Friday, July 3, 2009

Sun, Sand and HORSE POWER = Daytona

1956 and Big Bill (France) started planning the BIG Track, and oh, what a time it was.

In 1956 we (the US of A) were on a roll, we’d won the war (the BIG one, WW II), we made more steel, cars, airplanes, TV’s, telephones, movies, radios, OIL, and just about every thing else than any other country in the world. And, we’d just launched the world’s first nuclear submarine.
The 1953 Buick Road Master—the name alone, Road Master, symbolized the era; at two and a half tons with a huge V-8 engine and an ultra smooth hydro-slush transmission it made a Greyhound bus seem like a nimble sporty drive by comparison. The car was so heavy and the ride was so smooth you could run over a concrete mixer and not notice it. We couldn’t make cars big enough, and we didn’t grasp the idea that there were limits to much of anything.
We had gasoline price wars, where filling stations would lower the price of gasoline to lure customers. In 1956, when Big Bill was planning the Big Track, during a price war in Cedar Rapids, Iowa, I filled up my ’47 Ford with gasoline, and took my date to Dairy Queen for malts, all on $2.35; gasoline was $0.09 a gallon.
And if gasoline was inexpensive, nuclear power was going to make electricity so cheap it wouldn’t pay the utilities to even meter it; in fact, we started designing nuclear powered everything: including cars.
The Daytona International Speedway mascot drawing is of a Ford Nucleon concept car circa 1956, and that thing which looks like a glorified spare tire cover on the back is actually the vent for a nuclear reactor. If you thought Ford had a problem with Pinto gas tanks, imagine a few million cars running around each with an unregulated nuclear reactor in the trunk. To understand the USA in the 1950’s you must realize that at the time we thought this was a good idea. A friend of mine worked at Westinghouse Nuclear, the company that built the reactor for the Nautilus, the first nuclear sub, they really were working on designing nuclear powered cars, trucks and trains. We were totally convinced that technology could solve all of our problems; we’d move to Florida or California and go surfing at least four days a week. Surfers were the icon of a carefree life; and the seemingly unlimited power of a nuclear engine symbolized our belief that we could run roughshod over everyone and everything. The term “ugly American” wasn't entirely undeserved.
As big and outlandish as the Daytona International Speedway now seems, and totally over whelmed by technology, it was a perfectly reasonable idea in 1956.
Build a track where race cars could go as fast as the engineers could invent motors to propel them, and the drivers had the nerve to keep their foot down. Same track length as the Indy 500 (2.5 miles per lap), but with two sweeping turns, and banked as steeply as could be paved with the technology of the day (31 degrees). If you’ve visited Charlotte, Atlanta and/or Texas, the tracks at 1.5 miles per lap seem incredibly huge, but they’re dwarfed by Daytona.

Talk about contrasts: from last week at New Hampshire a 1 mile track, and nearly flat (2 to 7 degree banking) to Daytona, 2.5 miles and about as steep as a mixing bowl (31 degrees). It is as far around the perimeter of Lake Lloyd in the Daytona infield as it is around the New Hampshire track.
And Daytona was indeed off to the races: faster and faster every year, until 1970, when NASCAR realized things (in fact the engineers and engine builders) were getting out of hand.
Detroit was producing engines with more than 400 cubic inch displacements, some were approaching 500, and at 195 mph the race cars were not staying on the ground. Old adage in engineering: given enough power you can make a lead brick fly.

Bobby Isaac won the NASCAR Cup Championship in 1970 and earned less than I did as a junior project engineer in a not very big steel company. A “well funded” NASCAR team had a sponsor, as in ONE, and a car, as in ONE. Isaac’s car still had windshield wipers on it, these were stock cars, even if Smokey Yunick did make a seven-eighths scale Chevy one year; sure had a lot less drag than everyone else had.

After a couple years of experimenting, NASCAR settled on the 358 cubic inch rule for engines in 1974, and there it has remained for 35 years.
Daytona International Speedway is completely out of the park in terms of size and banking (only other track in this league is Talladega); it dwarfs even the Michigan track, DIS is simply off the charts.
In 1956 no one thought the engineers could ever build a car fast enough that a driver would have to lift off the throttle, or that the cars would need to be limited in speed so as to not have them hurtling into the grandstands.

There's a "neutral" speed for a car on any turn of a banked oval track, the speed at which there is no side force on the car, neither up-hill or down, the rides around the turn only being pushed down squarely on all four tires.
The centripetal force tending to make the car slide uphill to the outside of the turn is just equal to the down-hill force (the pull of gravity) that is would make the car slide into the infield. Bigger tracks with a larger radius at any given banking angle allow for higher speeds. This graph illustrates the effect of turn radius on neutral speed as a function of banking angle.

