Seeing a few questions in here about speed sensitivity, downforce definitely does vary as the square of the speed (L = 1/2*density*velocity^2*coefficient of lift*area), however what I am more talking about is changes in flow separation and the coefficients of lift and drag varying with speed. Thanks for watching!
How do you design a fixed angle air foil with a large enough angle of attack for downforce at low speeds, but shallow enough to prevent flow separation from high momentum air at high speeds? Also what do you mean by "load" at 8:47 ? Thanks, love your vids!
I would like to recommend a topic for a future video. I think it would help educate people and myself, if my assumption is wrong: Would cars trailing a truck to lower their fuel consumption consequently increase the truck's fuel consumption? I think it won't increase the truck's fuel consumption (at least not significantly) but a lot of other commenters are saying it will because "nothing is free". I see it as if a snow plough pushed the snow out of the road and cars behind it are travelling more efficiently because of the absence of snow on the road. the snow plough's fuel consumption will not increase or decrease because of the cars that are reaping the benefits of the absence of snow on the road, whether those cars are 15 meters behind it or 1 km behind it. Now i know that analogy is not very accurate since snow does not flow back into place like air does so i hope you can make a video with a better explanation. Thanks!
I'm watching WTCR in nordschleife this weekend and the Lynk &Co have the rear wing with a very unusual angle. I think is an example of the Myth 1 of your video?
@@ccmckernan now a days you see a lot of flexible wings which deflect at higher speeds thus reducing angle of attack. Check red bulls flexi wing in vettels days for more info
@@sepg5084 It depends somewhat on the distance of the vehicles. But there has been wind tunnel research for example by Zabat et al on platooning. It showed that generally the drag decreases for the trailing cars and sometimes even for the leading car. The reason for the decrease at the trailing cars is the reduced speed of the incoming air in the wake. So effectively the incoming air is slower, which, as mentioned in the original post, influences the force in a quadratic fashion. The drag coefficent however, slightly increases (at least in the research I conducted) due to the higher turbulence, but its not as much as the decrease in velocity (at small distances under ~100m). Another project including trucks was the European SATRE Project, showing similar results. There were a few more, but just to give you a head start. If you want to look deeper into it, usually the expression 'Platooning' is used for convois of vehicles. Let me know if you are curious about more, cause that was part of my research over the last few years. Edit: Sorry, forgot about the secord part of your question: The leading vehicle usually is barely influenced. The results are not fully the same, but most research believes the drag of the leading vehicle decreases slightly as well. As vehicles are bluff bodies, usually you have a high pressure region in the front, working against the movement as well as a low pressure region, also puling the vehicle back. The trailing vehicle has a lower pressure in the front due to the lower speed. However, it also slightly increases the pressure at the back of the leasding vehicle. Most likely the air is slowed down in front of the 2. vehicle. Thus, the pressure in this region increases and also increases at the back of the leading vehicle (we are talking small distances here). Thus the suction on the back of the leading vehicle, pulling it back, reduces and the drag is reduces as well. If I remember correctly it was, depending on the experiment, in the region of a few percent - but do not quote me on that :)
They work primarily to produce outwash and divert the front tyre wake outboard, pulling this wake outboard means that it cannot 'leak' into the sensitive underside of the car and increases the effective width of your floor, similar to how winglets increase the effective span of an aircraft wing by relocating the tip vortices
Could you do a video on the subject of wheel arch vents: their appropriate time and place in race cars, and how they work? Also, the new Lotus Evija has some really interesting exterior design choices which could make for an interesting video.
Evija does indeed have some interesting aero. Ignoring the body styling to a certain extent the front wing/splitter and floor design is very much reminiscent of an LMP car.
My understanding is that venting wheel arch pressure is generally a good thing to reduce lift but how you do it can have an adverse effect on downstream aerodynamic elements
@@DjDolHaus86but were is the best Spot before at or behind the center of the wheel? Because if I remember correctly (did see a Video from a different guy) that has a huge impact on the wheel arc pressure and how it cann distort the air flow and effect all kinds of other downforce devices
@@DjDolHaus86 yeha though so much but a Video on that would at lest give us the knowledge to make assumptions too Figur it out our self if we have the drive too do soo
Could you do a video about the flow field and vortices around a modern F1 car, particularly how vortices are used to energise the leading edge of the floor and also how they are used to seal the underfloor?
Jeez. I just watched one of your earlier videos. You have evolved steve buscemi's eyes. Working at mercedes drained the life out of you. That said, awesome to have you back.
That last one makes quite a bit of sense. Because on aircraft, the multi-element flaps act as a single element when retracted and only become multiple elements when extended past a certain point. The goal of the flaps is to maximize lift at low speeds. So multi-element wings should really only be used at tracks where the top speeds are relatively low. Otherwise, the time gained in the corners will be negated by the greatly reduced top speed. I would like an in-depth explanation on how the slip ratio of the tire works.
Unless the rules allow for DRS. Then, you could potentially have higher downforce at lower speeds than a single element and put the elements into a 0 attack angle for the straits. The problem is, in many cases the elements are "designed" by the "looks good" or "worked for so and so..." method and achieve drag and lift coefficients no better than single element devices.
"I would like an in-depth explanation on how the slip ratio of the tire works." Beyond saying "tyres generate highest forces at certain slip angle/ratio ranges, which can shift depending on load, geometry, conditions, etc., and this is because they generate grip in many different ways, which vary in effectiveness with varying tyre conditions", it's a bit hard to go much deeper, unless you're trying to isolate why one specific tyre behaves like it does. Tyres generate their grip via multiple mechanism, like for example molecular bonding/adhesion (literally the molecules in the tyre and surface being attracted to each other), mechanical locking effects/deformation (microroughness on the track surface interacting with the rubber causing mechanical locking behavior) and tearing. All of these can produce different amounts of grip, and their individual behavior with regard to things like rubber temperature, contact patch load and slip angle/ratio can be very different. Tearing might produce relatively more grip at high slip angles while adhesion might provide less, and vice versa at lower slip angles. Having a wet track surface might remove adhesion grip almost completely out of the equation, one of the main reasons for why the "off-line" can be faster in the wet (rather than the rubber on the racing line being "slippery" in the wet, though that isn't irrelevant): Cars usually drive less on those lines, meaning the surface aggregate is generally less worn down and the microroughness is "sharper", which makes deformation grip more effective. Especially on street circuits, where the surface is pretty worn down everywhere, the racing line tends to be the fastest line even in the wet. So um yeah, they're a very complex subject, and the slip angles/ratios generating optimum performance vary massively depending on rubber compounds, tread patterns, tyre construction, vehicle they're used on (load, suspension geometry, etc.), rubber conditions (temperature etc.) and environmental conditions (wetness, temperature, driving surface condition, etc.). The one thing you can say for sure is that peak performance for any rubber tyre will be generated with some amount of slip.
multi-element flaps makes lot of lift but and drag too, because after every element, air stream is diverted for some degrees and after last element it can be 45 or more deg , and then starts turbulence that makes wake
I would be very very grateful if the next video teach us about building a proper diffuser, step by step. I love your videos, thanks for sharing your experience. 🏎️🏁
So glad you're back. I haven't gone through your whole library yet, but if you haven't already done so, I'd like to know more about the aerodynamics of brake ducting for cooling in Production Cars. i.e. The impact of turbulence or wheel arch pressure on cooling ducts that originate at the front of a car. Thanks!
