New Wing to Test - Page 7 - 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 12-23-2012, 01:57 PM   #121
Newb
 
Join Date: Oct 2011
Posts: 10
Total Cats: 0
Default

What's the logic/science behind the massive end plates?
Dr Pooface is offline   Reply With Quote
Old 12-23-2012, 03:43 PM   #122
Senior Member
iTrader: (1)
 
Join Date: Jun 2006
Location: Sweden
Posts: 1,391
Total Cats: 58
Default

Quote:
Originally Posted by Dr Pooface View Post
What's the logic/science behind the massive end plates?
Aerodynamic Yaw-angle stabilizers ...
NiklasFalk is offline   Reply With Quote
Old 12-23-2012, 04:11 PM   #123
Elite Member
iTrader: (1)
 
Leafy's Avatar
 
Join Date: Jun 2012
Location: NH
Posts: 9,092
Total Cats: 90
Default

Quote:
Originally Posted by Dr Pooface View Post
What's the logic/science behind the massive end plates?
I know on my wing the difference between the biggest size legal and U-Maryland style endplates was almost 80 pounds @ 60mph. U-Mayrland is know for having endplates so large that their cars can actually tip over in paddock in strong wing gusts.

Last edited by Leafy; 12-23-2012 at 05:22 PM.
Leafy is offline   Reply With Quote
Old 12-23-2012, 04:58 PM   #124
Junior Member
 
Join Date: Jun 2011
Location: Houston
Posts: 409
Total Cats: 17
Default

The wing works by creating a higher pressure on top than on bottom. Without end plates, the pressure would "spill" over the edge creating a vortex, decreasing the downforce created and increasing the drag. Endplates prevent this. In general, the bigger the better.
Handy Man is offline   Reply With Quote
Old 12-23-2012, 06:16 PM   #125
Junior Member
iTrader: (1)
 
Join Date: Feb 2012
Location: Hagerstown, MD
Posts: 140
Total Cats: 0
Default

I thought the end plates were supposed to have equal height above and below or biased towards being above the wing rather than below it.

I flew yesterday and the end plate on that wing was interesting. May just flip that design upside down and look fannccyyy.
ericwh is offline   Reply With Quote
Old 12-23-2012, 06:27 PM   #126
Senior Member
iTrader: (4)
 
Join Date: Aug 2010
Location: Farmington Hills, MI
Posts: 510
Total Cats: 15
Default

Quote:
Originally Posted by ericwh View Post
I thought the end plates were supposed to have equal height above and below or biased towards being above the wing rather than below it.
Nope. There are books full of data (that I understand a small portion of) documenting why.

There is a Racecar Engineering article I have at home that had a lot of data on wing end plate depth. I'll scan it when I'm back there after Christmas.
njn63 is offline   Reply With Quote
Old 12-23-2012, 06:32 PM   #127
Elite Member
iTrader: (1)
 
Leafy's Avatar
 
Join Date: Jun 2012
Location: NH
Posts: 9,092
Total Cats: 90
Default

Quote:
Originally Posted by ericwh View Post
I thought the end plates were supposed to have equal height above and below or biased towards being above the wing rather than below it.

I flew yesterday and the end plate on that wing was interesting. May just flip that design upside down and look fannccyyy.
Nope, you want it biased to the bottom. Because an efficient wing should create the majority of its force from the low pressure at the bottom of the wing, so you're going to have a lower pressure under the wing so air is going to want to flow into there from the sides more.
Leafy is offline   Reply With Quote
Old 12-23-2012, 07:46 PM   #128
Supporting Vendor
iTrader: (3)
 
Join Date: Jul 2006
Location: San Diego
Posts: 2,863
Total Cats: 485
Default

Sooo many of the wings on the market have terrible endplate designs. I have to assume it's just a trade-off decision; they assume the wing won't sell with a big form>function monstrosity of an endplate
ThePass is offline   Reply With Quote
Old 12-23-2012, 11:57 PM   #129
Junior Member
 
Join Date: Jun 2011
Location: Houston
Posts: 409
Total Cats: 17
Default

Another reason end plates tend to be larger on bottom is because regulations often require that no part of the wing protrudes higher than the roof line of the car... and since you want the wing itself placed up high to get into the cleaner airstream, it doesn't leave much room for a large end plate above the wing.

