Is There Really a Second-Place Curse?

 Clint Bowyer, Dale Earnhardt Jr., Denny Hamlin, Edwards Carl, Jeff Gordon, Jimmie Johnson, Kasey Kahne, Keselowski Brad, Kyle Busch, Mark Martin, Martin Truex Jr, math, Tony Stewart  No Responses »
Dec 072012
 

One of the commentators after the final race in Homestead mentioned that Jimmie Johnson should be happy he finished in third because it allows him to avoid the “dreaded second-place curse”.
Anytime someone says something like that, it makes me wonder whether there really is a curse, or whether that person had just been talking to Carl Edwards.  So I analyzed a little data and guess what… there really IS a second place curse.

I used data from the last twelve years — from racing-reference.info, bless them!  After trying a couple of different approaches to making the data easy to visualize, I ended up with something a little more complicated than I would have liked.

Bear with me – it’s not as yucky as it looks.  I have plotted on the horizontal axis the place in which a driver finished in the first year listed, which we’ll call “X”.  I then calculated the change in positions of the same driver the next year (X+1) and plotted that on the vertical scale.  So the first set of data has X = 2000 and X+1=2001.

  • A positive number on the vertical axis means that the driver finished better by that many places in the following year. For example, +5 means that the driver finished five places better the next year than they finished the year before.
  • A negative number on the vertical axis means they finished worse the next year. A -5 means they moved down five spots in the final standings.

I went through and removed any special cases — like Mark Martin running full time one year, but not the next, Busch brothers missing races (that’s a different kinds of curse), people retiring, etc.  The graph below summarizes the top 16 finishing places and the change in final standing over the last twelve years.

There’s an obvious statistical implication:  If you finish second, for example, you have only one place to move up and forty one places to move down.  You’re either going to win the championship next year, become second again, or move down.  The probability is that you’re going to finish worse than second.

To look at the data in a slightly different way, I plotted it the same way they plot the daily activity of the the stock market:  the symbol shows you the average.  One line extends up to the maximum increase in position and one line extends down to the largest drop in position.

 

The first-place curse

In fact, if we’re going to call dropping in the standings a “curse”, then there is clearly a first-place curse that affects everyone except Jimmie Johnson.  Mose drivers who win the championship one year inevitably finish worse the next year.  When I say ‘drop in points’, it’s not a huge drop:  nine places was the most anyone who finished first dropped.

The average first time finisher fell almost five positions.  That’s including four consecutive ’0′s due to Jimmie Johnson.  If we exclude Jimmie just because what he did was really unprecedented (and unlikely to be duplicated), the average first-place finisher falls almost seven positions the next year – about the the same as the second-place driver.

The second-place curse

Second place shows a very similar story, only worse.  There is only one case in twelve years in which the second place finisher one year won the championship the next year.  That was Jimmie Johnson.  Whoops – Rick pointed out my mistake.  It was 2001 -2o02 and the driver was Tony Stewart!  On average (including Jimmie), the second place finisher finishes about seven positions lower the next year.

The three biggest drops in point standings (-15, -13, -11, -9 and -7) are due to Martin, Edwards, Biffle, Edwards and Hamlin.  There are no extenuating circumstances like crew chief changes, owner changes, etc. on which to blame the drops.  Four out of five of those drivers were all driving for Roush at the time… maybe there’s a Roush curse?

The bad news for Jimmie Johnson… and everyone else who made the chase

Here’s the bad news for Jimmie:  Yes, he avoided the second-place curse; however, no third-place driver has gone on to finish first or second the next year.  The best they’ve done was to match their third-place finish.

Yep, perhaps there’s a third-place curse as well, as third-place drivers finish an average of three places lower the following year.

In fact, you don’t find a finishing position in which there is an average probability of bettering your finish until 7th place.  On the graph above, you can see that the majority of finishes were improvements, although without one -11 change, it would be a much more positive number.  After that, it’s an oscillation between slightly better and slightly worse.

A caveat of this data analysis is that the Chase sort of messed things up going out past 10 because a driver in the Chase can’t finish lower than 10th, even if he misses races or otherwise would have fallen much lower without the Chase format.

 

Dover: Why Concrete Races Differently than Asphalt

 Asphalt, Bristol Motor Speedway, Dover International Speedway, Mark Martin, Martinsville, Materials, Tracks  6 Responses »
Sep 282012
 

One of the questions you’ll hear drivers and crew chiefs asked a lot this weekend at Dover is how the concrete track affects the racing.  Here’s how:

Asphalt vs. Concrete

Concrete and asphalt are father and son.  They have in common what you and would call it “rocks”, but professionals call it “aggregate”.  Aggregate comes in a huge variety of types, depending on the materials from which the rocks are made, the quality of the material, the size of the rocks and the distribution of sizes of the rocks.