He's technically right about the wings, and people thinking the top of the wing pushes the car down and creates downforce... But he's also, actually, technically wrong... Seeing as he's an engineer I'm surprised he didn't talk about how wings ACTUALLY work. There's no real thing as "suction", unless you're in a total vacuum (complete lack of air/gas/liquids- basically outer space) Wings work on the principle of pressure differential... There's still pressure pushing the bottom of the F1 cars wing... It's just LESS pressure than on the top of the wing. I'll try to make this simple - Basically it be like dis - the atmosphere at sea level is 14.7 PSI... Or 1 "bar" of pressure. This is a worldwide standard that varies slightly - but it's the accepted number by engineers. When the F1 car wing is functioning and creating downforce - all that's happening is the air on the bottom of the wing is moving faster than the air above the wing... Since you can only REALLY pressurize air in a sealed container - like a scuba or welding gas tank - you can slightly increase the pressure on the top of the wing in a very small area of that wing - but for the most part, the pressure on top is 15 psi or 1 bar of pressure. The faster moving air below may get down to, say 10psi or roughly 0.66 bar... That's still a reading of PRESSURE... AIR PRESSURE....Theres 10 lbs per square inch of pressure pushing the wing up. The wing creates negative lift (downforce) not because of "suction"... But because there is roughly 33% more air pressure on the top of the wing than there is on the bottom. You're not measuring suction, you're measuring differences in positive air pressure. The relatively stable atmosphere above the wing of 15 pounds is obviously more than the 10 lbs on bottom... So the wing makes downforce because of the pressure difference. Think of it this way - when something heavy (such as lead) is on top of something light, or light in comparison to the lead - such as water - it sinks. Pressure is pressure, regardless of which side of the wing its on. In a total vacuum - like outer space - the total lack of air pressure would cause a balloon to get HUGE and stretch before breaking. Blow up a balloon and then put it 100ft underwater - that balloon will be much smaller than its original size - because the pressure is acting on it from every possible angle. Think of a submarine - if it goes too deep, it will crush inwards from every angle of the sub. It wouldn't get flattened like a pancake - the pressure would try to smash it into a perfect sphere. So it's technically OK to refer to it as suction, because that's what you feel when you stick the vaccuum cleaner hose to your skin... But actually, that's happening because your body contains air and that air is 15psi. Your vacuum cleaner is creating lower air pressure by accelerating that air - but it is not creating a true vaccuum. A true vacuum is the complete non existence of any air or gas or liquid (gas of any type is still technically a liquid - look it up if you don't believe me.) So to summarize - the wing is ACTUALLY producing downforce because the air above the wing is about 15psi and underneath the wing let's just say it's 10psi. Just to make the math easy. Pounds of downforce can be calculated by taking the difference in air pressure between the top and the bottom of the wing, which we're saying is 5lbs per square inch... 15 lbs minus 10 lbs = 5 lbs. Let's say our wing has an area of 100 square inches. So if the wing created EXACTLY the same amount of downforce over its entire surface (it's more complicated and the outside wing tips create more downforce than the middle of the rear wing)... But if the pressure difference was equal at 5psi and we had a 100sq inch wing, we'd make 500lbs of downforce. In the real world, computer programs model the airflow and very accurately model and measure expected downforce - then they put the wing into the wind tunnel and put a scale under the rolling road. As air is increased in speed, downforce increases and the scale shows more weight on, so just subtract the cars weight from that entire weight measurement and boom - you have your downforce measurement. They measure drag in a similar way - there's a scale that is attached to the rolling road or the car itself that measures how much the car -"pushes back" or pulls against the scale. Giving accurate drag measurements. I'm not saying he's wrong - bc lower air pressure under a wing will make it feel as though it's being pulled down - but in reality, it's kinda both. Hopefully that makes some kind of sense to someone.
I want to see a video where you go over the aero on famous race cars from the past and talk about what we have learned since. I remember a video you did where you did something similar at a hill climb event and it was fascinating.
Hi Kyle ! Would love to hear you talk more about designing for front downforce in a typical time attack car, specifically the front diffuser shapes and ride height affects on them , these are rarely discussed elsewhere
Hey Kyle! Thanks so much for all the videos! I've learned so much and I got interested enough to get a couple books on car aeroydamics! My favorite so far is probably Competition Car Aerodynamics. That book helped clarify details on a lot of things for me and gave kinda general numbers on results related to a couple topics you covered. I've also tried finding some studies myself on things I was wondering about, but most of them are behind paywalls... One topic in particular I was wondering about is having windows down, and especially what can be done about it. Pretty much all track day groups and club level racing, at least in the US, requires the front windows to be down. From what I've been able to find there is benefit to venting the cabin. Would you maybe be able to discuss this? I found the abstract from a study saying that having windows open vs running air conditioning is more efficient until about 60 mph and then as speeds increase it get's increasingly worse. And an air conditioner takes about 4-5 HP to run! So it seems to me like there are potentially fairly big benefits. Especially for someone like me who primarily goes to 'horsepower' tracks where average lap speeds are at 70-80 mph even with a 2900 pound 200ish hp car on street tires. A couple things I've found so far: A decent amount of (front engine) sportscars in various GT series, from the Aston martin DBR9, to Ginnetta G50z, to the M3 GTR (most relevant to me haha), and even up to today with the lexus RC F have holes at the bottom of the rear windshield. In their cases (I assume) it's pretty much just to vent air they purposely let in to help keep the driver a bit cooler. But that does kinda prove to me that that is a 'good' place to vent air out. I had seen people in various forums claiming that it wouldn't work, and that air could even come in through there. But that area is typically going to be a relatively low pressure zone from my understanding so that doesn't really make sense. I've even read people saying some spec miata racers were being caught / penalized for leaving a gap at the bottom of their hardtop. Nascar teams were running NACA ducts backwards in their rear side windows to help evacuate air out of the drivers cabin until it was banned. I've read that the NACA duct isn't necessarily the best duct design as a vent like this, but it was good enough to be beneficial for them... Not really sure of what else to do other than limit window opening size as much as rules allow. Maybe use deflectors? Seems like that could very easily hurt more than it helps, though. At least on modern NASCAR it looks to me like the B pillar is sloped kind of as a deflector. Or at least in a way that definitely doesn't draw air into the car. I'm sure you've got a ton of video ideas already, but I think this could maybe be a good one? It would certainly be beneficial to pretty much every club racer in the US!
with the pressure side vs the vacuum side part at the beginning. its true that the pressure side is more important because they are the same thing. The "sucking force" is really just the lack of pressure pushing on that side of the aero feature. Also the pressure side can without a doubt create more force than the vacuum side because the atmosphere is only at such a high pressure, if you had a perfect vacuum on one side of a plate and atmospheric pressure on the other it would have the same force on it as if you had atmospheric pressure on one side and 2 atmospheres of pressure on the other. what i mean by this is the amount of + pressure you can create is less limited than the amount of "-" pressure you can make (basically limited bu atmospheric pressure)
In the physics community there seems to be some contention as to the Newtonian versus Bernoulli model on aerodynamic lift and I presume downforce as well. Why is this so if the low pressure zones are so much more effective than the high pressure zones?
Yes it's the difference, but which side really contributes to this difference? Consider an airfoil where the pressure side stays unchanged at an ambient pressure of 1 atmosphere, while the suction side is at an average of, say 0.25 atmosphere. The difference between the two is 0.75 atmosphere acting on the airfoil surface towards the suction side (lift/downforce depending on the airfoil's orientation), but in this example all of the difference was generated at the suction side. The pressure side doesn't contribute to the change. In a real airfoil there is usually an increase in pressure on the pressure side (hence it's name), but that is dwarfed by the decrease on the suction side, even with symmetrical airfoils.
@@ASJC27 well if it’s a difference there’s definitely 2 sides to the equation that describes the force. But as Kyle said the low pressure side is more able to be influenced so as a practical matter that is the focus.
Yes, but the difference is still how you look at it. You aren't trying to generate high pressure on the top side, you are trying to generate low pressure on the bottom.
Great Videos Kyle ! Could you comment on the new F1 2022 cars regarding aerodynamics? I rewatched your video "How Do You Fix Overtaking Aerodynamics in Formula 1? 6 Potential Solutions" ... and it looked like F1 was watching your video as well and to some extend, they changed the rules based on your video .
Really good video, particularly the rear diffuser size question, look forward to chatting next year re the C3 corvette next year Kyle, tks, Jon 🏴
Hello! I've being a huge fan of your post ever before the hiatus, so I'd like to suggest a topic for a future video covering the aero of the P1 class prototypes from Endurance Brasil. This is an endurance racing series where aero has a level of design degree of freedom similar to that of Time Attack or Pikes Peak cars, allowing teams to implement features like DRS (without limitations on use), underbody aerodynamics and many interesting solutions that are mostly forbidden everywhere else. Cars in this series are mainly spaceframe built in Brazil, like the Metalmoro AJR, Sigma P1 and DTR01, but there are also a couple modified Ginetta G58s, that went through a lot of mechanical and aero updates (DRS included), with more cars expected to join the grid in the near future.
Just found your channel and I’m really enjoying it! I’d like to see more of how some of these technologies apply to flight if that is something you can comment on, I think that there is a adverse correlation in how racing cars leverage wings and how a flying vehicle your benefit from that, considering lower Re from the larger camber of flying vehicles. Consider Cars look to see if they can go faster on corner then shed the drag to go faster, where a flying device is trying to transition to as slow as possible to transition for flight (land) then like the cars shed as much drag to go faster. I’m curious to see how you would leverage a multi element wing in the Re range of 2M to 4 M Re range. It’ll still enjoy your videos irregardless if you consider this :)
vortices are made because space or cross section of diffuser starts to be to big and laminar airflow can hold that big change , or can not slow down so fast so it keeps moving but around like vortices
I'm suggesting "suction" is not a thing. One has a difference in pressure. Using a straw to drink? One is creating a low pressure area in your mouth and atmospheric pressure is *pushing* the fluid into your mouth. The greater the difference between a low pressure area and a high pressure area the more force is applied. I'm suggesting you have a further talk to your dad.
