One of my friends used to drive a Mazda 323 GTX in high school. We used to joke about how its two "spoilers" generated infinite down force, and would allow it to fly if you managed to flip it. All joking aside, it's so cool to see the actual engineering and CFD behind that design choice. Nice work!

Once again: Place your rear wing to help your floor generate more downforce. Don't use the rear wing for downforce. Use it to help your floor generate even more. In other words, think of the car floor and rear wing as a two element airfoil. Car Floor is the larger first element. Rear Wing is the second element. Use the Second Element Rear Wing to keep flow attached while also adding energy to help evacuate more air from the low pressure side of the Floor to generate more downforce. This might mean you're not placing the wing high up, nearly above the roofline, as expected. The angle to the ground plane might even be negative. Though it's AoA to the airstream will most likely be just slightly positive. All to accelerate the air to help the Floor evacuate more creating lower pressure. Which would create even more downforce than just using the floor and rear wing as seperate devices.

I've been wondering for a while now, how a sunroof being all the way open or just popped up, affects the aerodynamics. I was hoping you'd already have a video on it but if anyone would do it, I think you would be the best one for the job. It would be awesome to see you make this happen! Thanks

Can you do a lorry aero test so i can know how deep I have to tailgate it for me to maximize my fuel efficiency?

As an scca racer who drives mk1VWs I'm very happy to have found your channel.

Mate, your vocal fry is on a californian girl's level.

I’ve owned a Mk2 golf 2 door for over a decade. I love this video. The fact that people (actual engineers) are still talking about and improving the Mk2 GTI makes me happy.

the funniest use of wings was on Renault Espace mk3 (1996-2002) and mk4 (2002-2015) and some Peugeot 807 models also had them. Would be interesting to see simulation on those boxy family cars

Might just be my misunderstanding, but how is this not a benefit to on track performance? Also, will you be looking at wheel well extraction? I've seen two approaches to this - one being to completely divert the wheel wake outwards similar to a bargeboard like on the M4 GT3 and the other being to vent it out like the R8 GT3 which seems to be the more traditional way of doing it.

Nice, even though as you state its a robust concept, i think a lot can be done on the flap design aiding in the turbulent flow direction where the flow detaches, i think that is key to optimizing the wing performance.

Very interesting video, in currently studying aerodinamics at university and seing it applied is very interesting and helps visualise it. To reduce the overall drag of the car are you allowed to make a diffuser for the underfloor? That should help reduce the base area on the rear and so the overall drag. If I said something wrong please correct me because I'm still learning so I appreciate any advice.

very good that you kept testing and learing, notice that you found out that it was from old rally cars, also hill climbs (pikes peak, some dakar and so on) but most of them use a different method instead of the flat flap following the roof, very glad you tested that one because thats my theory of putting the wing all the back you are allow and letting the air follow a better shape to decrease drag and lift on the body of the car ( having a so back wing also helps with making more leaver force to the chassis) some ideas that you can test on the rear back of the hatchbacks ( i have some already installed) using a flat flap, with gurney and other with spoiler but on the middle of the car below the wing, i believe that area can be used to get more effiency out of a hatchback form i saw the complete list of the touring aero you made and notice that you made a cut on the rear bumper, i am using one but from around the back axel 90 degrees diffuser ( same theory of a open door on the rear of a pickup) but upside down, racing with it at certain speed i have felt the interior that i made from sheet steel bending so i assume it works and create more pressure to the rear great content and hope that someday we can maybe chat about it, always it is a very good time talking on aero from race cars and dont feel that everyanswer has to be though because it is a business secret that sells thanks for the content and have a great day

Do you think the cheesegrater-style rear aero element from the first-gen Suzuki Alto Works, actually works? Brochures made a point over the reduced Cd it apparently did.

hello, what program do you use for the flow simulation?

