THE KNOWLEDGE OF DRAG RACING
ETHAN CULLEN
EXTENDED ESSAY
SEMINAR ADVISOR: DANIEL GALLO
TECHNICAL ADVISOR: CORRINE FIELDS
OCTOBER 4, 2017
WORD COUNT: 3,037
TABLE OF CONTENT:
INTRODUCTION………………………………………………………………PAGE 3
AERODYNAMICS.…………………………………………….…….….………PAGE 4
WEIGHT.…………………………………………………………………………PAGE 5
FRICTION.………………………………………………………………………PAGE 7
TORQUE.…………………………………………………………………………PAGE 8
ACCELERATION.………………………………………………..……………..PAGE 9
CONCLUSION…………………………………………………….……………PAGE 11
WORKS CITED.………………………………………………………………..PAGE 12
WORKS CONSULTED.………………………………………………..………PAGE 14
Introduction:
Drag racing has almost been around for a century now, ever since the invention of automobiles, many have been obsessed with it throughout every generation. One of the most iconic tradition throughout the world is bonding with a family member underneath a car and learning all the parts of the vehicle. This has inspired a large amount of the car community to pursue the hobby or career of drag racing. Drag racing in it’s simplest term is two cars racing from one point to another in a straight line. Professionally, drag racing becomes a little more complicated, there are rules and regulations, safety, and different classes to compete in. In each and every class, there is some differentiation, all the way from what fuel the engine uses to how much the car must weigh in order to compete. For example, the Top Fuel class is “Among the fastest-accelerating machines in the world, 10,000-horsepower Top Fuel dragsters are often referred to as the ‘kings of the sport,’ and with good reason. They are capable of covering the dragstrip in less than 3.7 seconds at more than 330 mph.” says NHRA, the largest auto racing organization in the world.
Winning a drag race is not only about having the fastest and most powerful vehicle in the sport but it’s also about having a greater knowledge of physics. Without a greater and proper understanding of the concept of physics, the ability to decrease your time and increase your performance in an drag racing vehicle would be very difficult. For example, when aerodynamics became a study of science, we changed the look of vehicles. They went from being wide and short such as commonly seen during the 20th century to becoming narrow and long which reduces the surface area of where the air can hit the car. Weight is also very important to drag hobbyists and professionals, they help increase friction from the wheels to the ground and also helps create a perfect launch from the starting point. Friction however can have downsides such as the friction inside the engine can decrease the power and torque which is why it’s important to also use the most efficient and correct oil.
Torque is crucial to executing a perfect launch from the start and those launches are usually what wins a race. Drag racing is a game of acceleration, and the victor is the one who reaches the highest speed the quickest. To do this, the torque from the wheels and axle will help launch the vehicle rapidly forward. The acceleration of any drag racing vehicle mainly depends on the aerodynamics, weight, friction, and torque. At some point, when a vehicle has efficiently and maximized the use the concept of physics on the vehicle, it becomes a game of technique and skill. That which depends entirely on the driver.
TITLE PAPER SECTIONS:
AERODYNAMICS:
Drag racing is usually fought in a quarter of a mile drag strip and can last from six to fifteen seconds. This means that for only a short amount of time, the aerodynamics of the car is affected by the wind. However, this does not mean that the engineers of the vehicle should disregard this factor. Once, the common knowledge of aerodynamics is achieved, it can be used as an advantage over the opponent. For example, on a front wheel drive car, the front end of the car is usually a little heavier than the back end. The most common solution to creating an evenly weighted car is to add a spoiler or a wing to the back end.
Installing a wing or a spoiler has two major effects on the vehicle. “A spoiler disrupts the airflow of the car and now, it will have a high pressure up on the top which causes it to be pushed down.” say Jason Fenske, a mechanical engineer from North Carolina State, who is also the owner of the Youtube channel, Engineering Explained. A rear wing on the other hand, has a sole purpose of creating downforce. Downforce, defined by Bryan Yager, is “A vertical force directed downward, produced by airflow around an object.” Having a rear wing on a drag racing vehicle since it is more advantageous on turns than in straight lines.
