Aerodynamic Drag - Explained
ฝัง
- เผยแพร่เมื่อ 2 ต.ค. 2024
- What is aerodynamic drag? What makes a vehicle aerodynamic? How does drag affect cars? Drag is the resistive force a fluid places on something trying to pass through it. As your car drives through the air, the drag attempts to slow it down, and you must provide power to overcome this. As drag increases exponentially with speed, so does the amount of horsepower required to overcome said drag. Cars like the Tesla Model S and Toyota Prius have very low drag coefficients, allowing them to drive more efficiently at higher speeds.
Explanation of P=Fv
1. Start with power, power is the rate of energy use. Power = Energy/Time.
2. Energy is required to accomplish work, which is defined as Force times Distance. Energy = Force*Distance.
3. Power = (Force*Distance)/Time
4. Power = Force*(Distance/Time)
5. Power = Force*Velocity (P=Fv)
Please feel free to rate, comment, and subscribe!
And don't forget to check out my Facebook page:
/ engineeringexplained
Also check out my official website: Make suggestions, participate in forums, learn through logically ordered lessons, read FAQs, and plan your future!
www.howdoesacar...
Now on Twitter:
/ jasonfenske13
NEW VIDEO EVERY WEDNESDAY!
so pretty much to go 300mph, I need 1000hp and a Prius. okay.
+TheEVGAftw Don't forget balls of steel. Tesla with 1000hp would be even better and stable.
hahahahaahaha i like this guy. thumbs up 😂😂😂👍👍
Kawasaki Nerd I like all three of you! Thumbs up all around! 👍🏎👍🏎👍
There's a guy with a 2JZ swapped Prius... Not sure exactly how much HP it makes, but you can imagine how fast it is.
I knew all of these these theories but you explain them so freaking well that it organizes my own thoughts. Thanks buddy!!!
You got it, thanks for watching!
I wouldn't have guessed that the Prius is more aerodynamic than a Veyron.
I guess racing cars need some amount of aerodynamic drag for traction.
The Prius is probably optimized for max mileage.
xXshishamastaXx Yes, i understand that, you need the car to act like a car at 250mph and prevent it from getting unstable. But still i would not have guessed 0.23 about the prius.
The Veyron needs downforce, the Prius does not. A Prius at high speeds would be incredibly dangerous, where as the Veryon feels solid. F1 cars have terrible Cd's in comparison to road cars, but much higher downforce.
Engineering Explained can you explain this in more detail? Specifically, which factors determine CD. I, too, am surprised that a monstrosity like the Escalade has the same coefficient of drag as the Veyron.
In addition to downforce, the Veyron also needs much more cooling than the Escalade, meaning more inlets (which create drag).
thanks for keeping your promise and starting the topic of aerodynamics of cars
You got it, patience and I'll eventually follow through. :)
Yes!!!!!! You're making the series I asked you to make! I'm going into Automotive Engineering, and I really wanted to know about aero. Thanks, Engineering Explained!
Haha, finally got around to it. Some requests do get honored. :)
Nice video, can you please explain 4 wheel steering?
Great video! I see the 350z at .30 so I was curious and I went to wikipedia to check out the list to see the G35. The G35 coupe back in 2005 with a .26 drag coefficient. The G35 looks better for a reason, better design!
Awesome explanation. What I took from that video was: put a Veyron's motor in a Prius and boom. You're knocking on the door to 300 mph. Haha but seriously you're videos are great. On a different note, an Escalade and Veyron have the same drag? How is that possible?
My guess is the Veyron has less frontal area than the Escalade so it still has less drag overall.
For this reason maths is so important
It would be nice if you did a video explaining the trade off between low drag coefficient and downforce and bigger air intakes for cooling.
