The submitted OEM bodies are scanned in the wind tunnel and compared to the submitted CAD for each design, with strict tolerances enforced to ensure each test article is representative of the design intent. Cookie Policy. More Storage. One example was the use of Kevlar composites to form the seals between the exhaust and the cockpit, which appear to have resulted in greater conduction into the steel chassis of the car since no heat is dissipated from the composite surfaces. Conversely, drag is a resisting force parallel to, but coming opposite from, the moving object. [18], Air curtains divert air flow from slots in the body and guide it towards the outside edges of the wheel wells. Testament to all three of the manufacturer aero teams is they all passed their submission tests on the first attempt. PRO NOTE: There are three components to the coefficient of friction when dealing with soft, stretchy materials like rubber: adhesion ( molecular interaction between tire and road); hysteresis (due to deformation of the tires) and cohesion (due to wear and tear). The flap was originally designed to operate via a pressure base deployment system, but it was found to be much more effective to deploy the diffuser flap via mechanical release connected to the right-side roof flap by a flexible cable. Minor improvements in shapes, fit and finish yield greater results at the front of the car, where the highest energy air is found. This allows direct estimation of the drag force at a given speed for any vehicle for which only the drag area is known and therefore easier comparison. A rear spoiler design that stands off the rear deck lid will increase downforce, reducing lift at high speeds while incurring a drag penalty. The winged wonders (Daytona and Superbird) were capable of 160 mph with the standard 3.23 rear. 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. The NASCAR Truck Aerodynamic Improvement team is tasked with providing aerodynamic analysis and improvement to Ford Performance and their factory supported team Brad Keselowski Racing for their Ford F-150 race trucks. The above model for air drag does not extend to all fluids. These issues had not arisen during single-vehicle testing, due to some seemingly minor design differences between the prototype vehicles and production. Open wheel cars have extremely high drag coefficients. Lets say it takes you 30 lbs of force to push the file cabinet on the wood floor. The term drag area derives from aerodynamics, where it is the product of some reference area (such as cross-sectional area, total surface area, or similar) and the drag coefficient. This effect is more pronounced in the incremental drag data in Fig. 98.12. Does anyone have any information on how many millimetres of rubber deposit there is on a track after heavy use? According to. With confidence in the CFD predictions and a need for more rear downforce, a multi-week CFD study began to refine the diffuser. 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. The difference is one is purposefully built, the other had to pretend to be for other reasons. The process was primarily undertaken in CFD, with over 2000 runs dedicated to underwing development for both performance and lift-off safety testing. 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. of just 0.28, by way of comparison the Ferrari F40 has a drag coefficient of 0.34, the Lamborghini Murcielago measures in at 0.33, and the McLaren F1 sits at 0.32 - smaller numbers mean less drag. NASCAR has had to step in and carefully regulate the aerodynamic features of each vehicle in competition to keep a level playing field. We characterize this interaction by the coefficient of friction, represented by the Greek letter mu (), which is pronounced mew, like a kitten sound. This mitigates the amount of drag by decreasing the frontal area of the blade. 8. The drag coefficient of a vehicle is affected by the shape of body of the vehicle. Minimizing variables is always a good thing. Deletion can be as simple as removing an aftermarket part, or part that has been installed on the vehicle after production, or having to modify and remove an OEM part, meaning any part of the vehicle that was originally manufactured on the vehicle. A low coefficient is conducive to high top speed and low fuel consumption, while a higher drag coefficient is generally found in cars searching for high cornering speeds influenced by downforce. Drafting can be a very powerful racing technique, but it has a serious liability. Drag force can either be seen as a help or a hindrance depending on the automotive application. Flaps recessed into the car's roof, another safety feature, begin to rise if air pressure suddenly drops above the car, blocking air flow [Source: Leslie-Pelecky]. "NASCAR's Screech and Slam? 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. The grille in most production vehicles is generally designed to maximize air flow through the radiator where it exits into the engine compartment. But lift doesn't necessarily mean an upward force countering gravity. It was understood early in the process that the reduction of rear side force due to body symmetry would impact the useable aero balance, but initially it was a guessing game, although not entirely without value. Nevertheless, the Superbird was a success at NASCAR and beyond. