That's actually a thing! Confirmed added drag at highway speeds when the lights are up. Just might possibly affect the wing's downforce but I think it would be negligible if at all.
@@danielskrskr they could create a vortex that runs along the top edge and flows into the wing. I would actually like to see the fluid dynamic effects beyond "adds some drag" and also how it interacts with a convertible up and down and with a wing and without just because.
I used to have a Miata and this confirms what everyone told me about wings. if you're gonna do it go big or go home they say make it higher than the roof
Hey Guys, sorry for the mic in shot and the somewhat questionable audio, I just moved and the echo level in my new room is absolutely insane! Will be doing some acoustic work on it in the new year for sure. Hope everyone has a great Christmas and New Year and I'll see you all in 2022!
Hi just hang some rugs or blankets on big flat surfaces of wall and put some stuff in corners. May be it's bit ghetto style studio solution but takes only about an hour to set and reduces echo significantly. I done some Internet radioing doe years ago and it was may be not pro lvl but far better than nothing
Really interesting video! This definitely covers the most common case of traditionally shaped roadsters/convertibles that people can actually afford, but also raises the question of whether the more "purpose built for speed" convertibles behave. Stuff like the convertible versions of many Ferrari and McLaren cars, or an even more extreme case in the Pagani Zonda Cinque Roadster. Cars which have significant structures and most of the shaping still there behind the drivers, instead of this classic design with essentially nothing past the A-pillar, except maybe the quarter window. Basically getting into the territory of "can you make the aero on a convertible work without going all out to something like an LMP900 car", with a normal windshield and a wing that's not lifted high up in the sky and twice the width of the car. =)
Thanks Kyle ! very interesting. Would you test a no windshield condition for a race Miata. I know the frontal area would be reduced by 50% ish but I would like to see the effect on the rear wing.. probably less wing will provide more or same downforce with less drag. You're the one who can answer that for sure !!
Yes, I've seen a comparison of the airflow to the rear wing for an evo with vortex generators and an sti without, and the evo configuration works much better
It might make a slight difference, but the separation bubble is so big and the angle on the roof so steep with relatively sharp edges. I doubt it will do a lot.
There are several hundred of us that have converted a Miata into an exocet. While saving huge weight, the aero is horrible. There are some things that could be helpful though. Obvious ones are no windscreen, cover over passenger side (no passenger seat) and probably large wheel fenders. But your take on what could possibly be done to improve aero on an exocet would be fantastic, considering the majority of Exocets are built to drive on track.
Super interesting! Thanks Kyle, I have often wondered about this myself. I Think a fair few miata people will be watching this one. Definitely curious about how effective vortex generators are on the air down the back of the hard top also. Would also be interested to see what if any benefit on the rear wing swapping the mirrors to so a small race mirror type there is.
Thanks Kyle, this is wonderful information as always. Roofless miata owner here, I'd love to know if there's anything I could do to improve air flow without a roof with a ducktail. Would a Gurney Flap on the top of the windshield help or hurt? Would vortex generators on the top corners of the windshield help? Or at the bottom near triangle windows? Would covering the passenger area with a tonneau cover make a difference? Would a bikini top wrapped over the roll bar help? I'd be happy to toss some money towards this type of testing info on Miata's and I would think and hope other's would too. Do I hear a gofundme? or similar option for this? Thanks again Kyle!
I would love to hear your thoughts on the 2022 F1 cars and their pitch sensitivity. The Indy car guys have more experience with ground effects than F1 guys. Honda is powering enough Indy teams, if I were Red Bull and or Honda I'd be on the phone to HPD powered Indy teams and get as much data on car setup as possible. McLaren already has an Indy team, probably gonna help them tons with the new car. If nothing else they have a setup direction.
still from 2020 and till now you look tired no joke, but the content and the detail of the information on every videos are worth it. Absolutely love your video man
I watch your video on removing the bumper in order to use the rear end as a diffuser. Along with this video they have answered a lot of questions I've had since I started working at the local track. I've seen top up/down, no top at all just roll cage. One had no windscreen and an active aero rear wing. Rear bumper on or just a couple bars welded on. I guess it boils down to the series you're racing in and personal preferences. Bravo Zulu sir.
