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

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 10-20-2020, 07:17 AM   #3591 (permalink)
Long time lurker
 
AeroMcAeroFace's Avatar
 
Join Date: May 2019
Location: Uk
Posts: 132
Thanks: 59
Thanked 102 Times in 78 Posts
Why does the mass location not make any difference? Would the car be as likely to tip in cross winds if the mass was concentrated 100 feet in the air? Maybe resistance to sliding, turning or being a weather vane is related to total mass but I don't understand how the mass being lower wouldn't improve crosswind tipping resistance.

If the mass was infinitely high it would be an inverted pendulum and any breeze would topple it over.

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 10-20-2020, 07:25 AM   #3592 (permalink)
EcoModding Apprentice
 
Bicycle Bob's Avatar
 
Join Date: May 2008
Location: N. Saskatchewan, CA
Posts: 1,648

Appliance White - '93 Geo Metro 4-Dr. Auto
Last 3: 42.35 mpg (US)

Stealth RV - '91 Chevy Sprint Base
Thanks: 82
Thanked 374 Times in 261 Posts
Quote:
Originally Posted by AeroMcAeroFace View Post
Why does the mass location not make any difference? Would the car be as likely to tip in cross winds if the mass was concentrated 100 feet in the air? Maybe resistance to sliding, turning or being a weather vane is related to total mass but I don't understand how the mass being lower wouldn't improve crosswind tipping resistance.

If the mass was infinitely high it would be an inverted pendulum and any breeze would topple it over.
If the mass were very high, it would take the centre of pressure up with it in any realistic visualization. However, the mass itself will always be acting straight down, and as long as the road is level and straight, will have the same effect.
__________________
There is no excuse for a land vehicle to weigh more than its average payload.
  Reply With Quote
Old 10-20-2020, 12:32 PM   #3593 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 18,769
Thanks: 5,217
Thanked 6,188 Times in 4,958 Posts
Quote:
That VW has a gurney flap on the diffuser, is that for diffuser function or air flowing over the top of the diffuser? Has anyone seen any evidence for this or heard of it before?
At 4:00 — "It extends the effective length, apparently."

The postal truck has a central peak. How does that affect crosswind performance?
__________________
.

Face the danger and row away from it.
David B. Frohnmayer
_________________
  Reply With Quote
The Following User Says Thank You to freebeard For This Useful Post:
aerohead (10-21-2020)
Old 10-21-2020, 10:07 AM   #3594 (permalink)
Master EcoModder
 
kach22i's Avatar
 
Join Date: Jul 2011
Location: Ann Arbor, Michigan
Posts: 3,797
Thanks: 46
Thanked 2,521 Times in 1,764 Posts
Could of went faster but for the crosswinds.

https://forums.pelicanparts.com/off-...ures-2393.html


Article:
https://www.automobilemag.com/news/s...on-car-record/
__________________
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 User Says Thank You to kach22i For This Useful Post:
aerohead (10-21-2020)
Old 10-21-2020, 12:57 PM   #3595 (permalink)
Master EcoModder
 
kach22i's Avatar
 
Join Date: Jul 2011
Location: Ann Arbor, Michigan
Posts: 3,797
Thanks: 46
Thanked 2,521 Times in 1,764 Posts
Cool scale model.

AutoCult 1/43 Audi Front UW8/40PS Jayray 04026
https://houseofhobbies.com/products/...s-jayray-04026
Attached Thumbnails
Click image for larger version

Name:	Jayray-scale-model.jpg
Views:	26
Size:	37.6 KB
ID:	29407  
__________________
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 User Says Thank You to kach22i For This Useful Post:
aerohead (10-21-2020)
Old 10-21-2020, 01:08 PM   #3596 (permalink)
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 12,357
Thanks: 19,872
Thanked 6,198 Times in 3,825 Posts
Gurney flap

Quote:
Originally Posted by AeroMcAeroFace View Post
I wouldn't fancy driving that delivery vehicle over a windy bridge, you would hope it has a low centre of mass so it doesn't tip over.

