Keyboard Dancers I don't think you can compare them, one is a mechanical engineer and Kyle is fluid mechanics... both are great and but not comparable.
you are an inspiration to me man. Currently studying Aerospace engineering B.S. at the University of Washington with a specific interest in applied aerodynamics and you have some brilliant explanations for a lot of crucial topics! Cheers
TL;DR version: Around 100kph/62mph, downforce starts to make a worthwhile improvement. Speeds that less attentive drivers might notice the difference are closer to 160kph/99mph, if not faster. So just focus more on mechanical grip if your trackcar won't be hitting much faster than those speeds.
I got: If your aero is SERIOUS and well designed you can expect an effect at around 100 kph but only if your car is VERY LIGHT. If your car is heavy and you slap a massive wang on it you get nothing even at very fast speeds.
The Ti22 was one of the very early cars with serious down force. So much so, at 100 mph, it could have driven upside down on the race track. Its first race, it lapped the complete field within the first 5 laps of the race. Unfortunately, the loss of down force due to traffic, resulted in loss of control and a serious crash. Being they crashed, they did not get the sponsorship they needed to continue racing, and struggled heavily to stay in business. That is why you don't hear much about them in the history of Can-Am.
DUUUUUUUDDEEEEEEE I'm currently 2nd year Mechanical Engineering and I LOVE your videos! Man, you answer a lot of the questions I've had about aerodynamics, etc. Thank you. Please keep it up!
Maybe I'm wrong, but I'd venture to guess your audience has a rather large % of nerdy car enthusiasts that are also non racers. I appreciate you and several other RU-vidrs explaining in detail the parts, functions, and physics of aerodynamics, mechanics etc. as related to automobiles. However, as good as it is to dream about driving an F1 vehicle and obsessing about different aero features etc. I'd really love to see more information that is more applicable to real world applications and common modifications / mistakes. For example a common mod is coilovers / lowering springs, and while there are commonly explanations about why lowering a car is better for performance, I've not heard much about what happens if you lower either the front or rear too much in relationship to each other (both from an Aero, weight transfer, brake bias, etc. perspective). I'd very much love to see more science applied to road cars. While your formulas go deep into cornering speed with the aid of down force, I'd very much like to see some info about aerodynamics and stability in a road car.
Ppl be trippin bcos i put my bonnet scoops on left to right right to left. Only bcos i want the air to travek over motor and take heat out with it aswell as make downforce i own a suv 2013 trax chevrolet which is prone for heat in engine.it has a flush front and its not really made for 140 km/h standards. So i checked my temp i have dropped it from 105c temp to almost 90c by doing this.yes it looks awkward at fist sight.but i got my achievment done.im also gwtting downforce on front tyres.as the car use to feel really light as i hit ,140km/h speed bands. Thanks to this guy.he made me think of the best output i could of done with bonnet scoops.i was aiming more for outcome then what it looked like. Less turbulans under bonnet and more out going heat flow
What i don’t understand is why in automotive aerodynamics you calculate ClA with the frontal area and not the top area as you would do with plane wings. I imagine you can get this coefficients from simulations in which you can choose what area you want to relate to, but still it sounds strange
From my understanding aerodynamic forces acting on any form of wing are usually considered more of a pull than a push as it's the lack of air underneath that sucks "pulls" it down opposed to the denser air above "pushing it down" a bit pedantic but had to get it off my chest, please correct me if you think I'm wrong and why.
Excellent Presentations. Keep up the good work. I WOULD though love to see some explanation of the working of the kind of front splitter mounted vortex generators that have sprung up all over the place in prototype racing. Because to me they seem to generate a vortex spinning in the wrong direction. ...??
The more common the information becomes, the more common the knowledge of that information becomes. Of course the desire to learn is required. Honestly though it wasn't that complicated, at least in my opinion. Interpreting the equation of lateral g is probably not intuitive, but he does show the curve on a graph in his spreadsheet.
I like College level stuff. Even if I don't understand what's there the first or 2nd time, if I keep at it, eveuntally I will get an understanding of what's being said.
I don't know if this is a stupid question or not but is a car more aerodynamic in higher altitude then lower altitude because of having less air to cut through?
According to Clapeyron's equation gas density is proportional to pressure and inversely proportional to temperature (k*P/T). If you compare Zugspitze, (3 km over sea level 701 hPa, 270 K) to sea level (1013 hPa, 293 K) you should notice about 25% lower air density, which should decrease drag. On the other hand you have over 30% lower oxygen pressure which makes breathing and burning fuel much more difficult.
