Drag Downforce DRAfting

Transcription

1 GRES 5 7 rag ownforce Rfting n erodynamics STEM Learning Guide There s more online! You can go to accelerationnation.com to create a custom profile, earn badges, and learn more about the Three s of Speed!

2 The 3 s of Speed uring a NSR race, race cars can reach speeds of more than 200 miles per hour! Races are won and lost by just fractions of a second. To be the first across the finish line, drivers rely on three key aerodynamic features: drag, downforce, and drafting. rag s a race car zips along the track, it experiences drag, or air resistance. ir pushing against the car as it moves causes it to lose speed. To fight this slowing force, designers work to create cars that are more streamlined so air flows easily around them. ownforce Race car drivers rely on downforce to help their cars firmly grip the track. ownforce occurs as air moves under the car faster than it does over the top. The slower air on top creates an area of higher pressure above the car that pushes it downward. This provides more traction to its tires and gives the driver better control while steering. rafting uring a race, drivers can get a speed boost by lining up their race cars. This is a formation called drafting. When cars draft, the leading car blocks the movement of air, creating low pressure behind it. High-pressure air moves forward to fill the space between cars, tugging the trailing car forward while reducing the leading car s drag. s a result, both cars reach higher speeds.

3 rag Explore the science of aerodynamics. RG downforce 94 RG slow-moving air: high pressure fast-moving air: low pressure TIVITY rop a flat sheet of paper from a height of about 3 feet while a friend times how long it takes to hit the floor. Now crumple a sheet of paper into a ball and repeat the experiment. id you notice how the object s shape affected how it moved through the air? The flat sheet of paper met resistance and moved slowly. rumpling it into a ball reduced its surface area, so the second sheet dropped to the ground faster than the first.

4 drafting Learn how NSar drivers use drafting to race ahead of the pack. rafting Stage 1: rafting Stage 2: Low pressure between the cars pulls the trailing car forward slow-moving air: high pressure fast-moving air: low pressure oth cars go faster NSR drivers try to strategically improve the performance of their vehicles using the Three s of Speed. One technique they use is called drafting - where race cars closely line up one behind the other to gain a boost in speed on the track. When race cars draft, the leading car blocks the air, creating an area of low pressure behind it. t the same time, low pressure also pulls the trailing car forward toward the leading car. This pushes the highpressure air over the lead car s spoiler, reducing its drag. The result allows both cars to go a few miles per hour faster. Try this quick trick to visualize drafting: take two marbles to your kitchen sink. Run the water from the tap. Hold one marble under the running water - and then hold the second marble under the first. See how the second marble gets less wet because more water is blocked by the first? Imagine that the water is air and you re on your way to understanding drafting in NSR racing.

5 downforce ISOVER THE SIMILRITIES ETWEEN RING N FLIGHT THROUGH EROYNMIS. NSR race cars rely on a key element of aerodynamics air pressure to stick to the track. ir pressure is a force caused by the weight of air molecules pushing against an object s surface. The shape of a plane s wing, also called an airfoil, works with the opposite combination of high and low air pressure. The splitter on top of a NSR race car forces fast-moving air underneath the car and the skirting prevents slow-moving air from slipping underneath the sides of the car. Fast-moving air causes low air pressure and slow-moving air creates high air pressure. The combination of high pressure above and low pressure below pushes the car down so it stays on the track. TIVITY Hold the short end of a sheet of paper with your hands pointing up. low forcefully over the curve of the paper. heck it out: faster-moving air over the top of the paper creates lower pressure above and higher pressure below. That creates lift, causing the paper to rise. Next, fold a 1-inch flap along the short edges of the paper.turn the paper over and fold another 1-inch flap on each edge. Sit the paper on a tabletop so that there is a tunnel you can blow through. low forcefully through the gap. Faster-moving air below the paper creates an area of low pressure below and high pressure above. This creates downforce, causing the paper to sag.

