflow. The diagram here is from Ford Racing and shows the turbulence on the 2013 Ford Fusion.  This visualization shows you where there are big changes in the airflow.  You can see the giant wake behind the car. It’s strongest the closest to the rear of the car, but note that the wake extends almost two car lengths behind the car.

2013_FordFusion_CFDTopandSide

If you want to learn more about Ford’s CFD calculations and the role they play in designing racecars, check out their YouTube video – it’s worth a gander.

The wake creates drag on your car and slows it down just a little, but as the driver of said car, it’s not really a big concern. For the guy running behind me, however, my wake is a really big problem. Laminar air makes downforce. Turbulent air doesn’t.

And that’s the origin of the passing problem. A fast car catches up with the car ahead of it. As the trailing car research the leading car’s back end, the turbulence from the wake of the first car makes the flow over the front of the trailing car turbulent, which means the trailing car loses downforce or becomes ‘aeroloose’. And you can see from the CFD calculation that you don’t have to get so close for aeropush to become a problem.

Right after the Michigan race last week, NASCAR ran a big test (10 teams) to try out some options for possible rules changes for the 2015 season.  In case you think this is a simple problem to solve, they had two approaches: more downforce and less downforce.

On the increase downforce side, the first change was to a bigger splitter – nine inches tall.  The problem with increasing the splitter is that it unbalances the car. One of they key principles in racing is that you can only go as fast as your least grippy tire. Grip is proportional to downforce.  If you increase the rear downforce without making a commensurate change in the front downforce, you get a really tight car.  Lots of grip in the back, but the front tire – the ones that turn the car – don’t have enough grip.

Increasing the front splitter has its own challenges, so NASCAR turned to dive planes. Dive planes have been used for a long time on sports cars. They’re simply small, curved pieces of metal or carbon fiber composite. NASCAR used two dive planes – one above the other – and put one set on each side of the car.  The dive planes started at the front fascia and swoop upward, ending at the front fender. The pictures below are from the twitter feeds of @nateryan (top) and @2spotter (Joey Meier, bottom).
divePlane_NateRyan

DivePlane_Joey

The principle behind the dive plane is that it takes the turbulent air coming onto the front of the car and funnels it to make the flow more laminar.  More laminar flow should translate to more downforce.

NASCAR made the point that the dive planes may not be part of the final rules package; however, having the dive planes allowed them another little benefit – they could put pressure sensors on the dive planes and measure how the downforce changed for the different configurations.

The ‘prime rules package’ that was tested consisted of the larger spoiler, a lower rear differential gear, and decreased horsepower.  They tested 850hp, 800 hp and 750hp.  The second test package was actually a lower downforce package, in which they went with a smaller spoiler and they removed an underbody piece that had been new this year.  The estimate is that these changes decreased the overall downforce by 28-30%.

And (of course) the drivers were not very enthusiastic about the prime rules package. They liked the lower downforce better. Reporting from the track suggested that the prime rules package gave rise to in-line racing, while the lower downforce package got drivers really excited about possibilities for passing.

Unfortunately, there’s no time for another test because NASCAR really needs to have the 2015 rules finalized pretty darn quick so the teams have time to prepare for next season.  Right now, a bunch of NASCAR engineers are sitting back at the R&D Center, trying to make sense of the gigabytes of data they collected during the test. I’m sort of glad I’m not the one who has to make this decision!!

I didn’t mention one of the big changes in this blog post – the ability for the driver to modify the trackbar position from inside the car, but I will comment on that in the near future.

Jul 252014
 

One of my favorite memories from Nebraska was coming home from the I-80 Speedway  covered in a dusting of red clay. (Planting in that clay was another question entirely.) But there’s something about dirt tracks you just don’t get at the asphalt ones.

It’s great that NASCAR is bringing a little of that spirit to the Truck Series.  Wednesday’s Mudsummer Classic race at Eldora Speedway was a great show. A dirt track challenges drivers and their crew chiefs who are mostly used to asphalt and an occasional foray into concrete.  A lot changes when you trade surfaces: Set ups, driving approaches, pit strategy and, perhaps most significantly, tires.

Some people made a lot of noise about Goodyear and their ability to produce a tire that would stand up to dirt-track racing, but Goodyear has a long history of equipping cars for the dirt. The tire they developed for NASCAR’s first foray into dirt in 40 years (in 2013) was based on rhwie standard 10-inch wide dirt modified tire. They started testing with that tire with Tony Stewart and the Dillon brothers (that sounds like a gang from the Wild West, doesn’t it?)  at Eldora back in October 2012.   They modified the tire based on that test, making it a wider (11 inches) to help with grip. Trucks, being on the order of a thousand pounds heavier than a typical modified, require greater force to turn.