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); This site uses Akismet to reduce spam. Associated Press. In fact, downforce is a form of lift -- negative lift. "Passenger Car Aerodynamics." 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. (Accessed 12/14/08) http://www.circletrack.com/techarticles/0304_aerodynamics_tech_definitions/index.html, Cislunar Aerospace. A rear spoiler usually comes standard in most sports vehicles and resembles the shape of a raised wing in the rear of the vehicle. Racecar Engineering is the worlds leading motorsport technology magazine. 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. To ensure the most accurate and repeatable testing environment possible, NASCAR uses a dedicated submission vehicle capable of having different OEM body panels mounted to it. One of the first production passenger automobiles to swap out mirrors for cameras was the Honda e, and in this case the cameras are claimed by Honda to have decreased aerodynamic drag by "around 90% compared to conventional door mirrors" which contributed to an approximately 3.8% reduction in drag for the entire vehicle. The Next Gen features the passively deployed bonnet (hood), and roof flaps NASCAR uses in all its vehicles, but the diffuser presented a new opportunity to add another safety device a diffuser flap. This article will demystify NASCAR lingo, starting with the phenomenon of aero push. Drag force on a vehicle acts on the same plane as the direction of motion (horizontally) and increases exponentially as speed increases. HPDs CR-V Hybrid Racer: A 2024 INDYCAR Powertrain Lab, McLaren Motorsport confirms the new 720S GT3 EVO. [23] A kammback is a truncated boattail. Perhaps the best place to start is at the nose of the vehicle. The danger is especially present when a car is spinning, which radically alters the aerodynamic forces in play. 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. In order to reduce this impact a grille block is often used. 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. Drag coefficient Cdfor a sphere as a function of Reynolds numberRe, as obtained from laboratory experiments. Too much lift can cause the vehicle to lose road traction which can be very unsafe. Race drivers - particularly NASCAR drivers - make a convincing case for platooning, although drafting is the term the drivers prefer. On a track like Daytona, with its long straightaways and banked, sharp corners, the designs tend toward keeping drag to a minimum. How much of it to apply? The most common methods for increasing the downforce of a vehicle involve reducing the air pressure underneath the vehicle. However, the introduction of evocative coupes such as the Ford Mustang and Chevrolet Camaro meant fitting the production body style onto that sedan greenhouse proved challenging. on the actual NASCAR. F . The 3rd Generation (E34) - YouTube", "Honda Civic CRX - Car Cutaway - Modern Racer - Features", "Vehicle Coefficient of Drag List - EcoModder", "Five slippery cars enter a wind tunnel; one slinks out a winner", "Design, Engineering Contribute to ATS Fuel Economy", "Chevy's new Impala provides a breath of fresh air", "1992 Alfa Romeo 155 1.8 Twin Spark technical specifications", "2011 Alfa Romeo MiTo Twinair S&S technical specifications", "Technische Daten Audi A4 2.0 TDI (103 kW)", "Fiat Tipo - Al lancio le Opening Edition benzina e diesel", "All-new Ford Focus C-Max - Ford Forums - Mustang Forum, Ford Trucks and Cars", "Vehicle Specifications - 2006 Honda Accord Coupe - Honda Owners Site", "Vehicle Specifications 2005 Honda Accord Hybrid", "2014 Toyota Corolla Product Information", "Nio is Tesla's biggest competitor in the Chinese electric-vehicle market here's how its ES8 SUV compares with Tesla's Model X", "Chrysler Concorde Specifications - Dimensions", "Perodua Bezza officially launched first ever sedan, 1.0 VVT-i and 1.3 Dual VVT-i, RM37k to RM51k EEV", "The All-new 2013 Dodge Dart Redefines Performance", "All-New Honda Insight Hybrid Vehicle Introduced in Japan", "First Look: 2011 Hyundai Elantra - Motor Trend", "The koda Fabia: Best-in-class for aerodynamics", "2017 Toyota Camry Product Information Sheet", "NIO ES6: Racetrack performance and SUV comfort", "The BMW 5 Series History. The trailing car suffers a reduction of downforce on its front tires, resulting in a loss of stability and handling coming out of turns. Your email address will not be published. [10][11] In order to decrease the impact that side mirrors have on the drag of the vehicle the side mirrors can be replaced with smaller mirrors or mirrors with a different shape. The behavior of the Drag Coefficient was further investigated by analyzing how it varies with velocity. A much more common option is to replace the windshield wipers with lower profile wipers, or to only remove the windshield wiper on the passenger side of the vehicle, and even to fabricate a deflector to deflect the air up and over the wipers.[16]. This force also depends on the. [15], The effect that windshield wipers have on a vehicle's airflow varies between vehicles; however, they are often omitted from race vehicles and high efficiency concepts in order to maintain the smallest possible coefficient of drag. 