I guess this is where the Peugeot 205 T16 rear wing design came from.

Already a huge improvement to the thing’s mentioned the other day. Much better (slower) pace and the pictures/comparisons are easy to understand. The graphs at the end might still need to be paused and have a closer look at to really digest, but that’s not much you can do about that and not a big deal. Nice work on the aero and the improved video. 👍👍

"just 20% more drag" That's what I call an 'aerodynamical heart attack'

This video should get more attention

I think it would be worth testing the wing in a setup where the flap extends all the way to under the rear wing. That seems to be the case for the WRC cars and I wonder if provides better support for the rear wing. Maybe even build a slight tail cone off the top of the roof into the flap to keep the flow smoother. Also I’m curious to how the TCR cars are getting their downforce as they all run a traditional rear wing without any window flap to help and those cars are producing pretty respectable downforce

This is a pretty nice improvement. I do think it's funny that your first solution, the spoiler + wing approach, is basically just fixing the hatchback wing performance issue by giving it a simulated sedan trunk lid.

That explains a lot on why I see some wings in that particular form. Thanks!

Make sure you test wings/airfoils seperately and compare them to xfoil or wind tunnel results. When I first started getting into aero I was getting very different results. Turns out that a good transition model is key to get these low reynolds number airfoils working. That's probably one of the reasons why you are always getting so much separation on your wings.

Something of note is that (at least, supposedly, I've not come across an accurate enough model to check via CFD myself) during the development of the modern Fiat 500 (Mid 2000s-Current) the designers wanted to avoid a rear spoiler, the Abarth models in particular though had them introduced purely on merits of drag reduction alone. As a consequence, the electric models of the hatchback sport a similar spoiler as drag reduction is also key in that application.

A lot of people has done the flap before the wing on hatchbacks or similar time attack cars, not to the complete world to know but they do from long time ago ( in pro and in also amateur, me using this idea on my civic around 10 years ago and actually test it around 5) it is amazing to see the cfd on what was on my mind, thank you very much

Looks like a shift of the wing forward an up at the end of the roof section would work much better, since it will be aligned with the flow on the roof. Though some regulations might not allow wings that high up.

Thanks for sharing the video. Your models explain this dynamic very clearly.. The wing options make sense when you show them. Reminds me of the Peugeot 205 T16 with its huge rear wing. and also like you said the current WRC cars use the flap on the rear window to improve the efficiency of the rear wing.

Amazing info! Earned yourself another sub. Thanks so much for this!

yo that was really interesting to watch! hopefully you'll keep doing this type of content, subbed :)

this is fantastically interesting and also really usefull info

the videos from this guy are so comfy

Great video. I think this was researched by some teams during group B era and i think some car between renault, peugeot or lancia had a wing that looked similar. With cars also being quite boxy like this example's golf. dunno why this is not used widely today though.

There is a 1990's Honda Civic aero kit that has that extra duck tail under a wing. I always thought it served zero purpose, and it was more for looks, but it all seems to make sense now :).

Ford's RS2000 was originally designed with 3 wings - the final production version had only 2. On Wheeler Dealers, they added the missing 3rd wing. Hatchbacks like Golf mk1/mk2 benefit a lot from a lower rear splitter. Reduces dirt on rear window, too.

I didn’t understand 90% of what was said in the video because I’m not versed in this topic, but I enjoyed watching and learning!

great stuff.

Some race cars had this worked out. Look at the 205 T16 Evo II, that thing had the wing of wings in the hatchback style of car. An interesting comparison would be the 205 GTi vs the 205 T16 Evo II. Also the 306 S16 vs the 306 Maxi Phase 1. The latter 306 had a shopping trolly style wing on it which from what I can see only generated lift...

Nice video. What cfd software do you use for this analysis? Have you ever done an aero study on common SUVs like Honda HR-V or Toyota Raize?

Hello! You are doing amazing job! Do you have a video for hatchback aerodynamic for the drag race ?

This is awesome tech nerdy stuff! Have you tested what would happen if you lower the secondary flap under the rear window (2:23) like they've done in some aftemarket kits for hatchbacks?

