Thermography: A New Weapon in the NASCAR Arsenal

What’s Wrong With this Cow?

Can you tell?

If you said the cow is the wrong color, you’re close. But there’s more to the story.

And What’s That Got to Do with NASCAR?

Competition in NASCAR is getting tighter and tighter. As NASCAR’s ramped up penalties for rulebook violations and started encumbering wins, teams are looking for other ways to gain an advantage. Some are trying ‘big data’: gathering every bit of statistical data they can about different races and trying to find patterns that will allow them to predict the best course of action in a given circumstance. Some have instituted detailed inventory programs that track how long every part on the car has been used.

Others are just looking for a new way to ‘see’ things.

What and How We ‘See’

But the way most people thing of ‘seeing’ is very limited. Human eyes are engineered to detect a very narrow range of electromagnetic radiation. We don’t call it electromagnetic radiation: We just call it light.

 

What we see as white light is made up of light of all different colors. You can see this by passing light through a prism. Red light is refracted less than the violet light, so the colors separate.

 

They behave differently because different colors of light have different wavelengths; Red light has a bigger wavelength than violet light. Violet light is around 400 nanometers in wavelength. (A nanometer is a millionth of a meter). Red light is around 700 nanometers in wavelength.

You might be thinking ‘wow – I can see light from 400 nanometers to 700 nanometers. That’s pretty impressive.

Actually, it’s not because electromagnetic radiation comes in a huge, huge range of wavelengths.

A note about the graph below.

Each tick mark is a factor of 10. So the wavelength of electromagnetic radiation we know about goes from 0.001 nanometers (gamma rays) all the way up to 1,000,000,000,000,000 nanometers (which is 1,000,000 meters or 1,000 kilometers).

The microwaves in your oven have a wavelength of about 12 centimeters. That’s absolutely HUGE compared to visible light, which is why you can’t see microwaves.

X-rays, on the other hand, range from a hundredth to 10 nanometers. This is so much smaller than visible light that we can’t see them, either.

In fact, we don’t see much of the world with our eyes.

But, being resourceful humans, we figured out how to ‘see’ using other wavelengths.

We developed radar (which has wavelengths in the centimeter range) to detect incoming airplanes long before they were visible to the eye.

We use radio wave telescopes for astronomy.

We use ultraviolet waves at crime scenes to detect blood and urine. And other things.

The Magic of Infrared

Infrared radiation is just to the right of the visible spectrum on the diagram above. “Infra” mean larger than; infrared radiation has a larger wavelength than red light: from about 800 nanometers to 1000 nanometers (which is 1 millimeter).

We can’t see infrared radiation with our eyes, but we feel it as heat. About half the energy the Sun puts out arrives not as visible light, but as heat.

You and I emit infrared radiation. In fact, that’s how the found the Boston Marathon bombers: they detected their heat signatures.

Anything hot emits infrared radiation. And therein lies the utility. Even a plane invisible to radar is emitting heat.

The first thermographic cameras were developed for military use. They use semiconductors, which are sensitive to infrared radiation wavelengths. At first, these cameras were very noisy. They had to be cooled to liquid nitrogen temperatures (or lower) to work with any precision and the pictures were still very blurry.

We improved the semiconductors and got them to the point where they didn’t have to be cooled to work well. By the 1990s, the cost had come down to the point where they were affordable and compact enough for non-military uses.

In fact, you can buy an attachment for your phone to turn it into an infrared camera for a couple hundred dollars.

Depending on how much money you have to spend, you can get cameras with much higher quality, frame rates and precision. FLIR is the leading player in the market and, in fact, even sponsored Jamie McMurray a couple years ago.

How Thermography is Useful for Motorsports

An infrared camera is a great toy, but motorsports has found a lot of uses that might give the smart team a big advantage on track.

IMPORTANT: The colors you see on thermographic images are all made up. Basically, the sensors detect the wavelength of the light (which is invisible to our eyes) and assign a color scale to the temperatures to make it easier for humans to interpret the date. This is done in warm colors, but there’s no reason you couldn’t do it in blues or greens.

Finding the Best Line

Last week in New Hampshire, one of the television commentators finally mentioned that teams are using infrared imaging to try to help their drivers determine the best line. How do you do that? Take a look at the video below, which shows the heat trail from cars on an expressway in Germany.

Notice how the pavement heats up after the car passes? Imagine how the pavement heats up when there are 40 stock cars passing over it almost continuously. Thermography tells you the track temperature.  You can see the trail of the tires in the pavement during the burnout in the video above.

