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

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 08-14-2009, 09:47 AM   #41 (permalink)
EcoModding Apprentice
 
Bicycle Bob's Avatar
 
Join Date: May 2008
Location: N. Saskatchewan, CA
Posts: 1,803

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

Stealth RV - '91 Chevy Sprint Base
Thanks: 91
Thanked 459 Times in 327 Posts
I think a bit of wiggle is OK, as long as the tell tales stay flat, but keep checking. A kamm back is generally close to vertical. The roof and sides can usually taper in at 15 degrees on the way to Kamm's truncation, the bottom at 4, but other details will affect the optimum angle.

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 08-14-2009, 03:41 PM   #42 (permalink)
Master EcoModder
 
orange4boy's Avatar
 
Join Date: Aug 2008
Location: The Wet Coast, Kanuckistan.
Posts: 1,275

The Golden Egg - '93 Toyota Previa DX
90 day: 31.91 mpg (US)

Chewie - '03 Toyota Prius
90 day: 57 mpg (US)

The Spaceship - '00 Honda Insight
Thanks: 100
Thanked 306 Times in 178 Posts
I had disappointing results with the mpg and seat of pants from the new back. I had thought the angles were wrong. Top was 15-17 and sides were 15-20. I changed to 12 top and 12 sides but the van still seems to be sluggish on coastdown. It was much better with just the short extensions. It's possible the cooler weather is affecting the results. Just how much difference is there in air density between 85F to 70F? Or could the half shell create some massive vortex, increasing drag?

Of course it could be a dragging brake or some other increased friction like a toast bearing. I guess I should take the sucker off and try it that way.
__________________
Vortex generators are old tech. My new and improved vortex alternators are unstoppable.

"It’s easy to explain how rockets work but explaining the aerodynamics of a wing takes a rocket scientist.


  Reply With Quote
Old 08-15-2009, 04:11 PM   #43 (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
disappointing

Quote:
Originally Posted by orange4boy View Post
I had disappointing results with the mpg and seat of pants from the new back. I had thought the angles were wrong. Top was 15-17 and sides were 15-20. I changed to 12 top and 12 sides but the van still seems to be sluggish on coastdown. It was much better with just the short extensions. It's possible the cooler weather is affecting the results. Just how much difference is there in air density between 85F to 70F? Or could the half shell create some massive vortex, increasing drag?

Of course it could be a dragging brake or some other increased friction like a toast bearing. I guess I should take the sucker off and try it that way.
With just the 1/2 shell, it's predictabilty lies in the realm of the netherworld.My intuition suggested benefit,but no science to support it.----------- No books with me here so I cannot address the air density question,sorry.Falling temps will also affect all your lube viscosities and wheel bearing grease and tire RR.Lots of variables which is really bad for testing.------- If I lived next door,I'd help you fabricate sides and bottom for a re-test,back -to-back,same day,with and without,to minimize those variables.
  Reply With Quote
Old 09-12-2009, 11:01 PM   #44 (permalink)
Gen II Prianista
 
Rokeby's Avatar
 
Join Date: Jul 2009
Location: Ballamer, Merlin
Posts: 453
Thanks: 201
Thanked 146 Times in 89 Posts
aerohead,

Finally, I found a true overhead shot of the iMIev Sport Air all-electric concept car... 80 mph, 73 mile range:

http://photo.netcarshow.com/Mitsubis...9_photo_12.jpg

From this site, which has more Sport Air info than most folks will ever want to
know:

Mitsubishi i MiEV Sport Air Concept (2009) with pictures and wallpapers

Hmmm... no windshield wipers in any of the views. Clearly, still in the
concept car stage.
Attached Thumbnails
Click image for larger version

Name:	Mitsubishi-i_MiEV_Sport_Air_Concept_2009_800x600_wallpaper_12.jpg
Views:	138
Size:	53.1 KB
ID:	4246  

Last edited by Rokeby; 09-12-2009 at 11:26 PM..
  Reply With Quote
The Following User Says Thank You to Rokeby For This Useful Post:
aerohead (01-27-2015)
Old 09-15-2009, 04:18 PM   #45 (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
overhead

Quote:
Originally Posted by Rokeby View Post
aerohead,

Finally, I found a true overhead shot of the iMIev Sport Air all-electric concept car... 80 mph, 73 mile range:

http://photo.netcarshow.com/Mitsubis...9_photo_12.jpg

From this site, which has more Sport Air info than most folks will ever want to
know:

Mitsubishi i MiEV Sport Air Concept (2009) with pictures and wallpapers

Hmmm... no windshield wipers in any of the views. Clearly, still in the
concept car stage.
Rokeby,thanks for the pic.There is definitely some camber to the sides of the body and gradual taper to the aftbody.Windshield also has generous radii around the sides.They could have done a lot worse.
  Reply With Quote
Old 09-15-2009, 05:35 PM   #46 (permalink)
Master EcoModder
 
orange4boy's Avatar
 
Join Date: Aug 2008
Location: The Wet Coast, Kanuckistan.
Posts: 1,275

The Golden Egg - '93 Toyota Previa DX
90 day: 31.91 mpg (US)

Chewie - '03 Toyota Prius
90 day: 57 mpg (US)

The Spaceship - '00 Honda Insight
Thanks: 100
Thanked 306 Times in 178 Posts
Quote:
I had disappointing results with the mpg and seat of pants from the new back. I had thought the angles were wrong. Top was 15-17 and sides were 15-20. I changed to 12 top and 12 sides but the van still seems to be sluggish on coastdown.
Turns out my brakes were dragging. Time to rebuild the right front caliper. The rear drums were also dragging because of the automatic adjusters. Now disabled!

Posted my best ever highway 36mpg. Go kamm.
__________________
Vortex generators are old tech. My new and improved vortex alternators are unstoppable.

"It’s easy to explain how rockets work but explaining the aerodynamics of a wing takes a rocket scientist.


  Reply With Quote
Old 09-15-2009, 05:50 PM   #47 (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
Kamm

Quote:
Originally Posted by orange4boy View Post
Turns out my brakes were dragging. Time to rebuild the right front caliper. The rear drums were also dragging because of the automatic adjusters. Now disabled!

Posted my best ever highway 36mpg. Go kamm.
Glad to hear that the beautiful stainless steel will be making a comeback! Thanks for the info and update.
  Reply With Quote
Old 03-01-2010, 12:14 AM   #48 (permalink)
EcoModding Lurker
 
Join Date: Feb 2010
Location: Omaha
Posts: 52

BigWhiteWhale - '01 Ford F250 Lariat Crew Cab Superduty
Thanks: 12
Thanked 17 Times in 9 Posts
So where do I put this curve?

So where should I put this curve, and is the numbers 10,20 the percent of length?

Attached Thumbnails
Click image for larger version

Name:	BWW1a.JPG
Views:	287
Size:	58.9 KB
ID:	5686   Click image for larger version

Name:	BWW2a.JPG
Views:	261
Size:	58.9 KB
ID:	5687  
  Reply With Quote
Old 03-01-2010, 12:19 AM   #49 (permalink)
EcoModding Lurker
 
Join Date: Feb 2010
Location: Omaha
Posts: 52

BigWhiteWhale - '01 Ford F250 Lariat Crew Cab Superduty
Thanks: 12
Thanked 17 Times in 9 Posts
wrong pic

doubled the first set..
Attached Thumbnails
Click image for larger version

Name:	BWW1a.JPG
Views:	238
Size:	60.2 KB
ID:	5688  
  Reply With Quote
Old 03-01-2010, 08:32 AM   #50 (permalink)
Left Lane Ecodriver
 
RobertSmalls's Avatar
 
Join Date: Aug 2008
Location: Buffalo, NY, USA
Posts: 2,257

Prius C - '12 Toyota Prius C
Thanks: 79
Thanked 286 Times in 199 Posts
Bajascoob, the template doesn't work when it's not lined up properly.

You've got the ground planes aligned correctly, that's good. Then you have to make the template as tall as the truck, then move it forwards or backwards until the highest point on the template (where the arrow is) lines up with where you start your teardrop shape. Assuming you won't be using a sawzall, that's the end of the cab.

Then look up a top view of the truck, make the template + its reflection just as wide as the truck, and align the arrow with the back of the cab.

And yep, the 20, 30, etc is % of its length. If you get to 70%, you're going to have a drag coefficient that would be respectable for a car. Yep, trucks have terrible aerodynamics.

  Reply With Quote
Reply  Post New Thread


Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Maximum angle for boat tail? abcdpeterson Aerodynamics 80 11-03-2021 12:55 PM
Aerodynamic Streamlining Template Part-B aerohead Aerodynamics 8 05-31-2013 12:23 PM
LED Headlight captainslug DIY / How-to 82 11-15-2011 01:32 AM
Aerodynamic Streamlining Template: Part-A aerohead Aerodynamics 0 07-18-2009 02:37 PM
All items I scanned in the new product showcase dremd The Lounge 0 11-08-2008 04:14 PM



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