I think you'll enjoy some of the coming videos. :)
You think maybe you could touch base on some common aerodynamics of modern vehicles? Things like the little flaps in front of the wheels. I've seen cars that have the flaps in front of the two front wheels, some only in front of the rear wheels, and very few having them at all corners. I've never seen on suv/trucks or anything with considerable approach clearance at the front, but I'd think the same parts could apply, especially with larger vehicles having more surface area of the tire exposed. Likewise, what about mudflaps and how much drag they create compared to going without, compared to having the flaps in front of the same wheels. Also, (I know, bear with me) newer vehicles have more of a flat front cap, whereas cars similar to my old 93 240sx have a cap that turns inwards closer to the ground. Sharknose specifically. It doesn't "look" aerodynamic, but Nissan advertised the car as having a cd of .31, wind-tunnel tested and all by the engineers of Nissan back in the day, which was surprising to me! I also notice a lot of mid-optioned cars and wagons come equipped with spoilers, which iirc basically elongate the "trailing pocket of air", which helps reduce drag. On the same note, some spoilers (mostly aftermarket) and nearly every wing have a gurney flap at the trailing edge to increase effectiveness. Comparing to exact spoilers, one straight and one with an effective gurney, would there be a negligable difference? Ah, another thing on spoilers I've noticed is that, generally, on higher-end cars sporting a high-rake spoiler, there's essentially a matching diffuser underneath. Most run of the mill cars have nearly a straight, parallel spoiler and a large sealed rear bumper cover. Anyways, just a couple things I've noticed and wondered a little about through the years lol. There's definitely more that I come up with, I'm sort of a backyard engineer. I just finished fabbing a fitting a front shroud for my radiator yesterday, attempting to see what the old "30% opening expanding into the full face of the exchanger" would do for the cooling system. Well, that and mainly to seal the inherent openings off. Waiting some hot summer weather now haha. I think I've rambled enough for now man, I love your channel, keep it up!!
not sure if anyone else has said this but generally the A/C compressor kicks off when Wide Open Throttle (WOT).
Please do a video on tire tread/traction!
Going further, Drag is commonly made of two components; 'Form drag' and 'skin friction'. Form drag being associated with the area of the object that crashes directly into the air particles & skin friction being the drag that resists the air from flowing smoothly over the object. Great video, that! Very well explained :)
I was surprised that the Veyron has the same CD as an Escalade. That is very counter-intuitive. According to Wikipedia, they are about the same width, but the Escalade is roughly 30" taller. Even if you take into account about 8" of ground clearance that's a significant difference.
It may seem counter-intuitive at first, but start to think about what the Veyron needs. It needs good downforce at high speeds (this increases the Cd), and it needs a huge amount of air to cool the incredibly powerful (and "wasteful") engine. I say wasteful because gas engines are typically about 30-40% efficient, meaning the rest ends up as heat. A lot of this escapes through the exhaust, but much of it needs to be cooled with a radiator. The big air scoops to cool this monstrous engine reduce the aerodynamics of the car. The fact that it can go around 270 mph and yet has a CD of 0.36 is actually fairly impressive.
thanks alot .. you have always good and easy explanition :)
when an escalade is more aerodynamic than your car
Great video once more. What do you think about explanation of F1's new engines, ERS ?
2014 F1 Engine - Explained
Aerodynamic drag sounds soooo much better than flying cross-dresser XD
Great Vid ! Keep going !
I just want to know, how do you estimate the amount of power actually used for drag ? I understand that you have some losses (heat, ....) but how do you evaluate theses losses ?
1970 plymouth superbird had the drag coefficient of .28
There's a general hate for the Prius which I think it's a fantastic car to be honest.. aestetics could be argued by some and that's fine (even though I quite like those too), but from an engineering perspective Toyota did a great vehicle, they really focused on everything related with sustainability and efficiency, the only other cars I see does that now is the BMW with the I series and Tesla.
I was reading GM also tested the Prius in their windtunnel and started arguing that the Toyota actually had a higher Cd.. nothing against them, but instead of testing Priuses I think it would be better to follow what the Japanese are doing instead of sticking on their sharp edged boxes.
exactly. i dont know why people hate the prius. it was never made to be a good looking car nor was it made to be a performance car. people are complaining on how its ugly and slow to drive, yet they dont notice its the most affordable fuel efficient car you can buy in the US. the efficiency to price ratio is currently THE best. sure a Volt or Model S is all electric, but you're paying much more for one of those. also consider that the Prius is one of the most reliable hybrids you can buy on the market. its also much more versatile compared to a Insight or other hybrids.
bmwmsport11 Yes, I agree. The Japanese really managed to make a car which was a great engineering innovation combined with the first and best hybrid market success. I am really hoping BMW will do the same, I personally think what they did with the I series is just faboulus from all points of view.