In addition to the individual tire construction, Goodyear also provided some built-in stagger.  Put a red Solo cup on its side and give it a push. It automatically rolls in a circle because the drinking end has a larger circumference (distance around) than the bottom. The same strategy is used for race vehicles that only turn one direction.  At the 2013 race (I’ve been unable to find the specs for this year), the left-side tires had a circumference of 85.8 inches compared to 88.5 inches on the right.  Teams got four sets of tires for the event.

Goodyear_Wrangler_G23DirtTireRegardless of whether they were left- or right-side tires, the tires used at Eldora have two primary differences compared to the standard truck tire used at the other races.

The first is that dirt-track tires have treads. The Goodyear Wranglers employed for the Eldora race use the G23 tread pattern (shown at left). The treads serve the same purpose they serve on rain tires – they provide a path for loose dirt to move out of the way so that the rubber can grip the track. The edges of the blocks provide bite. The tread compound used is a softer compound, which again improves grip on the dirt surface.

The second difference is that the tires used at Eldora are bias-ply tires, not the radial tires that are standard in NASCAR.  Let’s back up a little and remember a little tire anatomy 101.  The diagram at right is from the Michelin website (the people who led the way in popularizing radial tires way back, just a little after WWII).

Tire_Anatomy_new

The part we’re interested in for the sake of this discussion is the plies.  Plies are a type of fabric made up of layers of rigid cords embedded in rubber. The body plies run from the outer bead to the inner bead. The reinforcing fibers (cords) have been made from materials like cotton, rayon, polyester, steel, fiberglass and aramids like Kevlar.

If you ask Goodyear which materials they use in their race tires, they will neither confirm or deny any particular material or combination of materials they use — which should give you an idea how important the cords are in terms of giving the tire desirable properties..

tirecords_wikipediaIf everything works the way it should, you will never see tire cords. When a driver hears during a race that the tires that were just removed had cord showing, they know there’s either a problem with the setup or with their driving. The cords are there for strength and stability. A tire’s grip comes from the tread – not the cords.

The plies have directionality, depending on how cords are arranged.  They are usually parallel to each other – it you look carefully at the picture to the left, you can see the rows of cording.  Whether a tire is radial or bias-ply depends on the way the cords point.

The first tires appeared in the mid-1800s and were simple pieces of solid rubber. They provided a bumpy, uncomfortable ride. The pneumatic tire was introduced in the mid 1800’s, but a tire made soley of rubber didn’t last very long, nor allow you to go very fast. Tires needed to be stronger and more resistant to road hazards. The idea of using cords in tire plies to increase strength was introduced in the early 1900s. A number of plies was used – two to four was common – to reinforce the rubber in the tread.w

The first tires were bias ply tires, which literally means that the cords in different plies were oriented in alternating directions running between 35-60 degrees with respect to the bead, which increases the strength of the tire, as shown in the diagram below, at right.

radialvsbiasply

In a radial tire, the cords go straight across the tire, as shown in the left picture. The cords are 90 degrees with respect to the direction you’re going. The radial tire was patented in 1915 and, as I mentioned earlier, Michelin really pushed the development of the radial tire starting in 1946.  Radial tires didn’t offer as smooth a ride as bias-ply tires; however, the gasoline crisis of the 1970’s made people value their improved gas mileage (which happens because they have less friction.) Almost all passenger car tires at this point are radials.  Because the radial cords go in one direction, the tire isn’t as strong, which is why radial tires have an additional belt package. Belts made of steel, polyester or Kevlar-type polymers are inserted over the plies and under the tread. Those belts greatly increase the strength of the tire..

Bias-ply tires create more friction and thus more heat and more wear.  A bias ply tire is inherently round, which means that the contact patch is smaller. Extra rubber has to be built up at the shoulders to provide a flat surface. Importantly, the sidewall and the tread on a bias-ply tire are one piece, which means that they move in concert with each other.  As a result, a bias-ply tire will give more in a turn because of the lateral force. The separate belt package in the radial separates the sidewall (the plies) from the tread (the belts) so the sidewall can flex, leaving the tread to hug the ground. Bias ply tires give more and allow better grip on an irregular surface like dirt. Radials would make the racing a lot harder — and not just for the drivers who don’t have much prior experience on dirt!

Many lower level series, as well as weekend racers, use bias-ply tires for another very important reason: they’re (in general) cheaper than radial race tires. This doesn’t mean they’re cheap, but it does help cut costs a little, which means more money to put toward going faster.

 

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