@@bradsmith3123 I think you may have misunderstood time scales, this was explained to me nearly 25 years ago, when I was a Child, so a simplified explanation was appropriate.
Very clarifying :) As a video suggestion I'd be interested in your take on DPi cars especially the Acura. As design references to the road vehicles are more or less desired there are many different takes on modifying the aerodynamic package and I'm wondering what you could read of the designs from a performance perspective.
First time seeing your video and I really like it! Being both a gear head with some engineering background and a race car driver this look into engineering is fascinating.
"Aerodynamics of race cars in fixed conditions is not that high, but the condition sensitivity of devices is high". Could you explain what and why that is a bit more? Thanks, good video.
Hey Kyle, I would love to see a video about aero dynamics regarding drift cars. I have seen a few crazy sideways wings that drifters have attempted to use to improve grip while in drift. Do those do anything? Its an interesting subject because even at the highest level of drifting they seem to completely disregard aero still. Obviously due to cost and issue of repairing after a crash mid event but still an interesting subject I would love to hear about.
Could be interesting. The one thing I've been wondering w.r.t. drift aero is the lack of sideforce aero. If you look at the rally cars of the early 00s, they often had big and numerous vertical elements in the rear wings to provide a sideways force while sliding. This both stabilizes the rear and can help push the car towards the inside of the corner (or at least help keep it from going wide). In current WRC cars these devices are banned from the center of the wing (region of 55 cm on both sides of the centerline of the wing), and as a result you don't see many of them (Toyota did use some), but the endplates on the rally rear wings can be massive. Someone might say that features like that would go against the intended target of drifting, but having worked with some professional drifters, many tend towards making their setups really understeery anyway, relying on both the handbrake and insane power to force the car sideways, but trying to prevent the car from wanting to go overboard. Something like this might help them increase their speeds around corners while making the car less likely to get out of control when really torturing it hard.
Wouldn't effective aero defeat the whole point of drifting? Isn't getting as much angle as possible part of the scoring? It'd also seem to me that a cars predictability is far more important than anything else and aero would make the car less predictable.
@@snek9353 Speed is also a key factor, they tend to run the highest grip tyres they can (D1GP was once won with racing slicks, which were subsequently banned), so good side force that would allow higher cornering speeds and stabilise the rear a bit could work, in theory at least. They have more than enough power to force the tyres to lose grip if they really need it.
@@jubuttib I'll take your word for it, only drifting I've watched is putting on Cletus when bored. I think it's a dumb sport. It is however an interesting thing to think about. How about hinged flaps like the roof flaps used in NASCAR. A set for each direction so when sliding right one set open and when the direction changes they close and another set opens.
sharp edges is also a problem not only in aerodynamic but in engine tuning of two strokers where people tend to knife edge al over inside the cylinder where its airflow.
My friends and I need a debate settled and I think you’re exactly the person to settle it. Another aerodynamicist recommended the bottom edge of our front splitters to be rounded and the top edge to be cut squarely. I know it doesn’t matter: but we all have Miatas.
Awesome video! Can you make a video of the aerodynamics of rims? Especially about what is the best for brake cooling or ventilation drag and how the perfect rim for efficiency would look like. Does it make sense to apply a wheel cap for aerodynamic purposes? I am currently writing a thesis about this topic and it would be perfect!
I'm new to your stream and enjoying learning through the videos. Thanks. My suggestion for a possible future subject is to expand on the effects of fender top vents on LMP/DPi. In particular, I was watching the in-car cameras of the DPi cars at Daytona. From inside the car, you could see that the combination of high downforce at speed and the banking, had the cars at full bump with the top of the tire seeming to be above the top of the fender. I would be curious to understand how airflow on the top of the tire would affect local downforce, drag, and down stream flow. Thanks again. Jac
Point no. 1 is one good reason why attachments on aircraft wings, e.g. engines, flap actuators are usually all on the bottom. (The pressure side) It's less of a concern keeping the airflow attached on that side, whereas over the top of the wing (equivalent to the bottom of a car wing) the airflow can easily separate under the wrong conditions and cause the wing to stall
The new HA-420 Hondajet airplane placed the two engines on the upper surface and more towards the rear of the wings. So there goes that theory. I reiterate another point I made in a post regarding the video’s 1st point which is that suction is a virtual and apparent force but it is not a real force. In an aerodynamic surface like an airfoil there are two forces generated by air pressure differences. The less curved surface generates a greater force normal to that side and thus creates lift or down force depending on which side is facing up or down. Like centrifugal force suction is only a virtual or apparent force. It is not a real force. An excerpt from a Wikipedia article on suction and its reference source follows. Gasses or liquids that move along a pressure gradient can exert forces on objects. Objects can only be pushed by gases or liquids. The correct terminology used depends on whether they are pushed from a pressurized zone towards ambient pressure (blown out) or from ambient pressure towards a low pressure zone (sucked in). Gases and liquids cannot generate pulling forces on objects[1]. ([1] Quora. "There's No Suction In Space, Because Suction Is An Illusion". Forbes. Retrieved 2024-01-16.) I cite this article because it explains well what I am talking about.
I've been watching your channel for a while with great interest but my race car world is somewhat different to everybody else's. I'm near the end of building a 4WD streamliner to take a shot at 500 mph. It is only 36" wide, 33" high & nearly 40ft long. It would be interesting to say the least to get your opinion on what I'm doing here. It has four full length stakes on each side & the top where the center two blend into an intake duct then terminate at two tail fins then I'm creating a sharkskin type surface between those. There is no driver pop-up, it's a lay-down configuration with the windshield being part of the nose. Should be ready for shakedowns in May or June.
I would like to see you analyse vintage F1 cars - and how you would improve them - using todays knowledge and technology. I suggest cars such as Lotus 72, Williams FW10, McLaren Mp4/4 and RedBull RB9. PS - congratulations on a great 2 years with Mercedes.
Could you make a video on wheel arch and front end design of enclosed wheel cars in particular please!! This is what my dissertation project is based on (Scanning, Modelling, CFD/Wind Tunnel testing a Civic EF hatchback) so I would appreciate your take on it!😄
i love your videos! can you make a compairson video between 1980/1990s group c cars and todays lmp1 cars? i think that would be awesome. either way great video!
It’s not entirely wrong. Obviously as you get slower the air moving over surfaces is gonna be slower and so you get less downforce/drag. And it’s really blown out of proportion but the effect is still there. It’s not gonna kill you but the car probably won’t have the same balance as it did and if you aren’t used to that you can overdrive. A lot of it depends on your tires too. If you have lots of aero and really skinny tires the shift from aero grip to mechanical would obviously be bigger. So it’s a lot of factors
@@cademckee7276 It is entirely wrong, ab lowered speeds the decrease in "centrifugal force" is always greater than the decrease in grip due to lowered downforce. There is never a point that you can regain grip by going even faster. Also as far as tires are concerned there is no difference between "mechanical" and "aero" grip, tbh those terms make very little sense anyway. Maximum grip is directly proportional to the normal reaction force between the car and the road, the source of this force is irrelevant (weight or aero).
@@Bruno-cb5gk you are looking at this from a directly physics stand point. I am looking at this from haven driven a car with decent aero grip. As you slow down you can not only feel the wings working less but the balance of the car changing and when you get to a low enough speed you can feel that the wings aren’t doing anything because the balance of the car has shifted.
Hi Kyle. I enjoy watching your channel. Do you have any suggestions on how to reduce aerodynamic drag while trailering my 2005 Searay sundeck boat behind my pickup truck at 65MPH. Gas mileage is horrible. A 10% improvement would help. This is an unexplored market for technology to reduce drag. I normally tow with no highway covered and the center console door open to let wind go down the center of the boat. Any suggestions you have would be appreciated. I am a retired Electrical Engineer so I may try some experiments. Thanks Joe
Kool video .dose the same rules apply to RC cars and Scalextric ?? Also idea for video getting downforce without drag ...such as drag cars also air going into engine bay the effect on air flow such as air scoops bonnet scoops ECT
I think people get "stall speed" from when automotive journalists talk about race cars and mention how they need to be going a certain speed for the aerodynamics to take full effect, I could be wrong tho.
I think it's way more simple than that - people assume that they understand aerodynamics SO much better than they actually do(the amount of times I've had to tell people "...YOUR EYEBALLS ARE NOT A WIND TUNNEL..." in response to a car's "horrible aero" - even though it was designed by damn engineers with huge budgets and all the resources...), and everyone thinks "aero doesn't make a difference unless you're going fast enough". I HOPE that people don't actually think that aero acts almost like a light switch that is "on" at a "certain speed", I think most understand that it doesn't work that way. But there's this idiotic idea that "downforce doesn't matter till 60MPH/100MPH"(those seem to be the go-to numbers) - in spite of all of the open class autoX & Formula SAE cars absolutely proving otherwise. Typical problem of people "knowing just enough to be dangerous", the classic Dunning-Kruger Effect - they learn a LITTLE about the subject, think that they have an "inherent understanding" because it makes sense to them, drastically overestimate their understanding, so then they just start making assumptions that "make sense" based on the tiny amount of knowledge that they have, while not realizing how little they actually understand.
