Why is Slipstream GREAT but Dirty Air AWFUL?

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thanks nordipn now enjoy the video [Music] so a question i and a lot of people still get asked a lot is why is it that slipstream is such a good thing that drivers seem to desperately chase for a bit of extra speed but dirty air is such a bad thing that slows the cars down when you know both things adjust the effect of following another car and i did actually do a video on this in the way way back when with a janky bit of power pointing and a webcam microphone but since it still asked aplenty i thought it deserves a full remaster that i can be proud of now it's easy to forget as we walk around the air is physically present all around us this sounds a bit silly but on a human scale at normal human speeds it's easy to completely forget it's there at all that is until you for example stick your face close to an open car window while traveling and get absolutely blasted with the stuff until your eyes water and your hair gets knotted or if you just remind yourself of jeremy clarkson's atom face yes air certainly is made of stuff it has mass and pressure and buoyancy all the good stuff it's easy enough to walk through but it gets harder and harder to push through as you try moving faster and faster air like water is a fluid and if you've gone swimming or even just moved your hand through a body of water you know how much force it can take to push through it it resists you and it's probably easier to keep thinking of air as water in this video as the human experience in water is much closer to how an f1 car experiences air it is thick and resistant if you're moving on a little raft and you stick a flat hand or an ore face into the water to your left the left side will break as the water resists it and the raft will turn to the side as the right side outpaces the left similarly if an f1 car would stick a big flat piece of air onto one side it too will be pulled in that direction as the braking takes effect from the air resisting it the fluid air resisting forward motion is drag it's what keeps the parachute from plummeting to earth and it's what holds an f1 car back as it tries to accelerate as the car powers forward it is resisted backward by the air it's trying to push through and the amount of drag force pulling back on the car depends a lot on the size and shape of the car as well as the density of the air itself so if f1 cars were just big cubes on wheels they would experience a much higher drag force than the pointy slippery shapes they actually are but whatever the shape of the car or the thickness of the air the size of the drag is always proportional to the velocity of the car squared now this is a dramatic effect so say at 50 kilometers an hour your car experiences this amount of drag force it doesn't matter what the exact value is just call it f or whatever if you double your speed to 100 kilometers an hour the drag increases by two times squared so you're now experiencing four times the drag you did at 50 kilometers an hour at 150 kilometers an hour three times the original speed you'll have nine times the original drag at 200 kilometers an hour you'll be fighting against 16 times the original drag and by 350 kilometers an hour which is the kind of top speed you'll be reaching on the straights the drag force is now 49 times that of the drag you felt at 50 kilometers an hour now 50 kilometers an hour is basically nothing in an f1 car but try and remember sticking your hand safely out of a car window at 30 miles an hour and how thick the air feels pulling back on your hand now imagine 50 times that amount it's a lot and f1 cars are pulling a lot of power overcoming that those rear wings are dragging hard and that's why drs even exists to flatten the wing and alleviate a bit of that resistive force but that's why the slipstream is so powerful that's why you see drivers positioning themselves behind other cars on long straights and in the races and in quality when a car passes through the air at such speeds it pushes the air away on mass creating a low density hole in its wake and with less air in the slipstream there's less air to be fighting against and a significantly less drag and when the forward force to rearward drag balance tips forward that results in better acceleration and a quicker path to maximum velocity so on long straight slipstream can be super powerful you don't have to take as long getting to high speeds and overall you'll take a shorter time from corner exit to corner entry and high speeds mean overtaking you can use the slipstream to accelerate harder while your rival is fighting the drag and outpace them down to the next corner lovely now we saw a great example of that at the start of the russian grand prix sochi has a very long run to the first braking zone at turn two russell from third got a better launch than science in second but russell was out on his own pushing against the full wall of air and experiencing maximum drag science though tucked himself into norris his slipstream was able to accelerate at such a pace that he took the lead by turn two what a visible difference it made okay so dirty air then we talk about how following in another car's wake is so good for speed and error efficiency but we also talk about how following another car's dirty air slows you down and makes overtaking so much harder it's a real bug bear of f1 and the massive 2022 rule changes have a lot of focus around fixing that specific issue everyone complains about it i even made a song about it so how do these two ideas marry up consistently well it's actually pretty simple really and as with all things it's about the balance between cornering and straight line speed before we even consider other cars aero wakes we can consider the car on its own it has been designed and tuned to master the trade-off between going as fast as possible on the streets and being able to rock it through the corners traits which get in each other's way see if you just wanted to go fast on a straight line you wouldn't have this massive rear wing on the back which acts basically like a big parachute for all intents and purposes they add masses of drag which as we just covered is bad for outright speed but to turn through the corner at the kind of speeds f1 cars are capable of you need to push the tyres into the track hard the relationship between how hard an object is pushed against the surface and how much it resists sliding is linear and that just means if you push it down twice as hard it will resist being pushed along the surface twice as hard if you're going to throw an f1 car around a corner 150 kilometers an hour obviously you're gonna have to fight the natural urge of the car to just fly off the outside of the corner and these are 750 odd kilogram machines that's a lot of momentum to overcome just to get the tyre to grip hold of the track and allow them to take corners that fast you need downforce pushing them firmly into the ground downforce comes from the arrow the weight of the car alone isn't enough to push it down while drag pulls the cars backward downforce pushes the cars down i've got videos where i go into actual aerodynamics in more detail but to keep it simple here just think that if we use the car's arrow to force large masses of air upwards then those large masses of air will be forcing the car downwards no action without reaction and all that so in this case having a hefty load of thick air is useful to you you can push against it and make it work for you back in our raft example we could push the water with ores to propel and steer the craft you push the water back the water pushes you forward but imagine trying to paddle underwater just not really being there where you need it or being thin bubbly inconsistent like there's nothing really to push against well then you couldn't really control your raft well at all and that's the thing with dirty air when following a car around a corner it messes up all the nice thick consistent air you need to generate downforce so you can't push as hard in the corners you have to go slower you fall further behind and you lose opportunity to stay with the car ahead for when overtaking opportunities come on a straight or into a braking zone i mean dirty air is a little more specific than just the big hole left in the air behind the leading car f1 arrow is designed to do very specific actions like generate or boost powerful vortices off the front wing or throw out some of the air like a wall to dispel the messier from the tyres and all of these effects create chaotic conditions in the air behind so the air isn't just thin it's messy disruptive unpredictable the 2022 rules reduced designers ability to make such a mess with their overbody aerodynamics in an effort to improve quality of air behind and give chasing cars a chance to stay close to the corners we'll see how well that works soon enough but tldw for this video cars create wakes and mess behind them that reduce drag and downforce drag is bad for straight line speeds but downforce is good for cornering speeds hope that's clear [Music] do [Applause] you

