Aerodynamic Discussion Thread - Page 33 - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


Race Prep Miata race-only chat.
Sponsored by:
Sponsored by:

Reply
 
 
 
LinkBack Thread Tools Search this Thread
Old 12-19-2014, 06:47 PM   #641
Senior Member
iTrader: (3)
 
Join Date: Dec 2008
Location: KY
Posts: 670
Total Cats: 41
Default

Quote:
Originally Posted by Supe View Post
Yes, to both photos. On AB's car, it's suspended between the two vertical strakes. Bit dark, but you can still make out the end plates and all.
I'm on a real computer now. I'm still not seeing the wing on AB's car. Looks like a modified Elise diffuser to me, with a gurney added to the center section.

Attached Thumbnails
Aerodynamic Discussion Thread-lotus-elise-diffuser.preview.jpg  
jpreston is offline   Reply With Quote
Old 12-19-2014, 06:48 PM   #642
Senior Member
iTrader: (3)
 
Join Date: Dec 2008
Location: KY
Posts: 670
Total Cats: 41
Default

Attached Thumbnails
Aerodynamic Discussion Thread-2014wtac_ambeclipsepitlane.jpg  
jpreston is offline   Reply With Quote
Old 12-20-2014, 09:52 AM   #643
Junior Member
 
Join Date: Dec 2012
Location: Charlotte, NC
Posts: 231
Total Cats: 14
Default

Could be wrong, wonder if its been changed? Thought there used to be an open section forward of the diffuser/wing/whatever it is, but you're probably right.
Supe is offline   Reply With Quote
Old 12-21-2014, 01:38 PM   #644
Senior Member
 
Join Date: May 2011
Posts: 502
Total Cats: 50
Default

I've often wondered if you could do both... Using the picture of the c6r vette as a reference. One could use the a diffusor like this, albeit a large one with more clear space behind it... and drop an aerofoil in behind/beneath it. Although I'm not sure one could achieve this with the proper angle of egress for the speeds for our typical none of the horsepower speeds.



the C7 used a similar setup but it was adjustable instead of fixed angle.


Just to show the evolution - The c5r had a more standard diffusor/strake setup that us meer mortals are more familiar with.
Attached Thumbnails
Aerodynamic Discussion Thread-6_06he_7.jpg  
EErockMiata is offline   Reply With Quote
Old 12-21-2014, 02:07 PM   #645
Elite Member
iTrader: (1)
 
cordycord's Avatar
 
Join Date: Dec 2011
Location: SoCal
Posts: 1,748
Total Cats: 142
Default

Quote:
Originally Posted by EErockMiata View Post
I've often wondered if you could do both... Using the picture of the c6r vette as a reference. One could use the a diffusor like this, albeit a large one with more clear space behind it... and drop an aerofoil in behind/beneath it. Although I'm not sure one could achieve this with the proper angle of egress for the speeds for our typical none of the horsepower speeds.



the C7 used a similar setup but it was adjustable instead of fixed angle.


Just to show the evolution - The c5r had a more standard diffusor/strake setup that us meer mortals are more familiar with.
A diffuser only really works well when you also have a flat under-body. Unlike a standard wing, it is free aero as the only induced drag is already there (the car).

edit--check out that massive transaxle cooler with fan on the back of the Corvette.
cordycord is offline   Reply With Quote
Old 12-21-2014, 02:10 PM   #646
Senior Member
 
Join Date: May 2011
Posts: 502
Total Cats: 50
Default

Quote:
Originally Posted by cordycord View Post
A diffuser only really works well when you also have a flat under-body. Unlike a standard wing, it is free aero as the only induced drag is already there (the car).

edit--check out that massive transaxle cooler with fan on the back of the Corvette.
right... i was adding to the discussion on the previous page regarding aerofoils within the egress airflow of the under tray and diffuser.
EErockMiata is offline   Reply With Quote
Old 12-21-2014, 04:16 PM   #647
Supporting Vendor
iTrader: (3)
 
Join Date: Jul 2006
Location: San Diego
Posts: 2,706
Total Cats: 357
Default

Wasn't the change to the new-style short/wide flat rear planes due to a change in the rules by IMSA that no longer allowed diffusers with vertical fins?

So an airfoil builds pressure on the top surface, and for a diffuser you want less pressure/faster moving air on the underside. These two interests clash a bit. A pressure map of a typical diffuser shows the majority of the vertical force happening at the beginning of the angle change, so that is where you would least want to have an airfoil undernath - that's ok because that wouldn't work anyways as there is no ground clearance there.
So then looking further back... even though the forces are towards the front of the diffuser, the air's behavior all along the length of the diffuser dictate how effective it is. Placing the airfoil underneath the diffuser surface near the back (like the BMW on the last page) is going to create an obstruction to the diffuser's airflow as the topside of the airfoil slows air and builds pressure in the region between it and the diffuser.

