Aero/wing question...with a twist...and my name is not Hyper - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


General Miata Chat A place to talk about anything Miata

Reply
 
 
 
LinkBack Thread Tools
Old 12-09-2009, 01:35 PM   #1
Elite Member
Thread Starter
iTrader: (12)
 
Join Date: Sep 2007
Location: Charlotte, NC
Posts: 6,868
Total Cats: 66
Default Aero/wing question...with a twist...and my name is not Hyper

So, next year I plan on running a wing for autoX. I've been reading the rules for mounting such a rice device, and they are as follows...

-May be no more than 8 sq/ft
-May not hang further back thatn the rear most part of the rear bumper
-May not be wider than the body of the car
-May be NO higher than 6" above the highest point of the car (windshield frame)
-Must mount no further than the center point of the rear axle.
-No part of the wing can exceed 6" forward of the rear axle line.

So with that layed out, I got to wondering, I know everyone tends to mount wings to the most rearward position. Also, we know the Miatas profile isn't very friendly to aerodynamics...and in my case, I don't have a hard top. So I'm wondering about mounting a wing to the forward most possible position (within the rules allowed). My reasoning to seek insight is based partly on the old Chaparral race cars that had the wings mounted in middle of the car and on the idea of catching air right as is expands/sinks off the rear roof line to restrict airflow under the wing but not sit it right up against the top.

Attached is my quick rendering of the restrictions.

What do you guys think would be the effects of mounting a wing like this?
Attached Thumbnails
Aero/wing question...with a twist...and my name is not Hyper-wingbox.jpg  
Doppelgänger is offline   Reply With Quote
Old 12-09-2009, 02:24 PM   #2
I haz no trubo
iTrader: (2)
 
Oscar's Avatar
 
Join Date: Jan 2007
Location: Bolton, UK
Posts: 3,021
Total Cats: 114
Default

placing it there should expose it to clean air and generate downforce at a relatively low AOA and reduce drag. Going to build one yourself or use an of the shelf solution?
Oscar is offline   Reply With Quote
Old 12-09-2009, 02:31 PM   #3
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,356
Total Cats: 1,322
Default

The further back you mount it, the more leverage you get on the rear tires. Put the element wherever you want, but make sure it mounts as far back as possible.
Savington is offline   Reply With Quote
Old 12-09-2009, 02:35 PM   #4
meatbag
iTrader: (50)
 
gospeed81's Avatar
 
Join Date: Nov 2008
Location: Houston, TX
Posts: 7,357
Total Cats: 26
Default

Placing it forward will also apply the downforce right on the rear axle, as opposed to creating a moment about the rear axle which (slightly) unloads the front tires.

It would be a very small difference, and is surely offset balance-wise by the weight of the turbo kit, and placing it further back applies the force behind the rear wheels without adding pendulum-like weight back there.
gospeed81 is offline   Reply With Quote
Old 12-09-2009, 02:49 PM   #5
Trackspeed Engineering
iTrader: (9)
 
Join Date: Jan 2008
Location: Bay Area, California
Posts: 937
Total Cats: 10
Default

This is what you want for auto-x.

crashnscar is offline   Reply With Quote
Old 12-09-2009, 02:51 PM   #6
meatbag
iTrader: (50)
 
gospeed81's Avatar
 
Join Date: Nov 2008
Location: Houston, TX
Posts: 7,357
Total Cats: 26
Default

^^^holy ****! lol
gospeed81 is offline   Reply With Quote
Old 12-09-2009, 02:57 PM   #7
Elite Member
Thread Starter
iTrader: (12)
 
Join Date: Sep 2007
Location: Charlotte, NC
Posts: 6,868
Total Cats: 66
Default

Funny thing about CSP...

They are allowed to add an element to the rear of the car, but it cannot act as a wing....so they're running those spoilers. I've often wondered how much difference in benefit there is between a large spoiler and a large wing like Chris Swearingen's car...

Doppelgänger is offline   Reply With Quote
Old 12-09-2009, 04:11 PM   #8
Junior Member
iTrader: (1)
 
Join Date: Jul 2006
Location: Colorado
Posts: 403
Total Cats: 2
Default

You might notice in that picture there is a spoiler and a wing. I believe that to be a legal configuration, but have never run it at a "big" event, so I don't know how it would hold up to protest.

I did a quick cut and past to show the comparison of mounting locations for you. I don't know that the forward location will get as clean an airflow as the rear section will. If you add a diffuser as part of the rear valance, the further back will help improve the performance of the diffuser.

Edit: I added my proposed splitter/air dam and canard changes as well
Attached Thumbnails
Aero/wing question...with a twist...and my name is not Hyper-wingplacement.jpg  

Last edited by Chris Swearingen; 12-09-2009 at 04:26 PM.
Chris Swearingen is offline   Reply With Quote
Old 12-09-2009, 04:52 PM   #9
Elite Member
iTrader: (5)
 
Join Date: Apr 2007
Location: Wellford, SC
Posts: 1,704
Total Cats: 1
Default

Quote:
Originally Posted by Savington View Post
The further back you mount it, the more leverage you get on the rear tires. Put the element wherever you want, but make sure it mounts as far back as possible.
This is quoted for the truth... The further the point of applied pressure (wing) is from the fulcrum point (rear axle) the greater the torque (downforce) will be applied to the system. It's Physics baby!!!
thagr81 us is offline   Reply With Quote
Old 12-09-2009, 05:04 PM   #10
Senior Member
iTrader: (12)
 
Join Date: Nov 2005
Location: Murfreesboro, TN
Posts: 596
Total Cats: 3
Default

Yep, you want a wing, not a spoiler like shown on the black car above. This is what we run on the car I am driving.
It is an APR piece. If you tell them you are an SCCA member, they give you a nice discount too.