@@RyTrapp0 slight insert here: part of the reason that the F-SAE cars have "effective" aero at low speeds is due to their light weight (requiring less aero force to have a large relative effect). On something as heavy as a street car (e.g. street legal sportscar that you take to a trackday), that amount of downforce won't be noticeable at the low speed since it is much smaller relative to the other forces at work due to the higher weight.
I want to dig in on your claim about myth 1. I think you mostly worded everything correctly, but I wonder if you might inadvertently be communicating a new misconception. While it is true that the *math* of the coefficient of pressure leads to a cap on the pressure side of a wing and no limit on the 'suction' side of the wing, isn't that just a quirk of the math? I don't see any reflection of that in physical reality. I don't think there is a physical mechanism for a gas to pull on a wing. There are either particles of air exerting pressure on the surface of the wing, or there aren't. If there aren't, the pressure is zero, and that's the lowest possible pressure. On the other hand, there is no upper limit (within reason) on positive pressure. I'll grant you that dropping the pressure on the underside of a wing (on a car, or the upper side on a plane) may contribute more to the downforce than building pressure on the upper side does...*but the pressure on the upper side is the only reason there is any downforce at all.* There is no physical mechanism for a lack of particles on the underside of a wing to pull that wing down. Positive pressure is the only physical thing that gases can exert. If you drop the pressure on the under side of the wing, the gas has no mechanism of attracting the wing downward. It's just not pushing upward as much any more. So the upper side may be the pressure side, but the under side is not a 'suction' side. It's just a side lacking pressure.
I think the movement of gas particles from high to low pressure regions is what he is referring to as 'suction' here. While a physicist might see his explanation as semantics at best and misleading at worst, for an aerodynamicist, or even a casual car enthusiast, the difference is important. As he mentioned, there's not much more a car designer can do to increase the pressure on the pressure side (beyond CP of 1), but there are performance gains to be had through decreasing the pressure on the under side of the wing, or in everyday language, by generating more 'suction.' At the end of the day, in my understanding it's the pressure differential that matters. I feel like he somewhat overstates the degree to which it's "wrong" to say that the high pressure side is pushing down on the wing, due to the physical process which you describe. Then again I am just a layperson watching youtube videos while he is an expert on the subject. But it could be his professional context that leads him to describe these aero effects the way he does.
@@zvexevz I *think* I understand what he's aiming for, which is why I would like to hear from him. I think his explanation is problematic, instead of wrong, which is again why I would like to hear from him. My thinking is that fixing one misconception by introducing another doesn't move the conversation forward. I know he's trained in aerodynamics, but in this context, he's an educator. And the shared goal we should all have with education is to develop a fully accurate understanding--one that satisfies people that are concerned with the math, *and* one that satisfies people that are concerned with the physical reality, *and* one that satisfies the people that just want a car to go faster. In that spirit :) --- "...movement of gas particles from high to low pressure regions" is more akin to flow than to suction. In this context, he is using suction to describe a pressure differential *without* flow between those two regions. For the case of a splitter, we're talking higher pressure on one side of the splitter, and lower pressure on the other, and (ideally) *no* flow through or around the splitter. A differential can be achieved by increasing pressure on one side, decreasing it on the other side, or both. *However,* downforce is *always* created by the side with higher pressure. I really don't think it's correct to describe it as suction. Low pressure cannot pull--instead, it just doesn't push. So a more fully correct way to explain what's going on with a wing, is to say that you achieve greatest gains by reducing the push on the underside of the splitter. There *is* a limit to this (unlike what the equation he's referencing indicates). You can't go into negative air pressure.
Great video. Have you ever considered doing a video on the flexible front wings as used in F1 (notability Red Bull) in the early 2010s? I'd be interested to hear your thoughts in what Red Bull were trying to achieve, and how they were able to overcome the technical challenges to get them to work. Especially in comparison to say Ferrari where they had obvious hysteresis/porpoising problems.
Enjoying. I went back multiple times few seconds to look again at graph or listen again what you are saying, but no amount of coffee can save my half sleeping brain today. My question: how high can diffuser start so that it still works. And I am remembering that they do not work if underbody is not flat before it - from your 2017 videos. But is there any usefulness.... Another one is that how making flat floor under the front engine bay can help, and in that case how to successfully still direct engine air like stock, underneath the car? I quess my question is how long under tray at front is beneficial in drag reduction? And how short diffuser and at what height is minimum for any use.
Can you do more car aero reviews like you did the One:1 and McLaren P1? I would like to see the Jesko (track and absolut edition), the SSC, and maybe the 919 Evo it’d be really interesting to see why manufacturers chose what they chose! Oh and you mention Gordons car in the other video, when can we expect to see that vid?
May I asking 1 ridiculous thing For space reason, Can be expansion chamber of diffuser designed to be expanded sideway while maintaining the height rather than expanded upward like most diffuser do? Can it work synergistically with normal upward ex chamber diffuser on either side of it?
If I build a tube framed race car with the intention of having a functioning front and rear diffuser and flat floor. Should I design it with a rake at a certain angle to start with? Or should it be designed completely horisontal and you only manage the air within the diffuser designs? Because simply putting a rake on it afterwards would compromise the suspension compared to the horizontal plane.
I would like to see a subaru wrx with and without the big spolier on the bag like the 2004 model. Does that big wing make a difference? Also the wrc one had the spolier further back on the boot lid
![Lp. Сердце Вселенной #60 РОЖДЕНИЕ ЛОЛОЛОШКИ [Финал] • Майнкрафт](http://i.ytimg.com/vi/YoR0pAV9FVQ/mqdefault.jpg)
Seeing a few questions in here about speed sensitivity, downforce definitely does vary as the square of the speed (L = 1/2*density*velocity^2*coefficient of lift*area), however what I am more talking about is changes in flow separation and the coefficients of lift and drag varying with speed. Thanks for watching!
How do you design a fixed angle air foil with a large enough angle of attack for downforce at low speeds, but shallow enough to prevent flow separation from high momentum air at high speeds? Also what do you mean by "load" at 8:47 ? Thanks, love your vids!
I would like to recommend a topic for a future video. I think it would help educate people and myself, if my assumption is wrong:
Would cars trailing a truck to lower their fuel consumption consequently increase the truck's fuel consumption?
I think it won't increase the truck's fuel consumption (at least not significantly) but a lot of other commenters are saying it will because "nothing is free".
I see it as if a snow plough pushed the snow out of the road and cars behind it are travelling more efficiently because of the absence of snow on the road. the snow plough's fuel consumption will not increase or decrease because of the cars that are reaping the benefits of the absence of snow on the road, whether those cars are 15 meters behind it or 1 km behind it.
Now i know that analogy is not very accurate since snow does not flow back into place like air does so i hope you can make a video with a better explanation. Thanks!
I'm watching WTCR in nordschleife this weekend and the Lynk &Co have the rear wing with a very unusual angle. I think is an example of the Myth 1 of your video?
@@ccmckernan now a days you see a lot of flexible wings which deflect at higher speeds thus reducing angle of attack. Check red bulls flexi wing in vettels days for more info
@@sepg5084 It depends somewhat on the distance of the vehicles. But there has been wind tunnel research for example by Zabat et al on platooning. It showed that generally the drag decreases for the trailing cars and sometimes even for the leading car. The reason for the decrease at the trailing cars is the reduced speed of the incoming air in the wake. So effectively the incoming air is slower, which, as mentioned in the original post, influences the force in a quadratic fashion. The drag coefficent however, slightly increases (at least in the research I conducted) due to the higher turbulence, but its not as much as the decrease in velocity (at small distances under ~100m). Another project including trucks was the European SATRE Project, showing similar results. There were a few more, but just to give you a head start. If you want to look deeper into it, usually the expression 'Platooning' is used for convois of vehicles. Let me know if you are curious about more, cause that was part of my research over the last few years.
Edit: Sorry, forgot about the secord part of your question: The leading vehicle usually is barely influenced. The results are not fully the same, but most research believes the drag of the leading vehicle decreases slightly as well. As vehicles are bluff bodies, usually you have a high pressure region in the front, working against the movement as well as a low pressure region, also puling the vehicle back. The trailing vehicle has a lower pressure in the front due to the lower speed. However, it also slightly increases the pressure at the back of the leasding vehicle. Most likely the air is slowed down in front of the 2. vehicle. Thus, the pressure in this region increases and also increases at the back of the leading vehicle (we are talking small distances here). Thus the suction on the back of the leading vehicle, pulling it back, reduces and the drag is reduces as well. If I remember correctly it was, depending on the experiment, in the region of a few percent - but do not quote me on that :)
I would live to see a super in-depth look at the bargeboard area of an f1 car and how all the various devises work and what they're used for
This.
