I believe he said downforce not downtorque. :noob:

JFWY.

1,432 Leafys then.

That about 5.2 hustlers, right?

I didnt realize hustler was that obese. I wouldnt think he could even fit in a miata.

If you ask him, all the mass comes from muscle.

Some say that the densities of his muscles rival depleted uranium. And that he is listed as a ITAR sensitive weapons system as a result. All we know is, he's called The Hustler.

Its the ego.

Lol. Those two are giving each other the "How YOU doin' " look.

Ok let keep on track

It is hard to tell, do to you would need wind tunnel testing to get definite a answer. Your question is also vague, at what speed 100, 120, 160mph... Higher the speed the more downforce and drag. Even if you know what speed, no one would really have an answer for the downforce numbers

The quality of his question is precisely the reason for the quality of the answer he recieved ;)

Ok, ok. What I was trying to ask was, which miata has the most time, money, and r&d in; not really physical downforce numbers. The s13 with the huge diffuser designed by the ex McClaren guy is what prompted me to ask. Also, I've never seen a miata at the WTAC so I was wondering if there are some race teams doing legitimate cfd or wind tunnel development. (Disclaimer: I know the WTAC isn't the only show in town and that Emilio and possibly autokonexion do some of this kind of stuff)

I have about 40 hours of CFD into my wing. The number I was getting from the CFD put it near the top of the heap for a wing in SSM around the 400lbs @ 60mph range. No idea for the full car because I havent had time to start trying to take one of the existing models of the whole car and convert it into a format I can edit.

Adaptronics 13b turbo NA was at WTAC last year.

Dann

What would be a ball park price to have custom uprights machined. I bought a gtc-200 local, but has the super short mounts. I used the template ThePass made for his and put it into slid works and made it into a 3D image.

Wouldnt a machinest just need the file to make the data points and put it into a cnc? Or would it be cheaper another way? I can upload the file if anyone is interested in it.

i don't think using ThePass's wing mount design will work with the GTC-200. The upper mount for those are different. the front slides into the bottom mount, the back has an area for the turnbuckle to slide in to:
https://www.miataturbo.net/attachmen...ine=1362325217

What software are you using? Did you do a 3d or 2d analysis?

When I was working on my wing design, I did the 2d analysis in matlab using the pannel method. Now I have connveted my code to octave (free program like matlab). I did the 3d analysis in OpenFOAM. Just curious, what turbulence model did you use?

I was using COSMOS because its easier. a good 1/4 of that time I was using the wrong conditions and did mostly 2d stuff. I only used 3d to figure out the end plates. I'm wacking 70 pounds off of what the cfd gave me for the real version not quite being perfect, the wing supports that werent factored in, and the effects of the car. I'm probably being generous. I'm going to be moving to doing analysis in openFOAM once I have time.

Matt Andrews' car is probably in the top 5:
https://www.miataturbo.net/attachmen...ine=1362369713

Gotcha. OpenFOAM has a big learning curve. I switched from ansys, and it still took me a while to pick it up. Good luck !

I figured Matt's car would be up there. Why is it beneficial to ditch the back glass? I would think that glass would smooth the flow of the air going over the roof, down the glass, and spilling over the rear quarters and under the wing.

With a rear window the cabin is a big parachute. Taking out the back window gives all the air coming in thru the windows somewhere to go.

i'm not so sure about that. not having the rear glass definitely affects some of the flow coming down off the roof.

Also notice the windows are also open/no windows.

Not really the reason.. Cabin pressure builds up the moment you are travelling at speed. Then air doesn't 'parachute' into the cabin much at all.

The reason for guys removing the rear window in the hardtop has to do with the fact that they found that the wing was more effective this way. No way without a wind tunnel to say if it's because it alters the air's flow as it comes off the top towards the wing, or if the wing is actually getting airflow that is coming out of the rear window hole, but either way, the whole reason is because it aids the wing.

By that theory an aerodynamicaly formed cone would form in a regular parachute and it would be ineffective at slowing anything down. Although some density change happens the air doesnt just form a perfect shape. You get a ton of turbulence.

