E30 Aerodynamics

[2mAn]

So I bought some Vortex Generators made by airtabs. I'm not exactly sure how far back I should install them on the roof. I had planned to put them all the way back but the roof starts to slope down.

Anyone tried using VGs on the E30 roof?

edit: Heres some pics from earlier that I just placed on the roof

Not actually going to install these for a little while since a rear wing would be a good idea to add with it. I've got plans but for now I'm still learning the ideal location. I'm pretty sure I bought enough of these little guys but who knows.

I knew I wouldn't be able to go all the way to the rear window so I need to see if that's a problem, but I hope more reading will give me the answer.

For now, here's some pics since that's what we all want to see

At the edge...


Where it's flat:



Probably how they will get mounted, with a little more precise measurements:



Another option:


From the front


The second option leaves enough space between the outer ones that I can add more airtabs if I need it, but from an article I read, this many is about where any more and it doesnt really make a difference...

[squidmaster]

Eric, come by the shop when it opens in about a month and we can 3d scan your whole car to see how it can be improved.

Great photos. Did you make the aero yourself?

[e30_302]

For the airtabs: where it's flat and spaced the way they tell you to. Mine are laid out exactly as in your second picture, and on the rear quarter panel, and my wing end plates, and on the bottom of my splitter....I got a little carried away.

[squidmaster]

Anyone actually tested those to find out where/why/if they work?

[e30_302]

Nope, just seen the propaganda the manufacturer puts out.

[squidmaster]

But the manufacturer did? Do they have suggestions as to placement or anything? I've always been curious about those

[e30_302]

http://www.airtab.com

[squidmaster]

So, I understand the concept, however installing them on the roof would detract from the wing's operation.

a wing operates when it creates downforce, which it does by taking a perpendicular force and redirecting it.

Using those basically gives you a bubble butt to a teardrop taper-- and causes the air to condense back onto itself more efficiently (the "hyper fuel efficient" car design has a very long, fine taper at the end... usually).

These are moving the air AWAY from whatever's behind them. You'd probably have to extend your wing even higher to make proper use of it.

[2mAn]

Correct me if I'm wrong but I think the idea is that these pull the air off of the rear window, which can then be successfully directed to a proper rear wing to aid in downforce.

Without them, the air sort of slopes down the rear window and creates a low pressure zone as it circulates up and meets up with the air that's flowed over and under the car.

The sharp drop angle of the regular E30 rear glass ( and why the angle changed on the M3) isn't ideal. The air tabs are supposed to prevent that pressure zone. Combine this with a slippery belly and it should reduce the overall drag the car has

[e30davie]

Check out this video the youtube video by channel "kyle drives" on vortex generators. Gives you an idea on how they work, and might aid in your decision.

If i remember correctly he talks about them on an evo, which is also an aerodynamic box, so perhaps quite simliar to an e30.

[squidmaster]

Are you disagreeing with me by partially agreeing with me and reiterating what I said? Could you maybe clear that up for me I guess I'm confused.

And what do you mean by "then be successfully directed to a proper rear wing to aid in downforce." Who's doing that? Where's that happened? How's that happening? With the airtabs? What are you basing that on? I'm sorry man but you've lost me on what exactly you're talking about. I'm talking about airtabs.

anyway I mocked them up and tossed them on my super basic e30 m3 model that I use for basic testing....... You can see the results for yourself here: http://sssquid.com/v2/airtabs/

I spent all day doing exactly this same thing so this is all I'm going to spend time on now. If someone wants to find out how their aero works, contact me.

[e30_302]

Airtabs on the top of the cab. As stated, they help keep the air uniform coming off from a sharp angle in body work vs tumbling.

[e30_302]

I'm going to the track mid March, I'll put some wool tufts on my rear window and film it.

[Eric]

Eric, come by the shop when it opens in about a month and we can 3d scan your whole car to see how it can be improved.

Great photos. Did you make the aero yourself?

I need to! I want to get the M3 tuned in February/March. I just bought 1/5th of a spec e30 to use in WRL, so the tune money went away last month! Haha!

Front splitter is a flossman replica, not that great and I modified it. I want to mount it differently and possibly skin it to make it stiffer.

Rear wing was given to me by a buddy in Germany. He found it in the basement of his house and gave it to me for my old ring beater. My brother in law cut out the uprights at his shop and I welded up all the bits.

So not exactly off the shelf but not all home brew either.


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[2mAn]

Are you disagreeing with me by partially agreeing with me and reiterating what I said? Could you maybe clear that up for me I guess I'm confused.

And what do you mean by "then be successfully directed to a proper rear wing to aid in downforce." Who's doing that? Where's that happened? How's that happening? With the airtabs? What are you basing that on? I'm sorry man but you've lost me on what exactly you're talking about. I'm talking about airtabs.

anyway I mocked them up and tossed them on my super basic e30 m3 model that I use for basic testing....... You can see the results for yourself here: http://sssquid.com/v2/airtabs/

I spent all day doing exactly this same thing so this is all I'm going to spend time on now. If someone wants to find out how their aero works, contact me.

I think this was directed at me. Let me start by saying that Im an idiot and know very little about this, but Im trying to learn. I was also posting it on my phone while I had a few minutes of down time at work, so...

My comments are just to try and get more info out and to help the wealth of info. After doing some more reading and research it seems that the airtabs help to keep the air connected to the car by creating the tumbling effect. This seems like it would help a lip spoiler generate more downforce, by keeping more air connected to the body down the rear glass and onto the spoiler. (again, no idea if Im remotely correct).

Your modeling is good, but that only works for the M3, as the regular E30s have a different angle on the rear glass. Is it hard to make another model with the basic E30 angle as well? Then if its possible to add the M3 rear wing and maybe a crazier M3 type wing, I dont think the Evo M3s ever got the crazy Evo wings that the Cosworth 190s got, is that possible to model as well. Im just thinking out loud here, but I think the combo of airtabs with a big wing would be beneficial

I watched that video that was recommended "kyle drives" and it didnt help me much, but this other video I found seems to be a little more helpful. not with the VGs but aerodynamics in general