Is lift considered in your calculation? I think most steet cars would normally generate lift as they go faster. So compared to lift, some little downforce should add significant cornering force.
Yo, I just recently found your videos and they really pulled me in, so great stuff. Anyways what I really wanted to ask is: I'm looking to studying Aerospace engineering or Racing engineering(leaning more towards aerospace) so I would like to ask where should I do that? I live in Lithuania so there isn't really that much into such things, and I would like to get into a strong University/College if possible, so I would like to get some recommendations.
Very interesting! Where do you think Cl would go for F1 if there was no such limitation? Or what kind of Cl numbers you think are in the best time attack cars? Almost begs the question -> would it be almost better to lower Cd in terms investment (time & money) unless you can afford to do really serious aero The impact of aero is indeed quite small
Im in no place to critisize, but its meant to be constructive: you didn't mention that a wrx without wings probably has a positive CL, so if the wings cancel that out ... Actually im rethinking that: does it make a difference in grip-difference (delta grip if you will) if you go from a CL of 0.3 to 0.5 or -0.5 to -0.3. In other words does less lift give the same proportional grip benefits as more downforce and especially how does that apply in a real word condition with the wrx? Is it easier to cut lift than to create downforce? Might the wings of a wrx have more of an effect than you pictured?
Kalimerakis The rear wing on a WRX is about 0.3m^2 in area, and given its terrible profile probably only has a Cl of about 0.3 off this area. This would be a whole car CL change of 0.3*0.3/(1.5*1.6) - wing Cl times area/the approx frontal area, which gives 0.0375 change in Cl for the whole car. More extreme wings with say 1m^2 surface area and a CL of 1.5 will give substantially more gain (around 0.625), however note that that is a really good Cl and pretty extreme wing area, yet is still only 0.625. Your laptime difference is roughly proportional to the delta, there is some degree of nonlinearity, but it's pretty close to proportional. Cutting lift and creating downforce are really the same thing, in saying that it's probably easier to cut lift as it just means you have to fix poor design, while increasing downforce means you need to come up with something special. A time attack aero kit on the WRX will have more effect than I've shown here, but the factory wing or a small GT wing will not.
+KYLE.DRIVES Hey Kyle I love your videos. I really would love to see if possible if you could get a car like a WRX STI into a wind tunnel so we can see not just the air flow but if aggressive wings from the manufacturer actually produce downforce and reduce drag. Thanks and keep up the good work!
The thing with wind tunnel testing is, when you are doing it properly, you actually don't see anything! Normally us use force measurements, pressure probes and PIV, all of which take non visual measurements. Perhaps though the youtuber GraysGarage might be of interest to you, he uses hydrogen bubble visualisation in a water tunnel to look at aerodynamics. Thanks for the compliments!
+KYLE.DRIVES Yes I absolutely love Grays Garages videos! Maybe you guys could team up and do a video one day. I know that most OEM spoilers will help with reducing the high pressure areas at the rear end of vehicles. However I was just curious if high wings and such actually make real down force, with the exception of supercars and hypercars which most do.
+Kalimerakis this video makes some great observations, specifically that even in supercars that are production cars, the downforce is trivial. but your observation is important. for a production / sports car the goal is to get rid of lift. they did a lot of work to get near zero! you kind of need to on a fast car just to make the car not kill you. drive a random 70's car 100MPH, the front steering is LIGHT. i will argue with kyle on 1 thing, and claim eliminating lift isn't exactly the same as adding downforce: a spoiler might be useless for downforce but could eliminate some lift, if it breaks the car's intrinsic airfoil-like shape. a front air dam might reduce lift but not create downforce. weatherstripping rear edge of hood the same. of course for a new car the manufacturer has already done this perhaps. i suppose first question is 'what is the mission?' -- in racing, 1MPH average might be difference from first to last. for a street car your first yield will be cutting weight.
I have not seen any your videos of canards yet. Also I've seen small projections near the side mirrors of a Toyota Vios and most Lexus sedans. Does this explain the buffering low rumble when you open the rear windows? Thank you for your very informative lectures.
Colin Terry I believe Engineering Explained released a video on this recently you may want to check out, I can do another one in my style on it if you would like? A lot of people have said they prefer my in depth approach more, so I understand if you are still requesting it.