Even at 31 degree banking the neutral speed at Daytona is less than 100 mph. At any speed faster than the neutral speed, the tire friction must hold the car and prevent it from sliding up-hill and off the track, or into the outside wall. If the tire-track coefficient of friction is 0.8 then one can calculate the maximum speed a car can go around any turn, if you know the radius and the banking.

The coefficient of friction is approximately the ratio of the force required to pull a car sideways divided by the weight of the car.

Coefficient of friction ordinarily varies between 0 and 1; good, new clean tires on a smooth asphalt highway and a passenger car tire might have a coefficient of friction of 0.6, on wet, smooth ice the coefficient of friction is less than 0.05, nearly 0. Hot, new, race tires on smooth asphalt may be 0.8 or 0.9.

The graph illustrates that the maximum sustainable speed through the turns at Daytona are on the order of 200 mph with optimal tire traction, somewhat above the speeds now encountered with restrictor plates. But as the tires wear and friction decreases (lower friction values in the graph) the cars are capable of going at the very limit of the tires, and beyond, which is where the driver skill part of the equation comes into play.
Adhesion of the car to the track is improved by adding down force, in the form of aerodynamics, the shape of the car and its attitude (pitch of the car, nose down), which acts to push down on the car.

An airplane wing is designed to lift the craft off the ground, race cars are intended to be inverted airplanes where the aerodynamic shape is intended to add down force to the car and push it down and increase the load on the wheels—making the tires stick better to the track.

The keys to running well at Daytona can be distilled down to two elements: (1) the right set-up so that all four tires work almost equally, thus minimizing the rate at which the tire adhesion decays with laps.

How far down the purple line, at 31 degree banking, does your car degrade as the laps build up? The car with the best combination of springs, shocks and sway bar will have the best tires and the driver can maneuver the car where they want, following the draft at will.

(2) The second key element for Dayton is "The draft," several cars in line have less drag than the same number of cars running individually.

To a large extent the closer the cars are together the better, aerodynamically at least; up to the point where they touch and then it’s not such a great idea.

With restrictor plates limiting the power and hence speed of the cars, the aerodynamic down-force on the cars is actually secondary to the banking of the track. In order to keep the cars on the ground and out of the grandstands it is necessary to reduce or limit the power, consequently speed, that can now be produced by a 358 cubic inch engine, albeit an archaic design at that.
By 1970 the engineers and engine builders had trumped the concept of big high banked track designs, just eleven years after the first race at Daytona. A 358 cubic inch engine is equal to 5.87 liters, nearly twice what is allowed in F1 (3.0 liters) and yet the F1 cars go faster because they develop nearly twice the power of a NASCAR Cup engine. But F1 cars have a huge down-force from their wings, more than three times the weight of the car, compared to a down-force of less than one-fourth the weight of a NACSCAR Cup racer. With NASCAR Cup cars in their current configuration, DIS is a dinosaur: run over by technology.

We’re not going back to 1956 in any sense of the word.

Can NASCAR re-invent racing, and make tracks such as Daytona and Talladega relevant again?

Thursday, June 25, 2009

Land of the Damn Yankees

NASCAR racing in its essential form has been preserved in New Hampshire, ironically in the land of the damn Yankees.
In early colonial times New York City was called New Amsterdam because it was owned by the Dutch, but it was a hotly contested area with the British.
The derisive Dutch term for Englishmen of the day was “John Cheese,”—due to their affinity for the food of the same name— the intended slur if pronounced with a Dutch accent sounds like “yan kees,” that became "Yankees." New England colonists of the British persuasion actually liked the term and adopted it.
The mascot for New Hampshire International Speedway is the "Quarter Minute Man," the pit crew that can at the drop of a yellow flag consistently turn fifteen second, one quarter of a minute, pit stops all day.
There are several “Minute Man” statues, but the pit crew “Quarter minute man” is patterned after the statue by Daniel Chester French (the real Minute Man is on display at Concord, MA, not New Hampshire, but it’s only 40 miles from NHIS)—French is better known for his statue of Lincoln which resides in the Memorial in Washington DC.

New Hampshire is yet another 1960’s track, originally built as Bryar Speedway, a sports car road course replete with a lake in the middle of it. Too bad the lake’s been filled in, as it would make for an interesting challenge; if you are speeding leaving pit road you could end up in the lake. A new sign would have to be added inside the cars: “In case of a water landing your seat cushion may be used as a flotation device.”