Looking at the section with the flap and wing combination is this ignoring the side edges of the hatch? Can air be brought in from the sides to modify the circular airflow over the rear window?

what about the consept of clean seperation edges, I mean this car is kinda boxy so it comes kinda like that from factory, but if you have extended flaps from sides in a negative angle to give smaller wake area and better separation edge does this do anything

If the wing extends off the sides of the hatch it just produces more drag because there is no roofline to guide the air

One thing I would like to know is if there is anything I can do or add to my van to stop road-spray or rain and just the general dirt and muck from being sucked up off of the road and attracted to the rear windows like a black hole attracts matter. Maybe some kind of wing or vanes to let clean air blow down over the glass from the roof. I don't care much about drag, since my van is an 8 ft. tall brick as it is. I have an older conversion van with the high roof, and 2 doors on the rear. (Just look up a pic of a '90 Dodge Ram B250 conversion van) I have installed a rear-view camera just behind the glass, and if it's raining, or the roads are wet, the crud just gets sucked up and all over the glass, obscuring any view or hope of seeing rearward via the camera or interior mirror. Anyone who has ever had a "flat-back" vehicle, as in a van, wagon, minivan, bus, RV etc, with no rear wiper/washers will know the struggle.

So the VW TCR race car wing that comes on the car from the factory could be considered as useless?

Interesting thanks! Can you show us a Holden Commodore wagon? Stock and some thing after market?

With the configuration at 0:08, a positive aoa (so positive lift in free stream) should result in attached flow. Since the relative aoa that the wing sees is still negative, you make downforce and you could even get a bit of thrust because of the angle of the airflow. Now you are just stalling the wing big time, indicating a too high (or too negative) aoa.

Great channel, would it not be more beneficial to use devices at the back end of the roof to redirect air into the low pressure zone behind the car to just reduce drag. And maybe use a flat floor with splitter and diffuser to create some negative lift for the car? i'd love to see that visualised

ok, I took a screenshot of the config at 0:30 because I was really curious about how strongly the air is pulled down. The angle of the tailgate to roof transition is dead close to 30 degrees. That is the angle with the most induced drag for a hatchback rear end based on Ahmed body experiments, so it does explain your findings, especially that the model doesn't have any trips at the transition. The effective angle of attack because of the downwash is ~40deg, so yeah, no chance that would stick. At 3:45 it's ~25-30deg so again, separates. The second part of the rules you posted does appear to ban the plate, as it is a spoiler, but I'd be asking for a clarification. I.E the Civic running in improved production now has the integrated tailgate trip & a rear wing. On a separete note, would you be open to sharing a picture with the mesh shown? The model looks pretty smooth, but the vector arrows look pretty sparse and that could have an impact on some results.

So whats the conclusion form your data ? Rear wings work if you use the standard flat spoiler too. Im always looking a wrc and rally 2 cars rear spoilers

What wing/flap would be best for a 2020 chrysler pacifica?

at my work i learned one big thing about wing and flap and flap squarre, a wing without a flap isn't as effectif as a wing with a flap, and flap squarre is as important

What anout civic eg spoon spoiler?

Hi, Nelson, could you possibly reccomend a CFD software? i tried following open foam tutorials but could not manage to geit ti running

On an all out race car with full aero an ultimate way to benefit could be to create a wing that actually created a little lift at the rear. Creating a "lever" effect slightly increasing the rake of the car (a force actually lifting, infact lets think of it more as twisting/levering) the rear with a little upwards force but with the equal effect of also pushing down the front a little. That lever force could then be used to alter the flow of the air around the rest of the car itself, but the main goal of creating Lower pressure under the car for example, essentially sucking the car to the ground more. More net downforce. This would ofcourse require careful consideration and design of the rest of the aero etc of the car. On a basic off the shelf road car hatchback its probably not going to do much, infact youll end up with more net lift. But something with carefully designed aero on the underside, acting as a package utilising the rear wings rake boost, well, thats wheres the aerodynamic performance gains could be at for sure.

