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ProDarwin MegaDork
12/21/20 5:31 p.m.
Keith Tanner said:

I guess it comes down to the complexity of the implementation. Is it easier to move a chunk of body around or to come up with a way to activate brakes on individual wheels on a car that was not designed that way from the factory?

On a challenge car for sure moving around panels is either.

I think there are some diff/yaw options on the table for challengers.  Like sleepyhead mentioned.

Also there are a few cars out there with yaw capabilities parts could be robbed off of?  I know honda ridgelines and TL AWD setups have some torque vectoring electronically controlled diff engagements?

I wonder if there is some magic that could be done with parts from a Prius or RX transmission.

Robbie (Forum Supporter)
Robbie (Forum Supporter) MegaDork
12/24/20 9:39 a.m.

In reply to sleepyhead the buffalo :

I 100% agree you can't use the wing by itself. That's why I'm so stuck on the idea that an air brake will likely impact downforce of the entire vehicle (perhaps massively).

Still very interested in this thread and more thoughts on how to analyze an airbrake overall. Keith's data and driving feedback is very intriguing for sure.

There's a video from julian edgar - I'll try to link to it later - that talks about an SAE study by kia or hyundai that shows the massive impact in downforce at the front wheels by the addition of a relatively minor spoiler on the trunk on one of their early 2000s sedans.

Robbie (Forum Supporter)
Robbie (Forum Supporter) MegaDork
12/24/20 10:18 a.m.

Here's the video:

sleepyhead the buffalo
sleepyhead the buffalo Mod Squad
12/24/20 12:53 p.m.

I haven't forgotten about this thread either.  In digging in a bit more, I've realized a couple things...

1) I got my sign conventions wrong on the last page, and I need to redo a couple of the images.  surprise

2) Making a "simulation" of the airbrake on a closed course is going to take a bit of work.  I've been using OptimumLap a fair amount this year, and I reckon I can use it... but it really doesn't have the ability to have a changing drag coefficient through the course of a lap.  Fortunately, though, it does have a layout from the 2010 Solo Nats... which I can use to generate some data, which I can suck into a spreadsheet to massage it a bit manually to try and come up a ballpark idea of the effect on times.  (probably Autocross just at first... maybe Tracks, once I can refine the 'massaging bit' so that it's relatively non-time consuming.


BrianC72gt (Forum Supporter)
BrianC72gt (Forum Supporter) Reader
11/10/21 2:00 a.m.

Awaken zombie thread.   Could you datalog downforce effectiveness utilizing headlight levelling sensors?   I meant to add a ways back that grafting some headlight levelling sensors from an HID light equipped car - arms and linkages attached to potentiometers - between the body and the suspension should give you a simple way to measure downward movement at speed.  On a long smooth straight road you could measure how much the car deflects down - or up- at various speeds and aero settings. 

Keith Tanner
Keith Tanner MegaDork
11/10/21 8:10 a.m.

Totally. I have a set of GM ride height sensors I was going to use for this someday. 

silvermane_1 New Reader
12/10/21 7:13 a.m.

Keith Tanner, here's kinda of a weird question; do you have access to a wind tunnel?

Keith Tanner
Keith Tanner MegaDork
12/10/21 11:21 a.m.

I have access to straight roads :) I'm not sure there's a vehicle-sized tunnel within several states. 

stafford1500 Dork
12/10/21 11:24 a.m.

In reply to Keith Tanner :

None that will typically allow CARS into

Keith Tanner
Keith Tanner MegaDork
12/10/21 11:27 a.m.

I do know someone pretty high up in Lockheed Martin space flight in Denver. He even races a V8 Miata. They wouldn't have one, would they?

1miracle2 New Reader
4/15/22 1:00 a.m.

What up y'all, I don't believe I've commented before but here goes...
So I built a D.I.Y. Active Aero'ish for my Mustang Ecoboost and wanted to share with y'all how I did it (its not a fancy setup by any means). It's NOT a tutorial, just a general video.
No I don't track the car but a guy can dream. I just wanted it cause I thought it was cool af.
Anyway, enjoy. 
D.I.Y. Active Aero


jfryjfry SuperDork
4/16/22 1:11 p.m.

nice job, that's a lot of work! eager to see how it works on track.   the nice thing is you can do a few laps with it disconnected and then a few with it connected to see an immediate back-to-back comparison

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