Go Back   EcoModder Forum > EcoModding > Aerodynamics
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 09-21-2017, 11:05 AM   #11 (permalink)
Aero Wannabe
 
COcyclist's Avatar
 
Join Date: Dec 2007
Location: NW Colo
Posts: 738

TDi - '04 VW Golf
TEAM VW AUDI Group
90 day: 53.2 mpg (US)
Thanks: 705
Thanked 218 Times in 169 Posts
Quote:
Originally Posted by JockoT View Post
I wouldn't imagine that would be an aid to fuel efficiency.
Exactly. Although a flat belly pan to an upslope of a 4 degree diffuser can reduce drag. I am getting better mpg with this setup on my Golf. On sports cars the diffuser is usually much steeper to create downforce at the expense of extra drag.

__________________
60 mpg hwy highest, 50+mpg lifetime
TDi=fast frugal fun
https://ecomodder.com/forum/showthre...tml#post621801


Quote:
Originally Posted by freebeard View Post
The power needed to push an object through a fluid increases as the cube of the velocity. Mechanical friction increases as the square, so increasing speed requires progressively more power.

Last edited by COcyclist; 09-21-2017 at 11:37 AM..
  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 09-21-2017, 11:18 AM   #12 (permalink)
Master EcoModder
 
kach22i's Avatar
 
Join Date: Jul 2011
Location: Ann Arbor, Michigan
Posts: 4,158
Thanks: 120
Thanked 2,790 Times in 1,959 Posts
One can suck the car down on the road so much, it would be like adding a thousand pounds, and that's going to cost you some energy and efficiency.

Can a Formula 1 Car Drive Upside Down?
Can a Formula 1 Car Drive Upside Down? | Bleacher Report
Quote:
There’s some disagreement over how fast an F1 car would need to go to generate the necessary downforce, but it is scientifically sound. So long as a car is producing a force equal to its weight, anyway...............
__________________
George
Architect, Artist and Designer of Objects

1977 Porsche 911s Targa
1998 Chevy S-10 Pick-Up truck
1989 Scat II HP Hovercraft

Chin Spoiler:
http://forums.pelicanparts.com/off-t...effective.html

Rear Spoiler Pick Up Truck
http://forums.pelicanparts.com/off-t...xperiment.html

Roof Wing
http://ecomodder.com/forum/showthrea...1-a-19525.html
  Reply With Quote
The Following 2 Users Say Thank You to kach22i For This Useful Post:
JockoT (09-22-2017), Xist (09-21-2017)
Old 09-21-2017, 07:09 PM   #13 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 27,562
Thanks: 7,738
Thanked 8,554 Times in 7,041 Posts
This one's my favorite:



It doesn't really show in the picture but the fences are curved outward the width of the rear tire tread. With a 4% flat roof this would create a divergent duct with minimal downforce.

And the wheelwell turbulence is segregated and thrown out from 'under the bus.'
  Reply With Quote
Old 09-22-2017, 01:33 PM   #14 (permalink)
Master EcoModder
 
Join Date: Jun 2008
Location: Earth
Posts: 5,209
Thanks: 225
Thanked 811 Times in 594 Posts
Need to remember that a road car doesn't just have to deal with aerodynamics, in most places it has to handle hydrodynamics and snowodynamics* as well. And tire chains.

*A timely thought, as we got our first mountain snowfall yesterday.
  Reply With Quote
The Following User Says Thank You to jamesqf For This Useful Post:
aerohead (10-07-2017)
Old 09-22-2017, 05:11 PM   #15 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 27,562
Thanks: 7,738
Thanked 8,554 Times in 7,041 Posts
I'd attach the roof to the chassis and the outer fences, trimmed to a reasonable departure angle, to the rear suspension. I think the open side snowplow shape would shed better than a conventional mudflap.
  Reply With Quote
Old 09-30-2017, 03:26 PM   #16 (permalink)
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 15,861
Thanks: 23,922
Thanked 7,207 Times in 4,640 Posts
wheel fairings

