The following is a small part of the story of its development from an aerodynamic standpoint, as told by managing director of aerodynamics for NASCAR, Dr Eric Jacuzzi. Two cars drafting together can go 3 to 5 miles an hour faster than a solo car, and extra trailing cars add a little more speed, which is why the drivers spend so much time in single-file. Most hatchback and saloon car producers want you to seem like youre coursing down the motorway at 70mph without disturbing the slightest bit of air, cutting through it like a slippery salmon. If its hotter, it may need less. Overall, the path of development for the underwing was aggressive but successful, thanks to the strong correlation between CFD and the wind tunnel. The Physics Behind Auto Racing. Every issueprovidesunrivalled technical analysis ofeverything fromWorld Championship series including Formula 1, to grass roots racing. A rear spoiler design that stands off the rear deck lid will increase downforce, reducing lift at high speeds while incurring a drag penalty. What worked in spring wont necessarily work in fall. Terms & Conditions | Another was at the rear of the car, where the production wheel tubs further closed off the rear of the boot (trunk) area, sealing in hot air from the transaxle cooler. This is done to direct airflow around and over the vehicle rather than allowing air to travel under it. The drag coefficient is a common measure in automotive design as it pertains to aerodynamics. With confidence in the CFD predictions and a need for more rear downforce, a multi-week CFD study began to refine the diffuser. The harder the car is pushed against the track, the greater the frictional force. But the advantage of the way theyre doing it is that they can make measurements quickly enough to determine whether they need to apply more PJ1 Trackbite before a race. Early aero development focused on matching the evenly distributed downforce number. Please copy/paste the following text to properly cite this HowStuffWorks.com article: "How Stock Car Aerodynamics Work" (Accessed 12/17/08) http://www.bmwsideskirts.com/history.php, Boone, Jerry F. "Bad Air? Because speed is, obviously, the main factor in NASCAR races, aerodynamics is a crucial element in stock car design. Several concept cars of the 2010s are replacing mirrors with tiny cameras[12] but this option is not common for production cars because most countries require side mirrors. A large share of the drag on a NASCAR race car is due to the highly separated underbody flow (see Figure 6). That said, the Generation 6 cars had become substantially developed to take advantage of the high-speed undercar flows. To understand exactly what this value means, lets take a look at the engineering equation used to calculate the coefficient: FD - Drag force - Air density V - Air speed A - Frontal area. A speeding stock car pierces the air as it travels. Because of the enormous time demands of three manufacturers wind tunnel testing in the same period, three clones of the submission vehicle were produced for the OEMs to use in their private testing efforts. A boattail can greatly reduce a vehicle's total drag. You hear number for stock-car tire coefficients of friction around 1.0 to 1.5. Speaking of the tail, another key feature of NASCAR vehicles is the spoiler. The reduction of drag in road vehicles has led to increases in the top speed of the vehicle and the vehicle's fuel efficiency, as well as many other performance characteristics, such as handling and acceleration. F 5.43. [17], When air flows around the wheel wells it gets disturbed by the rims of the vehicles and forms an area of turbulence around the wheel. Drag force can either be seen as a help or a hindrance depending on the automotive application. In order to reduce this impact a grille block is often used. The wide slicks used for racing are designed to maximize the coefficient of friction between the tire and the racetrack. The value of drag coefficient for a something of the general dimensions of a car lies around the 0.3-0.4 mark. The advent of a new vehicle allowed NASCAR and the OEM aero teams to further refine an already tight Gen 6 submission process. drag area F The removal of this part has led to increases in fuel efficiency in several studies. = Cookie Policy. However, achieving all that presented significant aesthetic challenges for manufacturers and NASCAR, since car designs not only had to be stretched at the rear, but also have different shapes on the left and right sides. Aero push -- and all of racing aerodynamics, for that matter -- is all about the downforce. The engineering goals are to curtail the amount of air flowing underneath the chassis to ensure a closer attraction between the tires and the ground and to provide easy escape for air that does get underneath. Ford Performance, reached out to an MSOE student and asked if a Senior . 