Wings and Spoilers; Lift and Drag | How It Works

Wings and Spoilers; Lift and Drag | How It Works


Bricks Teslas Splitters Wings – Spoiler alert, we’re talking about aerodynamics (electronic music) There are sleek cars and boxy cars There’s weird things sticking out of race cars and rice cars and they’re all trying
to take advantage of aerodynamics Aerodynamics is the study of how gases interact with moving objects. The two basic aerodynamics forces are drag and lift Drag is the force air exerts
against a car as it moves, while lift is the perpendicular force exerted by the air on the car. Lift includes both positive lift that’s the flying kind and negative lift and that’s down force. Air moves in a very similar way to liquid, you just can’t see it. If you think about it,
every time you drive, you’re practically
swimming through an endless air ocean Air obviously isn’t as dense as liquid, but it’s still touching stuff. So there’s friction when something moves
through it and that makes drag probably the most important
aerodynamic factor that we have to consider. And drag is basically a
things velocity squared multiplied by it’s drag
coefficient and it’s frontal area. Drag coefficient depends
on a lot of factors some of which are an objects overall shape, surface roughness and speed A brick has an awful
drag coefficient of one, while a teardrop, the most
aerodynamic shape there is, has a drag coefficient of about .05. When you’re loafing around at low speed, the air’s not much to be worried about so there’s not much drag and cars have plenty of power
to push the air out of the way even if it’s shaped like a brick. In the very early days of automobiles, manufacturers really didn’t
have to car about shape because cruising speeds
barely got up to 45, but I don’t know, maybe if
Model T was more aerodynamic, it could’ve gone 50. – 50. – The earliest land speed record racers quickly realized streamlining their cars are gonna make it way
better for going fast. Because of that velocity
squared part of the equation, drag increases significantly
the faster you go. Some might call it exponentially. At 70 miles an hour there’s
four times more drag than there is at 35 miles an hour. That means it takes a lot more work to push something through the air. Looking at a fast-moving,
non-aerodynamic brick, air’s gonna pile up in front of it and create an area of high pressure there. At the back a low
pressure air pocket forms and creates a pressure differential. So not only is there frictional
drag simply from the motion, now there’s another force trying to drag the brick backwards. All this makes drag a really big factor in determining fuel
efficiencies and top speeds. A reduction in drag coefficient from point three to point .25 would increase fuel economy
by about a mile a gallon. By the same reasoning, an electric car can go further on a charge the more aerodynamic it is. That’s why they look so weird. Now that we’re regularly
cruising at speeds over 70 miles an hour, we got a new focus on fuel efficiency or battery range Production car designers try to get the lowest drag
coefficients possible. Most modern cars have a drag coefficient somewhere between point .25 and point .35. With SUVs and trucks somewhere around point
three and point four. The electric Tesla Model X is a super sleek crossover with one of the lowest drag coefficients of
any production car, .24. But if two different cars
are going the same speed, there can still be more overall drag on the really aerodynamic bigger car than on a less aerodynamic smaller car You can calculate how
draggy a particular thing is by multiplying it’s drag
coefficient by it’s frontal area, which is called drag area Let’s compare the slippery Model X to the Nissan 350z which has a mediocre CD of .31 with a frontal area of 20.88 square feet, it’s got a drag area of six .47. The Model X has a larger
frontal area, 27.88 square feet and with it’s low .24 drag coefficient, it has a bigger drag area of 6.69, and therefore it’s got a bit more drag. More drag. So maybe now you’re thinking, ‘Hey, F1 cars ‘are really fast, I bet they’re’ crazy aerodynamic Well, you’d be wrong They got a drag coefficient
of about point seven, that’s more than a minivan, what? F1 cars and most race cars are designed mostly with lift in mind. Traction and grip are just as
important to fast lap times as speed and power. Turns out keeping a car from
flying off of the ground helps improve grip. (revving) (audience cheering) And pressing down on the tires with negative lift; downforce improves grip even more. Down force also creates a ton of drag but the trade-off is worth it because without all that down force, F1 cars would still be
spinning their tires at 100 miles an hour and with extra force
pressing towards the tires, they get increased lateral grip for better cornering speed A heavy car could achieve the same result but it wouldn’t be able to accelerate or corner as well as the light ones So, what’s creating
that lift or down force? – [Crowd] Yeah. – Like our super draggy fast brick with high pressure in front and low pressure in the back it’s created by having a difference in air pressure between the top and the bottom of a car. Let’s use the 350Z again and
say there’s a hypothetical one PSI, less pressure
on top than underneath, with a surface area of
about 12,240 square inches, there’d be about 12,240
pounds of air pressure lifting the car up. That would suck. To get the desired down force, we tapped into a phenomenon called Bernoulli’s Principle and that says that a fast moving fluid will have lower pressure
than a slower moving fluid. A wing mounted on a car
generates down force when air moves more quickly
across the bottom of the wing than it does across the top. In this case, the fluid’s the air. So the slower moving air
across the top of the wing exerts more pressure than the
faster moving air underneath resulting in Downforce But how do we get the air to do that? Make the wing an air foil shape. When air runs into a curved surface, it’ll try to follow that
surface and that’s called a Coanda Effect – [Men] Words, words, words- – [Woman] Coanda. – [Men] Words, words, words. – And the direction you mount the wing determines whether or not positive or negative lift is generated. The air that has to
travel farther speeds up and that creates a pressure
imbalance that produces lift or negative lift which is downforce But what if your car’s just got a little trunk spoiler tacked on the back? Well, it actually does something. Since the air follows a car’s
curved roof line down a bit and creates a fast and smooth flow, a lower pressure area of lift gets created around the rear end.
– [Children] Ew. – The spoiler interferes
with the air flow just a bit, helping to cancel out some of the lift. It spoils the air flow It’s a spoiler. (laughs) Anyway, they don’t generate
their own down force, but that’s why spoilers give you a little more
high speed stability, and if you look at the Audi TT, which is kind of like a
jellybean cut in half, it was getting in accidents
anything over 110 miles an hour. All they had to do was
add a little baby spoiler, problem solved. Say you got yourself a big wing, now there’s down force
pressing on your rear tires. What about the front? A lot of rear down force itself can cause – [Man] Boo, you suck. – And no one wants that. It’d help to balance things out to add down force to
the front tires using a splitter Like our brick, air stacks up
against the car’s front end and creates a high pressure area before moving either
over or under the body. When more air goes into that
tight space under the car than the amount of air that goes over it, well, you’re gonna have lift-off. (revving) (thud) Most production in street cars generate positive lift at
high speeds and like the wing, you’d really rather have low
pressure air go under the car whilst high pressure
air goes over the top. When a splitter is added, it the amount of air can stack up against while helping more of it move over the car Now with more pressure on top and lower pressure underneath you’ve got a net down
force on those front tires. We mentioned earlier that there’s not much
aerodynamic drag at low speed and that means there’s
hardly any down force either so as much as I wanna believe it, those splitters and shopping cart wings really aren’t doing much
for the average daily drive. – [Crowd] Aw. – But the good news is that downforce increases exponentially with speed, just like
that annoying drag does. – [Man] You suck. – So, what do air dams, canards, under trays, side skirts, vortex generators and diffusers do, what? No, the people need to know this, Eddie. (light music) Well, it looks like we’re out of time. Look, there’s so many aero accessories that we can’t explain
them all in one video. So, guess what? We’re gonna do more videos on aerodynamics Spoiler alert! Never miss an episode of Science Garage, we do this every Wednesday. Click this big ol’ subscribe
button so you don’t miss out. You like spoilers? Check out this Up to Speed on the WRX. Check out this Wheelhouse on the best racer according to Nolan. Follow me on Instagram @bidsbarto and follow Donut @donutmedia. Don’t tell them how spoilers can be for things over than safety.

