The Secret to Bugatti's Aerodynamic Success: Dimples and Bubbles
At low speeds, air travels along the ball surface in nice orderly layers, all going the same direction. This is called laminar flow. As a ball moves faster, the inertia of the faster air overcomes the viscosity forces that were keeping it stuck to the ball. And so, the air detaches and separation leaves a large low-pressure wake that gradually fills with detached air tumbling into it. This causes the pressure drag we were talking about before.
So how do dimples help with separation? Well, the dimples create microscopic areas of high and low pressure. These turn the boundary layer of laminar air into turbulent air. So, the layers are no longer gliding smoothly past each other. This turbulent air has less inertia, so it can stick to the surface of the ball longer. It's not much extra stick, but a dimple golf ball can fly twice as far as a smooth one.
Now, let's compare this to what Bugatti is doing with the Bolide. The Bolide suffers from the same detaching air dilemma as our flying golf ball. At speeds over 50 miles an hour, the air passing over the intake scoop would detach instead of following the curve of the roof line. As the car increases in speed, the wake of the hood scoop would reach further and further back, eventually producing a low-pressure area around the rear wing, making it way less useful.
Bugatti brought in the bubbles, like the dimples on a golf ball, to prevent separation by creating multiple areas of high and low pressure. All those small pressure differentials produce turbulent air that can stick to the surface of the car and follow the curve of the body towards the rear wing. When Bugatti says that those bubbles reduce the aerodynamic drag of the scoop by 10%, they're not talking about the air resistance at the front of the scoop. They're talking about the pressure drag behind it.
Bugatti is actually not the first company to use bubbles like this to reduce pressure drag, but they are the first to make those bubbles active. Why not just have the bubbles inflated all the time? Well, below 50 miles an hour, the air is moving over the intake slowly enough that it doesn't detach. If the bubbles were there, they would just create drag in the form of air resistance.
Dimples on a golf ball have the same problem. The perfect golf ball would have active dimples that don't appear until 55 miles per hour. When their positive impact on pressure drag will outweigh their increased air resistance. It seems I found out how to make a lot of money, make an active golf ball, and sell it to cheaters. All golfers had cheated at least once in their golfing life, right?
So why use bubbles instead of dimples? Dimples would create areas of low pressure but probably would be less effective than bubbles, which protrude into the air flow. Maybe they'd work even better if the bubbles had dimples, but that's untested speculation.
And unfortunately, so is a lot of what Bugatti is saying about the Bolide. According to Bugatti, the Bolide's massive power, lightweight, and high-tech design mean it could lap The Nurburg ring in five minutes, 23 seconds. It could lap the 24 hours Le Mans circuit in three minutes seven seconds they say. Seven seconds faster than the fastest race car.
Bugatti says the Bolide could do these things, but they haven't actually done it. The Bolide is a real functional car and it looks pretty sweet. But apart from the weight and the horsepower, every number Bugatti has said is based on computer simulations. The Bolide has not run from zero to 60 in 2.1 seconds. It hasn't hit 311 miles per hour. It has not produced 5,700 pounds of down force.
Those magic bubbles on the roof they've never produced a 10% reduction in drag. Those bubbles' success is all based on simulations too. It's like the matrix over there, Bugatti. I wanna believe all those numbers are possible. I really, really do, but for me to believe it, I need more than just a simulation. I need to see it.
I didn't believe in Brendan Fraser until I saw him in a Walmart in Rancho Cucamonga. He's a nice guy. Where has he been? Nobody knows since I saw him there. Thank you guys so much for watching this episode of B2B. Follow us on Instagram @donutmedia. Follow me on Instagram @jeremiahburton. Click like and subscribe that really helps us out. Let us know how we're doing in the comments. You guys liked this nerdy stuff? I hope so, until next week. Bye for now.