Very interesting, I myself made a "drag style" wing for my rover 100. But added a bill/wicker/gerny at the end of it. It made a noticible difference in downforce with the rear being more stable but no idea if it actually reduced drag or its creating a bunch more

sweet ass video, subbed, will enjoy seeing you grow soon

Now I’m curious towards the cosworth double wing design effect.

on the mini R53 people run the standard spoiloer along side the GP wing before this video i was thinking about removing my factory wing for looks when i get a GP one but keeping it as it actually improves the downforce

Cool! Could you do a video analyzing a Saab 900 turbo? Like the effectiveness of the aero parts, the rear spoiler and the rims.

This is super interesting and kinda explains ’98 Toyota Corolla WRC wing design. It didn’t attach to the top of the hatch, rather halfway the window

You should look at FWD RC racing. The last style wing minus the mid section is basically a 1/10 Touring car Spoiler. If the rules allow we usually use those on the back of the body when we need a lot of read down force. Although the aero is pretty diffeerent due to the inner of the body the outside may give you some ideas :) Love the video...

Fantastic! Thanks!

Great video, I subscribed. I've been wondering for a couple of months now, since I stuck one of those little model spoilers on AliExpress to my friend's fiesta, how much downforce does it actually produce. If you think it'll turn into a fun/educational video, I'd love to see it

Great content! I will ask you an opinion on how to place a wing on a car that's already pretty aerodynamic but need just some downforce on the rear axle...

Good afternoon, please could you do a video on the following. I would like to know the down force difference between the porsches with "Ducktails" and "Whaletails".

Hold on a second. There is a production hatchback that has a spoiler half way down the rear window. That's the EU/JP 2005 Honda Civic. So it's not like this thought doesn't exist. Obviously it doesn't have a rear wing though. It's absolutely spectacular in person though. It feels a very similar shape visually from all sides, some sort of optical illusion, it's basically like an UFO floating in front of you, and the design details with smooth polycarbonate grill decoration with reverse side detail and angular handles are very striking as well. And like it stays planted, it turns, it's decent. Futuristic design extends to the dashboard as well.

Hi, how did you do this simulations ? Nice video by the way.

Subaru hatchback owner here. 1995 Impreza rally car. I feel like I have been denied my god given birth right to a sick ass rear spoiler. If I am gonna have to put up with Subaru mileage and head gaskets, I want a spoiler, dammit. However, all the stock GF8 wings have big time weenie hut junior energy. Another local driver has more or less taken the WRC shelf + spoiler approach on his car. Both of us compete in ARA, which has some pretty clearly defined (and restrictive, depending on who you ask) aero rules, chief among which is how far outside the existing outline of the car you can put a wing. I'll have to consider this approach if I decide to build my own wing, and whether I can fit it into their rules

You just got yourself a new subcriber!!! Please can you make a video for Mazda mx5 mk1 with softop,hardtop and without, also ductail rx7 front lip to see if they do anything and maybe more aggressive aero options simulations?

Great video! Which software are you using for these simulations? I would love to improve aero on my formula predators pc010, but I have no idea how to get started

Could you test if the first-gen Alto Works (CC72V) cheese grater rear aero element (spoiler? wing?) actually works? The brochures certainly made a point about the aerodynamic drag coefficient reduction it allegedly did.

Really nice video, i really want to see an investigation on whale tail wings on drag cars and what do they do maybe it could be an idea for a future video

I really apricate the effort you're putting into these videos. I need to know more about this design. We're currently running a hatch in hill climb, and I was about to put a lot of time into a rear wing with a swan neck mount as shown in the first diagram . But after seeing this, not any more. Design #4 seems to be the way to go, but your diagram isn't very clear. Does it hang or is is it a flush mount to the body ? Would a support structure under it interfere with high or low pressure ? Does the leading edge protrude in from the rear of the car like the old Group B Peugeot 205 ? and is it flat, or does it have a foil profile.

That final wing design reminds me of what was used on the Lancia ECV prototype. Maybe they came to a similar conclusion.

Hey, have you experimented with adding vertical side profiles to the rear spoiler similar to the GTI Mk7 Clubsport? It should reduce pressure under the spoiler, as it inhibits airflow along the sides of the car from going to that area.

