Ariel.Club Forum

what I've noticed kind a confirms what Henry said. At Spa francorchamps with having front and back on "showstyle" aka minimum setting I noticed the front was quite light, I think lighter than with no wing at all, felt like it created lift, putten the thing almost all the way down...way better, more stable and didn't feel like the car would blow away from the track on higher speeds.

Sometime later on a small track (Zolder) the car was kind of light in the rear and I gave the rear aboout medium, which gave me more confidence to make a follow through turn on high speed, saved me quite some time per lap, but mostly confidence and trust in the rear.
so my current setup is front almost maxed out and rear medium, about what Henry said

[quote=speedmachine post_id=296316 time=1570556455 user_id=4255]
What does medium AoA mean?
[/quote]

I believe it stands for Angle of Attack..

Please correct me if I'm wrong.

What does medium AoA mean?

The Atom 3 wings we always said were just for looks - because we never tested them and we are ok with that!

Then we tested them - and found that you can put in too much Angle of Attack on the rear one - it negates the effect of front aerofoil doing its job at Maximum AoA. The air is dirty back there (for Atom 2 / 3 3.5) [b]However [/b]there are measurable and repeatable gains.

The Atom 4 wings have had many hours of testing thrown at them, and provide much more downforce than the Atom 2 / 3 / 3.5 ones. Maybe one day we will have some real world figures to publish. The likelihood is that we wont... Sorry...

Were not big on publishing figures for things like aero - if we put it £ per KG of downforce, it would look fairly meagre. The car is also not a 'downforce car' like a Radical.
So we keep the details to our selves and attempt to make setup choices much simpler. On the whole - this is where we aim, and where most of our customers are in the spectrum.
Serious racers and lap time junkies will buy an F3, Formula Renault, Radical etc etc etc where milimeter measurements on wings do actually count...

From our Experience at MIRA:
There isnt a huge amount of downforce with Atom 3 wings (but we all knew that). The thing that they do achieve however is to settle the car into a much more neutral and predictable attitude (and do provide some downforce!)
The Rear wing affects the car much more than the front.

An advised wing setup would be - Rear Minimum - Medium AoA, Front Medium - Maximum AoA - depending on how much drage penalty you want to sacrifice. Long fast tracks id say keep the AoA 'flatter' and shorter tracks, increase it a little.

If in doubt, set the rear to minimum and the front to maximum and leave it there! Its not the most efficient setup, for drag or downforce, but its the easiest to achieve.

Any more questions - please email me on my work email address!

All the best :tu: and happy wing fiddling...

I would love to see actual published figures. When I started doing the wings I actually went to my old uni and used their wind tunnels to do some basic analysis on the wing profiles but realised very quickly the numbers would just not be the same in real world application because of the turbulent air, so never published them as actual claimed figures.

I'm still in touch with the professors at my old uni (some of who have done a lot of work in various aspects of the aerospace industry) and was actually discussing some work with them as a potential project for a Masters student on some bodywork design not long ago.

[b][i]I believe this thread could be misleading.[/i][/b]
:tu:

Henry, any reason why the factory don't publish aero measurement stats for the cars?

This "the wings are just for looks" story never ends .. which must be irritating considering all the work that has gone into their design.

If anyone wants to discuss Aerofoil benefits of the Atom 4 - please get in touch with the factory.

I believe this thread could be misleading.

Many thanks!

Henry @ Ariel

I have opted for Aero on my 4. I expect straight line speed to be a bit compromised on circuits where you have big straights )like Spa.) I expect it to go round fast corners a bit quicker but overall lap time probably won't be much different. Any kind of plus will be a bonus. I would gain way more time by being a lot braver and generally being a less lazy driver who does left foot braking and all that shizzle.
I do fully expect to get a more than slight fizzling in my undercrackers every time I walk into the garage though. You are all welcome to take that image for free. :-*

Cheers,
Stu

FWIW, I'm not suggesting either wing set ups (for the 2/3/3/5 vs 4) are tremendously effective; as previously mentioned, the air flow over any Atom - regardless of version - is not conducive to such a thing. Furthermore the 4's rear aero sounds like it may have a diffuser, which would be kinda compromised by the air flow under the car, I think?

Let's face it, the main reason people like buying aero on any Atom is because it looks as sexy AF. Period. To argue about how effective any of it is is (largely) missing the point..

Cheers,
Hedge

[quote=hamtt post_id=296275 time=1570457967 user_id=2907]
No in that picture they've basically stuck a grid of pitot tubes behind the wheels to analyse how the air is coming over the wings. This is probably either to see how the front winglets are throwing the air over the wheel or to see how the air is coming behind the wheel so they can design the side of the car accordingley.