A really good design would use uprights as end plates.
Handy Man is offline   Reply With Quote
Old 12-24-2012, 12:07 AM   #130
Elite Member
iTrader: (2)
 
Mobius's Avatar
 
Join Date: May 2008
Location: Portland, Oregon
Posts: 3,178
Total Cats: 267
Default

Attached Thumbnails
New Wing to Test-2010-ferrari-f1-car.jpg  
Mobius is offline   Reply With Quote
Old 12-24-2012, 12:19 AM   #131
Junior Member
 
Join Date: Dec 2012
Location: Indianapolis
Posts: 65
Total Cats: 35
Default

Quote:
Originally Posted by Dr Pooface View Post
What's the logic/science behind the massive end plates?
Many have no logic or science behind them

Large endplates seen on open wheel race cars do serve a purpose. It is intended to reduce the effect of the "dirty" air disrupting the airflow to the wing.

Quote:
Originally Posted by NiklasFalk View Post
Aerodynamic Yaw-angle stabilizers ...
I like this because it could work and is funny!

Quote:
Originally Posted by Handy Man View Post
The wing works by creating a higher pressure on top than on bottom. Without end plates, the pressure would "spill" over the edge creating a vortex, decreasing the downforce created and increasing the drag. Endplates prevent this. In general, the bigger the better.
This is kind of true and kind of not. The wing works by creating a gradient of pressure. The bottom of the wing (on a car designed to make downforce) will be doing most of the work. Aka more low pressure is created than high pressure. Endplates to help with spill over. Endplates cause vortices also. Also without an endplate, drag would most likely be reduced since the induced drag would be decreased. The efficiency of the wing however would drastically decrease. Bigger isn't always better. Proper analysis and testing is better.

Quote:
Originally Posted by ericwh View Post
I thought the end plates were supposed to have equal height above and below or biased towards being above the wing rather than below it.

I flew yesterday and the end plate on that wing was interesting. May just flip that design upside down and look fannccyyy.
Don't do this.

Quote:
Originally Posted by Leafy View Post
Nope, you want it biased to the bottom. Because an efficient wing should create the majority of its force from the low pressure at the bottom of the wing, so you're going to have a lower pressure under the wing so air is going to want to flow into there from the sides more.
This is true.

Quote:
Originally Posted by ThePass View Post
Sooo many of the wings on the market have terrible endplate designs. I have to assume it's just a trade-off decision; they assume the wing won't sell with a big form>function monstrosity of an endplate
This is true, most endplate designs are terrible. I would also go out on a limb and say most wing design are terrible also. They are taken off some racecar in the past without knowledge on the performance. Real racecars have specifically designed wings for their application. Changing applications might make the wing not perform properly.


The much greater low pressure at the bottom can be seen in this cfd pressure plot below. This is of a wing I currently in the process of designing (except now it uses my own airfoils that I designed instead of one available). The current iteration performs much better

Name:  04_zps55e3f454.png
Views: 27
Size:  101.0 KB


This is a cfd pressure plot across the wing to show how endplates interact with the airfoil. This is my current single element design (endplates still being optimized). Also this is one tested on a Miata so this is not seeing all free-stream air.

Name:  s_5_pressure_plot_6_zps02dbeeaf.png
Views: 26
Size:  391.6 KB
plucas is offline   Reply With Quote
Old 12-24-2012, 01:01 AM   #132
Elite Member
iTrader: (2)
 
Mobius's Avatar
 
Join Date: May 2008
Location: Portland, Oregon
Posts: 3,178
Total Cats: 267
Default

Awesome!
Mobius is offline   Reply With Quote
Old 12-24-2012, 02:14 AM   #133
Senior Member
iTrader: (3)
 
Join Date: Dec 2008
Location: KY
Posts: 699
Total Cats: 50
Default

Quote:
Originally Posted by ThePass View Post
Hmm I see what you are saying. But, don't know how you figure there is more frontal area. Same number of bolts, same thicknesses of materials, in fact using the same exact hardware too. If you mean the frontal area shifted because the bolt locations moved, that I agree on.
The frontal area thing was more related to the turnbuckles/deflectors. That just looks like way more area than a bolthead/nut. Not significant from the normal perspective of frontal area/drag, but it looks like it could hurt the airflow in that region pretty bad and lead to a lot of separation farther back on the wing.

Quote:
As for the rear hole, as great as it is in theory, the carbon was already F'ed up from mounting/dismounting in its previous life because that hole is so close to the airfoil. I knew if I used that hole, through just tool contact, mounting/dismounting, etc. it would get a lot worse. I'd like to avoid causing a weak point in the airfoil over time.
I've wondered how consistent the spacing is on that rear hole... mine was also really close to the wing and the bolt heads barely fit, but I guess I got lucky and the mechanics that worked on mine were gentle. I bet they used a standard hex bolt and nut on yours, which would definitely mar the wing if I tried it on mine. I use a socket head cap screw with a regular hex nut. With the SHCS, you can hold the nut from rotating with a wrench and then spin the screw with an allen key and not mar the wing. It's so close that the difference between a socket head and a button head is too much...