sbrian2 is offline   Reply With Quote
Old 12-09-2009, 05:09 PM   #11
Elite Member
iTrader: (5)
 
Join Date: Apr 2007
Location: Wellford, SC
Posts: 1,704
Total Cats: 1
Default

Quote:
Originally Posted by sbrian2 View Post
It is an APR piece. If you tell them you are an SCCA member, they give you a nice discount too.
Name:  orly753415.jpg
Views: 4
Size:  21.7 KB
thagr81 us is offline   Reply With Quote
Old 12-09-2009, 05:20 PM   #12
Junior Member
iTrader: (1)
 
Join Date: Jul 2006
Location: Colorado
Posts: 403
Total Cats: 2
Default

When you talk to them (APR) you want the 55" GT-II wing, but you want both elements to be the 7.5" high camber wings. You will wind up building your own end plates (14x14 inches to take full advantage of the allowance) and adding a Gurney flap to the upper element. Talk to them about custom mount spacing as well if you want to mount at the edges of the trunk lid.
Chris Swearingen is offline   Reply With Quote
Old 12-09-2009, 05:53 PM   #13
y8s
2 Props,3 Dildos,& 1 Cat
iTrader: (8)
 
y8s's Avatar
 
Join Date: Jun 2005
Location: Fake Virginia
Posts: 19,038
Total Cats: 406
Default

Quote:
Originally Posted by Savington View Post
The further back you mount it, the more leverage you get on the rear tires. Put the element wherever you want, but make sure it mounts as far back as possible.
Quote:
Originally Posted by thagr81 us View Post
This is quoted for the truth... The further the point of applied pressure (wing) is from the fulcrum point (rear axle) the greater the torque (downforce) will be applied to the system. It's Physics baby!!!
sav's description seems slightly incorrect, but thagr81's clears it up to make me happy.

center of pressure * distance from pivot (wheels and/or CG) = rearward downforce moment. further back = more rear downforce.
y8s is offline   Reply With Quote
Old 12-09-2009, 05:59 PM   #14
Elite Member
iTrader: (2)
 
Join Date: Jan 2007
Location: Los Angeles, CA
Posts: 8,782
Total Cats: 119
Default

I think you are going down the wrong direction. For big aerodynamics it would best to take the body off your car and weld a boxfish shaped sheetmetal to your frame.



Boxfish.



See what I'm getting at?
Faeflora is offline   Reply With Quote
Old 12-09-2009, 06:28 PM   #15
Elite Member
iTrader: (10)
 
rccote's Avatar
 
Join Date: Jan 2008
Location: Buffalo NY
Posts: 1,595
Total Cats: 17
Default

Quote:
Originally Posted by faeflora View Post
I think you are going down the wrong direction. For big aerodynamics it would best to take the body off your car and weld a boxfish shaped sheetmetal to your frame.
You should probably worry about your own welding endeavors for now.
rccote is offline   Reply With Quote
Old 12-09-2009, 06:51 PM   #16
Elite Member
iTrader: (5)
 
Join Date: Apr 2007
Location: Wellford, SC
Posts: 1,704
Total Cats: 1
Default

Quote:
Originally Posted by y8s View Post
sav's description seems slightly incorrect, but thagr81's clears it up to make me happy.

center of pressure * distance from pivot (wheels and/or CG) = rearward downforce moment. further back = more rear downforce.
Glad I could bring some science to the conversation... I am a chemist afterall. Haha
thagr81 us is offline   Reply With Quote
Old 12-09-2009, 09:19 PM   #17
Elite Member
iTrader: (2)
 
Join Date: Jan 2007
Location: Los Angeles, CA
Posts: 8,782
Total Cats: 119
Default

Quote:
Originally Posted by rccote View Post
You should probably worry about your own welding endeavors for now.
Oh shut up. I am being a little silly with the boxfish thing but it's true:

See:

The bionic car - MSN Autos
Faeflora is offline   Reply With Quote
Old 12-09-2009, 09:20 PM   #18
Elite Member
iTrader: (2)
 
Join Date: Jan 2007
Location: Los Angeles, CA
Posts: 8,782
Total Cats: 119
Default

Quote:
Originally Posted by Doppelgänger View Post
What do you guys think would be the effects of mounting a wing like this?
My thoughts are that you should get a magazine feature before messing up the profile of your car. You have one of the best looking Miatas ever. Seriously..
Faeflora is offline   Reply With Quote
Old 12-10-2009, 12:18 AM   #19
Elite Member
Thread Starter
iTrader: (12)
 
Join Date: Sep 2007
Location: Charlotte, NC
Posts: 6,868
Total Cats: 66
Default

faeflora-Don't worry, I have a spare trunk lid that i'll be using to affix any aerodynamic aids to...and will be keepinf the one that is currently on the car nice and cherry
I wish I knew someone who could help me get the car into a mag. SCC was going to do it, but they folded right in the middle of our discussions.

Chris- Don't worry, I have no forgotten a single thing you have discussed with me about aerodynamics I was just contemplating and take all information in. I wish we could run diffusers in SSM :(

thagr- I knows, about wing placement and how the rear axel acts as a fulcrum point. I am curious as to what might be the effects of putting the weight straight down on the wheels.
Doppelgänger is offline   Reply With Quote
Old 12-10-2009, 01:05 AM   #20
Elite Member
iTrader: (2)
 
Join Date: Jan 2007
Location: Los Angeles, CA
Posts: 8,782
Total Cats: 119
Default

Why not try for a feature in a good import/car blog?
Faeflora is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
He got banned! Lmaorofl levnubhin Insert BS here 11 02-25-2009 02:32 PM
There's no need to fear!!!! Braineack Insert BS here 4 02-20-2009 11:50 AM


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 09:11 PM.