1 Although both methods can be accurate, nothing in the engineering world beats physical testing, where the true real world effects of the air passing over the car can be recorded to influence any design tweaks needed to the bodywork. This article will demystify NASCAR lingo, starting with the phenomenon of aero push. With these elements settled, the OEM aero teams and design studios went to work on what would become their 2022 challengers. Its development has spanned several years, thousands of hours of design and testing work, numerous suppliers and, of course, one global pandemic. This effect is more pronounced in the incremental drag data in Fig. 2023 Chelsea Magazine Company | More Technology", "2022 Wagoneer / Grand Wagoneer Specifications", "Taking the drag out of aerodynamics: Aerodynamics world champion in almost all vehicle classes", "Renault: la Vesta 2 plus performante en 1987 que l'Eolab en 2015", "Specs of Mercedes-Benz Bionic Car Concept (2005)", Improving Aerodynamics to Boost Fuel Economy, Tel Aviv University reduces drag on trucks by 10%, Simple roll-down test for measuring Cd and Crr for cars and bikes, https://en.wikipedia.org/w/index.php?title=Automobile_drag_coefficient&oldid=1136187000, Nissan 350Z Coupe Base and Enthusiast models, 0.212 (1:5 model test, 1:1 car = 0.36, see above), 2013 Mercedes-Benz CLA 180 BlueEfficiency, This page was last edited on 29 January 2023, at 04:24. After reviewing ride height data from early tests and determining where the drivers felt comfortable after the car was adjusted, it was easy to identify that it correlated with a downforce distribution of approximately 30 per cent front. (Accessed 12/14/08) http://www.circletrack.com/techarticles/0304_aerodynamics_tech_definitions/index.html, Cislunar Aerospace. HPDs CR-V Hybrid Racer: A 2024 INDYCAR Powertrain Lab, McLaren Motorsport confirms the new 720S GT3 EVO. coefficient and the aerodynamic interaction between the front wing and the vehicle other components is probably not quite simple. Sport utility vehicles (SUVs), with their typically boxy shapes, typically achieve a Cd =0.35-0.45. Rear downforce performance is largely constant over a range of ride heights, and floor pressures are very consistent across a range of ride heights. The application of new parts and concepts onto the vehicle design are easier to include when in the design stage of a vehicle, rather than in aftermarket (automotive) parts, however, the fabrication of these parts assists in the streamlining of the vehicle and can help greatly reduce the drag of the vehicle. How much of it to apply? Over two sweltering hot and humid days it became readily apparent the production cars were much hotter than either of the test cars NASCAR had previously utilised. Studying downforce means paying attention to its opposing force, lift. The wheel wells are another area to shape. While roof racks are very useful in carrying extra storage on a vehicle, they also increase the frontal area of the vehicle and increase the drag coefficient. MEW really? So its not like you can say that Bristol always needs x amount more friction in the upper lane. This leads to various interpretations of what is acceptable, and often lengthy lists of revisions from NASCAR in terms of qualitative styling, as compared to the production vehicle. A well-prepared student entering a world of possibility and excitement, with a proud group of invested parents standing behind it, wishing it every success. Some sports cars have a surprisingly high drag coefficient (such as the Ariel Atom at 0.40), but this is to compensate for the amount of lift the vehicle generates, while others use aerodynamics to their advantage to gain speed and as a result have much lower drag coefficients. A Superbird has a .31 coefficient of drag while a Daytona's drag coefficient is .29about a 20-percent increase in aerodynamic efficiency over the standard Charger. If you restrict the competition to solid objects, still the half sphere wins with a drag coefficient of 1.17. ", Circle Track. The drag coefficient is a unit-less value that denotes how much an object resists movement through a fluid such as water or air. This video, from Harvey Mudd College, shows the experiment pulling a block, but cmon a tire would be much more interesting, wouldnt it? What is the drag coefficient of a Nascar? "Going With the Flow." 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Most vehicles with very low drag coefficients, such as race cars and high efficiency concept cars, apply these ideas to their design. Associated Press. The winged wonders (Daytona and Superbird) were capable of 160 mph with the standard 3.23 rear. Fender skirts are more commonly found on the rear wheel wells of a vehicle because the tires do not turn and the design is much simpler. But how do they know when they need it? Using the expertise of industry professionals, we look in detail at racecar design and innovation, whilst also keeping you up to date with news and developments from all the major race series across the globe. The F1 cars are still faster than most other race cars because they weigh very little, their their center of mass is very low, and they make huge downforce with their wings and bodywork. the weight of the car). This mitigates the amount of drag by decreasing the frontal area of the blade. If youre racing, you want a high coefficient of friction. The Gen 6 was optimised to race on left-turning, high-banked