WEBVTTKind: captionsLanguage: enBricksTeslasSplittersWings- Spoiler alert, we're talking about aerodynamics(electronic music)There are sleek carsand boxy carsThere's weird things sticking out of race carsand rice carsand they're all tryingto take advantage of aerodynamicsAerodynamics is the studyof how gases interact with moving objects.The two basic aerodynamics forces are dragand liftDrag is the force air exertsagainst a car as it moves,while lift is the perpendicular forceexerted by the air on the car.Lift includes both positive liftthat's the flying kindand negative liftand 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 practicallyswimming through an endless air oceanAir obviously isn't as denseas liquid, but it's still touching stuff.So there's frictionwhen something movesthrough it and that makes dragprobably the most importantaerodynamic factorthat we have to consider.And drag is basically athings velocity squaredmultiplied by it's dragcoefficient and it's frontal area.Drag coefficient dependson a lot of factorssome of which are an objects overall shape, surface roughnessand speedA brick has an awfuldrag coefficient of one,while a teardrop, the mostaerodynamic 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 aboutso there's not much dragand cars have plenty of powerto push the air out of the wayeven if it's shaped like a brick.In the very early days of automobiles,manufacturers really didn'thave to car about shapebecause cruising speedsbarely got up to 45,but I don't know, maybe ifModel T was more aerodynamic,it could've gone 50.- 50.- The earliest land speed record racersquickly realized streamlining their carsare gonna make it waybetter for going fast.Because of that velocitysquared part of the equation,drag increases significantlythe faster you go.Some might call it exponentially.At 70 miles an hour there'sfour times more dragthan there is at 35 miles an hour.That means it takes a lot more workto push something through the air.Looking at a fast-moving,non-aerodynamic brick,air's gonna pile up in front of itand create an area of high pressure there.At the back a lowpressure air pocket formsand creates a pressure differential.So not only is there frictionaldrag simply from the motion,now there's another forcetrying to drag the brick backwards.All this makes drag a really big factorin determining fuelefficiencies and top speeds.A reduction in drag coefficientfrom point three to point .25would increase fuel economyby about a mile a gallon.By the same reasoning,an electric car can go further on a chargethe more aerodynamic it is.That's why they look so weird.Now that we're regularlycruising at speedsover 70 miles an hour,we got a new focus on fuel efficiencyor battery rangeProduction car designerstry to get the lowest dragcoefficients possible.Most modern cars have a drag coefficientsomewhere between point .25 and point .35.With SUVsand truckssomewhere around pointthree and point four.The electric Tesla Model Xis a super sleek crossover with one of thelowest drag coefficients ofany production car, .24.But if two different carsare going the same speed,there can still be more overall dragon the really aerodynamic bigger carthan on a less aerodynamic smaller carYou can calculate howdraggy a particular thing isby multiplying it's dragcoefficient by it's frontal area,which is called drag areaLet's compare the slippery Model X to the Nissan 350zwhich has a mediocre CD of .31with a frontal area of 20.88 square feet,it's got a drag area of six .47.The Model X has a largerfrontal area, 27.88 square feetand 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 aerodynamicWell, you'd be wrongThey got a drag coefficientof about point seven,that's more than a minivan, what?F1 cars and most race carsare designed mostly with lift in mind.Traction and grip are just asimportant to fast lap timesas speed and power.Turns out keeping a car fromflying off of the groundhelps improve grip.(revving)(audience cheering)And pressing down on the tires with negative lift; downforceimproves grip even more.Down force also creates a ton of dragbut the trade-off is worth itbecause without all that down force,F1 cars would still bespinning their tiresat 100 miles an hourand with extra forcepressing towards the tires,they get increased lateral gripfor better cornering speedA heavy car could achieve the same resultbut it wouldn't be able to accelerateor corneras well as the light onesSo, what's creatingthat lift or down force?- Yeah.- Like our super draggy fast brick with high pressure in frontand low pressure in the backit's created by having a difference in air pressurebetween the topand the bottomof a car.Let's use the 350Z again andsay there's a hypotheticalone PSI, less pressureon top than underneath,with a surface area ofabout 12,240 square inches,there'd be about 12,240pounds of air pressurelifting the car up.That would suck.To get the desired down force,we tapped into a phenomenon called Bernoulli's Principleand that says that a fast moving fluidwill have lower pressurethan a slower moving fluid.A wing mounted on a cargenerates down forcewhen air moves more quicklyacross the bottom of the wingthan it does across the top.In this case, the fluid's the air.So the slower moving airacross the top of the wingexerts more pressure than thefaster moving air underneathresulting inDownforceBut 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 thatsurface and that's called a Coanda Effect- Words, words, words-- Coanda.- Words, words, words.- And the direction you mount the wingdetermines whether or notpositive or negative lift is generated.The air that has totravel farther speeds upand that creates a pressureimbalance that produces liftor negative liftwhich is downforceBut 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'scurved roof line down a bitand creates a fast and smooth flow,a lower pressure area of lift gets createdaround the rear end.- Ew.- The spoiler interfereswith the air flow just a bit,helping to cancel out some of the lift.It spoils the air flowIt's a spoiler. (laughs)Anyway, they don't generatetheir own down force,but that's why spoilersgive you a little morehigh speed stability,and if you look at the Audi TT,which is kind of like ajellybean cut in half,it was getting in accidentsanything over 110 miles an hour.All they had to do wasadd a little baby spoiler,problem solved.Say you got yourself a big wing,now there's down forcepressing on your rear tires.What about the front?A lot of rear down force itself can cause- Boo, you suck.- And no one wants that.It'd help to balance things outto add down force tothe front tires using a splitterLike our brick, air stacks upagainst the car's front endand creates a high pressure areabefore moving eitherover or under the body.When more air goes into thattight space under the carthan the amount of air that goes over it,well, you're gonna have lift-off.(revving)(thud)Most production in street carsgenerate positive lift athigh speeds and like the wing,you'd really rather have lowpressure air go under the carwhilst high pressureair goes over the top.When a splitter is added, itthe amount ofair can stack up againstwhile helping more of it move over the carNow with more pressure on topand lower pressure underneathyou've got a net downforce on those front tires.We mentioned earlierthat there's not muchaerodynamic drag at low speedand that means there'shardly any down force eitherso as much as I wanna believe it,those splitters and shopping cart wingsreally aren't doing muchfor the average daily drive.- Aw.- But the good news is thatdownforce increases exponentiallywith speed, just likethat annoying drag does.- You suck.- So, what do air dams, canards, under trays, side skirts, vortex generatorsand diffusersdo, 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 accessoriesthat we can't explainthem all in one video.So, guess what?We're gonna do more videos on aerodynamicsSpoiler alert!Never miss an episode of Science Garage,we do this every Wednesday.Click this big ol' subscribebutton so you don't miss out.You like spoilers?Check out this Up to Speed on the WRX.Check out this Wheelhouseon the best racer according to Nolan.Follow me on Instagram @bidsbartoand follow Donut @donutmedia.Don't tell them how spoilers can befor things over than safety.