I was wondering if you could expand on this with a popular race configuration of a convertible in which the windshield is removed? Perhaps one with the cockpit open and another test with a tonneau that encloses the passenger area with the exception of the driver? I know the necessary roll cage and the drivers body would disturb airflow to the wing to some degree but it would be interesting to see if it is worse or better than either of these two configurations.
Great video as always! Would be interesting to see the effect of a bumper cut on a MX-5. There are a lot of arguments about it on the forums but no clear data.
@@Pocket4ce The last time he covered cuts it was a little simplistic, (fair enough too). One of the main elements of the rear bumper that miata people discuss is how from the inside it looks like a scoop or parachute. Some people will cut a few holes in it with for this reason. (totally ineffective I would think). So the cut is thought to be sort of doubly effective on a miata. In the model on Kyles sim there is a bit of a cavtity on the stock bumper but not as much as there is in real life. Though saying all that I imagine that everything he says in that video still holds true despite this.
@@nehok Small world, ex-spec Miata mechanic here. We've never cut the bumpers in our spec cars, but our SCCA STL cars had the bumper bar "relocated" to make room for a cut even with the trunk floor. We didn't bother with cutting holes or anything like that. I've actually consulted with Kyle on the aero package of my autocross/track day car a few months back and left with a really novel solution to rear aero. I am more than satisfied! JKF Aero's standard fees are super reasonable (more than you would imagine) and honestly, a huge value. I suggest shooting Kyle an e-mail! He is a busy guy, but I'm sure he will respond.
@@Pocket4ce Cheers! Sounds like you have far more experience than I! I just track my miata atm, though I'd like to do some sprint racing in the future. I find aero tuning a really interesting avenue to get faster. Especially as there are very little reliability downsides as aposed to adding turbos etc which i'm lothed to do. When i dirve my car to the track and you think about the amount of money each day costs.
I just discovered your channel a day or two ago and I have watched all of your videos since you came back to RU-vid one year ago! Being interested in cars, tuning and aero myself, I am absolutely enjoying the hell out of your videos! Cheers to you and all your wonderful knowledge
Well that was almost what I predicted, however I didn't predict the use of a wing that was almost 50% wider than the vehicle, which is basically what through off my prediction 😀
I think that was mostly the case with the large rear wing because removing the roof prevented the wing from receiving smooth air to cause drag/downforce.
An analysis of a targa top like the RF with center portion removed would also be nice to see. I wonder how much the open portion would change both the drag and downforce
I was so stoked to see you post, you videos are so informative and quite interesting, especially when you use common cars that a TON of people modify. I bet if you tackled the most common cars and modifications, you not only would have a bunch of "material" but i can only imagine the algorithms/the amount of clicks/connections would be wild because people are already searching those cars and mods. Could even "mock" items/brands and run them side by side in test.
good god... during the flow analysis i noticed that when you have a wing not only does taking the roof off reduce the effective area of the wing but it creates huge low pressure zones right behind the supports due to how the air moves. note to self, keep the roof on
A quality write up, very informative and well researched. Could I briefly note my appreciation for the rear spoiler on the back of your head? 11/10 on commitment to the subject!
Hey Kyle, could you make a simulation to show why the back of some SUVs are so squared (like the Chevy Equinox or Honda CR-V) yet, they are very aerodynamic vehicles.
Very good video, great analysis. I do wonder though, what would your take be on the soft tops? They typically have the same general shape as the hard tops (well, with the humps of the supports) but probably have higher drag due to the texture of the fabric. I would assume that they would be somewhere in the middle, but my guess would be the higher end since it resembles the shape of the hard top. Would be great if you could make an analysis on it!