Spoilers on the other hand, have a great significance in the drag racing world. While they are not meant to increase downforce on the vehicle, they are designed to reduce the lift in a car. Professor Anderson from Union College defines “lift is the force that acts on a vehicle normal to the road surface that the vehicle rides on. As its definition implies, lift usually has the effect of “pulling” the vehicle upwards – away from the surface it drives on.” To reduce the lift of a vehicle, drag racing enthusiasts will install a front spoiler and, or a rear spoiler. When they have been installed and are being used in the race, they allow the air that is hitting the vehicle to be heavier than the rest of the car.
During the 20th century, the science behind aerodynamics became more abundant and car enthusiasts and companies realized that it is more efficient to change the look of the vehicle. It went from being wide and short to narrow and long. The reason behind this change is to reduce the air resistance or more commonly known as drag, of the vehicle. As explained by my physics teacher, Corrine Fields, “The more area that the air has to hit the car, the more air friction there is to overcome.” This means that a decrease in surface area leads to less friction on the moving vehicle and results in the car reaching higher speeds faster.
WEIGHT:
Weight or more specifically, weight distribution in a drag race is fundamental for winning. If an automobile has seventy to eighty percent of it weight in the front it runs into the risk of spinning it’s rear wheels at the beginning causing time and most likely, the race lost. The same can be said about being to heavy on the rearend. If the friction on the rear wheels is considerably larger than the front wheels, the front-end of the automobile can lift itself up and execute a wheelie. While this is tremendously entertaining to watch, in terms of being useful to successfully winning a race, it is not. Many professionals have come to the conclusion that the most advantageous weight distribution is somewhere near fifty on the front end and fify on the back for drag racing.
It is important to say that there are advantages to having a drag racing vehicle front or rear end heavy. For example, if the vehicle was front wheel drive, it is beneficial to add a little weight to the backend because that will allow the rear tires to have more grip.(QUOTE) The same can be said about a rear wheel drive vehicle except it does not have to be taken to the fullest extent. The biggest difference between the two, are pulling and pushing, a front wheel drive car will pull the back wheels while a rear wheel drive will push the front. When looking at the greatest advantage between the two, rear wheel drive will win because of the weight. A stock front wheel drive vehicle tends to already have seventy percent of its weight in the front and the other thirty in the back because of where the motor and axle is located meaning that to evenly distribute the weight, you must add more to the rear end. Comparing that to a rear wheel drive which comes out of the factory closer to sixty to fifty-five percent front heavy meaning that there is less weight you must add on the end to reach the near equally distributed weight.
Weight has a great relationship with friction. As shown on The Summary of Friction, “If we add more mass we increase the normal force (N) (because the weight has increased) and hence we have increased the total frictional force. This is shown here where it can be seen that twice as much force must be applied to move two bricks instead of one (the force meter reads twice as large).”
FRICTION:
There are two different types of friction, static friction and kinetic friction. Static friction is the type of friction that drag racing hobbyists and professionals want to have on their tires. It allows the car tires to grip the road instead of sliding. Kinetic friction on the other hand, is what needs to be decreased on the tires but increased in the engine and all other parts of the drag racing car. As explained by EJM, “There are two kinds of friction important for wheels. ‘Static friction’ is what keeps two non-moving bodies from slipping against each other when you apply an external force.”
Static friction, as said before, is the friction that allows the car to move forward and not slip. When looking at a wheel roll across the road, there is only one point of contact. The point of contact being the the bottom-most part of the wheel coming in contact with the road. At these four points, the four wheels coming in contact with the ground, is where all static friction occurs. Since the definition of static friction means that the point of contact is in fact, not moving, because all they are doing is shifting the point of contact on the wheel, it must stay like that during the entire duration of the race. “Without friction, the wheel would spin, but if static friction is big enough to keep the wheel stuck at its contact point, then the wheel has to roll forward instead” says EJM.
Kinetic Friction on the other hand, is the friction you do not want to have on your tires. Kinetic friction in EDJ terms, “Kinetic friction produces irritating losses of energy. It comes into play only because real-world tires aren’t perfectly circular but deform. (The ground or road may be soft and deform as well). Any deformation means there is contact between the road and parts of the tire that other than the stationary point.” Ideally, the best way of removing most kinetic friction and increase static friction is through a mixture compounds in the tire but sadly, no company has yet perfected the best ratio.