ovals, generating stability in yaw via a large rear overhang and a 2.5in offset to the right. tells you how easy or hard it is to slide one material on another. To keep up with the latest innovations in aerodynamics, visit the links on the next page. The component within the equation that will have the largest effect on car design will be the frontal area, as this will shape the front profile of the car, influencing the rest of the design. The counter incentive this created was less radiator cooling flow, which resulted in more front downforce and less drag. The OEM vehicle(s) must pass the first gate with no radiator flow, which must be worse in lift and drag than the generic body. [1] There are many different ways to reduce the drag of a vehicle. The 4th Generation (E39). Race drivers - particularly NASCAR drivers - make a convincing case for platooning, although drafting is the term the drivers prefer. [13] It is estimated that two side mirrors are responsible for 2 to 7% of the total aerodynamic drag of a motor vehicle, and that removing them could improve fuel economy by 1.52 miles per US gallon. On the positive side, a greater number of vehicles can stay near the leader of the pack. Goodyear tailors the frictional properties of their tires to each track. Sport utility vehicles (SUVs), with their typically boxy shapes, typically achieve a Cd=0.350.45. Development of the underwing was done in parallel with common elements development on the body. Cowl induction at the base of the windscreen has been a mainstay of NASCAR competition for decades but is not compatible with heated radiator air exiting out of the bonnet. Goodyear produces different tire compounds for different tracks, as well as different left- and right-side tires. This is why something like a Bugatti Veyron sits nice and snug on the tarmac with a small and efficient frontal profile when compared to something like a family saloon or hatchback. Thats as bad as What kind of underwear does a mermaid wear? Without grip aka friction there is no racing. In fact, downforce is a form of lift -- negative lift. Coefficient of Drag List Stock Vehicles Frontal Area formula = Height * Width * .84 (Height and Width in feet) Frontal Area formula = (Height/12) * (Width/12) * .84 (Height and Width in inches) CdA formula = Cd * Frontal Area EcoModded Vehicles This page was last modified on 9 July 2018, at 08:44. Much like smooth wheel covers this modification reduces the drag of the vehicle by preventing any air from becoming trapped in the wheel well and assists in streamlining the body of the vehicle. Here's how it all works. As drag area CdA is the fundamental value that determines power required for a given cruise speed it is a critical parameter for fuel consumption at a steady speed. These issues had not arisen during single-vehicle testing, due to some seemingly minor design differences between the prototype vehicles and production. A rear spoiler usually comes standard in most sports vehicles and resembles the shape of a raised wing in the rear of the vehicle. With the greenhouse decided, the next step was to move to another stylistic sore point: the tail. . In an effort to draw in higher energy air from the outside of the floor, the rear of the rocker boxes is ramped upward, and the diffuser outer tunnels feature a double hump design. The effects are especially beneficial on straightaways. on the actual NASCAR. A coefficient of friction greater than one means its easier to pick up the object than to slide it. It was decided to keep its kick line (the most forward edge) as far toward the centre of the car as possible. A properly angled nosepiece, placed low to the ground, directs the majority of the air upward over the top of the car. For all of the technological prowess devoted to building up downforce behind the front wheels of the stock car, it's critical to consider balance. The body must fall within this box, or the test is considered a failure. The new MSN, Your customizable collection of the best in news, sports, entertainment, money, weather, travel, health, and lifestyle, combined with Outlook, Facebook . The discovery of the mysterious powers of downforce in recent decades sent the auto racing world into a frenzy of wind-tunnel testing and subtle tweaking of stock car bodies. Speed, air density, and car size, shape and design all determine the magnitude of a car's drag force. Plus free access to the digital archive over 100 back issues! Aerodynamic drag increases with the square of speed; therefore it becomes critically important at higher speeds. The drag area of a bicycle (and rider) is also in the range of 6.57.5sqft (0.600.70m2). This tray prevents any air from becoming trapped under the vehicle and reduces drag. {\displaystyle F={\tfrac {1}{2}}\times {\text{air density}}\times {\text{drag coefficient}}\times {\text{reference area}}\times {\text{speed}}^{2}} Aerodynamics is the study of how air moves -- especially how it interacts with solid, moving objects. This equation is simply a rearrangement of the drag equation where we solve for the drag coefficient in terms of the other variables. Drivers challenge each other less, riding