Why UKposts recommend this to me, I do not know but I'm glad it did.

So in other words, the spoiler delivers more high energy air across the suction surface. Without it, the downwash from the hatch is not aligned with the airfoil's AOA. I wonder what would happen if the airfoil's suction surface were aligned with the downwash from the hatch. Would it make the same downforce as the hatch with the spoiler?

I feel like there are probably some good high angle of attack flap/slat designs from aircraft that could be advantageous

I've seen plenty of WRC hatchbacks use a similar dual wing design, so this is clearly no secret in the racing world. See the WRC Fiesta for example.

So I’ve been contemplating a wing. I have a Zender spoiler on my hatch now and from watching this keeping that and adding the wing would be better than removing the spoiler when adding the wing?

Nice 👍

Id be interested to what modeling shows for multi spoiler hatchbacks like the EK civic type r, where it has a roof spoiler and mid-height spoiler at the base of the rear glass I've always been curious if it the second spoiler was just aesthetics or actually reduced lift and/or drag.

Great video, the photos really show your intentions. What kind of program are u using for your CFD?

Could you please do an analysis of a mk7 golf r with full oettinger kit? 😬

You should have a look at the style of rear wing (more of a spoiler) that drag cars use for hatchbacks. Look at 'Civic EG Drag Rear Wing' in google you'll get an idea. I don't know how effective it would or wouldn't be for road racing, probably not very given that you don't see it, but I'd love to see some CFD analysis of what it does for a hatchback body shape.

what program are you using to do these simulations? I would love to do this kind of thing for my sw20

Sounds like pinderwagon your referring to with the rear wing and wanting more rear aero

How effective would the voomeran style spoilers be?

Hey Nelson, try not using a Volkswagen shaped hatchback. I had a hyundai pony (real gutless) that got very bouncy at a quarter tank of gas. I made a wing that mounted on the hatch just above the latch it was flush with the roof line due to the downwash of the hatch. It had 1/4" Gurney flap that proved way too much and had to be flattened out again. So to say the effect is minimal is due more to the specific vehicle than the wing itself.

Could a vent in the bonnet help reduce front lift?

Ford used a vaguely similar system for the Group A Sierra Cosworth RS500. The spoiler was at the bottom of the long tailgate glass and the wing was on mounts above it half way up. The tailgate wasn't as steep as your model.

What if you use gradual slope on top of the roof instead of spoiler, something like semi roof fairing but concave

A few uneducated opinions on how I would solve the extra drag from the 3rd variant 1) roof vortices 2) have a secondary wing/structure that starts at the tip of the C-pillar (not unlike the Ford Cosworth), not for downforce but to channel high pressure air into the main plane and extended winglets 3) either multi-tiered flaps on the main plane for passthrough, or rally style spoiler channelers (the vertical columns seen on modern rally cars, like the 04 WRX STI

What about spoiler on 05 saleen focus. Does it work or just for looks?

How do you compute/compile the CFD? I recognize paraview from my graduate work using Nek5000, are you using something similar?

My Veloster N comes with a flat lip with a small spoiler directly on top of the flat lip, how would/might that style apply to this effect?

eg hatch here. my wing is attached to the car can u do a few lil sims on that variation they have a few options to n peeps run what is called a duck bill would be interesting to see that thing weird'ness.. i have the more drag style where it just runs off the back of the car. im not sure my wing helps wif downforce but should help wif drag a lil bit my car is stable till 110 then i feel like i needs more down force after that n then i run out of gear n tune

What if you put loads of dimples on the roof? Wouldn't that negate the lift?

what software are you using to measure aerodynamics?

Isn't this what the Sierra XR4 did? It's not exactly a hatchback but still

I would love to see a sim like this done for a 1987 Toyota Celica GtFour

I wonder if this would work on the back of the cab of a pick up?

So a question about this. The saxo VTS has a stock wing that's nearly flat, kind of like a spoiler. But judging from your video without a spoiler air would probably not separate that much and just stick to the body moving back down. Whereas it seems to me the spoiler would, to an extend, prevent this. What would the implications of this be in terms of downforce (or lift) and drag?