Concrete is an technically any mixture of rocks aggregate stuck together with a binder.  The type of binder determines the properties of the concrete and even the color.

Concrete is the oldest engineered construction material, dating back to the Roman Empire.   The reason only parts of the Roman Colosseum and the Pantheon are missing have more to do with humans than the failure of the materials.  Today’s concrete is more than ten times stronger than the version the Romans developed.

The most common binder in the concrete used in roads, parking lots and sidewalks is Portland cement.  Portland cement (and its close relatives) are mixtures of  limestone and clay, which are crushed to a powder and heated to over 2700 degrees Fahrenheit.  This is the form you buy it in.  To use is, you reconstitute the dry powder with water, and the individual grains form calcium-silicate-hydrate (C-S-H) bonds that make a very strong glue.

Asphalt is a type of concrete, that uses bitumen — tarry black stuff — to hold it all together.   A typical composition for asphalt is 80% aggregate, 15% binder and 5% air voids.  Bitumen comes from the heaviest components of crude oil, and has the consistency of molasses (which is why it has to be heated before being used).   Because bitumen derives from oil, the price of asphalt changes with the price of oil.

 

But Which is Better?

As with most “which is better”, the answer depends on what you what to use it for.  The primary difference between asphalt and concrete is the rigidity of the two materials and how they distribute the load over the base on which they are laid.   The more rigid the pavement, the more the load is distributed over the surface when something like a car move over it.

Asphalt, which is more flexible (relative to concrete), transmits higher, more concentrated loads to the base, as shown below.  I’ve drawn the stress distributions in red.  The concrete spreads out the stress over a larger area, while the asphalt transmits stress to a narrows area.  The narrower area and the same load means that the stress is more concentrated.

Because concrete is stronger, asphalt has to be thicker to get the same rigidity.  Asphalt does have an advantage, however, in that its flexibility allows it to expand and contract with temperature changes with less cracking.  Even so, concrete lasts 10-15 years longer than asphalt.

Asphalt is the traditional material for paved racing surfaces.  Only three Sprint Cup tracks feature concrete:  Dover, Martinsville and Bristol.  They have in common that they are all tracks of one mile or less with significant banking.  (OK – you may not view the 12 degree banking at Martinsville as ‘significant’, but those 12 degrees are the reason the corners are concrete while the rest of the track is asphalt.  The stress on the pavement in the corners necessitated replacing the original asphalt with concrete.)

Dover is one mile with 24-degree banking and Bristol is a little more than a half mile with 24-28 degree banking.  The steep banking and the tight curves make keeping asphalt in good racing condition a challenge.  Having concrete also gives a track a unique character – as well as the opportunity to have a really cool monster statue outside.

How Concrete Changes Racing

 

Grip Level

The grip level can be very different between asphalt and concrete, depending on a lot of factors.   Concrete is inherently more grainy, and its surface can be patterned to create more grip.  Drivers talk about bumps in asphalt as being large and wavy, while bumps in concrete they describe as  more vibrational.  Concrete usually has to be laid down in sections, which means you can have those bumps like you find between slabs on a sidewalk.  The picture at left shows the Google Earth view of Dover’s surface and you can see the individual slabs.

The grip on an asphalt  track depends  on the type of aggregate used, the degree of wear and the character of the bitumen.

For example, Atlanta has a very rough surface because its bitumen wears faster than the aggregate, as I’ve shown at right.   When an asphalt track is first laid down, the surface is very level.  As the bitumen wears away, the tops of the uppermost layer of aggregate are exposed.  The sharp edges of the aggregate are worn down by the tires rubbing against the rocks, but the aggregate sticking out provides a lot of grip.  Eventually, enough bitumen wears away that the aggregate starts coming out, which weakens how well the track holds together and necessitates a re-pave.

Concrete doesn’t wear as fast as asphalt and thus the grip level doesn’t change as much over long periods of time.

Light and Heat

Would you believe that the color of the track makes a big difference in how the track races?

Light comes in a range of wavelengths from smaller than billionths of a meter to larger than billions of meters long.  Our eyes detect a very, very small fraction of that electromagnetic radiation in the nanometer (billionth of a meter) range.  From red to violet, the wavelength ranges from about 800 nanometers to 400 nanometers.  The light from the Sun contains a wide range of wavelengths, including ultraviolet light (UV) (which is smaller wavelength than visibile light), all the colors of the rainbow, and lots of infrared  (IR) radiation.