I think the best application of the idea would be for the airfoil to be placed behind the diffuser exit. Use a wing with swan-neck style mounts or mount via endplates, suspended from the rear of the car, and the wing aoa adjusted for the airflow angle coming out of the diffuser. This way, the pressure build up above the wing can occupy the space behind the center of the rear of the car, and the diffuser's function isn't jeapordized.

That's how I'd do it at least.. but if the concept can work or not? Only one way for someone to find out.

-Ryan
ThePass is offline   Reply With Quote
Old 12-22-2014, 06:27 PM   #648
Senior Member
Thread Starter
 
Join Date: Oct 2011
Location: The Race Track & St Pete FL
Posts: 575
Total Cats: 49
Default

So this might not be aero related but, it is my thread. I think it's cool how the process of a test vehicle. So when I was at the Porsche Museum in Stuttgart Germany they had there Porsche 918 test car on display. So here are my pics

Production 918










918 Test Car















Attached Thumbnails
Aerodynamic Discussion Thread-dscn3486_zpsa89f9e07.jpg   Aerodynamic Discussion Thread-dscn3487_zps27ed8b43.jpg   Aerodynamic Discussion Thread-dscn3488_zps74fa04d5.jpg   Aerodynamic Discussion Thread-dscn3489_zps5e9fc0e5.jpg   Aerodynamic Discussion Thread-dscn3491_zps9c70ce62.jpg  

Aerodynamic Discussion Thread-dscn3492_zpsbcc25a10.jpg   Aerodynamic Discussion Thread-dscn3494_zps3feb16c8.jpg   Aerodynamic Discussion Thread-dscn3498_zps0be17c79.jpg   Aerodynamic Discussion Thread-dscn3493_zps3e29f85f.jpg   Aerodynamic Discussion Thread-dscn3499_zps9f3863cf.jpg  

Aerodynamic Discussion Thread-dscn3497_zps015ce1fd.jpg   Aerodynamic Discussion Thread-dscn3496_zpsd1a23a36.jpg   Aerodynamic Discussion Thread-dscn3495_zps8339b463.jpg  
1993ka24det is offline   Reply With Quote
Old 12-23-2014, 01:16 AM   #649
Senior Member
 
Join Date: Dec 2010
Location: Auckland, NZ
Posts: 701
Total Cats: 16
Default

Bloody Hell that has Mad Max or Back to the Future written all over it!

Pretty cool and intriguing to see that.
mx5-kiwi is offline   Reply With Quote
Old 12-23-2014, 08:20 AM   #650
Junior Member
 
Join Date: Dec 2012
Location: Charlotte, NC
Posts: 231
Total Cats: 14
Default

How come my race cars always look more like the test mules than the production cars?
Supe is offline   Reply With Quote
Old 01-17-2015, 11:00 AM   #651
Newb
 
Join Date: Jul 2014
Posts: 26
Total Cats: 2
Default

Quote:
Originally Posted by ThePass View Post
On an F1 car, upwards of 50% of the downforce can come from the underbody/diffuser, and that is with significant limitations on what they can do. An unrestricted car built around the most effective floor/tunnels their engineers dream up could produce incredible downforce without the use of relatively high-drag elements like conventional wings.

-Ryan
While reading through the thread, this called to mind an article I read a while back. After digging it up, the article doesn't appear to have been referenced in the thread yet after some in-thread searches.

It's one of the most appealing and creative uses of unrestricted aero that I've ever seen.

For My Ally Is The Force, And A Powerful Ally It Is - Speedhunters

Not much obvious on the outside:


But inside:





Using the low pressure behind the car to suck air out from under the car. Lots of downforce with extremely minimal addition in drag, if any at all. It might even be a drag reduction since the low pressure zone behind the car is partially pulling on air under the car, and less on the car itself
Attached Thumbnails
Aerodynamic Discussion Thread-gpevo-58.jpg   Aerodynamic Discussion Thread-gpevo-85.jpg   Aerodynamic Discussion Thread-gpevo-82.jpg   Aerodynamic Discussion Thread-gpevo-83.jpg  
yenadar is offline   Reply With Quote
Old 01-17-2015, 12:57 PM   #652
Senior Member
Thread Starter
 
Join Date: Oct 2011
Location: The Race Track & St Pete FL
Posts: 575
Total Cats: 49
Default

This is something I am working on this weekend. I will be placing a quite a few NACA ducts in my underbody to help move air for cooling.

Before resin



and finished for now





Attached Thumbnails
Aerodynamic Discussion Thread-dscn3608_zpsc39eedfa.jpg   Aerodynamic Discussion Thread-dscn3619_zps9ce905fd.jpg   Aerodynamic Discussion Thread-dscn3621_zps6d6e40ba.jpg   Aerodynamic Discussion Thread-dscn3616_zpsfccff003.jpg  
1993ka24det is offline   Reply With Quote
Old 01-17-2015, 04:35 PM   #653
Junior Member
 
Join Date: Mar 2011
Location: Melbourne, Australia
Posts: 129
Total Cats: 34
Default

What are you trying to achieve with the fibreglass rear?