This is especially useful at a track like New Hampshire, which treated the asphalt surface with VHT before the race. Teams have a lot of questions about VHT, especially about how it wears. It seems to last for a very long time at some tracks, and wears off in the middle of the race at others. We know that track temperature is a Goldilocks thing: it can’t be too cool and it can’t be to hot. By using a thermal imaging camera, a team can tell which areas of the track are getting too hot, or which areas might be too cold.

If you listen into a scanner and hear a crew chief or spotter telling a driver to ‘try taking the lower line’, but they don’t say it’s because another car is having success there, chance are someone has been studying the track with an IR camera and thinks they’ve found a good line in terms of track temperature.

Repaving

One of the critical factors that determines whether a piece of asphalt is going to retain its integrity is the temperature of the mix as it’s being lain down. A number of companies are now using infrared imaging to ensure that there aren’t hot or cool spots as the asphalt is being laid that could later turn out to be problem areas. This is being done on commercial roads, and being heavily used for testing of new asphalt mixtures.

The picture at right shows you the false color scale. You can see that they’ve used cool colors for the low temperature and red for the warmest temperature. The cool area in the middle suggests that there may be air gaps or some other inhomogeneity that could cause problems later.

Oil Spills

NASCAR itself has been using IR imaging for a few years now to spot things on the track. Track temperature is often around 130 degrees F; the oil inside a car is much hotter, so when a car dumps oil on the track, you might not be able to tell with your eyes, but an infrared camera will see it. The more sensitive the camera, the better it works because oil will cool as it spreads across the track. A cheap camera might not be able to distinguish between the oil spill and the track. (FLIR is also using their cameras to detect oil spills in water, too, as a way of monitoring and helping clean up if there is an oil spill.)

Tires

Take a look at how, in real time, the tires on this F1 car change temperature during cornering.

Right now in NASCAR, teams use a temperature probe to measure the tire temperature in three or four spots after they’ve been removed from the car. There’s nothing in the rules that would prohibit them from just taking infrared pictures of the tires. That might not be useful data during the race, but it could be analyzed afterward.

Brake Rotors

One of the big challenges at places like Bristol and Martinsville is the huge amount of heat generated by the brakes. The friction of brake pad on rotor creates a lot of thermal energy. A high-speed infrared camera (and when we’re talking high-speed, now we’re starting to get up into the $$$$ range) can capture brake temperatures while the car is on track.

IR imaging is already being used by brake pad and rotor manufacturers to test their new designs. You could imagine NASCAR teams using a tool like this during development to study how slight changes in the cooling duct arrangement affect brake rotor temperatures, or to compare different combinations of pads and rotors.

The Future of IR Imaging in NASCAR

It’s only going to get bigger. You’re talking less than $10K for a decent IR imager and maybe $40,000 for a really nice, high-speed “science-level” InSb sensor camera. That’s small potatoes for a top-level NASCAR team. Engine development companies are also using this technology to study combustion details and heat management in the engine system. Cooling efficiencies in the radiator and the oil lines can be studied with infrared imaging.

I can also imagine the slap-happy engineering staff finding some, uh… less car-related uses for the equipment.

Wait! What About the Cow?

I almost forgot.

Veterinarians use thermal imaging of animals because they can learn something from the thermal signature of an animal. Just like you and me, animals get hot when they’re not feeling well. In this case, the telltale sign in that the cow’s hoofs are warm. They shouldn’t be. What you’re looking at is a potentially sick cow.

Don’t laugh. When you’ve got a large herd of animals, disease can travel quickly, so identifying potentially ailing members of the herd quickly and getting them treatment is critical.

Plus, there are currently test programs to use thermal imaging at airports when there’s an outbreak of a disease like Ebola. The earliest sign of infection is a fever, so thermal imaging could be used to identify people who might warrant further testing.

 

 

Composite Race Car Bodies

You Never Forget Your First One

My first car was a greenish-brown 1969 Buick LeSabre with a 123-inch wheel base and a 230-horsepower two-barrel V-8. That puppy weighed about 4200 lbs and taught me everything I know about Bondo and car repair. My parents got me that car because it was a tank. They figured, with that much steel, I would be safe from just about anything.

Back in the day, we equated the weight and bulk of steel with safety, but that’s not the case now. When you’re talking vehicles, weight means money because (as Newton taught us) you need more fuel to accelerate a bigger mass. The search was on for materials that were just as strong as steel, but lighter– like aluminum alloys, . Because those materials cost more, they’re used mostly in aerospace, where weight is much more critical than in cars. As the cost has decreased, we’re starting to see them in high-end cars and eventually they’ll be standard in the cars us normal people drive.