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. 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. USA, Leslie-Pelecky, Diandra. Add in the fact that the ability of the rear of a car to generate downforce is hampered by the mass in front means, basically, that the front of any car has the first choice on making downforce. Many racing authorities have banned side skirts, but they remain a flashy feature of certain passenger cars [Source: BMW]. Comment with your thoughts below! [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. Dutton: 2008. This offset generates rear side force, resulting in a restorative, positive yawing moment to the car. 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. "Going With the Flow." NASCARs last generation vehicle, the Generation 6, or Gen 6, as its known, was introduced in 2013. (Specifications)", "Xpeng Starts Delivery of P7 EV Sports Sedan", "Alfa Romeo at the 2016 Paris International Motor Show", "Specifications of the all-new BMW 3 Series Sedan, valid from 10/2018", "The New Nio EC7 Wins The EV SUV Range Title With Up To 582 Miles On A Single Charge", "Aerodynamics: The best value of all current Porsche models", "Cheating Wind - Aerodynamic Tech and Buyers Guide", "NIO ET7 Achieves 0.208 Drag Coefficient", "NIO ET7: Our electric sedan with a range of up to 1000 km", "Tesla says the new Model S is the world's most aerodynamic production car", "The new EQS: passion for electromobility", "Lucid Air Touring and Air Pure Now Ready for the Road with Market-Leading Range and Aero; Air Sapphire Dominates Test Tracks on the Way to 2023 Introduction", "Here's the story behind GM's revolutionary electric car from the 90s that disappeared", "Lightyear 0 is the most aerodynamic production vehicle", "Part 3: Production, Physics, Politics Only the Strong Survive", "Volvo ECC the car that gave the world a preview of Volvo's future already back in 1992", "50 000 km avec une Citron Ax diesel, mon avis d'utilisateur ainsi que son cot kilomtrique rel", "Aerodinamica automobilelor si inventia inginerului roman Aurel Persu | Headline, Practic, Utile", "VISION EQXX taking electric range and efficiency to an entirely new level", "GM Unveils Concept Car That Gets 108 Miles A Gallon", "The Bizarre German Car That Was Ultra-AerodynamicAnd Totally Impractical", "Urbee 2, the 3D-Printed Car That Will Drive Across the Country", "D & H Enterprises, composites and fibreglass technology", "TU Delft students build a car with the lowest air resistance in the world", "(a bicycle's lower frontal area is offset by a higher drag coefficient)", "The Mayfield Company Homepage - Coefficient of Drag Tables and Curves", "World record defended: The new A-Class Sedan: none is more aerodynamic", "Mercedes' 2014 CLA is the new low-Cd king", "Technical Specifications BMW 520d EfficientDynamics Edition, valid from 03/2017", "The All-new Renault Clio: The icon of a new generation fully revealed at Geneva Motor Show", "Specifications of the BMW X1, valid from 09/2018", "2017 Pacifica is first hybrid minivan, rides on all-new FCA platform - SAE International", "2019 Ram 1500 More Space. Aerodynamics remains a vibrant and young field of engineering, with many innovations still to come down the road. Learn how your comment data is processed. To keep up with the latest innovations in aerodynamics, visit the links on the next page. Table 8.1 lists the drag coefficient for some simple shapes, (each of these objects has a Reynolds number of order 104 ). Introducing a symmetric body eliminated the majority of these issues and presented a car that is a near spitting image of its street counterpart. 2 So if the same vehicle with a drag coefficient ofCd=0.30 was measured in a different tunnel it could be anywhere from Cd=0.285 to Cd=0.315. NASCAR has to do this in a slightly more advanced way: Theyre interested in the grip all the way around the track, so they map the coefficient of friction values and collect them on a computer with a GPS index. A properly angled nosepiece, placed low to the ground, directs the majority of the air upward over the top of the car. In a streamlined design the air flows around the vehicle rather than through; however, the grille of a vehicle redirects airflow from around the vehicle to through the vehicle, which then increases the drag. 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. NASCAR previously investigated ducting radiator air out of the engine bay area of the cars at the 2019 All Star Race at Charlotte, and it was decided to implement this feature on the Next Gen in an effort to promote longer engine life spans and reduce car temperatures. MEW really? Racecar Engineering is the worlds leadingpublication for motorsport technology and engineering. Copyright Trivalent Productions 2008-2020, aerodynamic downforce and mechanical downforce, The Racing & High-Performance Tire: Using the Tires to Tune for Grip and Balance, Superspeedways: aka Power-Drag Limited Tracks : Building Speed, The force pushing the tires into the track. Stay up-to-date on the second race of the 2023 NASCAR Cup Series season. A coefficient of friction greater than one means its easier to pick up the object than to slide it. How hard the tires are pressed down into the track is determined by the combination of aerodynamic downforce and mechanical downforce (i.e. The advent of a new vehicle allowed NASCAR and the OEM aero teams to further refine an already tight Gen 6 submission process. . In addition to the usual friction, hot race tires molecules interact with rubber on the track. {\displaystyle F={\tfrac {1}{2}}\times {\text{air density}}\times {\text{drag coefficient}}\times {\text{reference area}}\times {\text{speed}}^{2}} 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. 