Is there more to come?
BEAVIS is offline   Reply With Quote
Old 01-20-2015, 04:16 PM   #654
Senior Member
iTrader: (1)
 
Join Date: Jun 2006
Location: Sweden
Posts: 1,372
Total Cats: 57
Default

Quote:
Originally Posted by yenadar View Post

Quote:
Originally Posted by 1993ka24det View Post
The one idea that pops into my head is to use the suction form the rear as exit for the transmission tunnel heat when closing off the floor. Just a couple of big air ducts from the diff across the trunk to the plate area. Could that be efficient enough to seal the floor completly (just have exhaust cooling exiting above the diffusor)?

But that's might be what RJ's showing?
NiklasFalk is offline   Reply With Quote
Old 01-26-2015, 08:41 AM   #655
Junior Member
 
Join Date: Apr 2013
Location: toronto
Posts: 120
Total Cats: 6
Default

endura is offline   Reply With Quote
Old 01-26-2015, 11:17 AM   #656
Elite Member
iTrader: (3)
 
Join Date: Mar 2008
Location: Granbury, TX
Posts: 5,889
Total Cats: 566
Default

I should show those NASA jocks how to REALLY torture the air with a Hornet!
hornetball is offline   Reply With Quote
Old 01-30-2015, 09:59 PM   #657
Senior Member
Thread Starter
 
Join Date: Oct 2011
Location: The Race Track & St Pete FL
Posts: 575
Total Cats: 49
Default

In the article I found these pictures, they were talking about outer most part of the diffuser isn't getting proper flow.

Rear Diffuser Issues - Forum - F1technical.net







Attached Thumbnails
Aerodynamic Discussion Thread-phase10underbodytraces_zps45b4a385.png   Aerodynamic Discussion Thread-phase10underbodyvelocityvectors_zpsb703c3ae.png   Aerodynamic Discussion Thread-phase10underbodyvelocitycontours_zps09c65ab8.png   Aerodynamic Discussion Thread-phase11diffuserpressure_zps3045e0a8.png  
1993ka24det is offline   Reply With Quote
Old 01-31-2015, 01:23 PM   #658
Junior Member
iTrader: (1)
 
Join Date: Apr 2012
Posts: 187
Total Cats: 2
Default

seems as though the strakes aren't doing what they are designed to do.
motormechanic is offline   Reply With Quote
Old 01-31-2015, 04:36 PM   #659
Senior Member
Thread Starter
 
Join Date: Oct 2011
Location: The Race Track & St Pete FL
Posts: 575
Total Cats: 49
Default

So I was looking around again at diffuser designs and I seen what slimjim8201 wrote on f1technical.net.
Interesting data on Straight, convex and concave diffusers. Each are tested at 5, 10 and 15 degs.

























Attached Thumbnails
Aerodynamic Discussion Thread-2ddata_zpsf18c30b6.png   Aerodynamic Discussion Thread-2ddrag_zps37cc6b88.png   Aerodynamic Discussion Thread-2dlift_zps2ebfa010.png   Aerodynamic Discussion Thread-2dratio_zps9dbca697.png   Aerodynamic Discussion Thread-2dvel1_zps8d5a3578.png  

Aerodynamic Discussion Thread-2dvel2_zps28847e20.png   Aerodynamic Discussion Thread-concavevectors_zps974eec9c.png   Aerodynamic Discussion Thread-convexvectors_zps4b74bce0.png   Aerodynamic Discussion Thread-straightvectors_zps6a5af7b1.png   Aerodynamic Discussion Thread-5degpressure_zps333ae813.png  

Aerodynamic Discussion Thread-10degpressure_zps66c69a70.png   Aerodynamic Discussion Thread-15degpressure_zpsa6536f3f.png   Aerodynamic Discussion Thread-pressurecomparison_zpse39be4a1.png  
1993ka24det is offline   Reply With Quote
Old 01-31-2015, 04:43 PM   #660
Elite Member
iTrader: (1)
 
Leafy's Avatar
 
Join Date: Jun 2012
Location: NH
Posts: 8,922
Total Cats: 93
Default

From that first set of images it looks like the strakes need to extend in front of the start of the diffuser. And thats on a car that already has a flat floor. Imagine how much of a disaster it looks like on a car without a flat floor.
Leafy is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
OTS Bilstein to motorsports ASN conversion stoves Suspension, Brakes, Drivetrain 5 04-21-2016 03:00 PM
My solution for Oiltemp and Oilpressure input into Megasuirt (MS3) Zaphod MEGAsquirt 41 01-24-2016 12:25 PM
Going back to stock. Need some 1.6 parts. Trent WTB 2 10-01-2015 12:15 PM
Leaky Wilwoods mx592 Suspension, Brakes, Drivetrain 1 10-01-2015 12:45 AM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

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 07:57 AM.