I want to try this mid flap and spoiler combo on my ek civic now

Oooooh. I wish you'd do a Corrado the same way.

some civic 6th gen hatchbacks can be seen with "middle" spoiler aswell ;)

can you do some research for chrysler 300c, station wagon, how to reduce drag and lift of boxy body

What if the rear wing was placed further up, offseting it from the car's body so it won't interfere as much. Not as elegant of a solution, but it could have a similar effect

What happens it you dramatically change the leading edge of the wing to "capture" more air and reduce its AoA (or incidence, I never know which is which in English)?

The air already did its job flowing around the main shape and it's just leaving, but then you give it an extra obstacle to solve, that's what you're seeing on those graphics. it's the same as having a lot of people leaving a crowded place after the show has ended and then you think it's a good opportunity to do a marketing move right at the exit, you'll only generate an unnecessary congestion right when people want to leave and go home.

i think they had something like that in some version of honda civic 6 gen although below the window

How effective is MINI GP3 rear wing?

can you please do an analysis of a car with windows up vs windows rolled down

So the best rear spoiler and overall body kit for mk1 Ford Focus will be '03 Focus WRC?

very interesting, I like this sort of stuff, but I don't understand all the acronyms

The youtube algorithm provides something interesting for once. Looking at this, Peugeot did their homework back in the day with the setup for the 205T16 E2...and Lancia for that matter with both the S4 and what they came up with later for the Integrale. Having watched this, I was wonder what effect the kind of setup that was on the Pikes Peak 205T16 had, where the wing was on top of the spoiler/flap and the endplates closed the gap between the two.... Also, I wonder if this is the same or related effect which lead to the rear wings on some Group C and IMSA GTP cars going lower and lower and closer to the diffuser exit, eventually resulting in the massive bi-plane wings of the early 90s...and maybe later as well with the LMPs rear wing endplates growing longer and longer to where before the rules were changed there just a small gap between the spoileresque rear bodywork and the endplates.

Somehow, even though I generally only watch car teviews UKposts decided I needed to see this... But my question is how much down force ia actually created by a typical wingat 100mph?

What is the software You use?

That's quite an increase in CdA tho, although I would assume it is a worthy trade off in this kind of competition.

What about a under body rear splitter?

how do you make these?

Hey, have you thought about making some MotoGP analysis as well?

this is huge

Or, you could just do what Porsche, VW, Peugeot and a lot of other car and aftermarket manufacturers did with their kits for hatchbacks in the 80's, and mount the spoiler just beneath the rear window. Essentially turing the car into a more sedan like shape airflow wise. Alledgedly this increases downforce in the rear, but at the cost of increased drag due to the negative pressure pocket created beneath the wing (behind where the numberplate and taillights goes essentially). Though on a race car, this could probably be mitigated by a properly designed Venturi tunnel.

Check Wheeler Dealer Ford Escort RS Cosworth with triple spoiler or the EScort WRC had some flat wings and also the Fabia mk1 WRC had a double spoiler like the 2006 Focus WRC... there were also some available manufacturer data from SEAT Motorsport about the client track car Seat Leon II with drag and lift for the rear spoiler, it had and awful aerodynamic and only the TDI engine made it succesful so it had to be made slower buy addig weight... but I remember rear spoiler going down meant you could reduce drag by diverting flow to fill the wake and even keep the lift neutral...many road cars have positive lift at high speed on the road... like the Cordoba, TT, Octavia, Toledo... and they need at least a lip spoiler to make it neutral and stable...being sedan body shaped... but hatchback definitely have a rear giant vacuum cleaner with all king of susrprising flows...as you say usual spoilers won't help much other than esthetics neither solve lift or lower drag or reduce wake or anything...

What about just a spoiler ?

@GearsandGasoline This might help out the civic

Your AoA @1:17 looks it's stalled the wing. Maybe consider setting the AoA relative to the airflow and not the the groundplane. It looks like you've got the wing set at 50* AoA to the airflow. I don't know of any single element airfoil that would do well with that.

@nelsonphillips - how can I employ your services for analysis on my Mk2 Golf hillclimb/TT car?