One of the big digs against NASCAR is that they’re stuck in the past, using old materials and old methods. Last week’s XFINITY race in Richmond was a step toward the future as NASCAR debuted its first composite body in its big three series.

Lower-level series like K&N and ARCA are already using composite bodies made by Twin Lakes, Wisconsin firm Five-Star Race Car Bodies. They were approved for tracks one mile and less in ARCA in 2015, for all tracks except superspeedways for the 2016 series. They’ve been testing the bodies at superspeedways and, in fact, have a test scheduled for November 7-8 at Talladega in anticipation of making them mandatory at all tracks for the 2018 season.

NASCAR has made composite bodies optional for XFINITY races at Richmond, Dover and Phoenix this year, optional at all tracks except superspeedways in 2018 and everyone expects NASCAR will make composite bodies mandatory at all tracks in 2019. I’ll have something to say about ‘optional’ later on.

What’s a Composite?

“Composite” is short for composition material, which is a material made from two (or more) materials with significantly different physical or chemical properties. When combined, the composite materials has properties that are significantly different from either material alone.

“But wait,” you say. “How’s that different than an alloy?” Alloys, like the different types of steel used now in NASCAR race car bodies, are atomic-level mixtures of different atoms. Composites are more of a macro-scale mixture, where each component retains its identity, but they must work together to be more than the sum of their parts.

Although composites can be made of more than two materials, we’re going to stick with two for the purposes of simplicity. Composites, then, are made up of a matrix and a reinforcement. The matrix is a material (like mud or cement or asphalt (for example), which has some desirable properties, but not quite desirable enough. We add to that a reinforcement that improves the properties of the matrix.

My favorite example is reinforced concrete (at right), where strong, ductile rebar (reinforcement) is used to improve the properties of the concrete matrix, which is relatively weak and brittle. You have to make sure there’s a good connection between the rebar and the concrete or the two don’t work as a single unit. Composites aren’t new and they aren’t all human-made.

The key, remember, is that you have to get a material with different (and hopefully better) properties that either material on its own. For example, bricks made of mud are not very strong, plus they crack because they don’t dry evenly. Some smart person figured out that if you add straw to the mix, the straw binds the mud together and also helps the bricks dry more evenly, so they don’t crack. Adobe is an incredibly durable building material for being, basically, dirt and straw. You can see from the table that we’ve been using composites in NASCAR for a very long time.

 

 

Given how many different types of matrices and binders there are, there are multiple types of composites, some of which are illustrated below.

Cement and asphalt are particle-type composites. We’re going to be interested in a variation on the fiber-based composites. When you’re talking about large pieces that will have to take force from different directions, you weave fibers (for example, carbon or kevlar or a combination) into a fabric.

You then mix the fabric with an epoxy resin that holds it all together. The key is to get really good connections between the fibers and the epoxy, so usually the process requires high temperatures, high pressures, or both. We’ve talked about this before when we’ve talked about the splitter, which is also a composite.

The photo below shows 100 sheets of (in this case) polypropylene oxide woven fabric put together. The top surface is what you get when you put those sheets together using heat and pressure. Any composite is made similarly: you start with a floppy fabric and you end up with a strong, rigid piece. Carbon fiber composites, increasingly used for seats and dashboards, are made the same way.

What is a Composite Laminate?

All the articles about the bodies use the phrase “composite laminate”, which is the terminology Five-Star uses on their website and promotional materials.

Remember when you were writing an essay in school about something and you didn’t actually understand it all, so you wrote down some words from your notes or the book verbatim without knowing what they mean? When the mainstream NASCAR press covers tech-y topics, you can always tell when they’re repeating what they were told: the same string of words keeps popping up. (hello “flange fit”! )

Here’s the issue: Carbon fiber has a very specific look. You see the fabric in the finished product. Carbon fiber is also very brittle: When it fails, you tend to get shards of material littering the track. Apparently, one of the reasons Apple hasn’t used a lot of carbon fiber to replace aluminum is that they don’t like the look. So a couple years ago, they filed a patent to sandwich (which is a fancy word for ‘laminate’ carbon fiber between other materials so that you get the benefits of carbon fiber without having to see it. The drawing below is from their patent application.

In the left figure, all of the first 7 sheets are carbon fiber. You’ll not that they alternate the weave direction, so that the composite material is strong in all directions. The last layer, however, is drawn differently. That’s the cosmetic layer, which is a different material. It gets bonded to the outside, so that’s what you end up seeing, not the seven (or however many) layers of carbon fiber.