Rebuilt in 1989 by a new owner and changed into an oval which incorporates one turn of the old track, New Hampshire is among the slowest (average speed) tracks on the NASCAR Cup circuit; Dover and Rockingham (before it was cut from the schedule) also 1 mile tracks, are both much faster.
However, New Hampshire preserves the essence of racing: finding the elusive optimal combination of driver, set-up, engineering (gear ratio in particular), and racing smarts. This track is oval racing at its finest, purest form. And it is due to the geometry of the track.

New Hampshire is among the flattest (2 to 7 degree progressive banking) of the 1 mile tracks and it also has the smallest turn radius, hence the lowest record qualifying speed (Phoenix, also a 1 mile track is much steeper —11 degree banking—and also has a larger radius turns, hence, qualifying speeds are about 2 mph faster than at New Hampshire). The relatively long drag race straights make up, to some extent, for the tight, flat turns.
To understand New Hampshire it is necessary to look at the detail of the corners.
Due to the laws of physics it is actually rather easy to predict fastest qualifying speed based on the geometry of a race track. If Michigan is big and steep compared to a general trend line of track designs, then New Hampshire is way off the trend line in the other direction--way, way off the trend line: small radius turns and flat.

An index that describes a track by a combination of size (distance around one lap) and banking angle is a good indication of maximum average speed a racecar obtain. There are a couple of notable exceptions, Pocono being much slower than the track geometry would suggest (because it is three different turns defying all attempts to optimize a car set-up for all three). The other is New Hampshire, also much slower than the geometry of overall track length would suggest. Physics of turning, described in the previous graph on banking and turn radius explain this outcome.

Since next week is back to Daytona, juxtaposed to New Hampshire, it illustrates the extreme contrasts in track design philosophy. New Hampshire speeds, from its road course antecedents, are limited by technology: adhesion of the tires to the track, requiring that the driver slow down for the turns thus lap times are a mixture of driver, machine, and engineering.
Daytona, like Indy, was designed with the idea of having a track where race car drivers could just wind it up and blow it out, no limit other than engine building and driver nerve: run wide freakin’ open the whole way around the track. In the fifty years between designing Indy (1908) and Daytona (1958) it was necessary to increase the banking of the track dramatically in order to run wide open.

Somehow, track developers don’t seem to bother looking at trend lines which are a consequence of engineering and technology. Engineers are forever trying to find a way to improve things, in the case of race cars, go faster, more reliably, using less and less fuel. It should have been evident from looking at the trend of qualifying speeds at the Indy 500.

The sudden jump in qualifying speeds in 1971 and onward can be explained in a single word: aerodynamics, and wings in particular. From this point forward the essential problem with racing is going to be to limit racing speeds to keep the cars out of the grandstands.

The problem of going fast, with a reliable machine had been solved; and it overwhelmed all then extant track designs.

In just a year more than a decade of racing Daytona was faced with the same problem, slowing the cars down in the interest of safety: for both drivers and spectators. The first attempt at this was to limit engine size, but NASCAR doesn’t seem to understand how engineers think and this was simply a delay not a change.

The engineers quickly found ways of increasing power even in a reduced engine block (the 358 cubic inch displacement rule still in place today). Finally, in 1988 restrictor plates were introduced and now cars are limited by a rules committee; engineering and driving have been marginalized.

Engineering and technology overwhelmed the track design,...20 years ago.

But real racing lives on, go to New Hampshire and see it; on the way there stop in Philadelphia, Boston, and Concord (both of them) and walk the trail of American history, it’s a fascinating tour.

And look for other Daniel Chester French (1850-1931) statues along the way, he was the preeminent sculptor of the day.

Wednesday, June 24, 2009

Driving Mr. Kahne

It was uphill the whole race.
Road Trip …to Sonoma and back (Part 2)
Hopefully everyone watching the race noted that Kasey cemented his race win on the restarts, pulling ahead of the 14 car going uphill through turns 2 to 4; there’s a reason why that worked, and he did it in California where you are your car.
The automobile, specifically American iron from the Detroit Big Three, was the quintessential icon of the USA at its uncontested zenith, the two decades from 1950 to 1970. And California was the epicenter of the car era.
In the 1960’s new state of the art road courses were built at Riverside, and Sears Point (Sonoma). But acting as a true bellwether for the direction that our country was headed, Riverside Raceway closed in the 1980’s and is now the site of a shopping center.
When the streets were ruled by American iron and the heart of every youngster captivated by Annette and Frankie, we all longed to be in California; trouble is too many of us actually went there.

