CB Aero Simulations

[Domesticated]

Did some quick 2D aero simulations. Vehicle speed is at 120mph. Mesh size for analysis was quarter inch squares. Figured the resolution was good enough. The aero above is fairly accurate, but below there are some obvious errors because I made it smooth so take it with a grain of salt.

It's crazy how much of an affect the front lip had. I was also surprised by how clean the streamlines are for a 20 year old car. I can retrieve any data related to flow. Lift and drag for any spot or the whole thing. I want to either make a full 3D model or if somebody has a file for it to do a full analysis of the vehicle. I could easily make a 3D blocky one that has the front and side profile, but not the blended surfaces in between fairly easily.

Stock Body Lines


Rear Trunk Lip Only


Front Greddy Lip Only


Rear Wing Only


Rear Wing and Front Lip

[KpoweredCB7]

So, what am I looking at here? Is blue good, like a low pressure area, I don't understand how to interpret this, it's cool looking though.

[Domesticated]

Color isn't good or bad. The color represents velocity, not pressure. But technically the blue behind the car means the air is stagnant. This is because of a low pressure region. A low pressure region behind the car is considered an adverse pressure zone, basically the vacuum pressure is pulling on the car. This just shows the streamlines and in a nutshell the smoother the lines the less drag. I didn't measure downforce or drag yet because the model is too crude, but when I do the objective is to compare downforce and drag vs small changes. Increase downforce and keep drag the same or reduce somehow is a win win. But realistically you want to tradeoff downforce and drag properly.

[KpoweredCB7]

Ok, that makes sense, cool I've seen models like this but never really had the desire to learn to much about it, I see it being useful when figuring out what aero stuff to use.
Thanks for the explanation!

[marcusv8thunder]

So a deep lip of some kind, greddy or legend for example does a good job of sorting the air flow out underneath. The CB doesnt have floors so its quite turbulent under there, particularly at the rear.

As you would expect the top of the headlight/bonnet and the top of the windscreen is the areas of most impact.

Would be interesting if you applied some rake to the car, maybe 10-30mm front lower than the rear, see how that affects things.

[Ralphie]

How come the rear underside spikes up?

Is that off or how the chassis is?

It's been a while since I had my cb, but I don't remember the rear underside raising up that much.


Just curious-


Good work dude. This is very fascinating and I for one will look forward to what results you will get with a better model and more time in.

And Deev thinks the scene is dead.

Shit is just getting started bwhahahha

[Domesticated]

I won't make anymore until I can get a 3D model unless I can find good correlation with the 2D model. May just use the 2D to measure differences and not actual values. Like dyno tuning.

The rear does rake up like that. I traced the silhouette of my car in this model. The rear sits up much higher than the front.

The scene definitely isn't dead for me. I've put close to 7k in my car in the last 3 years I've owned it being broke. The previous owner put about 3-4k into it. But I graduate in May and I already signed my employment papers where I'll be making 1200 a week, so things are really gonna pick up when I start working.

[sonikaccord]

Rear diffuser!! I guess I'll have to wait.

[Domesticated]

Well I can't do a rear diffuser until I have a 3D model. I could just steepend the angle of the rear bumper more. That is something I wanted to look into.

[jdm92_accorn]

can you do one with the oem rear lip spoiler and the greddy, just curious?

[P5ylance]

and also one with the sarona rear window spoiler!

[steelbluesleepR]

Send Lynx a PM, he's got the most detailed 3D model I've seen of the CB chassis. I am unsure if the file formats will match up, but it's worth a shot.

[sonikaccord]

Do you need a 3D model to see the variations of Cd (drag coefficient) as well? I would assume so but I'm double checking.

[Domesticated]

In 2D I can only measure changes, in 3D I can measure values.

[Quashish]

What about a sunroof visor?