Yeah I understand that's it's not a nice pretty bubble of pressure inside like having the windows up, it's very turbulent, but the 'parachute' effect is an exaggeration - I don't think the guys who pulled the rear window out were seeing significant MPH changes at the end of straights, from what I have heard it was much more differences in wing performance.

I run a rear lexan window though, so I cannot comment from personal testing. I've considered doing some sort of quick disconnects on it such as Dzus fasteners so that I could do back to back tests.

How high the wing is mounted plays a big role in that too though. The APR GTC-200 for example mounts pretty low, and IIRC even with the 2.5" risers still isn't at the roofline, so the no-rear-window configuration might benefit those wings much more than it would for someone who has gotten their wing up higher..

-Ryan

It seems to me that with the back window removed,

a) there is high-velocity air coming off of the rear roof lid meeting slower air
b) this is going to tend to pull air out the rear windshield opening, thus pulling air through the cabin windows.
c) this is also going to form a vortex with the axis of the vortex along the pitch axis of the car. The downward side of the vortex is going to hit the rear wing, effectively increasing its angle of attack.

This is from my 5 minutes of coffee & M&M's fueled cereberal CFD. Feel free to discuss.

I think you're right, without the rear window much more air is going to flow thru the cabin. Poor man's AC. ;)

Though I agree it may have more air hitting the wing, it's going to be highly turbulent and likely not beneficial. That's my guess anyways.

Why doesn't someone windtunnel Miatas already? :party:

Where is plucas when you need him? lol
he can model up a rear windowless miata and use his CFD program.

With the rear window removed, the air moves forward through the hole and into the cabin from the rear, then exits out of the side windows. Anybody who has ever had a zip-down plastic rear window can attest to this.

I'm here. I am busy at the moment with paying customers ;)

Maybe when my schedule clears up, or if somebody wants to pay to have it done (and allow me to share), it can be moved up the list.

True, I had a zip-down plastic rear window, and I always got air coming in from the rear.

The pulling only works with small openings. Example: windows cracked a little, air is pulled from inside the cabin by the boundary layer around the car. Windows all the way down, air enters the cabin, circles around, exits at the rear of the window opening.

So then the vortex is forming and moving air through the cabin and out the windows.

Never been in an NA with the window open. Interesting.

If I paid you, I wouldn't share it ;)

HATE the idea of removing rear windows.

Ya Tage Evanson, I was following him after this inspiring article "Anatomy of A Giant Killer"

1995 Honda Civic - 11 second Civic - Import Tuner Magazine

Sad what happened to his car, but now the car is a Phoenix

Most wouldn't want to share it since they are paying for the knowledge. This is why I can't share more information on some of my findings.

I'm not try to contradict the hive-mind here.. But my zip down rear window clearly blows air out. pulling it thru the windows..

I have a zip-down in my NB and I can definitely feel it circulating around behind my head, I wouldn't be surprised if it was in fact coming in through the rear..

Time for some tuft testing to see where the air comes from.

There's already tuft tests done with a hardtop. In such tests, you can see that the tufts are in fact going the wrong direction. Proof that air is separating and circulating a pocket behind the rear window. Now combine that with a window that's open, and the air now has somewhere to go (into the cabin)

In any car, having the windows down doesn't really move much air through the cabin. It is just a pressurized mess of turbulent air. If you open the cabin to an area of different pressure like a sunroof or the rear window, air starts to move.

In a miata with the rear window unzipped (or missing from a HT), the air gets pulled in from the back. In my sedan with a sunroof, air get pulled out the sunroof. In my truck with a sunroof and a rear window slider, air gets pulled in through the slider and out the sunroof.

The civic fire video clearly shows this. You can do the same thing with a can of smoke. Driving at freeway speed, reach out the window and release some smoke over the roof of the car. If air was exiting the rear window, it wouldn't end up in the cabin. Since the cabin will be full of smoke, try not to crash... :giggle:

:fael: Vids of this please. Preferably with additional chase car footage. Do they allow filming in Life Flights?