I would also like to see this!
They work primarily to produce outwash and divert the front tyre wake outboard, pulling this wake outboard means that it cannot 'leak' into the sensitive underside of the car and increases the effective width of your floor, similar to how winglets increase the effective span of an aircraft wing by relocating the tip vortices
@@liocla2331 i second that
He probably can't because of his NDA with Mercedes
Welcome back to the first video of regular scheduled programming since my return! Hope you guys enjoy it!
WE ARE ENJOYING IT BEFORE EVEN WATCHING
I love the content! I show your videos to all of my FSAE aerodynamics subsystem members for introductions into key concepts.
Glad you’re back
thanks, i really appreciate that
what's your opinion on exhaust blown diffuser ? Like naca duckt shaped exhaust tips integrated in to top of the diffuser.
“Wait it’s all rice?”
“Always has been”
“Finally! Someone who speaks English.”
Civics be like
It’s only rice when it’s cosmetic & not engineered
Could you do like a "CFD simulation for beginners" or something like that?
That would be great- I’m looking at going into aerospace so a video like that would be useful
Could you do a video on the subject of wheel arch vents: their appropriate time and place in race cars, and how they work? Also, the new Lotus Evija has some really interesting exterior design choices which could make for an interesting video.
Evija does indeed have some interesting aero. Ignoring the body styling to a certain extent the front wing/splitter and floor design is very much reminiscent of an LMP car.
My understanding is that venting wheel arch pressure is generally a good thing to reduce lift but how you do it can have an adverse effect on downstream aerodynamic elements
@@DjDolHaus86but were is the best Spot before at or behind the center of the wheel? Because if I remember correctly (did see a Video from a different guy) that has a huge impact on the wheel arc pressure and how it cann distort the air flow and effect all kinds of other downforce devices
@@TheLtVoss There is no singular answer to that, it would depend on a whole bunch of factors.
@@DjDolHaus86 yeha though so much but a Video on that would at lest give us the knowledge to make assumptions too Figur it out our self if we have the drive too do soo
Could you do a video about the flow field and vortices around a modern F1 car, particularly how vortices are used to energise the leading edge of the floor and also how they are used to seal the underfloor?
yes I would love this
Jeez. I just watched one of your earlier videos. You have evolved steve buscemi's eyes. Working at mercedes drained the life out of you.
That said, awesome to have you back.
That last one makes quite a bit of sense. Because on aircraft, the multi-element flaps act as a single element when retracted and only become multiple elements when extended past a certain point. The goal of the flaps is to maximize lift at low speeds. So multi-element wings should really only be used at tracks where the top speeds are relatively low. Otherwise, the time gained in the corners will be negated by the greatly reduced top speed.
I would like an in-depth explanation on how the slip ratio of the tire works.
Unless the rules allow for DRS. Then, you could potentially have higher downforce at lower speeds than a single element and put the elements into a 0 attack angle for the straits. The problem is, in many cases the elements are "designed" by the "looks good" or "worked for so and so..." method and achieve drag and lift coefficients no better than single element devices.
He has done a whole freaking 10 part series on tires already!
"I would like an in-depth explanation on how the slip ratio of the tire works."
Beyond saying "tyres generate highest forces at certain slip angle/ratio ranges, which can shift depending on load, geometry, conditions, etc., and this is because they generate grip in many different ways, which vary in effectiveness with varying tyre conditions", it's a bit hard to go much deeper, unless you're trying to isolate why one specific tyre behaves like it does.
Tyres generate their grip via multiple mechanism, like for example molecular bonding/adhesion (literally the molecules in the tyre and surface being attracted to each other), mechanical locking effects/deformation (microroughness on the track surface interacting with the rubber causing mechanical locking behavior) and tearing. All of these can produce different amounts of grip, and their individual behavior with regard to things like rubber temperature, contact patch load and slip angle/ratio can be very different. Tearing might produce relatively more grip at high slip angles while adhesion might provide less, and vice versa at lower slip angles. Having a wet track surface might remove adhesion grip almost completely out of the equation, one of the main reasons for why the "off-line" can be faster in the wet (rather than the rubber on the racing line being "slippery" in the wet, though that isn't irrelevant): Cars usually drive less on those lines, meaning the surface aggregate is generally less worn down and the microroughness is "sharper", which makes deformation grip more effective. Especially on street circuits, where the surface is pretty worn down everywhere, the racing line tends to be the fastest line even in the wet.
So um yeah, they're a very complex subject, and the slip angles/ratios generating optimum performance vary massively depending on rubber compounds, tread patterns, tyre construction, vehicle they're used on (load, suspension geometry, etc.), rubber conditions (temperature etc.) and environmental conditions (wetness, temperature, driving surface condition, etc.). The one thing you can say for sure is that peak performance for any rubber tyre will be generated with some amount of slip.
@@guest426 not just DRS, but also deformation
smaller elements don"t need to deform their support structure as much to twist out of the way
multi-element flaps makes lot of lift but and drag too, because after every element, air stream is diverted for some degrees and after last element it can be 45 or more deg , and then starts turbulence that makes wake
Great stuff as always. Glad some of the stuff you did for me made an appearance!
I love how none of these things that I knew already, and I'm an aero enthusiast.
That happens when we watch racing all the time.
I would love a video on exhaust blown diffusers, and other activitie flow control techniques.
I would be very very grateful if the next video teach us about building a proper diffuser, step by step. I love your videos, thanks for sharing your experience. 🏎️🏁
So glad you're back. I haven't gone through your whole library yet, but if you haven't already done so, I'd like to know more about the aerodynamics of brake ducting for cooling in Production Cars. i.e. The impact of turbulence or wheel arch pressure on cooling ducts that originate at the front of a car. Thanks!
I’d like to see this video too...
He's technically right about the wings, and people thinking the top of the wing pushes the car down and creates downforce... But he's also, actually, technically wrong...
Seeing as he's an engineer I'm surprised he didn't talk about how wings ACTUALLY work.
There's no real thing as "suction", unless you're in a total vacuum (complete lack of air/gas/liquids- basically outer space)
Wings work on the principle of pressure differential... There's still pressure pushing the bottom of the F1 cars wing... It's just LESS pressure than on the top of the wing.
I'll try to make this simple -
Basically it be like dis - the atmosphere at sea level is 14.7 PSI... Or 1 "bar" of pressure. This is a worldwide standard that varies slightly - but it's the accepted number by engineers.
When the F1 car wing is functioning and creating downforce - all that's happening is the air on the bottom of the wing is moving faster than the air above the wing... Since you can only REALLY pressurize air in a sealed container - like a scuba or welding gas tank - you can slightly increase the pressure on the top of the wing in a very small area of that wing - but for the most part, the pressure on top is 15 psi or 1 bar of pressure.
The faster moving air below may get down to, say 10psi or roughly 0.66 bar... That's still a reading of PRESSURE... AIR PRESSURE....Theres 10 lbs per square inch of pressure pushing the wing up.
The wing creates negative lift (downforce) not because of "suction"... But because there is roughly 33% more air pressure on the top of the wing than there is on the bottom.
You're not measuring suction, you're measuring differences in positive air pressure.
The relatively stable atmosphere above the wing of 15 pounds is obviously more than the 10 lbs on bottom... So the wing makes downforce because of the pressure difference.
Think of it this way - when something heavy (such as lead) is on top of something light, or light in comparison to the lead - such as water - it sinks.
Pressure is pressure, regardless of which side of the wing its on.
In a total vacuum - like outer space - the total lack of air pressure would cause a balloon to get HUGE and stretch before breaking.
Blow up a balloon and then put it 100ft underwater - that balloon will be much smaller than its original size - because the pressure is acting on it from every possible angle.
Think of a submarine - if it goes too deep, it will crush inwards from every angle of the sub. It wouldn't get flattened like a pancake - the pressure would try to smash it into a perfect sphere.
So it's technically OK to refer to it as suction, because that's what you feel when you stick the vaccuum cleaner hose to your skin... But actually, that's happening because your body contains air and that air is 15psi.
Your vacuum cleaner is creating lower air pressure by accelerating that air - but it is not creating a true vaccuum. A true vacuum is the complete non existence of any air or gas or liquid (gas of any type is still technically a liquid - look it up if you don't believe me.)
So to summarize - the wing is ACTUALLY producing downforce because the air above the wing is about 15psi and underneath the wing let's just say it's 10psi. Just to make the math easy.
Pounds of downforce can be calculated by taking the difference in air pressure between the top and the bottom of the wing, which we're saying is 5lbs per square inch... 15 lbs minus 10 lbs = 5 lbs.