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. At the other end of the spectrum are the single seat racers, with some heavily-aeroed Formula 1 cars seeing values of up to 1.1. Goodyear tailors the frictional properties of their tires to each track. During a high-speed spin, air can move rapidly enough over the roof and hood to produce a powerful lift force. - YouTube", "All-New 2017 Hyundai Elantra Brings Advanced Technology and Premium Convenience to the Compact Car Segment", "New 2020 Hyundai Sonata Makes Its North American Debut at the New York International Auto Show", "Mercedes-Benz S-Class, W 220 series (1998 to 2005)", "Attainable Premium, Actualized: All-New 2019 Toyota Avalon Beams Effortless Sophistication, Style, and Exhilaration at the 2018 North American International Auto Show", > "The new Jetta - world premiere - North American International Auto Show", "NIO Launched Smart Electric Mid-Large SUV ES7", "Sports car with a social conscience: Ars reviews the BMW i8", "Jaguar XE (2015) technical details and prices confirmed", "Mazda Launches Second SKYACTIV Model in Japan: Facelifted Axela", "Instantly thrilling: The new Mercedes-Benz C-Class Coup", "All-new Nissan Sylphy unveiled at Auto Shanghai 2019", "Calibra - Proof That Old School Still Rocks @ Top Speed", "Innovative aerodynamics concept of the Audi e-tron S models", "NIO Launches EC6 Smart Electric Coupe SUV", "NIO EC6: Our electric coup with a view of the sky", "2010 Toyota Prius Product Information | Toyota", "2023 NIO ES8 Specs, Price and Comparisons - Licarco", "2017 Hyundai Ioniq Hybrid and Electric Models Soon to Be Available to U.S. Consumers", "All-New Kia Optima Hybrid Unveiled At 2016 Chicago Auto Show", "Die technischen Daten der S-Klasse Limousine", "C-Class awarded Environmental Certificate", "Slippery Tesla Model S triumphs in wind-tunnel shootout", "The first-ever BMW i4. Drivers challenge each other less, riding in tight single-file rather than side by side. 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. A common way to measure the drag of the vehicle is through the drag area. 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). Early aero development focused on matching the evenly distributed downforce number. 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. [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. In fact, the. Body inspection at the track will still be conducted by NASCARs Optical Scanning Station, which compares a rapid photo scan of the car to the approved CAD surface of the vehicle. 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. While there certainly will be teething issues and uncertainty as teams adapt and learn at different rates, the Next Gen is a platform for the 21st century for both current and future new manufacturers in the sport. Also the shape of The drag coefficient is a common measure in automotive design as it pertains to aerodynamics. Some of this was attributable to inadequate insulation and material changes in production, but a great deal was due to the ingestion of hot radiator air into the cockpit and inadequate evacuation of air from the cockpit. 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. Without grip aka friction there is no racing. Are you surprised at how slippery some cars are compared to others? Extremes are created by such machines as the eco-friendly solar powered vehicles you see companies producing now and again like the Shell Ecorunner V that somehow achieves a coefficient of just 0.05. As expected, an aerodynamic body makes a big difference in lap time. With the greenhouse decided, the next step was to move to another stylistic sore point: the tail. It keeps the pressure underneath the car down, preventing lift. The sharp edge to the right-side window deflects air instead of letting it flow freely over the roof. Teams use tire pressure and small differences in circumference to further fine-tune grip. Speaking of the tail, another key feature of NASCAR vehicles is the spoiler. To accommodate the maximum suspension droop, these outer tunnels then move back downwards before resuming an upward trajectory. The value of drag coefficient for a something of the general dimensions of a car lies around the 0.3-0.4 mark. 