About the Author: Michael Flood

100 Comments

  1. I love this guys energy, could you imagine if all classroom teachers were as charismatic as this guy?

    Liked.

  2. You're actually wrong. You cited the Equal Time Transit theory when you said "Has further to go". That theory is so wrong and so widely accepted that NASA had to actually publish a blog on the official website to stop spreading it. Yet, here you are.

  3. I'm eventually getting a S197 GT/CS Mustang spoiler for my 2014 3.7L Mustang but need to have an extra $300 or more. I got dual sport stripes recently for a little less than that. Dang guy gave me a 1" gap instead of 2" like I told him. It looks okay but not as good as it would've. Oh well. Can't do anything about that. But yeah, can't wait to get my down force B)

  4. I wish there were more photos/illustrations so I can tell what the components are that do what was so well explained. I can now tell you why fast cars want downforce and sacrifice drag to get it – thanks, excellently done with great moving illustrations — but what is a dam vs. spoiler vs. wing vs. spoiler – not so much.

  5. STOP TALKING ABOUT BARNACLE'S PRINCIPLE. IT HAS NOTHING TO DO WITH LIFT GENERATION. THIS HAS BEEN A MYTH FOR TOO LONG. Wings are newtonian in nature and super duper simple! If you push an object through air and that air gets pushed upwards, then you get downforce! If you push an object through air and that air gets pushed downwards, you get lift! You don't even need a special shape to do this! You just need to deflect the air in a direction! The reason wings look the way they do is simply to minimize separation of fluid from them to maximize the amount of air they deflect! This is why when you stick your hand out your car window and rotate your hand, your hand will get pushed up and down! Look on the wikpedia pages for Lift and Bernoulli's principle and you will find: An airfoil generates lift by exerting a downward force on the air as it flows past. According to Newton's third law, the air must exert an equal and opposite (upward) force on the airfoil, which is lift.[13][14][15][16]. All bernouli's principle states in the scheme of this is that the flow must change velocity and thus must change pressure. That's it! I even saw a damned exhibit for this at a MUSEUM saying this is how airplanes fly! IT ISN'T! When you turn on your ceiling fan, it's pushing a wing through air that's shaped to push air downwards which creates lift as a byproduct!

  6. Yesterday at work I placed a pipe with the rounded side up under a dripping faucet – no more annoying drip sound! I guess this explains why that worked.

  7. I'm writing a book and there's going to be some streetracing going on, and this is a perfect crash course for me in the elements needed to rebuild a stock car for racing.

  8. I love Donut Media, but the way this dude talks, it's just terrible. Like someone who just pumped up a 10 miles long line of cocaine…

  9. That way of looking at Bernoulli's Principle is a gross and complete misconception repeated zillions of times, but it doesn't matter to hardly anyone except professional aerodynamicists. (Actual: Air speeds up because of a lower pressure ahead).

  10. …Did you break your neck as a kid or just that pompous. Quit staring at the camera with your nose turned up, makes yourself seem like an ass.

  11. I love these 2 videos about aerodynamics, i watch them time and time again since you guys explain this really well. And I think I talk about everyone when I say WE WANT SCIENCE GARAGE BACK!

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