in tight single-file rather than side by side. A larger cross-sectional area increases drag because more air molecules have to be moved out of the way" [source: Leslie-Pelecky]. It was therefore decided to take the engine air from the front side of the radiator core rather than create an additional opening in the front fascia for stylistic reasons. More Storage. (Accessed 12/15/08) http://www.recumbents.com/car_aerodynamics/, BMW. The Cd of a given vehicle will vary depending on which wind tunnel it is measured in. Stock cars circling oval tracks to the left are more likely to show their right face in a spin. The deletion of parts on a vehicle is an easy way for designers and vehicle owners to reduce parasitic and frontal drag of the vehicle with little cost and effort. reference area This resulted in a laundry list of changes that were implemented at the Charlotte Roval test in mid-September, which included windscreen driver cooling ducts, slotted rear glass, a full right-side window, the elimination of left side NACA ducts into the cockpit, a NACA duct on the floor of the car and opening up the rear to evacuate the transaxle heat. The air that glides smoothly over the roof grows turbulent above the rear window and behind the car, exerting a backward force on the vehicle. While skirts are effective at generating downforce in a simple manner, they give the appearance of the cars being sealed to the track, along with the inevitable and undesirable wrinkling and deformation they experience. (Accessed 12/17/08 via Google Books) http://books.google.com/books?id=OAK3yFlHoTAC, Tierney, John. The most common replacement for the standard car antenna is the shark fin antenna found in most high efficiency vehicles. Source: Brad Bruno i This data was collected using a data acquisition system as well, and processed with a u0002u0004 u0001u0004 u0001 PC. A stock Miata doesn't have a lot of drag, but it generates lift (positive Cl) while all the other body styles generate downforce (negative Cl). (Accessed 12/15/08) http://www.nytimes.com/2008/02/12/science/12tier.html?pagewanted=all, Special Offer on Antivirus Software From HowStuffWorks and TotalAV Security. 2 To provide a reference for drag coefficients given to certain cars, heres a quick run-down of some values that may surprise you: Car manufacturers have been including drag coefficients within their cars stats much more in the last decade, coinciding with the transition towards eco-friendly motoring. Actually if NASCAR cars had the same drag coefficient (Cd) as F1 cars they would be considerably slower. This map was later used in wind tunnel testing at Windshear wind tunnel in Concord, North Carolina. It is created as an extension of the rear of the vehicle, moving the rear backward at a slight angle toward the bumper of the car. Another factor in moving toward a symmetric body was the evolution of the NASCAR racing calendar. Where F D is the drag force; is the density of fluid medium that is air; A is the frontal area of the body facing the fluid; V is the velocity of the body; C D is the coefficient of drag of the body.. How hard the tires are pressed down into the track is determined by the combination of aerodynamic downforce and mechanical downforce (i.e. In all cases, the reference area is the cross section orthogonal to the flow direction. Contoured deflectors, or tire spats, are often made as part of the front bumper in order to direct airflow around the tire without having any increase to the outward flow. Perhaps the greatest departure of the Next Gen (Gen 7) vehicle from the Gen 6 is the move to a coupe-like roof line, and the symmetry of the rear of the vehicle. An accurate method of achieving this has been successfully developed at Loughborough University. Early in the process, the goal was to match the relative aero performance of the Gen 6 vehicle, primarily in terms of total downforce and balance. Drag is a force that acts parallel to and in the same direction as the airflow. You can do the same coefficient of friction measurement if you have a spring scale. Lift is an aerodynamic force that acts perpendicular to the airflow around the body of the vehicle. This downforce is the key to maintaining traction through the tight and constant turns of a short-track race. A coefficient of friction above one would be like trying to push your file cabinet along a really hot asphalt road if the bottom of the file cabinet is made of chewing gum. "ESPN Will Show the Unseen of NASCAR." Covering much of the rear deck with a new sloped piece of glass and significantly shortening the decklid was a quick, cost-effective solution that lowered the drag coefficient from 0.375 to 0.365 in wind tunnel testing. In order for the air to flow more smoothly around the wheel well, smooth wheel covers are often applied. Many racing authorities have banned side skirts, but they remain a flashy feature of certain passenger cars [Source: BMW]. Secondly, there has to be some weight on the tire besides the weight of the tire itself. On the one hand, many drivers can remain competitive in a close race by piggybacking on the lead vehicle, taking advantage of the increased