The Prius in an incredible vehicle. Anyone who simply wants a commuter with good gas mileage, a Prius C is incredibly difficult to beat. 50 mpg for $19k. They're fantastic.
Engineering Explained Btw, does the Drag force formula take into account both skin friction drag and pressure drag?
thank you
hi at 3:10 when you say plug in the data.. im struggling to understand that equation to end up with 900HP needed. Could you please write the equation in here so I understand. thanks!!
Awesome video! I can see now in more detail of how much of an aid DRS is in Formula 1 racing! haha
Also, a quick question about Aerodynamics and F1: By having a less Drag Coefficient, does that also allow greater downforce? Or is it just based on the design of the wings that allow an F1 car have that supreme downforce?
It's a balance between drag coefficient and downforce, typically they both increase together.
I would like to see a more in depth review of aerodynamics, if at all possible. Something that would explain how each component on the car's body is affected and how to achieve the most optimal shape. Just like they do that in a wind tunnel or in a simulation. For example, I heard that a very pointy nose is worse than a more upright nose.
I will have a few additional videos, and I have several already. It's worth checking out my playlist on F1 cars. th-cam.com/play/PLAC8F7A33D3F85C1E.html
If you want to dabble in engineering plz dont use imperial units. Ever.
Engineers learn to become comfortable with both. For those who are not, conversions are quite simple.
You're really good at explaining, keep it up, it's very helpful - THANK YOU ^^
On September 2, 2019; the Bugatti Chiron sped to the world record with a 304 mph run. Your video made me think: the next record to set: the fastest car with the AC on.
So considering high pressure wants to vent to low pressure in ordee to equalize, would a rear mounted radiator with intake ducts, mounted just behind and in between the taillights, have a vacuum effect on it due to the low pressure wake behind it? Also, would this radiator venting into this wake, help reduce the low pressure wake and thus reduce drag?
I have one issue with your analysis. Shapes (cars) do not have a single coefficient of drag. The coefficient of drag varies with Reynolds number (Re = (density*velocity*length)/(viscosity) ). The Cd of a Prius going 5 m/h does not equal the Cd of the Prius going 50 m/h. So my immediate question is at what Reynolds number is the Cd evaluated at.
The cool thing about this topic is that for a given shape, Cd = f(Re). That means if you know either the Reynolds number or the Cd and you know the trend of the shape in question, you can find the missing term. There are well documented Cd vs. Re graphs for simple shapes (smooth spheres, rough spheres, etc.).
I like the analysis, I just wanted to clear that up.
Hey man your videos are awesome !!!! Can i ask you a question? I've heard that you can increase the downforce a car produces but at the same time reduce the drag...is this possible ??
I suppose yes. If you have a very inefficient way of producing downforce (like a flat angled plate) and you then changed this to a more aerodynamic wing, you could maintain the downforce and reduce the drag.
Engineering Explained Cool ! Thank you for your answer :P
Fdrag=1/2pv^2CdA , so v must be constant velocity relative to the wind? How about if we are accelerating what is the formula? I'm sure if drove a bugatti I would smash the pedal lol
+Jomel Sagsagat To calculate your drag at any moment, you would use your velocity at that moment. If you're accelerating, that just means your drag is increasing.
hello, can you explain dual-mass vs single-mass flywheel?
Thanks
sir, i am a student and i work in an automotive team which participates in SAE student formula competitions, i would be really glad if you could let me know as to how to calculate the frontal area of a car. ?
Thank You.
will you please show some work on how to calculate coefficient of drag. thermal fluid which i fond very difficult.