Channel: Chain Bear

Views: 492,614

Keywords: f1, formula 1, explained, how to, racing, how does, chainbear, chainbearf1, chain bear, chainbear f1, chain bear f1, aerodynamics, aero, dirty air, slipstream, overtaking

Id: nivswe7Zyuc

Length: 10min 26sec (626 seconds)

Published: Thu Sep 30 2021

Reddit Comments

[u/JamesF890]

really cool video TLDR;

behind another car on straights - good

behind another car at corners - bad

[u/[deleted]]

Chainbear is repeating the same big mistake you often hear about slipstream: that it would be caused by the wake of a car having "less air" than the other air.

What's really happening is that an F1 car is pushing the air forwards, in fact exactly as much as the air is pushing the car back. At top speed an F1 car is acting as a 1000 horsepower fan pushing and pulling air forward (also upwards but that's less important here). It shouldn't be a surprise that the air right in the wake of a car is following the car a bit (that's precisely what a wake is), probably a few tens of milometers per hour. A car following closely will therefore experience a little less headwind, reducing the drag it experiences, and the top speed increasing by almost as much as that effective tailwind it is experiencing.

If that doesn't feel natural you can change perspective to a wind tunnel with two cars behind each other. The second car experiences the same air density, but is slightly shielded from the wind by the car in front.

The density of air really doesn't change significantly in cases such as these. For air density to change significantly you need to approach the speed of sound, that's how fast air is able to rush into a lower density region.

Some basic sources:

en.wikipedia.org/wiki/Slipstream has it correctly, though not that clear.

youtu.be/13PlkHbj3SM by an ex F1 earodynamicist, he does use pressure as part of his explanation but notice that he never mentions "density". Saying that a car has a low pressure wake is just saying that it sucks air forward.

[u/pHrankee1]

Chain bear is my favourite F1 YouTube channel by a mile. The animations are always on point and he makes good reasonable comments. Not a clickbaity chanel like several others.

[u/lukekennedy448]

Is it not the same thing? I always thought it was bad through the corners because of the loss of downforce for but good on the straights because of the loss of downforce.

[u/MrJacquers]

Cool, I was wondering about this.

[u/candidarchitect]

The thumbnail is actually enough to understand it.

[u/Risk_k]

Oh god that thumbnail. I can't be the only one

[u/markhewitt1978]

There's focus on next years cars no making dirty air. Does this mean they'll have less slipstream too?

[u/HTC864]

Good as always.