The mascot for Sonoma, Infineon Raceway, should be the
Indy-NASCAR-American LeMans Series woodie, with a motorcycle tied to the back of it.
In the '60's racing was still the test ground of the automotive industry with series such as CAN-AM which allowed almost anything with 4 wheels and an internal combustion engine to be raced, resulting in some truly ingenious machines (unfortunately, some fatally dangerous ones, too). Going fast for long distances was still a technical challenge and the machinery had not yet overwhelmed the track designs. Road racing was the consummate test of driver, machine and technology, a few laps of racing was more informative than months or even years of running production cars at street legal speeds.
In the 1960’s Henry Ford II (Henry’s son) wanted to include one more jewel in the company crown, a testament to the most successful car brand in history, to own Ferrari and dominate racing. Enzo Ferrari didn’t just say “no,” he said “hell, no,” in such an unpleasant manner that a rebuffed Ford II returned to Detroit still stinging from his rude rejection and ordered the Ford engineers to bury Ferrari at their most prestigious event: the 24 Hours of LeMans.
And they did; not just winning the race, but in 1967 finishing 1—2—3, several laps ahead of the nearest Ferrari in 4th.
Road racing had originated in Europe, partly for want of real estate; land was very expensive and it was much simpler to commandeer a few city streets for a race than building a track. The idea caught on in the US, and from 1908 through 1911 the world driving championship was decided in Savannah, Georgia, on a road course that used several city streets (fascinating book for history buffs, The Savannah Races by Dr. Julian K. Quattlebaum).

Oval racing was the singular province of America, starting in the 1890’s with horses running on simple dirt tracks at just about every county fair ground in the country. Bicycle companies then took advantage of the facilities and brought touring companies of riders and board tracks (assembled over the fair ground horse track) to stage races and market their product—the first iteration of “race on Sunday, sell on Monday.”
Car companies took up the idea and oval dirt track racing (along with board tracks) became a main stay of the American scene. It quickly became evident that speed was limited by a combination of the size (radius) of the turns and the banking of the track. Because the basic physics haven’t changed, this is still evident in a plot of record qualifying speed as a function of track length (as a general rule, larger tracks have bigger radius turns).

Note that at 2.5 miles, there is a group of tracks in a vertical line with Talladega and Daytona at the top, then Indy, Pocono, Watkins Glen and Sonoma at lower qualifying speeds: it’s in the banking. Daytona is steepest at 31 degrees, then Indy at 8, Pocono with three different turns (defying all attempts at finding a set-up that is optimal for all three curves), then Watkins Glen a road course with flat corners, and slowest of all, Sonoma with flat corners and a big elevation change—160 vertical feet—equal to a 16 story building (cars can’t go up and downhill as fast as on a flat course).
Elevation changes aren’t captured well on TV and so Sonoma is not fully appreciated by a viewing audience that hasn’t visited the venue in person, or been to some other road course track has significant elevation changes (Road Atlanta, Lanier, Georgia, being an interesting example).
It is amusing to follow the racing articles and blogs that complain about “the cookie-cutter” (somewhat similar 1.5 mile) tracks on the NASCAR circuit and then deride the tracks which really are different: Pocono and the road courses.
Shifting gears while turning left and right and also racing at the same time is an integral part of every NASCAR race, on oval courses they’re called pit stops. The majority of lead changes on oval courses now occur during pit stops, so this much maligned aspect of racing has become the best way to advance your track position on every NASCAR track. Think of road racing as very long winding pit roads with no arbitrary speed limit, just the speed limit imposed by the physics of the track and car set-up.
That Kasey Kahne secured his win by being able to pull ahead of the 14 car while going uphill is a testament to engine design and gear selection: the right engineering makes winning possible every time. Lifting a 3400 lbs car a height of 160 feet requires work, a lot of it, namely 3400 lbs x 160 ft = 544,000 ft*lbs (equal to lifting a 100 lbs weight from sea level to Denver, one vertical mile). The time in which this work is done is power (work divided by time equals power). But most significantly, the work done in lifting the 9 car ahead of the 14 isn’t done at a constant speed; the cars are accelerating. This is in racing jargon the essence of “power curve” or “power band” for an engine, the rate of work done by an engine at various speeds.

The new engine in the 9 car developed with the help of Dodge engineers has a broader power band and can provide close to maximum work over a wider speed range; this is what engine builders are paid to design and calculate. The maximum or peak power, what NASCAR measures, is still the same as before, but the power band is greatly improved.
Next week, New Hampshire, will be an entirely different problem, look back at the graph of qualifying speeds as a function of track size: New Hampshire is one of the flattest (12 degree banking) of the 1 mile tracks with the smallest turn radius, hence the lowest record qualifying speed (Phoenix, also a 1 mile track is actually flatter—11 degree banking—but has a larger radius turns, hence, qualifying speeds are about 2 mph faster than at New Hampshire

Sunday, June 21, 2009

Road Trip: Driving to Sonoma (part 1)