6 discovering drafting Winning a NSR race requires more than a super-speedy car. rivers also use a strategy called drafting to get ahead on the track. Read the passage below to learn about the technique s accidental discovery. Then answer the questions on the right. The iscovery of rafting hat was the central idea of the text? 1 W In 1960, racecar driver Junior Johnson was gearing up for the second ever aytona 500 race. ut he realized he had a problem. His car was much slower than those of the top contenders in the race. uring a practice run, Johnson noticed that when he pulled up close behind a faster car his vehicle sped up, too. y the final lap of his run, he d built up enough speed to overtake the other car. Johnson had discovered drafting. rafting occurs when a car lines up right behind the car in front of it, with just inches between their bumpers. Leading cars block the flow of air, creating an area of low pressure behind them. This area acts like a vacuum, sucking the trailing cars forward. The trailing cars push high-pressure air over the leading cars spoilers, reducing their drag and also giving them a boost. The more cars that are grouped in a drafting formation, the faster they all will go. rafting is a common strategy used in NSR races. rafting was first used by accident. y driving close behind other cars, racecars can move faster. car doesn t have to be the fastest to win a race. he purpose of the third paragraph is to: 2 T explain the science of how drafting works describe the first time that drafting was used in NSR detail how drafting has changed in the last 40 years list the pros and cons of drafting hat is a synonym for the word tactic? 3 W ability formation idea strategy Using the drafting tactic, Johnson won the aytona 500 even though his car wasn t the fastest on the track. Today, drafting is a common strategy in NSR races. 1., 2., 3. NSWEsS:

7 Kn Test your KnowlEGE hat does the science of aerodynamics 1 W study? The weight of objects he speed and flight of objects T The movement of air The sound of air hat are three key aerodynamics 2 W principles? rag, height, and acceleration rag, downforce, and drafting cceleration, downforce, and motion cceleration, height, and motion hat word describes a force that slows 3 W he goal of adaptations to NSR 9 T racecars is: an object when air pushes against it? rag ownforce rafting eceleration hat aerodynamics force is used to 4 W create both lift and downforce? ir speed ir pressure oth and N either nor rue or false? ownforce is caused by 5 T E hy is the science of aerodynamics 10 W important to racing? the combination of high air pressure pushing against the top of an object and low air pressure beneath an object. True False rue or false? ownforce is the opposite 6 T of lift. True False rue or false? rafting is a driving 7 T strategy that improves speed. True False prevent racecars from flipping over To or lifting. To provide more downforce to improve tire traction. T o force high-pressure air over the car to make sure it sticks to the track. To create more contact between the tires and the tracks. ll of the above ecause aerodynamics helps improve the safety of the racecars, keeping them on the track. ecause aerodynamics helps enhance the speed of the racecars, helping drivers zoom past the competition. ecause aerodynamics helps improve the performance of the cars, keeping them running smoothly and consistently. ll of the above You can go to accelerationnation.com to find out more! NSWEsS: wo or more racecars accelerate T next to each other with inches between them. Two or more racecars line up, one behind the other, with inches between them. Two or more racecars tap the bumpers of the cars in front of them. None of the above 1. ; 2. ; 3. ; 4. ; 5. ; 6. ; 7. ; 8. ; 9. E; 10. rafting happens when: 8

8 RER PTTIONS Each racing season, NSR sets rules that determine the shape and weight of its cars. heck out some NSR racecar principals and learn how they influence safety, speed, and racing aerodynamics. 1 Spoiler This device traps high- pressure air, creating downforce to provide more rear-tire traction. It also increases drag to prevent racecars from traveling at unsafe speeds. Strips 2 Roof These thin rails run along the roof edges to disrupt airflow and cut down on unwanted lift. Flaps 3 Roof These spring open if the car starts to slide or spin. They disturb air moving over the car, reducing lift so the car doesn t go airborne. 4 Skirting Edging around the bottom of the car prevents highpressure air from moving under the vehicle and creating unwanted lift. If the car starts to slide sideways, the skirting lessens the chance of the car spinning or flying off the track. 5 TIRES Treadless tires make more contact with the ground, increasing traction. 6 SPLITTER This flat strip runs parallel to the ground underneath the front bumper. ir accelerates more quickly under the splitter, leading to a low-pressure area that helps suck the car downward toward the track.