Quote:
The other thing I took into consideration was that the front holes stuck wayyy down low - this meant the angle of the uprights would have to be more severe because they would have less height in which to make the transition. I wanted to minimize the angles of the bends to keep the aluminum as strong as possible. As it is, they are only 7* and 9*.
I hadn't thought about this being a problem with the bent brackets that you guys are using, but I see what you mean now that I think about it. One more reason I'm glad I just hacked some slots into my trunk lid and used flat pieces of aluminum for the uprights lol. Because racecar.
jpreston is online now   Reply With Quote
Old 12-25-2012, 12:08 PM   #134
Junior Member
 
Join Date: Jun 2011
Location: Houston
Posts: 409
Total Cats: 17
Default

Quote:
Endplates cause vortices also.
Haha. Smart guy You are right, they do, but they move the vortices away from the surface of the wing, reducing their detrimental effects.

Quote:
Also without an endplate, drag would most likely be reduced since the induced drag would be decreased.
Surprisingly not. Adding end plates to most automotive style wings actually decreases drag while increasing downforce. Free Lunch! woohoo!

Quote:
Bigger isn't always better. Proper analysis and testing is better.
Of course, but if you aren't going to do the analysis and testing (like 99% of the people here) bigger is better is a pretty safe assumption. The only big downsides to larger end plates are drag and weight, and if you are cool enough to use end plates as uprights, those disadvantages disappear

For some great info on the subject check out these articles from Racecar Engineering: http://www.rightwheeldrive.com/Aero_articles.zip
Handy Man is offline   Reply With Quote
Old 12-25-2012, 12:35 PM   #135
Junior Member
 
Join Date: Dec 2012
Location: Indianapolis
Posts: 65
Total Cats: 35
Default

Quote:
Originally Posted by Handy Man View Post
Surprisingly not. Adding end plates to most automotive style wings actually decreases drag while increasing downforce. Free Lunch! woohoo!
[/url]
You are correct after I looked back at my old notes. Endplates increase the aspect ratio of the wing with decreases the induced drag.
plucas is offline   Reply With Quote
Old 12-25-2012, 01:37 PM   #136
Senior Member
iTrader: (1)
 
Join Date: Jun 2006
Location: Sweden
Posts: 1,391
Total Cats: 58
Default

Quote:
Originally Posted by plucas View Post
Quote:
Originally Posted by NiklasFalk View Post
Aerodynamic Yaw-angle stabilizers ...
I like this because it could work and is funny!
It would most probably have little effect at the speeds we think about.
It's based on the logic when the center of aerodynamic pressure (seen from the side) is behind the center of mass the car will straighten when it gets sideways.
This was one of the design objectives with the COT body design and it apparently worked since the COTs could drift a lot longer when the old style spinned.

Usure if the Miata (with normal HT) is aerodynamically unstable or stabilized this way.
F1-style dorsal fin?
NiklasFalk is offline   Reply With Quote
Old 12-25-2012, 03:10 PM   #137
Junior Member
 
Join Date: Jun 2011
Location: Houston
Posts: 409
Total Cats: 17
Default

The big difference is that COT's are going 200+ mph and we are going a LOT slower.
Handy Man is offline   Reply With Quote
Old 12-25-2012, 03:23 PM   #138
Tour de Franzia
iTrader: (6)
 
hustler's Avatar
 
Join Date: Jun 2006
Location: Republic of Dallas
Posts: 29,114
Total Cats: 351
Default

Attached Thumbnails
New Wing to Test-224992_307797592672287_352214309_n.jpg  
hustler is offline   Reply With Quote
Old 12-25-2012, 07:49 PM   #139
Elite Member
iTrader: (2)
 
Mobius's Avatar
 
Join Date: May 2008
Location: Portland, Oregon
Posts: 3,178
Total Cats: 267
Default

Hustler likes wings with *****.
Mobius is offline   Reply With Quote
Old 12-25-2012, 11:26 PM   #140
Junior Member
 
Join Date: Dec 2012
Location: Indianapolis
Posts: 65
Total Cats: 35
Default

What's with the *****?
plucas is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
3rd Time's a Charm...hopefully. zephyrusaurai Meet and Greet 2 09-28-2015 11:59 PM
Are my coils failing? viriiguy General Miata Chat 5 09-28-2015 08:39 PM
Compression test results Colipto General Miata Chat 3 09-11-2015 02:44 PM


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 05:09 PM.