Excluding drag from the equation, a duct that absorbs air at the front grill and move this air to the back of the car, to the rear spoiler, would increase the downforce? In that case, the air must be redirected to the upper part of the spoiler, or just throwing it in the general direction of the spoiler works? Thanks!
You just earned yourself another fan!
Thanks!
Sweet video mate. I knew how much effect drag has practically by experience but you've put it in numbers that are easy to understand and reduced it to it's mathematical form.
Once again, great work.
Did you know painting your car red increases horsepower by 200%?
That's only for brake calipers.
hahahaha so true
I think you got it confused with painting two white stripes along the middle of the car.
god why are all these intelligent people becoming more attractive. I'm so jealous.
Vw xl1
Cd=0.189 a=0.279 p=1.225
300mph needs roughly 77000watts which is around 100bhp
So 120bhp engine can get it up to over 300mph
This seems odd to me but the maths is right so plz correct me if I'm wrong
+Steve Zhang Just at a quick glance, you're showing the area to be 0.279 m^2. That sounds like a small go-kart.
+chitlitlah that's what wiki told me
That would be the area of a square roughly 1/2 meters or 1 1/2 feet on each side. There's no car anywhere near that small.
770kw = 1033 bhp
300 mph = 480 kph = 133 m/s
P(W)=0,5*0,189*0,279(m²)*1,225*113³= 44,6kw
P(hp) = 606 hp
OBS: Standing person has Cd= 1,2 A = 0,5m². Lying down Cd= 0,3 A = 0,097 m²
So, it's a Alladin's flying carpet with the driver lying down and powered by a compact jet engine. lol
Good video with one HUGE minus. All the units need to be metric. That is a standard EVERYWHERE in the world, even among American scientists. Most of the American public will most likely not understand it anyway, so why convert it to this idiotic system? Besides your videos reach broader, worldwide audience on TH-cam. From now on, if you want to be regarded as a serious guy, who wants to be respected in the targeted community, please use metric system (SI) only.
I guess I'll always be regarded as unrespectable and frivolous. Oh well, for the rest of the serious folks out there, fortunately unit conversions are astonishingly simple.
Engineering Explained Well, it is not about how easy or difficult conversions are. I am sure that in the professional engineering field also metric system is used, perhaps the exception might be some American mom&pop shops (just an educated guess from watching some TV shows). I believe it would be actually beneficial for you (broader worldwide audience) if you stick with widely used metric system, instead of referring to length in King's nose length increments.
Fair enough. As a professional engineer, working for a company much larger than Mom and Pops, I'll let you know that both units are used, and you should be comfortable with either. Metric is far better, and far simpler, but addressing your audience is important. I created two videos as an experiment before:
How Weight Affects Acceleration - English Units
How Weight Affects Acceleration - Metric Units
English units has double the views.
How can I use kilometers/h instead of miles/h ?
As for HP and CV (both translate horse power but have a slight different value in Watts - 746 and 736)
Or is it possible to use in Watts?
So he's saying that vans have a lot of drag because it's not that aerodynamic. Super cars are aerodynamic, the air flows by the smooth surface of super cars, therefore making them have less drag and makes them faster.
Area should be expressed in ft squared. Excellent video.
hi how are you doing?, i would like to know if the Cd is always constant, i mean it is gonna have the same value does`t matter at what speed you are going?, and if you know the Fd using CFD simulation, you can use it to find the Cd?, thanks
I really enjoy your videos on how you explain things. As a note, almost 55 years ago, a 1969 Charger Daytona had a drag coefficient of under 30. Look it up. However it was made especially for high speed oval racing
I swear to god Koenigsegg and McLaren together could make a 300mph car, easily
Can you tell me the relation between downward force and drag(Why drag increases with downward force)
Engineering Explained Fun fact is GTR also have 0.25 cd and F1 have 0.3-0.34. The reason is the "wing" and "flaps" Those create downforce by air pressure. Those amount of pressure also known as Drag. GTR doesn't have big wing or flaps. In other word, a Chevy crews and Prius may have better cd than a race car and a fast sports cars. like Agera and Bugatti.