To Sonoma and back, an American Saga

Most of the larger NASCAR teams get their Infineon Raceway road course racecars to Sonoma via Michigan in a “double,” a transporter that can haul 4 cars compared to the usual two. First leg is Charlotte to Detroit then turn left to Michigan International Speedway where the cars for MIS are dropped off while the two remaining cars destined for California continue on to the coast.
The track now known as Michigan International Speedway was dreamed up in the mid-1960’s when America was best described by the song lyric,…”we are the champions,…of the world” (written 25 years later by Queen, 1991).
Construction on the Michigan track was started in 1967, and the first race season began in October of 1968 with a USAC Indy car race. The track at Sears Point (Sonoma) was also started in 1967 and its first race was a SCCA Enduro, held on Dec. 1, 1968; twins separated at birth?
In 1967 we were the biggest, wealthiest, most powerful industrial society the world had ever seen. We produced the most, the best of nearly everything, from steel, to cars to movies, to telephones, and oil, too. In 1967 we were also one of the world’s largest oil exporters. We had it all.
The Michigan track measures a full 2 miles around one lap, and banked at 18 degrees in the turns.
Our cars in 1968 were great land yachts made of steel and iron, and there seemed to be no end to the engine size race from Detroit; comics of the day lampooned the Big Three for producing cars such as the Behemoth 11, with room for your entire football team (along with the cheerleaders), powered by the new V32 BelchFire 9000 engine (available only in Texas because you needed a private oil well to fuel the thing). It was funny because it was almost true.
The mascot for the Michigan International Speedway should be the Big Block.

The Big Block, 8 cylinders, 3072 cubic feet of displacement, made of solid American—by god—Iron.

MIS is an interesting track, 75 feet wide (equal to 5 standard Interstate lanes), huge sweeping turns and banked at 18 degrees which is steep by Indy car standards, although by NASCAR measure rather flat (Atlanta and Charlotte are 24 degrees, Daytona is 32 degrees, and Bristol is banked at 36 degrees).
There’s a trend line of banking and turn radius for the vast majority of tracks in the USA, shown here as a red fuzzy line, from Bristol to Milwaukee, nearly every track fits this pattern, with a few exceptions, Michigan being one and it is way off the trend: much steeper banking for tracks with a comparable turn radius.
As a result, the world’s record for a car on a closed course was set by a CART racecar (234 mph) on the Michigan track.
“C'mon and turn it on, wind it up, blow it out—GTO” (1966, Ronnie & the Daytonas); we were all going to California on Route 66 with the Beach Boys playing on the radio.

But 1969 was also the year of Woodstock, the hippies in Haight-Ashbury (San Francisco), and my father bought a VW beetle.
Only the morning sun rising in the west would have been more shocking, as Bob Dylan would sing, “the times are a-changing.”
Indeed, and today General Motors is bankrupt.
I grew up in a household where the idea that “what’s good for General Motors is good for the USA,” was a gospel fact; the universe revolved around Detroit and its center was built of American iron.

In 1968 the top 50 GM executives made more (including stock options) than the President of the USA, the Vice-President, the military Joint Chiefs of Staff, 9 Supreme Court Justices, 435 members of the House of Representatives, 100 Senators, and the Governors of all 50 states—combined.
The year is now 2009, not 1969, and it was great fun to watch Mark Martin win another race, but he’s fifty years old. And my personal hero for aging interestingly if not quietly, Paul Newman, drove racecars until he was in his 80’s.

The recollections, however, just made Michigan a poignant and profoundly sad weekend. The story of what America once was, and unfortunately Mark Martin is the image of racing past, not racing future.

Detroit now has half the population it did in the 1970’s; vast areas of the city look like pictures of Berlin in 1947, and the 11th largest city in the country (almost 800,000 people) doesn’t have a single brand name grocery store. Wayne County (Detroit) is the poorest county in the country, it is a veritable wasteland.
The half hearted attempt by the Detroit Three to pretend they were still in the race seemed more like a wheezing 70 year-old trying for his last hurrah by playing street hockey against a bunch of teenagers. It isn’t a pretty picture.

After Michigan it is on to California; the trip feels like the American saga as told by the NASCAR schedule, we left the cold winters of Michigan to move to the sunny west coast, allowed our essential manufacturing capability to rust away while we dreamed that we’d all build computers in Silicon Valley, write clever software, go surfing everyday and get dot-com rich. Instead we find ourselves hedge-fund screwed
America, which is to say California, in the 1960’s and ‘70’s was the zenith of the car age: TV shows such as Sunset Strip, and the movie American Graffiti captured the era with Norman Rockwell clarity and pathos. Your car defined your station in life, and your car came from Detroit.

Part 2 after the checkers wave at Infineon.