WEBVTTKind: captionsLanguage: en(engine revving)- This is the Bugatti Bolidea new experimental hyper car builtaround Bugatti's eightliter quad turbo W16.And this is a golf ballthat was rolling aroundin the back of Cain's pickup truck.He's a Ford ranger guyso he's got a lot of stuff out there.He's got golf balls,he's got old golf clubs.He's got chairs, he's gotdead people. Ranger life.Now what do these twothings have in common?Well, supposedly they're aerodynamicsat least according to a bunchof articles and Bugatti themselves.Bugatti has the Bolide set to breaksome serious records.But how much of what they sayabout this golf ball arrow is really real.Well, turns out not all of it.Today we're gonna doubleon the black magicthat is aerodynamics.Explain the sciencebehind the Bugatti Bolideand see how much itand this old golf ballreally have in common.If there's one thing Ihate more than hypocrites,It's people who play golf.(chuckles)(upbeat music)- Looney, Looney Boonie.Are we good?- Thank you to off the recordfor sponsoring today's video.- Top of the morning to ya.St. Patrick's day is here,and I know how fun it isto go out for the holiday.But remember that the policeknow what this holiday means.And they'll be out lookingfor speeders, swerversand all kinds of reckless driving.That's why you need offthe record app downloadedon your phone, ready to go.Off the record off asa network of attorneysto fight your ticket.(beep)And even give you a refundif they can't reduceor remove it entirely.- Registernow to use code donutfor 10% off your first ticketat offtherecord.com/donut- Was that great? Did I Nail it?- Nailed it.- Yes.(chuckles)- A few years back Bugattiasked themselves what ifwe strip away all of theChiron's heavy bodyworkand creature comfortsand replace everythingwith the latest, lightweightaerodynamic partsand crank up that legendary engine.(shouts)- You ever seen someone crank up somethingon crank? You get it.The answer they came upwith is the Bugatti Bolide.Bolide is Italian for fireballand it's a track only monster weighingjust over 1200 kilos with 1800 horsepower.That's like the weight ofa Mini Cooper and the powerof two Indy cars,but a great power to weightratio isn't the only ingredientfor a fast race car.You need race car tires,race car suspensionand maybe most importantly,race car aerodynamics.But I'm not sure if race caraerodynamics is the right termbecause the Bolide has a featureI've never seen on any race car.On the roof is a giant air intakewhich feeds that massive W16 engine.And on top of that are 60inflatable bubbles that can extendup to 10 millimeters fromthe surface of the car.Bugatti says that this morefootball outer skin reduces dragand improves both agility and efficiency.They say it can do thisbecause those bubbles work justlike dimples on thesurface of a golf ball.So there you have it.That completely explainsBugatti's new golf ball arrow.Thank you for watchinglike, and subscribe.We're not done.Look Bugatti I get it.Arrow is complicated, but for startersthose are bubbles and golfballs they have dimples.Those aren't the same.They're kind of like the actual opposite.So let's pick up whereBugatti left off and seeif we can fill in some ofthe gaps in this story.Before we get into howBugatti's golf ball arrow works.We need to understand some ofthe basics of aerodynamics.Race car arrow is complexand involves many parts working together.But aerodynamic design isbased on a simple principle.Adding or reducing pressureto one side of an objectwill create an imbalancethat can move that object.Let me show you what I meanjust by being in our atmospherethese two ping pong ballshave a constant forceon them from both sides, about14 PSI or one atmosphere.Since the pressure is on all sidesit's balanced and theballs remain stationary.Now, if I add more pressure to one side,for example by blowing on it.It moves towards thearea of lower pressure.Now, what if instead ofincreasing pressure, we lower it.We can do this by usingthe Bernoulli principlewhich states that an increasein the speed of a fluidoccurs simultaneouslywith a decrease in static pressure.If we create a currentof air between the two ping-pong ballsyou might think this aircurrent would push them apartbut the moving air actuallyreduces the air pressurebetween them causing theballs to move inward.Increasing pressureor decreasing pressure it doesn't matter.Any imbalance will create motion.So how do these principlesapply to race cars?Vroom, vroom, let's go speed.Let's start with the most obvious exampleof race car, aerodynamics, the rear wing.It creates a verticalpressure differentialwith high pressure on topand low pressure below.This produces negative liftor down force pushingthe car into the trackwhich means more grip,which means faster speed,when you're going around corners.The Bolide has adjustablewings, front and rearand at 200 miles an hourand maximum attack angleBugatti says they're goodfor 5,700 pounds of combined down force.That's a lot of your mamas.Now another way race carsproduce down force isby taking advantage of ground effect.Similar to how creating a current of airbetween the ping pong balls caused themto move inwards towards each other,creating a fast moving currentof air underneath the car will cause itto be sucked down to the track.So why not just installsome six side skirtsand a huge wing, call it a day?Well arrow, isn't all that simple.All the down force producing partsof a race car can create huge amountsof grip and high speed stabilitybut they have to be preciselycalibrated to work in harmony.If the front splitters angleof attack is too shallowthis can create lift andthat lift can cancel outthe down force from the ground effectsand without ground effectsand a rear ring producinghuge down force on the rear of the car.Something like this can happen.