Yes, exactly. I like Engineering Explained for the large number of topics he covers, but like you say, I do prefer your approach. I like being able to have deeper understanding and I really appreciate you taking the time and effort in your videos. Thanks again!
I did not catch the program you use for your spread sheet. Would you share that? Sorry for that but it looks like a great tool. And I enoy your videos since the spoilers video. They have had a good impact for when I go to the race track with a race team.
Angel Alvarez Sorry, it's a JKF proprietary simulator sheet, you get it included with any of our aeromap packages or CFD design packages. Check this out for more detail: jkfaero.com/packages/ Thanks for the compliments!
Brilliant, Kyle. Is possible you could do some more maths work please. I am studying a BSC degree in motor sport. And find your clips brilliant as learning material.
I apricate what you've done here with all the maths ( Yes there is an S on the end of maths ) The presentation is very good and concise as well but you're missing the the main effect...... The phycological effect when you turn up a meeting with a massive aero package that makes the Bat Mobile look like wet paper bag..... even if weight of the kit adds more down force than the actual aero, the look and presentation of a monster aero set up is phenomenal.... But I do apricate your video and presentation. (Not trying to undermine your hard work)
Hey Kyle, I'm doing some simulations for drag strip times taking into account air drag and its x and y components. We agree on the drag magnitude equation, but you are simplifying its vector quality by just throwing all of it on the y axis for the cornering calculations, aren't you? Shouldn't you have a coefficient between 0 and 1, so that part of your drag is you just having a negative acceleration on the x axis?
Is the OEM really interested in down force to increase cornering speed with stock wings and aero? Couldn't it be primarily to stabilize a car at speed or fine tune handling characteristics.
In the case of most non-super/hyper cars, the wings are basically for looks only. They typically have minimal area and a poor profile which will do little at any sane speeds.
You'd need some strong tires I'd think, because of the amount of increased weight your car has while under a decent amount of downforce. Formula 1 cars produce about 1.5 tonnes of downforce while under 230km/h. The minimum weight for an F1 car is about 720kg, which means that at 230km/h the car has more than doubled its weight. The other problem is that downforce also creates drag. The third problem is the length of the corner. The faster you travel, the more distance you make.
At really high speeds Newtonian physics no longer apply, relativistic concerns come into play. The faster you go you will gain mass, so 'm' is no longer a fixed quantity. I'm not sure about how relativistic shrinkage of space in the direction that you are traveling would come into play..
I apologize for this question not applying to the topic but, i want a real experts opinion. I have a 1993 240sx s13 hatch with a Blown sr20det black top. is that sr20 worth rebuilding or would it be more cost efficient to buy a crated and remanufactured KA24de and if so would that motor be strong enough to run 6-12 lbs of boost on stock brand new internals?
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
Somewhat unrelated but... You calculate the dendity of air as 1.22. How would you. calculate the increase of relative air density when driving in rain and therrfore the increase in fuel consumption for a given speed? Just looking fof the maths 😃
Rain has almost no effect on air density, and at the speeds where aero matters you are far more affected by the loss of grip on the road (wheel spin in a straight line at high speed is possible). A very heavy rainstorm may drop an inch of rain in an hour - the necessary formulas are a bit beyond me, but fortunately someone else has done them already at www.dmcinfo.com/latest-thinking/blog/id/206/geek-challenge-rain-drop-density. The heaviest rainfall rate ever recorded was 1.23 inches in one minute (which would be nearly 74 inches if it had lasted an hour, but fortunately it didn't). The record for one hour is a 'mere' 13.8 inches.
I think most car enthusiast and modders are not race engineers, so my question is does Aero and Down Force play a role in other areas of driving for real world street applications? For example, I have a 2014 Honda Crosstour EX-L V6 AWD - 4,300 lbs - 4,900 lbs when loaded... It has a fake skid plate up front, that definitely pushes the air under the car rather than around it... So at 90 mph (144 kmh)... Does this kind of lift at highway speeds produce a noticeable difference in vehicle stability? And would adding down force be any effective in countering this for a regular street car... What about if you lower the car? Same skid plate but closer to the ground? Would the smaller gap increase the pressure underneath the car? generating more lift? Would Aero / Downforce be any different with a lowered car vs. a regular ride height car? Thanks.
Unless they somehow made some horrible mistake and the front end is picking up tons of air then the effects should be negligible. That is on regular road use, if however you were doing high speed races with hard cornering where every millisecond is the difference between winners and losers.... then you have reasons for concern.