Our eyes don’t detect the UV or IR light – we see the mixture of all the different colors of light together, which makes white.  Artificial light (like fluorescent) generates a different mixture of wavelengths, which is why it looks different than sunlight.

You see the colors of objects because all materials absorb some wavelengths (colors) of light and reflect others.  When light hits a red object, as I’ve shown at left, all colors except red are absorbed and what comes to your eyes is just the red light.

White surfaces reflect a wide spectrum of wavelengths and absorb very little of the spectrum.  The light that is incident on a white surface is reflected back to our eyes and the broad spectrum of wavelengths we see as ‘white’.  Black is the opposite:  black absorbs a lot of different wavelengths, so very little reflects back to our eyes and we get black.

 

In addition to the visible light, the spectrum from the sun includes the aforementioned ultraviolet  and infrared waves.  Infrared radiation has longer wavelengths than red light.  We don’t see it – we sense it as heat.  You’ll notice that the lamps they use to keep food warm always have a red glow:  they output some visible light, but they mostly output heat .  You will never see food being kept warm by blue light.

How is all this relevant to a racecar?

Put a piece of black paper and a piece of white paper in the Sun and feel their surfaces after a few hours.   The black paper absorbs a lot of the radiation from the Sun and gets very warm.  The white paper doesn’t absorb as much of the Sun’s energy (although it does absorb some), so it stays relatively cooler.  If you measure the temperature of a track over the course of a race, it can change by tens of degrees depending on the weather.

One effect of the changing temperature is how hot the tires get.  If the track is 60 degrees vs. 120 degrees Fahrenheit, that generates a very noticeable level of change in the grip.  But even more importantly, bitumen (the binder in asphalt) is a petroleum product.  As the temperature rises, oils in the bitumen get warmer and make the track more slippery.   Portland cement is crushed-up rocks which (when dry) are not slippery at all.

The end result is that, a concrete track doesn’t change over the course of a race nearly as much as an asphalt track.  Crew chiefs say that the track at Dover is easier to ‘keep up with’ because changes in temperature over the course of the race don’t change the racing surface as much with concrete as they do with asphalt tracks.

The Nature of Friction

There are two types of friction .  The first, called abrasive friction, is the one you learned about in school.  This is the type of friction between sandpaper on a wood block.  The second kind (which I never know about until I wrote The Physics of NASCAR) is adhesive friction, which is the molecular-level stickiness of the track combining with the molecular-level stickiness of the tires.  The heat generated by the tires makes the topmost layer of the track gooey.  The outermost layer of the tire also becomes gooey, resulting in an effect very much like chewing gum stuck on your shoe on a hot sidewalk.  The gooeyness of the track  bonds with the gooeyness of the tires for microseconds and resists forward motion.  That’s grip.

The nature of adhesive friction on asphalt is very different than on concrete because the two materials are so very different.  Concrete has much less adhesive friction.  This doesn’t change the grip level so much (because the abrasive frictions are different) – however, it does make a big difference in what happens when you lose grip. Think about sticking a weight to a piece of wood with gum.  The asphalt surface would be really sticky gum and the concrete surface would be dried up, not-very-sticky gum.  If you turn the wood so that the surface is vertical, the stickier gum is going to hold better.

In terms of a racecar, Mark Martin pointed out:

“… when you lose grip on a concrete surface, you feel like you just got cut loose from a rope. It’s amazing. It’s like losing half of your grip, rather than about 20 or 30 percent that you lose on asphalt.”

All the drivers’ intuitions that are developed on asphalt – which comprise the vast majority of NASCAR tracks – are thus challenged when they drive on concrete.

So there you have it – not necessarily better or worse, just different.

For those of you who have noticed the blog has been quiet the last two weeks, it’s because my older cat, Chaos, was very ill and finally passed away last Sunday. She was my race-watching buddy, although I have to admit that she usually fell asleep somewhere around lap 25 and woke up just in time to see the last 30 laps or so.

I miss her all the time, but I will especially miss her on raceday when she liked to compete with my computer for lap space.

Inforgraphic: Hendrick Motorsports – 200 Wins by Driver

 Brian Vickers, Darrell Waltrip, Geoff Bodine, Jeff Gordon, Jerry Nadeau, Jimmie Johnson, Joe Nemechek, Ken Schrader, Mark Martin, Rick Hendrick, Ricky Rudd, Tim Richmond, Uncategorized  3 Responses »
May 162012
 

Statistics Presented Without Comment

 

 

Source:  http://racing-reference.info/owner/Rick_Hendrick

Phoenix: Relay Race?