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. Indeed the drag coefficient follows the same trend as the downforce (Fig. A large share of the drag on a NASCAR race car is due to the highly separated underbody flow (see Figure 6). Streamlining the body requires assumptions about the surrounding airspeed and characteristic use of the vehicle. In most racing vehicles this is eliminated by covering the entire underside of the vehicle in what is called an under tray. fResults - Pressure fCoefficient of Pressure f Lift and Drag i The model, was connected to a dynamometer that measured force in both the x and y direction, essentially lift and drag. The introduction of more road courses and short tracks reduces the need for the cars design to focus on high-speed ovals, and more toward a shape that can do it all: ovals, road courses and short tracks. Dr Eric Jacuzzi explains how those involved in the aero development of the NASCAR NextGeneration racecar see it not so much as the birth of a new era, but more like the completion of a study course. The body uses flanges and a common mounting system to attach to the chassis, with adjustment built in of up to 0.15in in each direction to accommodate manufacturing tolerances. A boattail can greatly reduce a vehicle's total drag. Could NASCAR use more complex techniques to make this measurement? . This map was later used in wind tunnel testing at Windshear wind tunnel in Concord, North Carolina. benefit of reduced drag. Most vehicles with very low drag coefficients, such as race cars and high efficiency concept cars, apply these ideas to their design. Automotive designers and NASCAR teams rely on aerodynamic principles to create improvements in the power and handling of vehicles at high speeds. Race cars occasionally become airborne despite these devices. Aerodynamic force results from differences in pressure on the sides of the moving object. Divide the weight of your object by the force youre pulling with and voila! The body must fall within this box, or the test is considered a failure. One of the largest departures of the Next Gen car, aerodynamically speaking, is the lack of side skirts. Thats pretty much what they do: they drag an airplane tire around the track and measure how much force it takes. speed "Aero Push." Findings - By the CFD analysis, the drag coefficient without the spoiler is calculated to be 0. . If you're curious about aerodynamics, do further research on the Internet or at your local library. 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. When automobile companies design a new vehicle they take into consideration the automobile drag coefficient in addition to the other performance characteristics. The above dataset yielded an average drag coefficient of 10.5 and a standard deviation of 1.9. Please copy/paste the following text to properly cite this HowStuffWorks.com article: "How Stock Car Aerodynamics Work" In the real world, road cars only really need to decrease drag force, especially in this age of fuel consumption obsession. Today's fleet of cars is a vast improvement over the ornamental tailfins and boxy structures of yesteryear. "BMW Side Skirts." the weight of the car). Its drag coefficient is 1.42. 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. That said, the Generation 6 cars had become substantially developed to take advantage of the high-speed undercar flows. This is held in place at the centre of the diffuser and, when deployed, releases downward and blocks the central tunnel of the diffuser. As a result, this modification is more commonly seen in high efficiency vehicles rather than sports cars or racing vehicles. Drag is the major obstacle to acceleration and racing speed. An accurate method of achieving this has been successfully developed at Loughborough University. air density "A faster car experiences more drag because it has to push air molecules out of the way faster," Diandra Leslie-Pelecky explains in her book, "The Physics of NASCAR." But how do you know how much grip a racetrack has? This creates a low-pressure region behind the flap and increases the lift-off speed of the car when nearly backward by 10-20 per cent. reference area Just as a speedboat leaves the sharp line of a wake trailing behind it on the water, an automobile creates an aerodynamic impact as it slices through the air. Other molecules flow along the hood, only to come up against the windshield -- another source of drag. With these elements settled, the OEM aero teams and design studios went to work on what would become their 2022 challengers. With a drag coefficient of only 0.28, there are only a few cars today can brag similar slipperiness. 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. The removal of this part has led to increases in fuel efficiency in several studies. I couldnt believe you hadnt heard the mu joke but then I realized that Ive never heard the mermaid joke. Since the original introduction of the Next Gen was slated for 2021, it was decided that the only viable path to making the timeline was to go from CFD straight to full-scale testing. The back of the car must have its share of downforce to handle properly. Another factor in moving toward a symmetric body was the evolution of the NASCAR racing calendar. The Physics Behind Auto Racing. The thing about aero development in general is, its much easier to make front downforce compared to rear downforce. Using the spring scale, drag the object along the surface youre testing. Unseasonably cold weather may require more friction. Automotive engineers and pit crews strive to keep the two forces in balance. 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.