In the engine, friction is entirely different. Instead of static friction, the engine needs kinetic friction. For example, the pistons in the engine is where the energy for the car to start moving comes from. As the pistons move up and down in their cylindrical hole, there is friction along the walls. This friction causes the pistons to slow down and leads to energy being transferred from the piston to the wheels to be slower and potentially slow down the vehicle. The best way of removing the friction is through racing oil. “The key to selecting the right oil for any application is matching up how the engine is used with oil chemistry for that type of use.” “Simply put, the harder the engine runs, the less TBN your engine needs. That may seem counter-intuitive, but it actually makes sense when you know that Detergents and Dispersant compete against the Zinc anti-wear additives and EP extreme pressure additives your race engine needs.” says Hot Rod magazine.
TORQUE:
Torque is a quantity that measures the rotational force it takes to move an object around an axis. In drag racing, torque is how much horsepower it takes to rotate the wheels on the rear or front axle. For example, “so 1 lb-ft of torque produced during one revolution actually is about equal to 6.28 ft-lb of work or mechanical energy. Huh? Just recall your geometry: Find a circle’s circumference by multiplying its radius (r) by 2(pi). With a 1-foot lever:
2(pi)r x 1 lb-ft of torque = 2 x 3.1416 x 1-foot lever x 1 lb-ft = 6.2832 ft-lb of work” explained by Hot Rod Magazine. Many have argued over the use of torque, some believe it’s a way of time and all concentration should go into increasing horsepower. Horsepower and torque are directly connected to each other. In an equation that James Watt created; (torque rpm)5,252=HP
Where the confusion on what to increase becomes imminent, is when professionals have to decide where they would like to add it into. For example, if a vehicle makes 400 lb-ft of torque at 2500 rpm, revolutions per minute, makes 190 horsepower.
(400 2,500)5,252=190hp
Now of course making a couple modifications to the drag racing vehicle can increase it’s performance to a point where it’s making 280 horsepower by doubling it’s rpm. The largest reason on why many hobbyists and professional drag racers increase horsepower of how effective and inexpensive it is to do. “Torque is what really moves the car, but it gets lost in the bench racing sessions when everybody only wants to talk about horsepower. But let’s go back a bit and look at engines like the Buick and Pontiac 455 ci engines. They made great torque but because of their limited cylinder head size and greater internal friction from long strokes, these larger displacement engines were not as efficient in terms of horsepower per cubic inch.” says Jeff Smith, a writer for Power Performance News.
ACCELERATION:
Acceleration is one of the largest components of drag racing. Without a greater understanding of the concept of acceleration, drag racing would have never become as popular as it is today. Acceleration, a=t=f-itf-ti, is equal to the change in velocity divided by the change in time. Drag racing, as stated before, is a competition of acceleration, meaning the less time it takes a car to reach a certain speed, or at least faster than the opponent’s vehicle the more likely it is to win the race. The greatest part of drag racing is the infinite amount of customizability which allows the engineer of the car to perfect it in his or her own way. Most engineers have realized that the most effective way of completing this, is through decreasing or increasing weight to the optimum level and increasing power.
When adjusting the weight of the vehicle, it becomes a give and take situation. For example, a out of the factory, 650 horsepower, supercharged 6.2 liter V-8, 2017 Chevrolet Camaro ZL1 with a curb weight of 3,912 pounds can reach 60 miles per hour in 3.5 seconds, according to the Chevrolet website.
a=t=f-itf-ti
a=60mph – 0 mph3.5 seconds
Convert 60 miles per hour to 0.016 miles per second
a=0.016mps3.5 second=0.0047619mps2
=4.810-3mps2
Comparing that to its competitor, a stock 526 horsepower, 5.2 liter DOHC V-8, 2017 Ford Shelby Mustang GT350R with a curb weight of 3,713 pounds, only 199 pounds lighter than the Camaro. Caranddriver.com has told us the GT350R can reach 60 miles per hour in 4.2 seconds. With the next equation all that is needed to be done is replace the 3.5 seconds with 4.2 seconds.
a=0.016mps4.2 seconds=0.00380952mps2
=3.810-3mps2
If the acceleration was constant throughout the entire race then the Camaro ZL1 would have beaten the Mustang GT350R.
Conclusion:
In conclusion, having a greater understanding of physics can help understand drag racing a little bit more. From aerodynamics where having a smaller surface area can help increase the acceleration of the drag racing vehicle. Also the aerodynamics of the car mattered a lot to deciding whether or not the vehicle could win the race. Having a spoiler or rear wings on the drag car can help a lot, a spoiler reduces the lift of the car leading the rear wing to increase the downforce of the vehicle. Downforce is also very helpful for drag racing, when weight comes into play, not only does downforce help while driving having a equally distributed car is important.