My basic understanding of fluid dynamics leads me to guess that the texture has a negligible effect on drag when there are much larger forces at play from the pressure distribution. If anything, the slightly textured and non-uniform surface of the soft top may behave like a golf ball and create a slight layer of turbulent air around the top. And in principle, just like a golf ball, that turbulent layer would help to reduce the wake produced by the top as the flow "bends" back down towards the trunk. That's all highly speculative though and now I'm curious to see an actual analysis haha. Not sure how easy it'll be to simulate a soft top in CFD though.
So, I drift, obviously, we are sideways, or at least moving through the air at a none direct angle. I would love to see some tips and tricks based around that. I assume a flat underbody will be a massive help, but you can often feel a car's aero fighting against you, rather than helping.
Okay but this is only for the NA, the NB has significantly redesigned aerodynamics. Could you do this for the NB and also include ducklip spoilers bc they stick up a bit higher than the lower lying spoilers?
Genuinely speaking, the canopy on the truck in my avatar ,being a fastback shape, would result in an improvement of function for a "Bonneville Spoiler" Vs a "flat" Tonto cover/tarpauline. Especially when exceeding 200mph( 320kph) ( current Target is 227.8mph)
I havnt seen any proper videos regarding WRC aero, they have a massive rear wing which would indicate that they have pretty decent downforce at the front but they only really have a small splitter, no venturies, wheel arches and pressure cut outs at the front so im struggling to see how they have so much front end downforce that they need such a large rear wing for. Can you make a cfd video on this pleaseeee
Hi! Mechanical engineering student with a heavy interest in motorsport here. I'm just wondering out of curiosity, how do you develop your models for CFD analysis? I will begin to learn CFD in my coursework soon, but I would love to do some experiementation on my own so I was just wondering about sourcing the models you use in your videos. Thanks! Keep up the awesome content!
I’d actually find a video on sunroofs interesting. I tested the average gas milage in my car on a stretch of straight road and saw a much larger decrease in fuel mileage with the sunroof open than with the windows. I’d be interested in seeing how it affects drag. Here’s the data I collected. 2021 Chevy Spark 1.4L Windows closed, sunroof closed, A/C off MPH - MPG (rounded to nearest 1/2) 20 - 67 25 - 76 30 - 72 35 - 69.5 40 - 61 45 - 60 50 - 50 55 - 49 60 - 46 65 - 44 70 - 37.5 75 - 33.5 80 - 32 85 - 28 90 - 27 A/C full 60 - 42.7 A/C medium 60 - 44.5 Window / sunroof cracked 60 - 45.5 Window / sunroof fully open 60 - 43.8 Window half, sunroof closed 30 - 71.7 60 - 45.8 Sunroof cracked 60 - 44.6
Would a bikini top help this situation with the Convertible? I have a giant wing, no roof, no windows and am considering making a bikini top (or tonneau cover but favoring the bikini top). I was even considering having it taper further down towards the back like a fast back. I do only autocross with average speeds of about 50mph and have a NA Miata with front splitter as well. Very similar to your model. Love your videos by the way.
it would be intriguing to see how much a vortex generator at the back the of roof section would effect the rear wings effectiveness ! if there's a way to model that it would make for some great additions
What about with wind deflectors many convertibles have that can be raised and lowered while driving, usually in the rear seat or just behind the front seats.
2 Questions: 1. Is this a full scale model? Like, was this Miata precisely designed to represent the actual vehicle, or has it been scaled down? (My guess is, it's a smaller scale 3D model) 2. How much does weight play a role in affecting aero? I know more weight will make the car more lower, hence it affects the drag and dforces. But, I want to know if it is true or I am incorrect?
I always fancied the idea of 'breadvan-ing' a convertible such as the MX5/Miata - I often wonder what performance gains or losses would be seen from it?
All these studies assume essentially "flat" oncoming air / level ground, but what happens if the front of the car is pitched up or down? I run an ND Miata with the Balckbird Fabworx lexan spoiler, which is primarily designed for autocross. However, last month at Road Atlanta I was doing about 115-117 on the back straight and as the car changed pitch all hell broke loose - the rear end flew up off the ground for what felt like an eternity. I took the spoiler off and it was fine for the rest of the event (top down at all times) but I'd love to see what that rear airflow looked like
Great analysis thanks. Building an MX5 NA for competition. Is there any drag reduction benefit from a spoiler on the back of the hard top to break the air flow away from it - assume no rear wing but maybe a boot spoiler could be added? Thanks!