Let's say our wing has an area of 100 square inches.
So if the wing created EXACTLY the same amount of downforce over its entire surface (it's more complicated and the outside wing tips create more downforce than the middle of the rear wing)... But if the pressure difference was equal at 5psi and we had a 100sq inch wing, we'd make 500lbs of downforce.
In the real world, computer programs model the airflow and very accurately model and measure expected downforce - then they put the wing into the wind tunnel and put a scale under the rolling road.
As air is increased in speed, downforce increases and the scale shows more weight on, so just subtract the cars weight from that entire weight measurement and boom - you have your downforce measurement.
They measure drag in a similar way - there's a scale that is attached to the rolling road or the car itself that measures how much the car -"pushes back" or pulls against the scale. Giving accurate drag measurements.
I'm not saying he's wrong - bc lower air pressure under a wing will make it feel as though it's being pulled down - but in reality, it's kinda both.
Hopefully that makes some kind of sense to someone.
I want to see a video where you go over the aero on famous race cars from the past and talk about what we have learned since.
I remember a video you did where you did something similar at a hill climb event and it was fascinating.
Very informative and straight to the point!
Aerodynamic is one of those fields that people think they understand but actually don't.
Hey! I didn’t realise you’re back! You’re videos were the best and most in-depth, I was struggling to find good information anywhere else.
Hi Kyle ! Would love to hear you talk more about designing for front downforce in a typical time attack car, specifically the front diffuser shapes and ride height affects on them , these are rarely discussed elsewhere
There is not enough content about aerodynamics here on youtube. Thank you
i have a question. a stalled wing generates next to 0 downforce. very understandable. but does it also generate nexxt to 0 drag as it stalls?
Kyle im so glad i found you. What amazing content!
Really fascinating watching as a driver and learning more about the cast intricacies of aerodynamics, thanks for the lesson!
Sooooo glad that you’re back!! Great video! Could you make an aerodynamic analysis of the Bugatti Bolide? Would love to see your take on that!
Hey Kyle! Thanks so much for all the videos! I've learned so much and I got interested enough to get a couple books on car aeroydamics! My favorite so far is probably Competition Car Aerodynamics. That book helped clarify details on a lot of things for me and gave kinda general numbers on results related to a couple topics you covered. I've also tried finding some studies myself on things I was wondering about, but most of them are behind paywalls...
One topic in particular I was wondering about is having windows down, and especially what can be done about it. Pretty much all track day groups and club level racing, at least in the US, requires the front windows to be down. From what I've been able to find there is benefit to venting the cabin. Would you maybe be able to discuss this? I found the abstract from a study saying that having windows open vs running air conditioning is more efficient until about 60 mph and then as speeds increase it get's increasingly worse. And an air conditioner takes about 4-5 HP to run! So it seems to me like there are potentially fairly big benefits. Especially for someone like me who primarily goes to 'horsepower' tracks where average lap speeds are at 70-80 mph even with a 2900 pound 200ish hp car on street tires.
A couple things I've found so far:
A decent amount of (front engine) sportscars in various GT series, from the Aston martin DBR9, to Ginnetta G50z, to the M3 GTR (most relevant to me haha), and even up to today with the lexus RC F have holes at the bottom of the rear windshield. In their cases (I assume) it's pretty much just to vent air they purposely let in to help keep the driver a bit cooler. But that does kinda prove to me that that is a 'good' place to vent air out. I had seen people in various forums claiming that it wouldn't work, and that air could even come in through there. But that area is typically going to be a relatively low pressure zone from my understanding so that doesn't really make sense.
I've even read people saying some spec miata racers were being caught / penalized for leaving a gap at the bottom of their hardtop.
Nascar teams were running NACA ducts backwards in their rear side windows to help evacuate air out of the drivers cabin until it was banned. I've read that the NACA duct isn't necessarily the best duct design as a vent like this, but it was good enough to be beneficial for them...
Not really sure of what else to do other than limit window opening size as much as rules allow. Maybe use deflectors? Seems like that could very easily hurt more than it helps, though. At least on modern NASCAR it looks to me like the B pillar is sloped kind of as a deflector. Or at least in a way that definitely doesn't draw air into the car.
I'm sure you've got a ton of video ideas already, but I think this could maybe be a good one? It would certainly be beneficial to pretty much every club racer in the US!
with the pressure side vs the vacuum side part at the beginning. its true that the pressure side is more important because they are the same thing. The "sucking force" is really just the lack of pressure pushing on that side of the aero feature. Also the pressure side can without a doubt create more force than the vacuum side because the atmosphere is only at such a high pressure, if you had a perfect vacuum on one side of a plate and atmospheric pressure on the other it would have the same force on it as if you had atmospheric pressure on one side and 2 atmospheres of pressure on the other. what i mean by this is the amount of + pressure you can create is less limited than the amount of "-" pressure you can make (basically limited bu atmospheric pressure)
Happy to have you back! I would love some videos on intro to common perhaps open source CFD software
In the physics community there seems to be some contention as to the Newtonian versus Bernoulli model on aerodynamic lift and I presume downforce as well. Why is this so if the low pressure zones are so much more effective than the high pressure zones?
Glad to have the best car engineering and race prep channel getting new videos!
Hey Kyle, is than an "Infinity Wing" on the front splitter of that Mustang on your monitor there??
Maybe it's an endplate? or just a vane/vortex generator.
Love your information. Any chance of a circle track, dirt, aero video. Such as sprint car, late-model, modified?
For myth 1 surely it’s the difference in pressure on either side of a surface that counts? It doesn’t make much sense to only talk about one side.
Yes it's the difference, but which side really contributes to this difference? Consider an airfoil where the pressure side stays unchanged at an ambient pressure of 1 atmosphere, while the suction side is at an average of, say 0.25 atmosphere. The difference between the two is 0.75 atmosphere acting on the airfoil surface towards the suction side (lift/downforce depending on the airfoil's orientation), but in this example all of the difference was generated at the suction side. The pressure side doesn't contribute to the change.
In a real airfoil there is usually an increase in pressure on the pressure side (hence it's name), but that is dwarfed by the decrease on the suction side, even with symmetrical airfoils.
@@ASJC27 well if it’s a difference there’s definitely 2 sides to the equation that describes the force. But as Kyle said the low pressure side is more able to be influenced so as a practical matter that is the focus.
Yes, but the difference is still how you look at it. You aren't trying to generate high pressure on the top side, you are trying to generate low pressure on the bottom.
@@Finnspin_unicycles that's a good way to explain it. I think we agree.
@@ASJC27 Thanks for clearing up, I thought that my whole understanding of pressure and "suction" was a lie
Great Videos Kyle !
Could you comment on the new F1 2022 cars regarding aerodynamics? I rewatched your video "How Do You Fix Overtaking Aerodynamics in Formula 1? 6 Potential Solutions" ... and it looked like F1 was watching your video as well and to some extend, they changed the rules based on your video .
Really good video, particularly the rear diffuser size question, look forward to chatting next year re the C3 corvette next year Kyle, tks, Jon 🏴
Hello! I've being a huge fan of your post ever before the hiatus, so I'd like to suggest a topic for a future video covering the aero of the P1 class prototypes from Endurance Brasil.
This is an endurance racing series where aero has a level of design degree of freedom similar to that of Time Attack or Pikes Peak cars, allowing teams to implement features like DRS (without limitations on use), underbody aerodynamics and many interesting solutions that are mostly forbidden everywhere else.
Cars in this series are mainly spaceframe built in Brazil, like the Metalmoro AJR, Sigma P1 and DTR01, but there are also a couple modified Ginetta G58s, that went through a lot of mechanical and aero updates (DRS included), with more cars expected to join the grid in the near future.
I just found your channel and it is great so far! I'm glad you are returning! Can't wait to see more!
Glad you return here!!!!
I would love tou see stuff like diy aero kit tutorial, or some cfd visualize RPOS vs CONS btw what about courses?
Came here after watching the news. Feels like a relief watching this
A wing can stall at any speed. Its ALL angle of attack.
Just happy to see you back on UA-cam! Thank you for the content.
Just found your channel and I’m really enjoying it! I’d like to see more of how some of these technologies apply to flight if that is something you can comment on, I think that there is a adverse correlation in how racing cars leverage wings and how a flying vehicle your benefit from that, considering lower Re from the larger camber of flying vehicles. Consider Cars look to see if they can go faster on corner then shed the drag to go faster, where a flying device is trying to transition to as slow as possible to transition for flight (land) then like the cars shed as much drag to go faster. I’m curious to see how you would leverage a multi element wing in the Re range of 2M to 4 M Re range. It’ll still enjoy your videos irregardless if you consider this :)
I'm so happy you are back
Question/idea: can you have a multi level diffuser with slots in the strakes to achieve multiple strake vortices on multiple levels?
vortices are made because space or cross section of diffuser starts to be to big and laminar airflow can hold that big change , or can not slow down so fast so it keeps moving but around like vortices
The day my Dad (an Aeronautical engineer) explained that a wing is sucked up, as opposed to pushed up, my mind was blown.