force and decreased engine strain. [19][20][21], The front grille of a vehicle is used to direct air through the radiator. While designers pay attention to the overall shape of the automobile, they also bear in mind that reducing the frontal area of the shape helps reduce the drag. (When making spherical-cow jokes, and only when making spherical-cow jokes, you may read it as moo.). The body must fall within this box, or the test is considered a failure. On a track like Daytona, with its long straightaways and banked, sharp corners, the designs tend toward keeping drag to a minimum. The highly concentrated vortex core suggests a stable vortex flow. When were back to normal and theyre trying to get qualifying and practice for multiple series before a race, there isnt time to shut down the track for a four-hour measurement. [14], While they do not have the biggest impact on the drag coefficient due to their small size, radio antennas commonly found protruding from the front of the vehicle can be relocated and changed in design to rid the car of this added drag. Streamlining the body requires assumptions about the surrounding airspeed and characteristic use of the vehicle. The NASCAR Next Generation (Aka Gen 7) vehicle took the track in earnest in late 2021, beginning the final team tests prior to its debut at the Busch Light Clash at the Coliseum, an exhibition race that starts the 2022 season. It first really dove into this experiment with the current S- and C-Class, getting these standard internal combustion sedans as low as a coefficient of drag number of 0.24. After nearly nine months of private development testing, all three OEMs submitted their vehicles at the end of August 2021 for three grueling days at Aerodyn wind tunnel in Mooresville, North Carolina. This is a 3.48% decrease in the drag coefficient and a 0.12% decrease in the lift coefficient (or 0.12% increase in downforce).10 Jan 2018 After Daytona, the NASCAR R&D aerodynamics team embarked on a month-long extensive study of the problem, thermally modeling the entire vehicle in much more detail than it had previously. Optimizing that is up to the teams. But, of course, Goodyear engineers cant just make the stickiest tire possible, because soft tires wear out faster. Unseasonably cold weather may require more friction. For the speed demon, more drag means lower speeds on the straightaway But more downforce means better handling on turns since the tires grip the track more securely. Its 200 mile per hour speed set in March 1970 . I couldnt believe you hadnt heard the mu joke but then I realized that Ive never heard the mermaid joke. Theyre probably also reading the temperature of the track at each spot. The outward sweep of the splitter footplate, which is a wear limiting device for track contact, proved to be a very significant generator of downforce. This added up to extremely hot engine temperatures. Aerodynamic force results from differences in pressure on the sides of the moving object. Racecar Engineering is the worlds leading motorsport technology magazine. Fans have complained that racing has lost some of its appeal, as riders remain in fixed positions for long stretches at a time. With a drag coefficient of only 0.28, there are only a few cars today can brag similar slipperiness. "Aero Push." Scale model options were evaluated as well, but with confidence in the simulation work and world class local wind tunnel facilities, it was decided to move ahead and target only four development tests of 20 hours each to finalise the underwing. In addition to the usual friction, hot race tires molecules interact with rubber on the track. The thing about aero development in general is, its much easier to make front downforce compared to rear downforce. Your email address will not be published. [265], in Range mode in combination with a low level and closed air intake flaps, w/ 19-inch AMG wheel/tire combination in "Sport" driving mode, toyotanews.pressroom.toyota.com/article_download.cfm?article_id=2633, Some sources also claim this figure relates to a T87 1:5 model test not T77a, Ivan Margolius & John G Henry, 'Tatra - The Legacy of Hans Ledwinka', Veloce, Dorchester, 2015, page 124, Optimization and computational fluid dynamics, Gbor Janiga, Springer, 2008, page 196, Winning the oil endgame: innovation for profits, jobs and security, Amory B. Lovins, Rocky Mountain Institute, 2004, page 53, Learn how and when to remove this template message, Volkswagen Cabriolet (Rabbit Convertible), Mercedes-Benz C 220 BlueTec BlueEfficiency, BMW 5 series (G30) 520d EfficientDynamics, "Reducing Drag on Cars and Trucks by 15-18%", "Aerocivic - Honda Civic modifications for maximum gas mileage -", "Aerodynamic Tips and Tricks You Can Use for Better Performance", "Mini-experiment: the wrath of roof racks", "These Mud Flaps Can Help Trucks Slash Fuel Costs", "Reflections on side mirrors: testing drag vs. MPG", The Aerodynamics of Heavy Vehicles: Trucks, Buses, and Trains, Volume 1, "First drive review: Porsche Panamera Sport Turismo", "Honda E To Get Side Camera Mirror System As Standard", "A mirrorless future?

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