Having a fifty percent weight on the front and fifty percent weight on the back can help with many things including the launch and travel of the vehicle. Also where the weight went depended on what type of vehicle it was, a front wheel drive or a rear wheel drive. Most start using a rear wheel drive since it comes out of the factory at an almost fifty percent front and a fifty percent back weight distribution. But in terms of which one is superior, neither of them come out a victor. Weight distribution not the only type of weight that helps win a race, so does the actual weight. With an increase of weight, the more it is pushed towards the ground and the ground pushes back causing friction.
Friction, or static friction is what is needed on the drag racing wheels. If there was no static friction in between them then the car would have nothing to push off of, causing the wheels to slip and slide, called kinetic friction. No company or person has been able to fully remove the kinetic friction off of the wheels of drag racing cars. It is important to note that there are other spots where kinetic friction is need such as in the engine itself. It’s one of the reason why we use oil in our engines, to lubricate as much as possible and keep moving parts from sticking to other moving parts.
Torque, acceleration and horsepower is where all the energy from the car is transferred to allow the car to move. Torque and horsepower have a love hate relationship, while both are extremely great to increase performance, many choose horsepower because of how effective it is. Not only that, but increasing horsepower is also very cost effective. Drag racing has always been a game of acceleration, and to increase that acceleration, learning the other concepts of physics such as aerodynamics, weight, friction, torque and power and increase an automobile's performance in a quarter mile drag strip.
WORKS CITED:
“Drag Racing Classes.” NHRA. https://www.nhra.com/nhra-101/drag-racing-classes. Accessed 09 Oct 2017.
Fields, Corrine. Personal Interview. 10 October 2017
Summary of Friction. http://zebu.uoregon.edu/1999/ph161/friction.html. Accessed 11 October 2017.
EJM. “Air resistance and rolling resistance losses.” http://geosci.uchicago.edu/~moyer/GEOS24705/Readings/Air_and_rolling_resistance.pdf. Accessed 11 October 2017.
“How to Choose the Right Racing Oil.” Hot Rod Magazine. http://www.hotrod.com/articles/how-to-choose-the-right-racing-oil/
“Engine Power Delivery Explained – What is Torque vs. Horsepower.” Hot Rod Magazine. http://www.hotrod.com/articles/hrdp-0401-torque-horsepower-guide/
Mercer, Dylan. “The Physics Behind Drag Racing: A look into Weight, Tire Pressure, Maximum Speed, and Time Relationships.” Christopher Newport University. http://www.pcs.cnu.edu/~David.Gore/Capstone/files/MercerD.pdf
Signel, Peter. “Static and Sliding Friction; Drag Racer Design.” 1 Feb 2017. M56.pdf
Fenske, Jason. “Spoilers and Rear Wings – Explained.” Youtube, uploaded by Engineering Explained. https://www.youtube.com/watch?v=DYpxcE7rBw8
Bryan Yager. https://www.nas.nasa.gov/About/Education/Racecar/glossary.html
Professor Anderson. “Race Car Aerodynamics Part 2: Lift and Drag.” http://antipasto.union.edu/~andersoa/mer331/Week8_Mer331_RaceCar_LiftDrag_W13.pdf
WORKS CONSULTED:
Beard, David. “2017 Ford Mustang Shelby GT350 Long-Term Test.” Car and Driver. https://www.caranddriver.com/reviews/2017-ford-mustang-shelby-gt350-long-term-test-review
Beckham, Brian. “The Physics of Racing.” 2008. PDF http://projectlab.engphys.ubc.ca/wp-content/uploads/Beckman_-_The_Physics_of_Racing.pdf
“2017 Camaro ZL1.” Chevrolet. Camaro-zl1
“2017 Chevrolet Camaro ZL1 vs. 2017 Ford Shelby Mustang GT350R – Head 2 Head Ep. 90.” Youtube, uploaded by Motor Trend Channel watch
“What Are the Different Types of Car Spoilers?” EBay, 3 Mar. 2016, www.ebay.com/gds/What-Are-the-Different-Types-of-Car-Spoilers-/10000000177635208/g.html.
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