 Electronic Fuel Injection, Engines, Fuel Mileage, Mark Martin, Rodney Childers, Tony Stewart  1 Response »
Mar 062012
 

The race at Phoenix was the first non-restrictor-plate race.  A number of drivers experienced engine-related problems, leading some media outlets to start blowing the “EFI problems” horns as loudly as possible.  Mark Martin, the pole sitter, was an unfortunate casualties of a “flipped circuit breaker”.  One of the most interesting exchanges to me was a series of tweets and a radio interview with Mark Martin’s Crew Chief Rodney Childers (@rchilders55) in which Childers repeatedly said it not “an EFI problem”, the radio commentators persisted in saying that it was.

Here’s his verbatim tweets (and if you’re not following him on twitter, please do!)

Man I hate that!! We had a breaker POP on our ECU for the fuel injection about half way. Which makes it switch to a safety fuel map.

It popped about half way.. it didn’t affect the performance. Just the Mpg, which made us have to pit. But we are really happy..

That made our mileage go from 4.2 to 3.8… And no way we could have made it. Good job to mark and all the Aarons guys though.

The EFI deal isn’t really the issue.. probably a wiring issue that we have to figure out. We had the same deal happen in practice.

Each car has a relay box, which acts sort of like Mission Control.  I’ve said before that the ECU (Engine Control Unit) is the brain of the EFI system.  The ECU collects information from a number of sensors located in different places on the car that measure things like humidity, pressure, temperature, and air-fuel ratio.  The ECU makes decisions on what to do next based on the information it gets from the sensors, and it acts on those plans by sending messages to the rest of the car through the relay box.

What happens if one of the sensors stops working (or a wire breaks and the sensor, even though it works, can’t send information)?  If the ECU believed the data it was being given, it would have a rather warped view of reality and could start telling the car to do all types of goofy things, including some that could actually damage the engine beyond repair.

The EFI system is smart – smart enough to know when it is getting suspicious data.  Instead of acting on that data, a relay is triggered and the ECU changes over to an alternate engine map (what Childers called a ‘safety fuel map’).  The alternate map isn’t optimized for performance – it’s purpose is to allow you to keep running, but your performance won’t be as good as you would have with the information from the sensor and the optimized engine maps.   As an analogy:  You eat more efficiently when your eyes are open.  If someone blindfolded you, you could still eat, but it wouldn’t be as efficient (or clean) as with your eyes open.  This relay system protects the engine from the actions of a confused ECU.  You might not run as well, but you also might not destroy a whole engine.
The relays work on the basis of a voltage threshold.  They’re like an electron bouncer.   A relay has a maximum current or voltage it will tolerate.  Bob Pockrass reports these relays have limits at 5V and 100 mA.   If an electrical signal comes through with a higher voltage (or current, depending on the type of relay), the relay switches everything to an alternative circuit.  Unlike the circuit breakers in a house (which are normally on/off, in contrast to these, which are circuit 1/circuit 2), it’s very difficult to re-set the relays.  It’s not like there’s a switch that the driver or a crew member can reach down and flip back.  When they flip, you’re pretty much stuck with them for the rest of the race.
Teams will be looking for anything that might cause the relay to flip.  That could be a wire that vibrated loose, or an electrical spike (like, say, the spike you get when you turn a switch on or off perhaps…?)  I understand some teams are switching to boxes without relays – but then you take a chance that something gets out of whack and you blow up your engine entirely.  One of the real pains in the neck with a short or a transient spike is that they can be hard to reproduce.  You can do the same thing 10 times and the problem may only happen one time out of those ten.  Makes for some long nights for the engine shops.
Childers tweeted that the mileage dropped from 4.2 mpg to 3.8 mpg – that’s just about a 10% drop in efficiency.  Phoenix is a one mile track, which means that the change in fuel mileage cost them nine laps per tank of fuel.  When teams are scrapping for one-percent increases, a 10% decrease is just going to kill you.
Keep in mind that we’re in uncharted territory.  NASCAR teams are subjecting these systems to environments they haven’t seen before.  I expected a few problems like this at Phoenix and I expect a few more in Las Vegas.  Teams will figure out how to make their system withstand the high-vibration/high-temperature world under the hood of a race car and drivers will gradually learn which of their techniques still work with the new system and which ones they’re going to have to change.
And if you’re wondering exactly what an engine map is, I’ve got a video going up on Friday to explain it.