I put this up because of the new active diffusers (front and rear) and that is so cool


Hopefully here soon we can see what new technology McLaren has learned in Formula 1 but can't use it. The McLaren P1 is heard of having gobs of downforce. Lamborghini always has crazy design style so there Veneno should have some weird aerodynamics.

Lambos are for posters IMO, the real racecar tech is coming from the companies actually participating in top-shelf racing. (Ferrari, McLaren, etc.) No doubt the Veneno will be fast, but it's not the same as the La Ferrari in my eyes.

-Ryan

the lambo veneno does not look very aerodynamic at all.

To be fair, while Lambo has essentially nothing in regards to historical racing performance, they are finally fielding factory cars in real racing, competing in FIA GT1 in 2011 and 2012.

But yeah I think McLaren's a ways ahead, to be sure.

It will be interesting to see how Ferrari does next year, and the years following, as their new F1 factory comes online and they start using their revamped wind tunnel, which supposedly will be state of the art after its upgrades. They were getting data from it which was, shall we say, perhaps not erroneous, but was not correlating with the performance of the car on track. They began using Toyota's wind tunnel in Cologne last year to compare data.

What makes you say that?

Looks can be deceiving. This is not me saying that it is aerodynamic either...which is also misleading. What is aerodynamic? Downforce, drag, or efficiency all are different aspects that could be different goals to be considered aerodynamic.

To me, aerodynamic means the best balance of the 3 you mentioned. I just feel like Lamborghini might just be trying to go over the top to compete with companies such as McLaren or Ferrari who years of racing experience.

That's basically always been their strategy.

The balance of the lift and drag is efficiency however. And being aerodynamic is just a word that can describe two totally different setups. A landspeed car can be very aerodynamic and a F1 car around Monaco can also be very aerodynamic. They just happen to be in different ways. I do not know which route that Lamborghini takes, but if I had to guess, it would be efficiency.

Great aero thread...
 

This has been a fun thread to lurk through, but thought i'd add my .02.

Briefly, it looks like Ross Braun's crazy contraption works using the Bernoulli principle, along with the angle of air as it enters. F1 tests everything via computer model, and then via wind tunnel. They could simulate an entire race at every track, including the velocity and angle of the wind as it enters the device, and plot the relative effectiveness.

I'm hoping to have some serious CFD (colorful, flowy designs) completed for the Catfish this summer, including the flat bottom, air flow in the engine bay, splitters, hood, diffuser and other elements of the design.

Some of the information will apply to the Catfish only, while others such as the flat bottom and the diffuser will have direct application to the Miata. This stuff will be published, so the usual secret racer sh*t mostly won't apply. Of course, not every step will be shown, but I'm looking forward to proving out the design via CFD.

Last, the data acquisition product I have would be able to control the linear actuators on a moveable wing...left, right, stop, flat on the straights, no problem. It makes you wonder if I've got a design already made...

I really dont know about your wing...... but stop getting sidetracked....where are the 5 stud hubs!!! :) :)

I'm a slave to my suppliers...

The rear hub application is done, and the front brake rotor is done.

The rear brake rotor is being a bitch, and the front hub was completely machined .0025 too small. Do-overs.

Frankly, the first part to be finished will probably be a replacement four bolt front hub with tapered roller bearings.

Such a sad day when the grinders cant read the mic right :/

In the end it was the monkeys with the micrometers. The grinders were spot on. It's double-frustrating, as it took a long time to have the drawings made, a long time to get the samples made, and even wasn't that easy to find the 4130 material in the size we need. FUBAR.

Well right, grinders are the people that grind shit. I was a grinder until last year. Made rotary dies down to the .0001 precision.

The way to fix it is to build up chrome (tool chrome, not bling bling chrome) and grind it again to size. It actually ends up being harder than the hardened to 59-60 rockwell steel.

Just out of curiosity, but who are you using to run cfd on your car?

Did not think of that! Is that something your typical metal finishing shop can accomplish, or can you recommend someone specific?