That VW has a gurney flap on the diffuser, is that for diffuser function or air flowing over the top of the diffuser? Has anyone seen any evidence for this or heard of it before?
I'd like the guy to expand on his thesis.
The original 1971 Gurney flap was intended for undisturbed, upper body flow.
Embedded within the wake, as it's shown, perhaps it's isolating the diffuser effect from the wake turbulence enough to marginally amplify the downforce. A direct explanation is always better than a guess. Especially mine.
__________________
Photobucket album: http://s1271.photobucket.com/albums/jj622/aerohead2/
  Reply With Quote
Old 10-21-2020, 02:39 PM   #3597 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 18,769
Thanks: 5,217
Thanked 6,188 Times in 4,958 Posts
Quote:
A direct explanation is always better than a guess. Especially mine.
I think we're all bozos on this bus.

I see it as a localized feature at the interface between the (more or less stagnant) wake and fast-moving air. In this case the fast moving air is in the diffuser. I wonder why it isn't inverted. It would be easy enough to test both orientations.
__________________
.

Face the danger and row away from it.
David B. Frohnmayer
_________________
  Reply With Quote
The Following User Says Thank You to freebeard For This Useful Post:
aerohead (10-21-2020)
Old 10-22-2020, 10:22 AM   #3598 (permalink)
Master EcoModder
 
kach22i's Avatar
 
Join Date: Jul 2011
Location: Ann Arbor, Michigan
Posts: 3,797
Thanks: 46
Thanked 2,521 Times in 1,764 Posts
https://myautoworld.com/gm/history/c...tte1-57ss.html
Quote:
The science of aerodynamics has progressed since the days when GM engineers conducted airflow tests with tufts of yarn taped to Zora Arkus-Duntov's 1957 Corvette SS.
Attached Thumbnails
Click image for larger version

Name:	1957_Chevy_Corvette_SS_--_011b.jpg
Views:	29
Size:	35.6 KB
ID:	29411   Click image for larger version

Name:	X02MO-CH004b.jpg
Views:	30
Size:	37.4 KB
ID:	29412   Click image for larger version

Name:	W57HV-CH018b.jpg
Views:	31
Size:	39.7 KB
ID:	29413   Click image for larger version

Name:	1957_Chevy_Corvette_SS-1b.jpg
Views:	31
Size:	59.9 KB
ID:	29414  
__________________
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
Old 10-22-2020, 11:10 AM   #3599 (permalink)
Master EcoModder
 
Join Date: Jun 2011
Location: Earth
Posts: 540
Thanks: 23
Thanked 128 Times in 99 Posts
Eco-Runner X:
Attached Thumbnails
Click image for larger version

Name:	Eco-Runner X.jpg
Views:	60
Size:	49.4 KB
ID:	29417  
  Reply With Quote
The Following User Says Thank You to sgtlethargic For This Useful Post:
aerohead (10-23-2020)
Old 10-22-2020, 12:25 PM   #3600 (permalink)
EcoModding Apprentice
 
Bicycle Bob's Avatar
 
Join Date: May 2008
Location: N. Saskatchewan, CA
Posts: 1,648

Appliance White - '93 Geo Metro 4-Dr. Auto
Last 3: 42.35 mpg (US)

Stealth RV - '91 Chevy Sprint Base
Thanks: 82
Thanked 374 Times in 261 Posts
Quote:
Originally Posted by sgtlethargic View Post
Eco-Runner X:
It is amazing how many sponsors don't mind looking 70 years out of date.

__________________
There is no excuse for a land vehicle to weigh more than its average payload.
  Reply With Quote
Reply  Post New Thread


Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Electric Cars Push Japan Engine Parts Makers to Crisis Mode tjts1 The Lounge 14 12-23-2012 12:47 PM
Name that Eco Car! Quiz: identify these aerodynamic production cars MetroMPG Aerodynamics 16 08-30-2009 05:24 AM



Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com