- Here we go.Oh my god. Oh my god.The Mercedes has taken off.- Your car stops being a car,and it starts being a plane.We don't want that.Planes are planes fora reason, right guys?(laughs)So now, you know the basicsmake everything work in harmonyand create tons of down force.Well, that would be greatfor high speed handling and braking,but it comes at a cost ofacceleration and top speed.Because most down forceproducing parts also create drag.Usually when we think of drag,the first thing that comesto mind is having topush air out of the way.But there's a secondarydrag called pressure drag,and it's just as important.Pressure drag is when afast moving object leavesa low pressure area orweight behind itself.And this weight increasesthe pressure differentialpulling the object backwards,slowing it down further.So how do we reduce this pressure drag?Well, in Bugatti's case,they turn to a concept that'sover 100 years old.And it looks like this.Like any object,a moving ball displacesthe air in front of it.And air has viscosity.It likes to stickto whatever surface it's traveling over.At low speeds air travelsalong the ball surfacein nice orderly layers, allgoing the same direction.This is called laminar flow.As a ball moves faster.The inertia of the faster airovercomes the viscosity forcesthat were keeping it stuck to the ball.And so the air detachesand that separationleaves a large low pressurewake that gradually fillsin with detached air tumbling into it.This causes that pressure dragwe were talking about before.So how do dimples help with separation?Well, the dimples create microscopic areasof high and low pressure.These turn the boundary layerof laminar air into turbulent air.So the layers are nolonger gliding smoothlypast each other.This turbulent air has less inertiaso it can stick to thesurface of the ball longer.It's not much extra stickbut a dimple golf ballcan fly twice as faras a smooth one.So how does this compareto what Bugatti is doing with the Bolide.The Bolide suffers from thesame detaching air dilemmaas our flying golf ball.At speeds over 50 miles an hourthe air passing over theintake scoop would detachinstead of following thecurve of the roof line.As the car increases in speed, the wakeof the hood scoop would reachfurther and further backeventually producing a low pressure areaaround the rear wing,making it way less useful.So, they brought in the bubbleslike the dimples on a golf ball,the Bolide bubbles prevent the separationby creating multiple areasof high and low pressure.All those small pressuredifferentials produce turbulent airthat can stick to the surface of the carand follow the curve of thebody towards the rear wing.When Bugatti saysthat those bubbles reducethe aerodynamic dragof the scoop by 10%, they're not talkingabout the air resistanceat the front of the scoop.They're talking about thepressure drag behind it.Bugatti is actually not the first companyto use bubbles like this,to reduce pressure drag.But they are the first tomake those bubbles active.So why not just have the bubblesinflated it all the time?Well, below 50 miles anhour, the air is movingover the intake slowly enoughthat it doesn't detach.If the bubbles were therethey just create drag inthe form of air resistance.Dimples on a golf ball,they have the same problem.The perfect golf ballwould have active dimplesthat don't appear until 55 miles per hour.When their positiveimpact on pressure dragwill outweigh theirincreased air resistance.I guess I found out howto make a lot of moneymake an active golf balland sell it to cheaters.All golfers had cheated at least oncein their golfing life, right?So why use bubbles instead of dimples?Dimples would create areas of low pressurebut probably would be lesseffective than bubbles,which protrude into the air flow.Maybe they'd work even betterif the bubbles had dimples,but that's untested speculation.And unfortunately, so is alot of what Bugatti is sayingabout the Bolide.According to Bugatti the Bolide'smassive power, lightweightand high-tech arrow means itcould lap The Nurburg ringin five minutes, 23 seconds.It could lap the 24 hours Le Mans circuitin three minutes seven seconds they say.Seven seconds faster thanthe fastest race car.Bugatti says the Bolidecould do these thingsbut they haven't actually done it.The Bolide is a real functional carand it looks pretty sweet.But apart from theweight and the horsepowerevery number Bugatti has said is basedon computer simulations.The Bolide has not run fromzero to 60 in 2.1 seconds.It hasn't hit 311 miles per hour.It has not produced 5,700pounds of down forceand those magic bubbles on the roofthey've never produceda 10% reduction in drag.Those bubbles success is allbased on simulations too.It's like the matrix over there Bugatti.I wanna believe all thosenumbers are possible.I really, really do, butfor me to believe it,I need more than just asimulation, I need to see it.I need to see it happen.I didn't believe in Brendan Fraseruntil I saw him in aWalmart in Rancho Cucamonga.He's a nice guy.Where has he been?Nobody knows since I saw him there.(chuckles)Thank you guys so much forwatching this episode of B2B.Follow us on Instagram @donutmedia.Follow me on Instagram @jeremiahburton.click like and subscribethat really helps us out.Let us know how we'redoing in the comments.You guys liked this nerdy stuff?I hope so, until next week.Bye for now.