There is also something known as lift and drag ratio. Is an easy formula:
force of lift/ force of drag.
If a car weight 1.36ton and have a drag of 800kg at 300km/h so the formula is:
1.36/0.8=1.7t
The thrust=weight/lift and drag ratio/ 1.36/1.7=0.8t.
The drag of a car can also effected by the density of air, car overall area and drag coefficient. The speed of sound on land in 15 degrees is 1225km/h, at 10000m where plane usually cruise at is around 1078km/h because the kg/m3 at 15degrees at 0m is around 1.225kg/m3 at 1000m is 0.413kg/m3.
Please bear with me one more time sir. I tried to plug these but i can't get the same answer as you. 1.225(density of air)*0.36*22.3*64,516(254^2) = 634,469.69
1.225 kg/m^3 for air density, and you're mixing that with 22.3 feet for the area. You'll get bad numbers from mixing units.
254 mph = 406 km/h = 113 m/s (rounded)
22,3 ft² = 2 m² (rounded)
Then:
P(W) = 0.5*density of air(1.225 kg/m^3)*0.36* "2" * "113" ^3 = 636kW
P(hp) = 865 hp ...
Please consider rounding 865 to 900 ...
That's it.
Lucas Detex Olá! Vi que você é brasileiro e queria te pedir que você me explicasse onde ele tirou 1482 pois eu não pude entender. Obrigado.
É exatamente o valor de "potência aerodinâmica" necessária para chegar aos 300 mph, o Jason fez uma regra de três, mas vc pode confirmar usando as fórmulas do quadro, mas tenha muito cuidado pq os americanos não usam o SI, pra vc ter certeza doque vc está fazendo, apenas use velocidade em Km/h, distância em metros, área em m², força em N e o mais importante Potência em Watts. Depois é só converter.
A galera nos comentários está errando por causa disso.
So if frontal sections and sleekness essentially of a car produce the efficiency of drag, why do F1 cars which are extremely low profile have such crazy high drag numbers like 0.7-1.1????
Apparently I dislike this. I have no idea why. I can't change it either... weird.
Good video as always. Any idea of the Cd of the new koenigsegg?
What do you know about the variable spring rate suspension system on the P1?
Hey, I want to ask ,all these calculations and studies are only effective in high speeds situations over 100km/h is that right????can i use these techniques in order to improve my car performance in events like autocross for example ????
Good explanation! I like how simple and direct it is! thanks!
mercedes cla is ever slipperier than the tesla s
Nice to see the calculations. But what about the physicals, like what happens to the air hitting leading surfaces and the low pressure behind the vehicle holding it back.
+satish jasti because when the friction increases between your tyres and the asphalt due to downforce, you get drag. I had a nerdgasm for being able to explain something to someone. I love learning.
Engineering Explained you should check out the 2200hp speed demon, the fastest pistonpowered car in the world
nowdays car companies should watch this video if they aiming for 300mph vehicle :D
Does lowering a car improve or worsen drag coefficient, or is that question too complicated to easily explain?
tesla model s has 0.23 (new model)
What is the dodge rams Cd?
That big brick wall grill
Why exactly do f1 cars have a much higher coefficient of drag?
Due to the massive amount of downforce they create.
very nice explanation..i wonder if u could explain some terminologies on active steering technology..
Nice explanation thanks. However what would make the car more aerodynamic? What can I do to it?
But cars still have a lot of drag in the first place, so you would either have to bump up the power, or make it more aerodynamic.
Engineering Explained Go look up F1 rear wing's lift coefficient.
I am not the best at math but I am interested in car design. Do you have any resources that could help relate math to car design.
Is the frontal area A only the 2d section of the front bumper or does it also include the windshield?
good job
is the pressure difference between the front and the rear of the car, a cause of drag. If no then what causes drag pls explain
A challenger has a CD of .39, that means it’s less aerodynamic then an Escalade 😢
why don't you show the calculation instead of equation. i mean live work.
How are F1 cars so fast with such a high coefficient of drag?