To measure the effectiveness of the rear wing you would have to stick pitot tubes INSIDE the wing facing up and also facing down, and span them across the wing. You would then measure the pressure as a function of speed in various conditions and repeat several times to get some sort of idea of how much downforce you're generating and how consistant or predictable it was.
[/quote]

Gotcha, I was meaning in a general sense... since until earlier this year I'd have had no idea what you were talking about, thought a pic like that might help others too.

[quote=phil4 post_id=296272 time=1570456986 user_id=4783]
[quote=hamtt post_id=296269 time=1570456228 user_id=2907]
The ONLY way to get real results of how well the aero is performing for the Atom is to stick pitot tubes across the wing and take it out on the track, or at the very least using a decent size scaled full model of the car in a wind tunnel.
[/quote]

Like this?

image.png
[/quote]

No in that picture they've basically stuck a grid of pitot tubes behind the wheels to analyse how the air is coming over the wings. This is probably either to see how the front winglets are throwing the air over the wheel or to see how the air is coming behind the wheel so they can design the side of the car accordingley.

To measure the effectiveness of the rear wing you would have to stick pitot tubes INSIDE the wing facing up and also facing down, and span them across the wing. You would then measure the pressure as a function of speed in various conditions and repeat several times to get some sort of idea of how much downforce you're generating and how consistant or predictable it was.

Hammt,

I agree that CFD is tricky and the models are only ever that, models. Real life may or may not be better or worse depending on your point of view.

I do think that, with even with some commoditised hardware, you can get some indicative information from the test data.

What I have learned from the basic model so far:

Atoms are not in any way aerodynamically optimised. A Cd of .82 is about what you’d get from a truck.

The rear wing needs to be clear of the dirty air for it to work.

The front wing can generate downforce and a lot of drag.

From on track experimentation:
The AoA the warmer I can get the tyres and the less scrub/slip I get in corners.




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[quote=hamtt post_id=296269 time=1570456228 user_id=2907]
The ONLY way to get real results of how well the aero is performing for the Atom is to stick pitot tubes across the wing and take it out on the track, or at the very least using a decent size scaled full model of the car in a wind tunnel.
[/quote]

Like this?

[attachment=0]image.png[/attachment]

[quote=Hedge post_id=296165 time=1570019692 user_id=1277]
[quote="Italianpaul"]Hi Hamtt, I know it has changed my specification for a 4. Paul[/quote]

I’d give the factory a call about this, were I you. They can tell you definitively about the aero on a 4 vs previous iterations.

Cheers,
Hedge
[/quote]

The rear wing on the Atom 4, as I've seen from the rendered images, will still be pretty much ineffective for true aero, unless they change something significantly or it's raised significantly higher.

CFD analysis on the Atom will be very very inaccurate. How air behaves around the tubular structurs and nooks and crannies on the Atom will be pretty much nearly impossible to emulate by CFD. Furthermore, the error in one calculation will be amplified when that result of that calculatin is taken in to account for the next calculation, so where vortices interect with other vortices, the error will be significantly huge.

CFD only works well with flat/linear/large surfaces, even then there are a lot of assumptions. Such as that the air will hit the wing in a certain manner or certain direction, or the density of the air. In reality the air never behaves as in ideal modelled conditions.

For good rear aero you need a significant body on the car, to route and direct the air how you want it to be when it hits the wing. The air on the Atom by the time it's reached the driver, never mind behind that, is so turbulent and messy that it would be impossible to streamline it again by the time it hits the wing, no matter how much you play about with the design of the rear of the car. Look at aeroplanes, the most aerodynamic onjects designed. Even they, when they encounter turbulent air or the wake left behind another aircraft start falling apart. This is why they have to wait a 2-3 minutes before attempting to land or take off following another plane, they have to allow the air to settle back down again or teh aero just doesn't work.

The math involved in CFD is very complex. This is one of the reasons why weather forecasting is so difficult, and one of the uses of the original supercomputers was this. Trying to do CFD on your average computers on anything besides fairly basic shapes will produce inaccurate results. Look at even the F1 teams on the lower budgets (was it Lotus a couple of years ago?) that try to rely on CFD alone for design, the results never match up.

The ONLY way to get real results of how well the aero is performing for the Atom is to stick pitot tubes across the wing and take it out on the track, or at the very least using a decent size scaled full model of the car in a wind tunnel.

Plus, and this is a big point. Wings look cool.




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