MsSomeonenew The rear is 3/4" lower than the front. With a fastback design and no real spoiler, there's definitely a steeper angle to increase lift. I had 4 people + gear in the trunk that definitely lowered it more in the rear (relatively). Even though I'm riding around 4,900 lbs, I can feel a huge difference in stability at speed... with the exact same setup (only difference is springs). Now, you could argue that because the springs are stiffer, I don't have as much traction in uneven roads, but I'm feeling the difference even on a straightaway with descent highway road surface... so I'd say the aero part of it is definitely a factor at speed... (I don't notice the stability issue under 70 mph for example).
You have almost an inch of height difference? That should not be there, and yes that would count as a serious defect that picks up tons of lift on the nose.
Aero plays a big role in speed wobble. By reducing a cars side area, you reduce the drag induced by cross winds. A real life example is on a motorway where you can travel at 100-140kph, which is fast enough for some significant aerodynamic forces to be at play. You may notice older "boxier" cars, or motorbikes, which have large lateral areas versus the overall volume of the vehicle, will feel a sidewind push on it more aggressively than a sleeker lower profile modern car. This is why modern cars are not optimised purely for the air coming face forward at it, but also you need to account for cross winds, so that you can comfotably drive in a straight line on a motorway without unexpected sliding (speedwobble) while driving in a straight line. So to answer, front end downforce/lift has not a huge effect, maybe keep the z force near zero or slightly at lift, but drag is important on the front on axis, to reduce fuel economy, and on the side on axis to reduce difficulty in steering at high speeds
the difference you feel is probably due to the changing Suspension geometry rather than aero.. 5000 pounds are almost not effected by small aero at low Speeds.
how can A be derived simply from frontal area? We know the floor of top class race cars makes the majority of downforce from the underside of the car, and the larger area of the floor will make more DF than a smaller one, yet the frontal area of a given flat floor is virtually nothing and the same if its 6 ft long or 16 ft long.
Typically A is derived from frontal area of the whole car this is due to the fact the floor has little to no effect on frontal area as you said... and it does play a big part in the generation of downforce. What I think your wondering is what is the Coefficient of Lift derived from, this is from the "Total area" of the vehicle typically viewed from the top down and bottom up. They take a measure of negative pressure underneath and positive pressure on top. There are also some forces that can be calculated from the front, such as wings and splitters, but these also incur a penalty which is that the force is split between vertically and horizontally this is what is defined as pressure drag. I hope this helps and I'm sorry if i am assuming your question wrong.
hmushmann2 Depends how big you go with your aero pack, as far as I'm concerned there is never a track that would be tight enough for aero (as a concept) to not work on as long as you have a light enough car with big enough wings for the job. One need only look at Monash Motorsport's dominance in Formula SAE, which probably has the tightest race tracks of any class. i.ytimg.com/vi/3o9fUmfntC0/maxresdefault.jpg
hmushmann2 Ridiculously short gearing, I raced one of these when I was back in university and you were maxing out 5th at about 150 km/h with a 14000 rpm rev limit! Pulled pretty hard to that point though.
KYLE.DRIVES reminds me of my 125cc shifter kart. Maxes out, depending on the final ratio, around 120km/hr; but that is with a 45hp motor, so relatively the kart has tall gearing compared to the F-SAE machines.
now....i aint too bright...and i was born that way....but if i understood ur video, then the ideal setup is active aerodynamics (cost being a separate issue)?
If you are doing high speed racing and every fraction of a second counts, then absolutely. For hobby driving however it will make more difference if you just imagine the car is faster.
I would say absolutely. They work always. Problems come from looks department, getting car through MOT and most propably managing heat sources under panels. I am trying to battle this on my own car (Z3 Coupe) too. But there is always upside, one of them is better economy.
I have always been of the belief that flat-sheeting the bottom of a car has to have advantages- if only to reduce the drag from all of the "lumpiness" under there- considering that the air travels under a car as well as over it! Most serious supercars have flat bottoms, and they have spent $$millions on R&D to come to this conclusion. A significant reduction in underfloor drag gives smoother, more laminar airflow- which is exactly what you would want feeding into a diffuser, as opposed to turbulant eddys. Also, compared to bolting on wings and dive planes- you would NOT be increasing frontal area and hence drag. The trick is in "fencing in" this airflow- if the car has to be road legal- you cannot have skirts down to 5mm off the ground for example- which is why supercars and such use clever vortex generators to contain underside airflow.