 

 

My guess is that this is what Five-Star has done, in part because it gives you a smoother, nicer surface to work with and in part for security reasons (which we’ll get to in a moment).  it’s a combination of different materials. xSo I suspect they’ve put some other type of material on the top to give it a good smooth finish for painting or wrapping. Apparently Apple was delaying using carbon fiber in its cases because they didn’t like the way carbon fiber composites look, so they came up with a way to essentially make a sandwich with fiberglass on the outsides so that you didn’t see the carbon fiber layers.

But Why Composites? Why Now?

Metal has had an advantage in being readily available, easy to work with, and cheap. Usually, when we talk about advanced materials, we’re usually talking about how NASCAR bans them. In this case, though, it makes sense.

Cost

Composites are typically seen in high-end products (cars, aerospace, golf clubs, bike frames, etc.) because composites are more expensive than other materials.

What makes the difference for NASCAR is labor and logistics. The new bodies have 13 panels that snap together and bolt onto the chassis. (That’s what ‘flange fit’ means: you bolt them on.) Even if a team purchased the comparable steel pieces pre-made, they would have to rivet and weld to get them put together and onto the car. NASCAR says this move decreases the time to hang a body from weeks to days. More importantly, if you do damage the body, you can change out just the body part that’s been damaged.

If your driver wrecks in qualifying or practice, you’ll be able to fix the body right there at the track, something you can’t do now. This is especially important for the West Coast swing, where taking a car back to Charlotte is very expensive. (Of course, if your driver hits hard enough to mess up the chassis, you’re still stuck.) It will be interesting, however, to see how inspection goes the first time someone has to replace a body part without all the stuff at the shop like surface plates and jigs.

Theoretically, teams should be able to have fewer people hanging bodies because it goes much faster – which likely means fewer jobs.

The panels are extremely uniform. If you get five side panels, they’re going to be the same shape and same weight. Anytime you have reproducibility on that level, life becomes easier.

Weight

Composites have a much larger strength-to-weight ratio than metals. If you compare a 1/2″ thick, 1 square foot piece of steel with a 1/2″ thick, 1 square foot piece of composite, the steel will be stronger — but also much heavier. You can replace that steel with a piece of composite much thinner, thus getting the same strength for less weight.

The new bodies are 150 lbs less than the current steel bodies. NASCAR is using that feature to encourage teams to switch because they don’t have to make up that weight with ballast. While using the new body is optional, running steel puts you at a pretty big weight disadvantage. If that’s not enough, NASCAR’s won’t let you use a radiator pan to help air pass more quickly under the car if you stay with the steel body. That’s why 90% of the teams used the composite body at Richmond: It was faster. The teams that didn’t are mostly lower-funded teams that didn’t have the capacity to implement a new body as quickly.

Compliance

NASCAR says that the teams are all for the new bodies, but this is a true win-win. NASCAR’s had big issues policing the garage this year, with growing consternation over encumbered wins and rising calls for taking away wins if the winning car hasn’t followed the rules. It just looks bad. The new body greatly decreases opportunities for the teams to mess around with the car. No bondo is allowed, not even to close up the cracks where the panels meet. No sanding is allowed. The panels are rigid up to 200+ mph, which means no flexing at speed, not matter how much you switch around the bracing.

The composite panels are also rigid when standing still, which means a pit crew member “accidentally” bumping into the side of the car to adjust the aerodynamics is just going to end up sore. The panel won’t budge.

To make sure teams aren’t testing the limits of The Aerodynamic Box, NASCAR put some security features on the body. The pic below (as well as the full body one above) are from a NESN source.

Note the hexagonal pattern covering the aerodynamically sensitive area of this part. The pattern, which is found on the quarter panels and A-, B- and C-posts, is raised, so it shows through a wrap or paint. (In fact, that’s a condition of passing inspection. If the officials can’t see the pattern, you fail.) If an official sees that the pattern is distorted in any way, they’ll know they need to look more closely.

I like this approach because it’s simple. It gives you a first-level screen that doesn’t require lasers and such.

Why, you might ask, does everyone in racing use hexagons so much? If you watch the NBCSN graphics, they use a hexagonal pattern — as did Fox Sports 1. Hexagons are associated with carbon, which is so prevalent in advanced composites. Carbon forms a couple different crystal structures, but one of the most interesting is when it forms sheets. This phase is called graphite. Graphite is good for pencils  lead because the stacks of sheets don’t have strong bonding between them, so they flake off and leave themselves on the page.