We have observed in practice that rear wing can and will increase rear wheel grip at high speeds. Also in context of pure downforce, it might not be much, but depending on where you place that wing you can shift the weight of the car and create a stable or predictable behavior in the high speed corners and at the same time very well rotating rear in the low speed corners. In general the closer to 90degrees the hatch is the more you get drag and less lift. And people rarely account the suspension dynamics when speaking about aerodynamics.

What about a 95 civic eg hatch with a "spoon" type spoiler?

This explains why the rear of my Focus is always the dirtiest the quickest.

Can you explore in more detail the effect of a 'midwing' on hatch aero?

Rally cars have wings for an exorbitant amount of reasons

It would be interesting to see the turbulence on an old Saab V4 95. It has a built in spoiler.

You should do a video on ute/'pickup truck' aerodynamics

so Wings West's mid hatch wing for the GTI was correct all this time? I just thought it was part of their tacky, bloated looking body kit to go along with 90s/early 2000s car styling. what about a small lip spoiler on top of the windshield and then a slightly larger moon shield lip spoiler __/ on top of the hatch glass? the idea is to slow the air going over the car, yes; or is it to make the air tumble?

hi, any chances of a episode on drag racing hatchback? :)

Good stuff! Would you call the tiny squishy lip on the back of a first gen CRX Si a type of spoiler?

Can you do the same analysis on a wagon?

I was interested of becoming an engineer and i'll keep looking at your channel to see if it's interesting to me. Thanks a lot!

Just a horizontal extension out to the max distance allowed would stop lift from the rear window...

what program is this ?

what’s the software ?

How do you do this simulations of air ?

My Corrado has an active rear spoiler. Comes up at 70mph.

We own a tucson 2005, will there be a good result if fitted with a wing?

What may be a silly suggestion. What happens if you mount the wings vertically behind the car. Obviously there will be rules not allowing it but just wondering if they can be made to reduce the drag. At a super loose interpretation the vertical wings could be called the end plates.

How much more effective would a wing be vs just a surface mounted spoiler? Or flap as I think you call it. Seems like a wing adds more drag than anything useful.

I'm more interested in keeping the rear hatch clean... Especially the window

From model aircraft and glider design, I know the Wortmann FX60-126 airfoil to offer a high Cl and L/D over a wide range of Reynolds numbers. For a laminar flow airfoil, its tolerance for turbulence is remarkably good as well. I know its characteristics from the ASK 21 gliders from first hand experience and can confirm that the last bit of these planes to stop flying are the wing tips which feature the FX60-126. Maybe run a simulation with this? An airfoil that produces a substantial Cl max from low Reynolds numbers as well is the RAF 32, which is not too popular with planes for its Cm₂₅ being pretty hefty. For use on a car, this would be very little of an issue, so it might be a good choice there!

Make the chassis of the car the shape of a functional downforce aerofoil

Надо не увеличивать прижимную силу установкой антикрыла и увеличивая аэродинамическое сопротивление, а уменьшать подъемную на задней оси, установкой спойлера и уменьшением аэродинамического спортивления, с целью уменьшения зоны разряжения позади автомобиля. Чтобы понимать о чем я говорю ознакомьтесь с ауди ТТ первого поколения

Only thing the rear spoiler did in my hatchback was to get dirt and dust stuck between them and annoying to clean

Once I saw the underside of my car and realised how not aerodynamic is seemed. Ever since I would like to make it more aerodynamic.

On the road they are not really useful especially if you follow the speed limit. Drag racing, not useful at all. Rally or race, definitely helpful and useful due to the sheer amount of variables involved in racing. Wind, high speed stability, stability overall, couple with the slaps (floor sidewing) makes a huge impact on reducing drag where you model completely ignored this aspect. That’s where the suspension starts to matter, how stiff or responsive can impact the drag differently. There is soo many things I could go for an evening.

A sissy little wing on a streetcar has no or not much use. At speeds achieved on streets, it generates not enough to have effect. If so the wings on sportscaster would be smaller .

I’m sorry but why are you talking so slow dawg

Wing looks too far back why not move it closer or right on top of the roof