@@arealassassin Reading your comment just gave me an epiphany moment. I always wondered why in videogames (I am too poor to afford a real car TT~TT) like Forza, adding skirts on the side of your car tends to reduce drag. It never occurred to me that these skirts provide an actual, functional purpose beyond matching whatever front and rear bumpers you put on it. But it makes perfect sense! It's kind of like the endplates on a wing, but for the entire underbody of your car!
You might be interested to know that some SCCA "A Modified" class autocross cars are making over 2000 lbs of downforce at only 35 mph! The downside to that is they are so draggy that they can't go much faster than 90 mph, even with 300+ hp.
bullshit 2000lbs = 8896 N 35 mph= 15,64 m/s -8896=0.5*1.22*15.64^2*Cl*A Cl*A=59.6. these number is really off, even if you have a total wing Cl of 10 (which is far from reality) you will need to have a total wing area of 5.9 m^2, which we know that it doesn't have.
there is no way!!! think of a light aircraft that has huge relative wings. they need over 35mph (like 35-70 mph) to get lift to overcome similar weight.
Hi there, I'm an irish engineering student doing the aerodynamics of my college's formula student car. Your videos have been a great help in researching the basis for my designs however I'm having trouble comparing my design iterations and I was wondering if you could please send me the excel sheet you have? it would really help me out so much!
I hate to say this but that spreadsheet was for his personal business, if you need something similar to this I would point you in the direction of a program called Optimum Lap, is a virtual lap simulator that provides much of the same information and some good help with adjusting things like gear ratio and seeing the potential benefit of aero iterations on lap times. ( Its also free to use)
Not useless if they are all extreme in nature (so much so they would be way over the top at any elevated speeds). In the case of typical street setups, absolutely useless.
Sometimes manufacturers design cars to be dangerous at highway speeds and those small aero mods can really make the car a lot more stable even at legal speeds. Some examples are minimum ride height requirements for different countries, as well as removal of trim like wings and fender flares to conform with specified standards.
Kyle I feel you are relying on the simulations too much, the numbers they generate as fact and not considering the human element. The difference in feel of a balanced car with even mild downforce is considerably different to that of mild lift at speed and in transient cornering situations. The ultimate grip may in fact not be that different, but the issue of driver confidence in a aerodynamically stable car is one that should be taken into account, particularly at speed and in varying aero conditions that usually occur on a circuit or in traffic.
Is is possible to crash cause you went "too slow". is it only a legend that for example you go in a corner 100kph and crash but if you go like 140kph you make it through?
If you are going slower then it will be easier to turn into a corner because your velocity forward less so, you need less sideways force to impact the direction of the car. In other words, when you are moving quick you need more sideways force or the forward force will take over and you will not turn as much.
An awful lot of filler before getting to the subject matter, sort of. I've always been guided by the take off speeds of STOL aircraft, the facts are there before your eyes with them.
I went to a hill climb event IN New Zealand where Rod Millen had his hill climb Celica with a massive wing ( jontheroadagain.com/wp-content/uploads/2016/07/DSC05997.jpg ) The claim was that the wing made a tonne of down force at less than 100km/h BS?
pfft "because you dont notice until real high speed" stick your hand out the window at 30 moh. feel that? boom. theres your proof its functional even at pretty low speeds.
you said at the 5:35 mark that "so now that we have the theoretical basis covered, lets have a look at some ACTUAL downforce figures are at SPEED." AND THEN YOU SHOW US SIMULATOR FIGURERS??!! WTF??!!
are you ok? Are you sure you understand the difference between theory and applied math? He plugged in real values, you don't need to see the formulae to understand these, so what he said was correct. Had he said "let's now look at experimental data" then your point would be valid.
Don't worry how the fuck I am. He's just piping in cl, cd, weight etc data.. I was looking to see actual wind tunnel or on track df figures not "simulated" results. Do you know what the definition of "simulated" is? His has merrit but there are some ppl who want to see real-time, bonified numbers when they're spending big money on aero.
haha you're pretty ignorant aren't you Andresa? You've somehow lost your way with your replies. Let me help you get back to smartville dumbass! How can you show the effect of downforce on different cars if the data is SIMULATED AND NOT hard data and expect ppl to believe you? Read that last sentence again so it can soak into your slow, thick, mushy material you call a brain. Oh I see you must be one of those dumbass ppl who have no common sense and are gullible to believe anything you hear and see on youtube. Ya you keep surfing Andresa.