I'm suggesting "suction" is not a thing. One has a difference in pressure. Using a straw to drink? One is creating a low pressure area in your mouth and atmospheric pressure is *pushing* the fluid into your mouth. The greater the difference between a low pressure area and a high pressure area the more force is applied. I'm suggesting you have a further talk to your dad.
@@bradsmith3123 I think you may have misunderstood time scales, this was explained to me nearly 25 years ago, when I was a Child, so a simplified explanation was appropriate.
Wow dude. It's good to see you back
Very clarifying :)
As a video suggestion I'd be interested in your take on DPi cars especially the Acura. As design references to the road vehicles are more or less desired there are many different takes on modifying the aerodynamic package and I'm wondering what you could read of the designs from a performance perspective.
Best tool for demonstrating the concept of flow separation: Line Rider ☺
First time seeing your video and I really like it! Being both a gear head with some engineering background and a race car driver this look into engineering is fascinating.
"Aerodynamics of race cars in fixed conditions is not that high, but the condition sensitivity of devices is high". Could you explain what and why that is a bit more? Thanks, good video.
about time!!!! good to have you back
Great to have you back !
I learned so much from this, as a car guy with a technical car education! Thank you!
Hey Kyle, I would love to see a video about aero dynamics regarding drift cars. I have seen a few crazy sideways wings that drifters have attempted to use to improve grip while in drift. Do those do anything? Its an interesting subject because even at the highest level of drifting they seem to completely disregard aero still. Obviously due to cost and issue of repairing after a crash mid event but still an interesting subject I would love to hear about.
Could be interesting. The one thing I've been wondering w.r.t. drift aero is the lack of sideforce aero. If you look at the rally cars of the early 00s, they often had big and numerous vertical elements in the rear wings to provide a sideways force while sliding. This both stabilizes the rear and can help push the car towards the inside of the corner (or at least help keep it from going wide). In current WRC cars these devices are banned from the center of the wing (region of 55 cm on both sides of the centerline of the wing), and as a result you don't see many of them (Toyota did use some), but the endplates on the rally rear wings can be massive. Someone might say that features like that would go against the intended target of drifting, but having worked with some professional drifters, many tend towards making their setups really understeery anyway, relying on both the handbrake and insane power to force the car sideways, but trying to prevent the car from wanting to go overboard. Something like this might help them increase their speeds around corners while making the car less likely to get out of control when really torturing it hard.
Wouldn't effective aero defeat the whole point of drifting? Isn't getting as much angle as possible part of the scoring? It'd also seem to me that a cars predictability is far more important than anything else and aero would make the car less predictable.
@@jubuttib You should take a look at outlaw figure 8 cars.
@@snek9353 Speed is also a key factor, they tend to run the highest grip tyres they can (D1GP was once won with racing slicks, which were subsequently banned), so good side force that would allow higher cornering speeds and stabilise the rear a bit could work, in theory at least. They have more than enough power to force the tyres to lose grip if they really need it.
@@jubuttib I'll take your word for it, only drifting I've watched is putting on Cletus when bored. I think it's a dumb sport.
It is however an interesting thing to think about. How about hinged flaps like the roof flaps used in NASCAR. A set for each direction so when sliding right one set open and when the direction changes they close and another set opens.
This channel is GOLD!!
Keep bringing this bombs of aero knowledge! 💪💪
sharp edges is also a problem not only in aerodynamic but in engine tuning of two strokers where people tend to knife edge al over inside the cylinder where its airflow.
As a uni student these videos are really helpful in understanding how the theory relates to application. This is awesome!
Great to see you making videos again.
Heyyyyy your back!!!!! Awesome I love your videos
I am so F'n happy you are making videos again!!
Great videos🙌. Could you teach us some Mathematical formulas, like theoretical top speed,....? And how to work with CFD Fluid Simulation.🙏
I would love to hear your analysis of the aerodynamic features of those used on the 1969 Dodge Daytona and 1970 Plymouth Superbird.
Really enjoyed that episode! More myth busters please.
My friends and I need a debate settled and I think you’re exactly the person to settle it.
Another aerodynamicist recommended the bottom edge of our front splitters to be rounded and the top edge to be cut squarely.
I know it doesn’t matter: but we all have Miatas.
Awesome video! Can you make a video of the aerodynamics of rims? Especially about what is the best for brake cooling or ventilation drag and how the perfect rim for efficiency would look like. Does it make sense to apply a wheel cap for aerodynamic purposes? I am currently writing a thesis about this topic and it would be perfect!
Suction is just low pressure is it not?
im glad your back
Thank you so much! Unquestionably, one of the best, most informative channels out there. Well Done.
His back! Lewis told me you dropped a clip. Very informative mate
Welcome back!!!!!!!
I'm new to your stream and enjoying learning through the videos. Thanks.
My suggestion for a possible future subject is to expand on the effects of fender top vents on LMP/DPi. In particular, I was watching the in-car cameras of the DPi cars at Daytona. From inside the car, you could see that the combination of high downforce at speed and the banking, had the cars at full bump with the top of the tire seeming to be above the top of the fender. I would be curious to understand how airflow on the top of the tire would affect local downforce, drag, and down stream flow.
Thanks again.
Jac
Glad you're back.
Myth #1 explains "Goose neck" wings.
Point no. 1 is one good reason why attachments on aircraft wings, e.g. engines, flap actuators are usually all on the bottom. (The pressure side)
It's less of a concern keeping the airflow attached on that side, whereas over the top of the wing (equivalent to the bottom of a car wing) the airflow can easily separate under the wrong conditions and cause the wing to stall
The new HA-420 Hondajet airplane placed the two engines on the upper surface and more towards the rear of the wings. So there goes that theory.
I reiterate another point I made in a post regarding the video’s 1st point which is that suction is a virtual and apparent force but it is not a real force. In an aerodynamic surface like an airfoil there are two forces generated by air pressure differences. The less curved surface generates a greater force normal to that side and thus creates lift or down force depending on which side is facing up or down. Like centrifugal force suction is only a virtual or apparent force. It is not a real force. An excerpt from a Wikipedia article on suction and its reference source follows.
Gasses or liquids that move along a pressure gradient can exert forces on objects. Objects can only be pushed by gases or liquids. The correct terminology used depends on whether they are pushed from a pressurized zone towards ambient pressure (blown out) or from ambient pressure towards a low pressure zone (sucked in). Gases and liquids cannot generate pulling forces on objects[1]. ([1]
Quora. "There's No Suction In Space, Because Suction Is An Illusion". Forbes. Retrieved 2024-01-16.)
I cite this article because it explains well what I am talking about.
I've been watching your channel for a while with great interest but my race car world is somewhat different to everybody else's. I'm near the end of building a 4WD streamliner to take a shot at 500 mph. It is only 36" wide, 33" high & nearly 40ft long. It would be interesting to say the least to get your opinion on what I'm doing here. It has four full length stakes on each side & the top where the center two blend into an intake duct then terminate at two tail fins then I'm creating a sharkskin type surface between those. There is no driver pop-up, it's a lay-down configuration with the windshield being part of the nose. Should be ready for shakedowns in May or June.
I'm so glad you're back.
So good to have you back, Kyle. ✌🙋🏻♂️🏁
KYLE returns!!!!!
Great video. Can you do a video on the 2021 rule change in F1 and why the high rake cars weren't as affected as the low rake cars?
7:57 he looked like he was gonna kill someone, lol
Blue Tomorrow with an implied...(jackass) at the end of the sentence
I would like to see you analyse vintage F1 cars - and how you would improve them - using todays knowledge and technology. I suggest cars such as Lotus 72, Williams FW10, McLaren Mp4/4 and RedBull RB9. PS - congratulations on a great 2 years with Mercedes.
Regulations for old cars were very loose, it'd be better to redesign the car from scratch
@@davidaugustofc2574 just a theoretical exercise - knowing what we know today how fast could the Williams or Maclaren of the 80s be.
Could you make a video on wheel arch and front end design of enclosed wheel cars in particular please!!
This is what my dissertation project is based on (Scanning, Modelling, CFD/Wind Tunnel testing a Civic EF hatchback) so I would appreciate your take on it!😄
i love your videos! can you make a compairson video between 1980/1990s group c cars and todays lmp1 cars? i think that would be awesome. either way great video!
Proud to say i knew everything except for the part about edge vortices at the end lol
The one that annoys me the most is that a lot of people think that for high downforce cars there is some speed below which they have no grip.
