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

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 05-13-2020, 04:45 PM   #21 (permalink)
Master EcoModder
 
Join Date: Nov 2017
Location: Australia
Posts: 382
Thanks: 28
Thanked 432 Times in 224 Posts
Quote:
Originally Posted by aerohead View Post
*Until you understand the implications of what the local pressure is at the separation line on top of the Cayenne,and what it would mean to move that separation line all the way back to the rear of the car,there would be no point discussing the degree of lift it can telegraph over the rear of the car.I recommend a brush up on Bernoulli.
What separation on the roof of the Cayenne? Have you looked at the wind tunnel video with smoke streams produced by Porsche? Just as one would expect, it doesn't show any separation on the roof.

__________________
Modifying the Aerodynamics of Your Road Car

The best practical introduction to aerodynamics for the car enthusiast that I've seen. - Adrian Gaylard, head of aerodynamics, Jaguar Land Rover
  Reply With Quote
The Following User Says Thank You to JulianEdgar For This Useful Post:
aerohead (05-15-2020)
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 05-13-2020, 08:06 PM   #22 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 15,800
Thanks: 4,116
Thanked 5,286 Times in 4,210 Posts
Won't someone think of the OP, eagle, and take it elsewhere? I suggest the form of a rap battle.

Quote:
Im guessing so the turbulent air can escape
My thought drift to the Merkur XR4Ti with it's biplane spoiler.


https://ecomodder.com/forum/showthre...tml#post267188

Just mounted at the top of the hatch and pancaked somewhat.

I know this is off-topic, but maybe those other two can take it off to another thread. I ran across it looking for a Merkur pic.

Behold, a fastback Porsche coupe with Template conformity, and a Coanda effect from the engine rear mounted heat pump.

__________________
.
Joe Rogan and Elon Musk agree: Aspire to be less wrong.

_________________
  Reply With Quote
The Following User Says Thank You to freebeard For This Useful Post:
Fat Charlie (05-14-2020)
Old 05-13-2020, 11:01 PM   #23 (permalink)
Cyborg ECU
 
California98Civic's Avatar
 
Join Date: Mar 2011
Location: Coastal Southern California
Posts: 5,567

Black and Green - '98 Honda Civic DX Coupe
Team Honda
90 day: 59.47 mpg (US)

Black and Red - '00 Nashbar Custom built eBike
90 day: 3671.43 mpg (US)
Thanks: 2,045
Thanked 1,755 Times in 1,187 Posts
Quote:
Originally Posted by freebeard View Post
... My thought drift to the Merkur XR4Ti with it's biplane spoiler.


https://ecomodder.com/forum/showthre...tml#post267188

Just mounted at the top of the hatch and pancaked somewhat....
I love that spoiler. I also suspect that the roof spoiler the OP is describing might not be so much to let air escape as it is for "tuning" the flow in some way. For example, Subaru apparently spent a lot of time and money tuning the position of those silly looking vortex generators you see on the STi from a fee years ago. The goal, I read, was to direct flow to the substantial wing on the rear decklid.
__________________


See my car's mod & maintenance thread and my electric bicycle's thread for ongoing projects. I will rebuild Black and Green over decades as parts die, until it becomes a different car of roughly the same shape and color. My minimum fuel economy goal is 55 mpg while averaging posted speed limits. I generally top 60 mpg. See also my Honda manual transmission specs thread.

  Reply With Quote
The Following User Says Thank You to California98Civic For This Useful Post:
aerohead (05-15-2020)
Old 05-14-2020, 01:59 AM   #24 (permalink)
Master EcoModder
 
Join Date: Nov 2017
Location: Australia
Posts: 382
Thanks: 28
Thanked 432 Times in 224 Posts
Quote:
Originally Posted by California98Civic View Post
Subaru apparently spent a lot of time and money tuning the position of those silly looking vortex generators you see on the STi from a fee years ago. The goal, I read, was to direct flow to the substantial wing on the rear decklid.
That was certainly the goal on the original Evo Lancer, and they did (according to Mitsubishi's modelling) work a bit.

Left with, right without:



It would be interesting to see the modelled pressures under the wing.
__________________
Modifying the Aerodynamics of Your Road Car

The best practical introduction to aerodynamics for the car enthusiast that I've seen. - Adrian Gaylard, head of aerodynamics, Jaguar Land Rover
  Reply With Quote
Old 05-14-2020, 10:51 AM   #25 (permalink)
EcoModding Lurker
 
Join Date: Dec 2016
Location: Florida
Posts: 45
Thanks: 13
Thanked 24 Times in 20 Posts
Quote:
Originally Posted by freebeard View Post
Won't someone think of the OP, eagle, and take it elsewhere? I suggest the form of a rap battle.