The A (cdA) component is tiny.
High power, light weight.
The new Bugatti Chiron has around 1500BHP, reaching a top speed of 261MPH with a drag coefficient of 0.35 when in top speed mode. But you said the old Veyron with a higher drag coefficient would only need 1570BHP to reach 300MPH. I don't see how the Chiron isn't getting anywhere near 300MPH even tho the drag is lower and it has more power.
+AHMAD FARWANA Chiron's top speed is estimated at 288; 261 is electronically limited. Check out my video "why has no car hit 300 mph"
you ask for almost 1600 horsepower, you get 1600 horsepower 3 years later
Hello there, as you can see my name is Jake Adamski, and I am doing a school project on Formula One cars. For my research I would like to use your video, but I'm having a hard tome following the equations and how I would plug in the information. If you could help explain/go through the information or even make another video, i would be very appreciative. Thanks for this great informational channel.
See the video description for a bit more detail. That's all I can offer for now.
What about the paint of the car, and if it's waxed etc, smooth. that would also make it more slippery right?
I've heard some sort of rumor (donna where) but to paint vehicles with Figher-jet paint since they use it because it gives less friction.
Just a thought, what do u think Enginner?
I think fighter jets travel at much greater speeds, so things like surface friction are much more important. It's probably very, very similar regardless of what condition your paint is in.
What is the minimum speed when the aerodynamics is applicable ??
Mercedes CLA180 BlueEfficiency .22
so is it true that by dividing the frontal area or the cd you'd go as fast with half the power?
Good video, well explained.
The New refreshed Tesla Model S 2021 has 0.208 Cd & 1020 hp.
please explain to me, if u can. How it possible - Mclaren F1 have less max speed than a VEyron, but has better Cd 0.32 instead of 0.36 Bugatti`s. Bug has worse power-weight ratio also. I can`t understand how it works. I try to understand, but I can`t. Explain to me somebody please.
How about the Mercedes-Benz CLA?
wait. Veyron has same Cd that Escalade does?
+Hea Mees i mean i know the Veyron has lot of cooling systems, but Escalade is a just a big box
+Hea Mees you're right, that does seem weird
That was really good, you've now sold me dreams of a tesla s with a 1200hp supersport engine achieving a dangerous 300mph with no downforce to keep it stable. 👍 good work
Haha, now you just have to add cooling ducts without affecting the aerodynamics. :)
Engineering Explained ahh there's always something lol 🙈
nice explanation! thanks!
this gave me a huge amount of respect for the prius
lowered Veyron and an Escalade have the same Cd? That cant be right surely. Source?
The cars are very aerodynamics, but they require a lot of downforce and cooling, which increase drag.
People better know fractions and algebra 1
Does anyone know how to calculate downforce?
Thanks for the vid. I'm bad at maths and still working to fix it. Kinda like 60% understandable and the rest are homeworks for me. Thanks a lot EE 😁
Compliments for your videos, they are great! What about a new video explaining engine knocking?
Thanks for the video, please post more videos related to aerodynamics.... And can you suggest some books to start studying the basics of automotive aerodynamics ?
I've always wondered about the aerodynamics of the veyron. It's no 458. The shape doesn't look too efficient as far as cutting through the air.
Tsx has a coefficient of .27. Pretty impressive for an everyday sports sedan.
You have to really take into consideration how much downforce is needed. A TSX does not need downforce, or as much cooling as a Veyron. Both of these create drag. The Veyron has a very stable shape at speed.
6:57 in a second ,your body language says, "Im a F******* Genius " :D
I did get a lot , Thanks for your time explaining this . :)
I just got home from watching the new Need For Speed movie. In the movie they clocked in a 900hp ford Shelby at 234mph. I am trying to check this or atleast estimate if that is even possible. so far I have found out that a Shelby has a coeficcint of drag of.36 and an area of 24.1sq ft
I tried it out and I got in order for the shelby to go anywhere near the speed that It went in the movie where they stated it had somewhere in the range of 900hp,should have at least somewhere in the range of 1522 horse power. does that sound reasonable?