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

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 06-11-2011, 05:02 PM   #11 (permalink)
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 12,358
Thanks: 19,873
Thanked 6,200 Times in 3,825 Posts
Sae

Quote:
Originally Posted by KamperBob View Post
In Hucho 4th Ed 1998 page 204 is figure 4.101 showing the corner radius effect work of D.M. Waters 1969. The same figure in German appears in Peschke & Mankau 1982 which is available as a Google Book.



Waters' work was based on a (camper) trailer (my area of interest) towed behind a car so the flow field conditions are not quite the same as a bus but I see a feature worth noting. The solid curve shows marginal diminishing return from nose rounding. The dashed curve shows much more dramatic improvement for a rectangular block with all corners radiused not just the front. I'd love to sink my teeth into Water's original paper.

Meanwhile, the rounded rump of a vintage bus seems pretty beneficial. A lot of Airstream trailers and other brands benefit from a similar shape by all accounts I have found (mostly owner reports comparing rounded to boxy units).
SAE Transactions,Volume 70,1962: General Motor's Chevrolet Truck Division did similar research.
*The 'oval',a 56-inch radius on a semi-trailer COE tractor had lowest drag,@ ---------------------------------Cd 0.547.
* 18-inch radius on same tractor= Cd 0.562
* 12-inch radius ---------------- Cd 0.562
* 6-inch radius------------------ Cd 0.725
* 45-degree chamfer------------ Cd 0.74
* square leading edges---------- Cd 0.88

  Reply With Quote
The Following 2 Users Say Thank You to aerohead For This Useful Post:
skyking (07-16-2011), slowmover (06-11-2011)
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 07-16-2011, 01:48 PM   #12 (permalink)
Master EcoModder
 
skyking's Avatar
 
Join Date: Apr 2011
Location: Tacoma WA
Posts: 1,365

Woody - '96 Dodge Ram 2500 SLT
Team Cummins
90 day: 23.82 mpg (US)

Avion and Woody - '96 Dodge/Avion Ram 2500/5th wheel combo
90 day: 15.1 mpg (US)

TD eye eye eye - '03 Volkswagen Beetle GLS
90 day: 49.05 mpg (US)

Mule - '07 Dodge Ram 3500 ST
Thanks: 708
Thanked 500 Times in 326 Posts
I've got a large travel trailer design in my head keeping me awake at night
I have 12" radii on the side/top joint to maximize volume and facilitate the pop up system, but the aft part will be able to follow the "template" perfectly. Thanks for this.
__________________




2007 Dodge Ram 3500 SRW 4x4 with 6MT
2003 TDI Beetle
2002 TDI Beetle

currently parked - 1996 Dodge 2500 Cummins Turbodiesel
Custom cab, auto, 3.55 gears
  Reply With Quote
Old 07-16-2011, 03:13 PM   #13 (permalink)
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 12,358
Thanks: 19,873
Thanked 6,200 Times in 3,825 Posts
aft part

Quote:
Originally Posted by skyking View Post
I've got a large travel trailer design in my head keeping me awake at night
I have 12" radii on the side/top joint to maximize volume and facilitate the pop up system, but the aft part will be able to follow the "template" perfectly. Thanks for this.
The $50,000 Bowlus 'Papoose' will have some company!
  Reply With Quote
Old 07-16-2011, 03:15 PM   #14 (permalink)
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 12,358
Thanks: 19,873
Thanked 6,200 Times in 3,825 Posts
GOOGLE IMAGES: Civis bus

This is worth checking out if you haven't seen it.
  Reply With Quote
Old 07-16-2011, 04:40 PM   #15 (permalink)
Master EcoModder
 
skyking's Avatar
 
Join Date: Apr 2011
Location: Tacoma WA
Posts: 1,365

Woody - '96 Dodge Ram 2500 SLT
Team Cummins
90 day: 23.82 mpg (US)

Avion and Woody - '96 Dodge/Avion Ram 2500/5th wheel combo
90 day: 15.1 mpg (US)

TD eye eye eye - '03 Volkswagen Beetle GLS
90 day: 49.05 mpg (US)

Mule - '07 Dodge Ram 3500 ST
Thanks: 708
Thanked 500 Times in 326 Posts
Thanks! My design has 5'9" headroom at the outside corners with the top lowered, and an 18" screw jack lift for the whole trailer roof. That makes for some nice headroom but keeps the highest point at 7'6" high when collapsed. You can still go in and use it when the roof is down, just a little crouched. I'll pick up the template station 0 at about 15' from the aft end, and the trailer would end at station 60. It scales off a ~35" drop over those stations, so outside height would go from 90" to ~55".
The trailer lower edges would go from 12" to 20" above the ground, and the sides would taper in from 8' to 6'.
Imagine a 3' by 6' oval spaceship arse end!

__________________




2007 Dodge Ram 3500 SRW 4x4 with 6MT
2003 TDI Beetle
2002 TDI Beetle

currently parked - 1996 Dodge 2500 Cummins Turbodiesel
Custom cab, auto, 3.55 gears
  Reply With Quote
The Following 2 Users Say Thank You to skyking For This Useful Post:
adriann (04-25-2012), aerohead (07-16-2011)
Reply  Post New Thread


Thread Tools




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