My thought drift to the Merkur XR4Ti with it's biplane spoiler.


https://ecomodder.com/forum/showthre...tml#post267188

Just mounted at the top of the hatch and pancaked somewhat.
"Biplane spoiler" or Hybrid aero device, or Wing supplemented with a spoiler, which can be rather dubious in that one can deduct effectiveness, depending on orientation to each other, from the other, unless cosmetic enhancement is the primary goal, in that it sells cars and earns profits, from the punters, IMO.

And I also don't see a lot of commonality with OP's pictured "guess" example.
  Reply With Quote
Old 05-14-2020, 05:16 PM   #26 (permalink)
Master EcoModder
 
Join Date: Nov 2017
Location: Australia
Posts: 382
Thanks: 28
Thanked 432 Times in 224 Posts
Quote:
Originally Posted by j-c-c View Post
"Biplane spoiler" or Hybrid aero device, or Wing supplemented with a spoiler, which can be rather dubious in that one can deduct effectiveness, depending on orientation to each other, from the other, unless cosmetic enhancement is the primary goal, in that it sells cars and earns profits, from the punters, IMO.

And I also don't see a lot of commonality with OP's pictured "guess" example.
Yes, I have always wondered how this was supposed to work. Has anyone ever seen a tech paper on this type of design? It would be really interesting to see some tuft testing.
__________________
Modifying the Aerodynamics of Your Road Car

The best practical introduction to aerodynamics for the car enthusiast that I've seen. - Adrian Gaylard, head of aerodynamics, Jaguar Land Rover
  Reply With Quote
The Following User Says Thank You to JulianEdgar For This Useful Post:
aerohead (05-15-2020)
Old 05-14-2020, 07:55 PM   #27 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 15,800
Thanks: 4,116
Thanked 5,286 Times in 4,210 Posts
I'll bet we could/should ask aerohead.
__________________
.
Joe Rogan and Elon Musk agree: Aspire to be less wrong.

_________________
  Reply With Quote
Old 05-14-2020, 07:58 PM   #28 (permalink)
106 diesel enthusiast
 
Join Date: Apr 2020
Location: Scotland
Posts: 9

Peamobile - '96 Peugeot 106 XND
Thanks: 6
Thanked 1 Time in 1 Post
To OP

I had a 2001 Volvo V70 T5 which had a high mount spoiler with a "hole/slot" in it.

Interesting thing happened, you could see the giant swirls in the mirror generated when it was raining in the spray. You could see 2 big swirls forming on the rear window coming down from the upper middle an spreading out. So looking from the rear, that's clockwise on the left and anti-clock on the right.

With the hole covered up, the dirt left on the rear window was more uniform spread. Fuel consumption was a little bit worse too, however the scale only reads to the nearest 0.1mpg (imp) so 0.4mpg improvement might not be as significant when you take in other factors.

so, I don't know what it was doing, but it was definitely doing something.

Perhaps it's performing a similar function on the fiesta?
  Reply With Quote
Old 05-14-2020, 08:02 PM   #29 (permalink)
Master EcoModder
 
Join Date: Nov 2017
Location: Australia
Posts: 382
Thanks: 28
Thanked 432 Times in 224 Posts
Quote:
Originally Posted by MHR1294 View Post
To OP

I had a 2001 Volvo V70 T5 which had a high mount spoiler with a "hole/slot" in it.

Interesting thing happened, you could see the giant swirls in the mirror generated when it was raining in the spray. You could see 2 big swirls forming on the rear window coming down from the upper middle an spreading out. So looking from the rear, that's clockwise on the left and anti-clock on the right.

With the hole covered up, the dirt left on the rear window was more uniform spread. Fuel consumption was a little bit worse too, however the scale only reads to the nearest 0.1mpg (imp) so 0.4mpg improvement might not be as significant when you take in other factors.

so, I don't know what it was doing, but it was definitely doing something.

Perhaps it's performing a similar function on the fiesta?
Interesting. Trailing vortices that rotate (viewed from behind) clockwise on the left and anticlockwise on the right are indicative of the body developing lift.
__________________
Modifying the Aerodynamics of Your Road Car

The best practical introduction to aerodynamics for the car enthusiast that I've seen. - Adrian Gaylard, head of aerodynamics, Jaguar Land Rover
  Reply With Quote
Old 05-14-2020, 08:13 PM   #30 (permalink)
106 diesel enthusiast
 
Join Date: Apr 2020
Location: Scotland
Posts: 9

Peamobile - '96 Peugeot 106 XND
Thanks: 6
Thanked 1 Time in 1 Post
Quote:
Originally Posted by JulianEdgar View Post
Interesting. Trailing vortices that rotate (viewed from behind) clockwise on the left and anticlockwise on the right are indicative of the body developing lift.
I think I got that right, it was in the mirror. If I still had the car I'd love to go and test it.

The droplets would run down from the upper middle of the screen, and spread towards the lower outer edges. So whatever direction that is!

The spoiler did angle down too, I'm sure I've got a picture of it somewhere I'll go have a dig.

  Reply With Quote
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com