Track cars are primarily concerned with cornering.Low drag might help you on the Mulsanne Straight at LeMans,but you need downforce in the curves.
I would never look to track cars for insight into low drag for passenger cars.
For low drag,the wheels and tires must be integrated into the body.You can use fairings to do it,or active suspension to bring them into the body at speed,or some of both.
__________________
Photobucket album: http://s1271.photobucket.com/albums/jj622/aerohead2/
  Reply With Quote
Old 10-02-2017, 02:33 PM   #17 (permalink)
EcoModding Lurker
 
Join Date: Mar 2015
Location: Texas
Posts: 29
Thanks: 15
Thanked 11 Times in 11 Posts
Granted, something like having a virtually non-existent wheel well gap on the inside of the front wheel for a standard shaped car (and almost no air gathering behind the front wheel) may be ideal, but

A) How can you fabricate something like that, that eliminates almost all air entering behind the front wheel, around brake lines, the steering rod, the suspension, and other parts?

B) For what air does gather right behind the front wheel, is it actually better to just let it sit there vs. form a vent to drain any air pressure behind the front tire out the side and thus add pressure behind the front tire's low pressure area?


I understand that it's ideal to fair the entire tire separately from the rest of the car body ALA that salt flat car design (option "C"?), but being able to custom-fabricate something like that is honestly beyond me.
  Reply With Quote
The Following User Says Thank You to mikesheiman For This Useful Post:
aerohead (10-07-2017)
Old 10-02-2017, 04:32 PM   #18 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 27,562
Thanks: 7,738
Thanked 8,554 Times in 7,041 Posts
aerohead only posts on the weekends so let me give it a try:

1983 Ford Probe IV Concept - conceptcarz.com


Quote:
One of Probe IV's most distinctive features are its fully-skirted wheels and tires which utilize membranes between the outer covers and the body. The membranes flex when the front wheels are turned and allow Probe IV to be driven normally, but drastically reduce wheel well turbulence and resulting aero drag.
BMW proposes a morphing skin:

BMW's New Concept Car Features Morphing Skin, Beast Mode. Sorry, Boost Mode.- Core77

  Reply With Quote
The Following User Says Thank You to freebeard For This Useful Post:
aerohead (10-07-2017)
Old 10-07-2017, 12:39 PM   #19 (permalink)
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 15,861
Thanks: 23,922
Thanked 7,207 Times in 4,640 Posts
A) and B)

Quote:
Originally Posted by mikesheiman View Post
Granted, something like having a virtually non-existent wheel well gap on the inside of the front wheel for a standard shaped car (and almost no air gathering behind the front wheel) may be ideal, but

A) How can you fabricate something like that, that eliminates almost all air entering behind the front wheel, around brake lines, the steering rod, the suspension, and other parts?

B) For what air does gather right behind the front wheel, is it actually better to just let it sit there vs. form a vent to drain any air pressure behind the front tire out the side and thus add pressure behind the front tire's low pressure area?


I understand that it's ideal to fair the entire tire separately from the rest of the car body ALA that salt flat car design (option "C"?), but being able to custom-fabricate something like that is honestly beyond me.
A) we'd have to take each car on a case-specific basis.And you wouldn't attempt these details until the rest of the car was 'done.' And you'd have to be REALLY motivated to take this on (bordering on obsession).The lowest drag concepts maintain some degree of the hour-glass openings to allow wheel flop at the front,so it may not be necessary to engineer for closing all of that off.Simulation of a totally-sealed belly in a wind tunnel would indicate if this fruit was worth going after.Tested models from the past indicate that Cd 0.13 is possible without wheel fairings,if this area is sealed.Today's cars use fairings to get the air to 'jump' the opening,then reattach downstream of the opening.
B) Ford's research with the Probe-IV indicated that there's no benefit doing anything behind the front wheels.Not so with the rears.This makes the front a little easier.
For the return trip to DARKO,I'll attempt to mimic a fully-streamlined belly,including full wheel fairings,just to isolate the effect of the hour-glass area.Measurements will tell me if it's worth the effort to pursue a 'streetable' version of the mods.
Get you car down to Cd 0.16,then see if you want to go further.

__________________
Photobucket album: http://s1271.photobucket.com/albums/jj622/aerohead2/
  Reply With Quote
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com