It’s not entirely wrong. Obviously as you get slower the air moving over surfaces is gonna be slower and so you get less downforce/drag. And it’s really blown out of proportion but the effect is still there. It’s not gonna kill you but the car probably won’t have the same balance as it did and if you aren’t used to that you can overdrive. A lot of it depends on your tires too. If you have lots of aero and really skinny tires the shift from aero grip to mechanical would obviously be bigger. So it’s a lot of factors
@@cademckee7276 It is entirely wrong, ab lowered speeds the decrease in "centrifugal force" is always greater than the decrease in grip due to lowered downforce. There is never a point that you can regain grip by going even faster.
Also as far as tires are concerned there is no difference between "mechanical" and "aero" grip, tbh those terms make very little sense anyway. Maximum grip is directly proportional to the normal reaction force between the car and the road, the source of this force is irrelevant (weight or aero).
@@Bruno-cb5gk you are looking at this from a directly physics stand point. I am looking at this from haven driven a car with decent aero grip. As you slow down you can not only feel the wings working less but the balance of the car changing and when you get to a low enough speed you can feel that the wings aren’t doing anything because the balance of the car has shifted.
Hi Kyle. I enjoy watching your channel. Do you have any suggestions on how to reduce aerodynamic drag while trailering my 2005 Searay sundeck boat behind my pickup truck at 65MPH. Gas mileage is horrible. A 10% improvement would help. This is an unexplored market for technology to reduce drag. I normally tow with no highway covered and the center console door open to let wind go down the center of the boat. Any suggestions you have would be appreciated. I am a retired Electrical Engineer so I may try some experiments. Thanks Joe
Kool video .dose the same rules apply to RC cars and Scalextric ?? Also idea for video getting downforce without drag ...such as drag cars also air going into engine bay the effect on air flow such as air scoops bonnet scoops ECT
You’re back!
I think people get "stall speed" from when automotive journalists talk about race cars and mention how they need to be going a certain speed for the aerodynamics to take full effect, I could be wrong tho.
I think it's way more simple than that - people assume that they understand aerodynamics SO much better than they actually do(the amount of times I've had to tell people "...YOUR EYEBALLS ARE NOT A WIND TUNNEL..." in response to a car's "horrible aero" - even though it was designed by damn engineers with huge budgets and all the resources...), and everyone thinks "aero doesn't make a difference unless you're going fast enough". I HOPE that people don't actually think that aero acts almost like a light switch that is "on" at a "certain speed", I think most understand that it doesn't work that way. But there's this idiotic idea that "downforce doesn't matter till 60MPH/100MPH"(those seem to be the go-to numbers) - in spite of all of the open class autoX & Formula SAE cars absolutely proving otherwise.
Typical problem of people "knowing just enough to be dangerous", the classic Dunning-Kruger Effect - they learn a LITTLE about the subject, think that they have an "inherent understanding" because it makes sense to them, drastically overestimate their understanding, so then they just start making assumptions that "make sense" based on the tiny amount of knowledge that they have, while not realizing how little they actually understand.
@@RyTrapp0 slight insert here: part of the reason that the F-SAE cars have "effective" aero at low speeds is due to their light weight (requiring less aero force to have a large relative effect). On something as heavy as a street car (e.g. street legal sportscar that you take to a trackday), that amount of downforce won't be noticeable at the low speed since it is much smaller relative to the other forces at work due to the higher weight.
I want to dig in on your claim about myth 1.
I think you mostly worded everything correctly, but I wonder if you might inadvertently be communicating a new misconception.
While it is true that the *math* of the coefficient of pressure leads to a cap on the pressure side of a wing and no limit on the 'suction' side of the wing, isn't that just a quirk of the math? I don't see any reflection of that in physical reality.
I don't think there is a physical mechanism for a gas to pull on a wing. There are either particles of air exerting pressure on the surface of the wing, or there aren't. If there aren't, the pressure is zero, and that's the lowest possible pressure.
On the other hand, there is no upper limit (within reason) on positive pressure.
I'll grant you that dropping the pressure on the underside of a wing (on a car, or the upper side on a plane) may contribute more to the downforce than building pressure on the upper side does...*but the pressure on the upper side is the only reason there is any downforce at all.* There is no physical mechanism for a lack of particles on the underside of a wing to pull that wing down.
Positive pressure is the only physical thing that gases can exert. If you drop the pressure on the under side of the wing, the gas has no mechanism of attracting the wing downward. It's just not pushing upward as much any more.
So the upper side may be the pressure side, but the under side is not a 'suction' side. It's just a side lacking pressure.
I think the movement of gas particles from high to low pressure regions is what he is referring to as 'suction' here. While a physicist might see his explanation as semantics at best and misleading at worst, for an aerodynamicist, or even a casual car enthusiast, the difference is important. As he mentioned, there's not much more a car designer can do to increase the pressure on the pressure side (beyond CP of 1), but there are performance gains to be had through decreasing the pressure on the under side of the wing, or in everyday language, by generating more 'suction.'
At the end of the day, in my understanding it's the pressure differential that matters. I feel like he somewhat overstates the degree to which it's "wrong" to say that the high pressure side is pushing down on the wing, due to the physical process which you describe. Then again I am just a layperson watching youtube videos while he is an expert on the subject. But it could be his professional context that leads him to describe these aero effects the way he does.
@@zvexevz I *think* I understand what he's aiming for, which is why I would like to hear from him. I think his explanation is problematic, instead of wrong, which is again why I would like to hear from him.
My thinking is that fixing one misconception by introducing another doesn't move the conversation forward. I know he's trained in aerodynamics, but in this context, he's an educator. And the shared goal we should all have with education is to develop a fully accurate understanding--one that satisfies people that are concerned with the math, *and* one that satisfies people that are concerned with the physical reality, *and* one that satisfies the people that just want a car to go faster.
In that spirit :) ---
"...movement of gas particles from high to low pressure regions" is more akin to flow than to suction.
In this context, he is using suction to describe a pressure differential *without* flow between those two regions. For the case of a splitter, we're talking higher pressure on one side of the splitter, and lower pressure on the other, and (ideally) *no* flow through or around the splitter.
A differential can be achieved by increasing pressure on one side, decreasing it on the other side, or both. *However,* downforce is *always* created by the side with higher pressure. I really don't think it's correct to describe it as suction. Low pressure cannot pull--instead, it just doesn't push. So a more fully correct way to explain what's going on with a wing, is to say that you achieve greatest gains by reducing the push on the underside of the splitter. There *is* a limit to this (unlike what the equation he's referencing indicates). You can't go into negative air pressure.
Great video. Have you ever considered doing a video on the flexible front wings as used in F1 (notability Red Bull) in the early 2010s? I'd be interested to hear your thoughts in what Red Bull were trying to achieve, and how they were able to overcome the technical challenges to get them to work. Especially in comparison to say Ferrari where they had obvious hysteresis/porpoising problems.
Looked like it was a structural issue more than an aero one
Enjoying. I went back multiple times few seconds to look again at graph or listen again what you are saying, but no amount of coffee can save my half sleeping brain today. My question: how high can diffuser start so that it still works. And I am remembering that they do not work if underbody is not flat before it - from your 2017 videos. But is there any usefulness.... Another one is that how making flat floor under the front engine bay can help, and in that case how to successfully still direct engine air like stock, underneath the car? I quess my question is how long under tray at front is beneficial in drag reduction? And how short diffuser and at what height is minimum for any use.
AJ Hartman sent me here, and I’m glad he did 😊 Great content!!
Can you do more car aero reviews like you did the One:1 and McLaren P1? I would like to see the Jesko (track and absolut edition), the SSC, and maybe the 919 Evo it’d be really interesting to see why manufacturers chose what they chose! Oh and you mention Gordons car in the other video, when can we expect to see that vid?
May I asking 1 ridiculous thing
For space reason, Can be expansion chamber of diffuser designed to be expanded sideway while maintaining the height rather than expanded upward like most diffuser do? Can it work synergistically with normal upward ex chamber diffuser on either side of it?
Could you pls talk about low drag front air dams? Of course avoiding lift. Thx
It'd be amazing if you could discuss the different aero philosophies used by F1 teams, shows some CFD simulations on various parts, etc
Can you do a video on how to make or where to buy flow vis?
If I build a tube framed race car with the intention of having a functioning front and rear diffuser and flat floor. Should I design it with a rake at a certain angle to start with? Or should it be designed completely horisontal and you only manage the air within the diffuser designs? Because simply putting a rake on it afterwards would compromise the suspension compared to the horizontal plane.
It would be nice to see what kind of airfoils, where and why are used on the various aerodynamic devices on a F1 car!
I would like to see a subaru wrx with and without the big spolier on the bag like the 2004 model. Does that big wing make a difference? Also the wrc one had the spolier further back on the boot lid