Wednesday, June 3, 2009

Doin' the Pocono Pretzel

Pocono 500
The mind bender track for crew chiefs and racecar engineers

Stroll back in history to 1971, when suddenly one day a successful, busy, wealthy Philadelphia dentist decided he’d had enough of the daily grind—seven days a week for eight years—he just packed it all in and went on holiday. The Pocono Mountains were the east coast getaway place; Dr Mattioli bought into some property for its land value and somewhat to his chagrin found himself also in the race track business. Long Pond, Pennsylvania, a little village less than 75 miles from Times Square in New York City, and less than 100 miles from Constitution Hall in downtown Philadelphia, it was a perfect market to attract the big city crowds.
What must have seemed like an incredibly clever idea: pattern your new race track after the most famous tracks in the country. Trenton Speedway, in Trenton, New Jersey, then the premier track on the east coast; the Indy 500; and the Milwaukee Mile, then the most famous track in the Midwest (less than 100 miles from Chicago). Use only proven designs and you don’t have to pay an architect to in an attempt to create something better than what was already considered the best race tracks in the world.

The Mind Bending Pocono Pretzel

Dover has Miles the Monster, Atlanta and Lowe’s have Lug Nut, Pocono needs the Pretzel, mind twistingly difficult to set-up a car for all three turns.
Opened for racing in 1974 the Pocono Speedway is unique in that it has three distinct turns, each one duplicating a turn of the most famous tracks of the day, and the track is huge: 2.5 miles for one lap, same as the distance around the Indy 500 track.

Turn 1 is the Trenton turn, 14 degree banking, radius is 500 feet a virtual copy of what was really an unusual track. The Trenton Speedway built on the grounds of the New Jersey State Fair property started automobile racing in 1900.

Trenton was a mile and a half course considered to be a 5 turn track, a kidney shape with a right hand turn in the middle of the back straight-away.

After eight decades of motorsports, the Trenton Speedway closed in 1980, and the New Jersey State Fair Grounds became the sculpture garden of an art gallery.

A drawing shows the comparison of Pocono, Trenton and Darlington.
Once around Pocono Turn 1 (the Trenton Turn) the cars race down the Long Pond straight-away (named for the stream that parallels the track) and into Turn 2, now usually called the Tunnel Turn, but its real name is the Indy turn. Again an accurate duplicate of a turn at a famous track, this one is Indianapolis. It’s a full left hand, 90 degree turn on a radius of 860 feet, with 9 degree banking in the corner, a carbon copy of the Indy track.

Then the cars race down a “short chute” (just like Indy) before entering the next turn, but this one is a corner from the Milwaukee Mile.
Racing started in Milwaukee on what was a one mile dirt oval in 1903, with races every year until 1953 when it was paved. Racing has been uninterrupted, now on a paved Milwaukee Mile making it the oldest continuously operated race track in the world; hosting races for every major racing series for more than a century. The winners at the Milwaukee Mile is a list of the most famous in the world from the ancients such as Barney Oldfield, Ralph DePalma, to A.J. Foyt, Mario Andretti, Bobby Rahal, Jim Clark, Alan Kulwicki and now Jeff Gordon, Dale Jarrett, as well as Dale Earnhardt, Jr.
After the Pocono Turn 3 (the Milwaukee Mile turn) the NASCAR Sprint Cup cars run down the front straight, 3780 feet, nearly three-quarters of a mile in length. Until very recently stock cars shifted gears on the front straight because it was so long and the engines would reach such high RPM’s that without shifting the engines would expire long before the 500 miles did. Now, better engine technology and NASCAR rules about gear ratios have eliminated the gear shift.
When racecars did shift gears many drivers called Pocono a “roval,” a cross between a road course and an oval, or a three turn road course connected by very long straights.

TV commentators make a great puffery about Darlington because the two ends of the track are somewhat different compared to all other ovals which are at least intended to be symmetrical. But the difference from one end to the other at Darlington pales in comparison to the differences in the three turns of the Pocono Speedway.

There are two critical elements to a turn, the radius of the corner and its banking, the illustration below shows those parameters for a few tracks.

Notice that the Darlington parameters for the two ends of the track are relatively close together and not all that far off those of Atlanta (which is also similar to Charlotte, and Texas). But the Pocono turns are WAY OFF, and each corner is vastly different from the others. It is simply impossible to find an ideal set-up for all three Pocono turns because they are from three completely different tracks.

But instead of mind bending the crew chiefs to set up just one common NASCAR Sprint Cup car to run all three turns, what if you could bring a car that was designed along the lines of the Pocono track concept; three different kinds of race cars bolted together to make a single vehicle.
What would that look like?

We invite you to send us your version for solving this puzzle; and enjoy the race at Pocono.