Really enjoyed your analysis of aero on convertible. I have a couple of questions. I removed the roof and side windows primarily to save weight. Should I replace the side windows with plexiglas? If I fill in space behind seats will that improve aero? What is optimal angle for rear wing, we are currently running 10 degrees Thanks in advance for your help
Hello Kyle! I would like to throw at you an idea you might find interesting for a video. The aerodynamic impact of louvers (i am talking about the rear window ones they put on old race and rally cars in the 70 and 80s). It would be very interesting to know how they work. Hope you are fine and thank you
I'm a bit confused. You went with a massively oversized wing to try and compensate for a foreseen problem, but used a stock-looking spoiler instead of doing anything to make it more effective. Even more confusing is that the spoiler is also present on the winged model. Looking at the CFD images it looks like a taller spoiler with a steeper angle of attack might have been more effective. Especially if it wrapped around the tail a bit like the iconic ducktail on the Gen 2 Firebird.
Thanks for the great video! In your opinion, if you are racing with a hardtop and open side windows, would holes in the rear window help the drag and downforce situation? IF they help, would you put them in the top or bottom of the window and what size would you make the holes? Thanks!
This is interesting, I just bought a Mini Roadster which has a retractable spoiler. If this data follows through, the spoiler gives drag with negligible downforce gain. So it is just a gimmick, essentially. Question: Does it make any different whether the driver / passenger windows are open or closed? I'm guessing it would cause negative pressure in the cabin and bring the over-body flow down earlier.
I’ve never seen any convertible racecars , do you have an example? :) I mean racecars have a roll cage and the top mechanism is either completely removed e.g. mx5 cup or a hardtop installed, most of the times they start from the coupe street version when developing a race chassis.
Very instructive video, thank you Could you explain or show how you modelize such detailed model of car ? Where did you get data from real car ? And eventually how do show the flow, but this point look more easy. Thank you again Cheers 🇲🇫
Excellent - Subscribed Thanks for adding some PROPER data (beats myths and hearsay everytime) ... This was super helpful for my #LotusElon project - ie maximising range.
Hey Kyle! A bit of a wiggling question in my mind has been bugging me since trying group C in the sim. The Mazda 787B has this low wing aero philosophy and that downward sloping rear end, but right at that tail section, there's a small gurney flap across the bodywork. Whats it for? Positive pressure over the rear bodywork? Stopping downwash/lift from the sloping bodywork? To help the diffuser/rear wing? I need answers!
I'd like to see a comparison between the oem and TRD spoiler on an AE86 3 door hatch. I'm curious about which one does a better job at reducing drag (less recirculating wake at the rear for faster acceleration) and lift and if the TRD spoiler produces any added benefit of down force because of the longer surface and rake.
I guess what I learned was have the big wing right behind the headrest. Maybe have it part of the automatic convertible... it’s in its “name.””🎅🏻😎🤛🏼🇦🇺🍀😎🤓
Thats cool... Still driving with my top down. If all I cared about was performance, a coupe flexes less anyway. Follow-up: What aero methods do you suggest for open-top race cars, both vintage and modern? Is there a wing design that can be more effective in this case?
I've seen many people build a cover over the cockpit for competition convertibles, I would assume it would allow airflow to reattach to the body before reaching the rear wing allowing it to work properly, but probably wouldn't reduce the amount of lift inherent on a convertible. Just what I would expect, im no engineer
Another thing I'm curious about is the current trend of oem spoilers having the middle section scalloped out so that only the ends are raised. What does that do to the flow profile and is there any aero benefit?
I have question about "flat" wings like Audi a7 first generation and many others , what is the benefit of these profile ? I think they generate low down force and lots of drag.
