Side Skirts, Diffusers, and Air Dams | How It Works | Science Garage

0:00 Sideskirts! Diffusers! Vortex generators! Canards? This is aerodynamics part 2. Son of aerodynamics! now that we've learned the aerodynamic basics of drag and lift and how splitters spoilers and wings work we can talk about when all those other Other cool aero things are doing First just a quick review. Previously on science garage. we saw that drag is the force air exerts against the car as it moves. While the lift is the perpendicular force exerted by the air on the car. Today, We're mostly concerned with lift and it's better half. Downforce. Now about that air? DAAAYUM! Air dam. The air dam usually has a couple of jobs.

0:48 It directs more air over the top of the car than underneath to reduce lift while also diverting air to the radiator to keep your car from overheating. In a sports car or a race car, the air dam is often designed to also shoot air directly into the intake intercoolers or oil coolers. It might route air through some ducts and the brakes to help cool those off too. The air dam also cuts down on overall drag. Even on a boxy vehicle without it. The air would be tripped up by all the blocky shapes. You usually find hiding behind you that smooth bodywork on the front on the corners of a race cars air dam, you might find. Canards, which are also called dive planes or dive plates. I don't know about you, but the word canard makes me think of ducks.

1:41 No, that's just me. Canards are usually flat wedge-shaped and angled upward toward the back of the car. They direct the air that moves around the side of the air dam upwards which creates a teensy-weensy bit of downforce. It's not much because they're so small. But it's enough to help fine-tune the balance between downforce on the front tires and the rear tires. Canards can also be used to deflect air around the front tires because they can be a source of drag or they can be used to direct more air up into the wings past at the back. Look if you want to get super serious about downforce, it's the stuff that isn't as obvious as a sick front fascia or a shopping cart wing that can make the biggest difference.

2:34 Underneath your car. There's a whole lot of nooks and crannies and junk like brake lines and exhaust pipes. They're all meshing up the airflow adding a smooth undertray to cover up all that stuff goes a long way to reducing turbulence and drag it lets the air move below the car much more quickly and that reduces the air pressure and can enhance the downforce but add a diffuser and now we're really making sausage. I mean downforce. A diffuser is typically a rear undertray shaped to make a gradually bigger space at the back of the car, but some racecars have front diffusers, too. It activates what's called a Venturi effect. Which is when a fluid speeds up as it flows through a more

3:20 constricted area like the space under your car and remember Bernoulli's principle? That says a fast-moving fluid has lower pressure. Yup, that means even more downforce! as the space at the back of the car gradually increases in size thanks to the diffuser all the fast-moving low-pressure air from underneath the car rushes up to fill that space this helps draw even more air across the underside of your car when it gets to the expansion area it slows down and gains pressure with high pressure surrounding the car on all sides and a lot less pressure underneath an overall vacuum effect occurs and it sucks the car down to the road! Now that slowed down air can smoothly join back up with the slower higher pressure air

4:11 flowing all around the car this gentle reunion reduces drag at the fact which results in even more downforce! Keeping the air flowing effortlessly without turbulence is what makes all of this work. So well So vertical dividers called strakes are placed in the diffuser to help keep the air orderly as we learned in our first arrow video, downforce and splitters and wings usually come at the expense of a lot more drag but adding a smooth undertray and a well-designed a diffuser can reduce drag so together they're one of the most important ways to increase downforce. Like Nolen without a glass of milk one without the other won't produce the desired effect.

4:56 All right. We've created an area of higher pressure all around the top of the car and an area of really low pressure underneath. We're good to go right? Wait! Now all that high-pressure air wants to rush into the low-pressure area and that is exactly what we don't want and that is what side skirts are for the ideal side skirts extend as close to the ground as possible to block that high-pressure air from sneaking back under the car and around the sides. That would increase lift and ruin the downforce that we just worked so hard to create. One of the most ingenious applications of underbody aerodynamics was Jim Hall's Chaparral 2J race car. The can-am series had just banned tall wings and moving aero devices for the

5:42 1970 season so Aero pioneer Hall developed some creative workarounds for his new cars Lexan side skirts were integrated with the suspension to maintain a constant one-inch clearance with the ground even around turns or over bumps and it's big! Boxy Booty were two big fans. Written by their own two-stroke 2 cylinder engine! The fans constantly pulled air through the underbody of the car creating so much of a vacuum that the 2J produced up to one and a half G's of downforce! But since the chaparral 2J fans moved air independently of the car speed, it produced about the same amount of downforce at low speeds as it did his high speeds.

6:31 This meant it could do lap times a full two seconds faster than the next fastest cars. Competitors really didn't like that nor did they like all the dust and rocks the fans threw in their faces. This car was banned after just one season last but not least are those little vortex generators and we're gonna talk about it. In Mitsubishi Evo in Civic Type-R, not f1 turns because let's be honest! You're not driving F1 So even though you can't see the air we know, pushing a car through it still causes some friction because it's got drag. Some air molecules get stuck near the surface and what's called the boundary layer. Meanwhile, the faster-flowing air tries to follow the curved shape of the roof and rear window and what's called an attached flow.

7:23 It would be perfect for the Evo and the Type R if the air smoothly and non Drag Olli. Followed the window down then float across the rear wing where it would generate downforce just like it's supposed to but is that what happens? No! Instead, the attached flow peels off right around the end of the roofline and becomes a separated flow, dispersing off into the atmosphere where you can even using that's why raindrops don't always blow off your back window when you're cruising down the freeway. There's just a swirling massive turbulence And that's not gonna make any downforce when it gets to the wing!

8:09 However, if four text generators are placed in the stagnant area around the trailing edge of the roof where the air starts to separate there. Yes! Generate vortices off of their tips and that helps draw the fast-moving air down into the boundary layer which keeps the airflow attached for longer so vortex generators are there on the Evo and Type-R to make sure air passes over the rear wing and generates downforce! Aerodynamics thanks to Skillshare for sponsoring this episode, Skillshare is an online learning community with thousands of classes and design, business, technology and more. You want to impress your friends?

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9:43 Skillshare! Subscribe to donut. More people who subscribe, the more cool stuff we get to do for you. Follow us on Instagram and Twitter at donut media. You follow me at This Bardo. Talk about Civic Type-R, you can check out the new car show where James drives one around. You guys want to see the blockbuster episode that started it all! Check out Arrow part 1. Don't tell my wife that I'm keeping the olds.