Thursday, May 28, 2009

Dover Monster tamed by math

Dover Monster Mile

The track that grabs cars as they exit the turns 2 and 4, and chews them up (crashing the cars against the outside wall)

In an interview Elliott Sadler described driving the Dover track as feeling like an amusement park roller coaster ride, however, he didn’t seem to realize he'd explained the car crushing feature of the Dover “Monster.”
It’s all about transitions, from the banking in the turns to the banking along the straight-aways. The track is 1 mile around (measured 30’ inside the outside wall, NASCAR rule), and has 24 degree banking in the turns (same as Atlanta and Charlotte—Lowe’s—) and 9 degrees on the straights; but as the track is only two-thirds size of the other two, the radius of the turns is smaller.
This photo (taken in the stands from Turn 1) shows how the track looks in person, along with section lines drawn into the picture to illustrate important points in the turn.

This cartoon sketch exaggerates the track but shows the idea, at section 1 the track is still banked at 24 degrees, by the time one gets to section 5, the banking is down to 9 degrees, as a result the runs uphill from the apex to line 1, over a crest (line 3) and then it is literally a down-hill run at the end of the turn exit (line 5).

In the traditional car chase scene over the hilly streets of San Francisco the hills are so steep that the cars literally are flying after they crest the hill. This is because the car drops at the acceleration of gravity, 32.2 ft per second per second; but if the road is dropping away more quickly relative to the forward speed of the car, then it goes air borne.
One can imagine in this sketch that if the car is moving slowly it stays on the ground, but at high speeds it does not. If one knows the curve of the hill it is easy to calculate the maximum speed that will still have the car on the ground, or conversely, the minimum speed to get it air borne (this is the essential calculation for stunt teams in doing ramp jumps).
Relative to the track at Dover, the crest of the hill for the drive path of most race cars occurs at about section line 3. Now if we look at the vertical profile of the drive path of the race car around the turn, it becomes more apparent what the effect is.
The car doesn’t need to actually become air borne to significantly change the handling of the car.If the car is still turning, the driver hasn’t straightened out yet, and the tires are pushing at their maximum side thrust to keep the car from sliding sideways, then unloading the car just a little bit, due to the road dropping away too quickly, results in the car seeming to “jump” sideways (and often into the wall).
The spring rates in a NASCAR Sprint race car are on the order of 300 lbs per inch, so if the racetrack drops away just 1 inch too much (the car continues on its arc as in the San Francisco car flight illustration, but the wheels follow the road) then the frictional load on the tires is decreased by 1200 lbs (300 lbs per inch of spring x 1 inch elongation of the spring x 4 wheels = 1200 lbs reduction in wheel load on the ground).

The teams which have 7 post rigs can predict the wheel loads for any given drive path on any track for which they have an accurate survey. It then requires a crew chief and driver to talk to the race car engineers to understand the relationship between drive path and ability of the car to turn at any given speed.

Consider an entire turn.

At point A the driver is at maximum speed from accelerating down the straight-away, and this is their lift point, the spot where they get off the throttle and onto the brakes to slow the car. As the car turns in, point B, the car is slowing and the driver is turning more to the left. By point D the car is at it slowest and the driver has turned the wheel to the maximum for this curve. From point A to D the car has been literally going down-hill due to the banking. At point D the car starts going up-hill, the driver starts accelerating and decreasing the turn of the steering wheel. As the race car exits the turn, through points E, F, and G, it is accelerating and going up hill, all the while decreasing the amount of turn in the steering wheel, the car is straightening out for the run down the next straight.

However, if by point G the car is still turning, and running as fast as the tires will allow without sliding, then as the car crests the hill at G and starts down towards section line 4, the wheels will partially unload and the car will suddenly slide sideways towards the wall: it actually appears to “jump” sideways.
Watch for TV views from the vantage point of looking down the straight-away towards a turn and see how often a car “jumps” sideways to get crunched by the Dover Monster.

Some drivers can learn intuitively what the drive path is that will allow them to defeat theDover Monster, but it’s a slow process; much easier and quicker if you have a good engineer.

All the big teams with 7 post rigs and race car engineers can calculate the path and show the driver where it is and at what speeds (engine RPM) they can negotiate the turn. The 7 post rig also allows the team to evaluate different set-up combinations, springs and shocks, for a given track, before they ever leave their race shop. This is in part why the well funded teams are the only ones that win, with the exception of a weather fluke as last week in Charlotte (Lowe’s).

Just having sophisticated equipment such as a 7 post rig is in itself not sufficient to win races, the crew chief must be technically astute enough to understand and utilize the information which engineers can provide; this is the essential skill of some one such as Chad Knaus (for the 48 car), Steve Letarte (for the 24 car) and Alan Gustafson (for the 5 car) in the Hendrick operations.

Friday, May 22, 2009

Carl 2 Long

Carl 2 Long
Or is NASCAR too short, again?

So, Carl 2 Long was found to have had an oversize engine, 358.17 cubic inches, over the allowed 358.000 as per the NASCAR rule book.
Not to be insulting but Carl Long is a back marker, something like 63rd in points the last time I checked; the 46 car wouldn’t be a threat to pull an upset win if you spotted them 17 cubic inches, much less 0.17 cubes.
It’s math time, students. First of all 0.17 above a limit of 358.000 is 0.04748 %, or less than half of one-tenth of one percent. If you weigh 180 lbs and take two quarters in change out of your pocket, you will weigh less (about 0.047 %), but it doesn’t mean you’ll suddenly be running the wheels off of Lance Armstrong in a bicycle race.
And how would you measure this difference?

The number we want is the total displacement of the pistons in the engine (the volume that is swept by the pistons moving up and down inside round tubes called cylinders), which are inside the engine block.

The idea is simple: measure the distance a piston moves, called the stroke, and multiply it by the area of the cylinder, remember that algebra thing?

However, since we measure diameter, we use

and area becomes

The area is pi times the square of the diameter of the cylinder all divided by 4; easy enough. But the level of precision required is not so easy.

A standard piece of notebook paper is approximately 0.0025” to 0.0035” thick, depending on the quality of the paper, the humidity and temperature of the room and if you’ve touched the paper. The make or break measurement for Carl 2 Long is on the order of 0.0005”, or one-fifth the thickness of one sheet of paper.

Now think of measuring out a ribbon that is to be three and a half feet long, 42,” and cutting it precisely to 42.000” in length, 41.999” is too short, 41.001” is too long. What does that look like? If you’ve measured out a length that is precisely 42.000” in length, see the arrow in the picture.

You must now cut it to precisely that length, and a line is drawn where the cut is to be made. If you cut to the left of that line, it’s too short, if you cut to the right it’s too long, you must cut right down the middle of that pencil line, the line itself is too wide to help, it is 0.0197” in width. You must measure to a level of precision that is one-sixteenth the width or thickness of this line.

In machine shops there are tools, called dial calipers, which have a precision of 0.001” (a tape measure at best has a precision of 0.0625”, too crude by a factor of 62).
Shown here we’re measuring the diameter of a piston from an RC car.

Imagine yourself to be a dutiful NASCAR inspector: does this piston have a diameter of 0.735” or 0.736”? The dial indicator is in between. If your call is 0.735” then Carl 2 Long must be renamed as Carl The Legal; and if your call is 0.736” then Carl 2 Long is a cheat and a liar. Notice the indicator doesn’t have another level of precision, so we can’t say precisely if it is 0.735” or 0.736.” The precise number is something between those two values. Now you the honest, diligent inspector, must make a judgment call.
To be really thorough, the inspector should measure each of the eight cylinder diameters and strokes (not just one and then multiply by 8). The dial in our one example seems slightly over the rule limit of 0.735”. But the next one might be slightly under, and the total of all 8 cylinder measurements would still meet the rule.
Just for laughs say that the engine which Carl 2 Long ran had a stroke length of precisely 3.250000000” allowing a piston diameter of 4.187066887” inches to meet the 358.000 cubic inch limit (never mind that this level of precision is down to counting individual molecules and there’s no way to do so).
But, just as in the example above, when you measure the piston diameter, it seems to be between 4.187” and 4.188”. Look at the dial in the picture above, if you say you’re going to “round up” and call that dimension 0.736” or, 4.188” in our example, then Carl 2 Long gets shorted 200 Large (street slang for fined $200,000). If you think the dial is slightly less than half way between the two lines and you round down to 0.735” (or 4.187” in this example), then Carl The Honest has been unfairly taken to the cleaners.

On the one-hand, NASCAR publishes a finding which purports to have found an overly large engine, but without any supporting data. What measurements were taken, by whom, using what piece of equipment? The NASCAR rule is 358.000 cubic inches but they only report 358.17 cubic inches, this alone is too crude a measure by a factor of 10. To put this in perspective it is the difference between 1/10th scale RC cars and real, full size cars.
Measurements at this level are very demanding, and now the consequences have been made very painful ($200,000 in fines and parked for 12 races), but so far the published reports don’t support the charges against Carl Long.
There are other micrometer calipers which can measure precisely down to 0.0001” but there’s no published supporting paper indicating that this was done.

In the world of technical experts who testify in liability trials, the case NASCAR has made public seems particularly weak and ill-founded at this point. Perhaps they have better data. For the sake of credibility this would be an excellent time to produce the numbers.