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

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 08-08-2014, 01:05 AM   #1 (permalink)
EcoModding Lurker
 
Join Date: Aug 2012
Location: El Cerrito, CA
Posts: 76
Thanks: 3
Thanked 6 Times in 3 Posts
More aerodynamic class C sleeper? Angled roof?

So my new touring vehicle is bought, and I'm starting the planning on how to
eventually get it comfortable for me, and as aerodynamic as I can.

It's a 10ft box truck, single rear wheels, almost no additional width in the box more than the front van width. Single rear wheels . Curb weight unloaded 6k lbs.

I'm going to have to make myself a sleeper for it, because the box will be used to store my robots and gear when on tour. Not much room for living after it's loaded.

So my question is this.
I plan on raising the roof from the end of the windshield above the height of the original box roof, then taper that high point at an optimal angle and curve back to the rear (then have a fold up boat tail to continue the taper.

The q is regards to height? If it tapers back at a good angle, and the air doesn't hit a flat wall up front, will the added height cause me to raise FE much?
Just will have a lot of time to think about this, and want to do it right to gain me the most extra space without turning it into a class C sail. How high can I go?
I'll post a pic of what I'm thinking in a few minutes.

I'm already going to do side skirts and a front air dam and boat tail, it's mostly the top that I'm unsure of. I know the template shows it should be a rounded roof, that's not a problem. It's just the amount of roundness that I don't know. Thinking about using steel sheet metal and maybe conduit for framing on the roof and welding or brazing the seams to stop any leaks.

So has anyone fooled with big vehicles like this from a roof modding perspective? Would there be a substantial difference if I stayed flat roof but tapered to the rear rather than curved?

Oh my brain....

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 08-08-2014, 01:31 AM   #2 (permalink)
EcoModding Lurker
 
Join Date: Aug 2012
Location: El Cerrito, CA
Posts: 76
Thanks: 3
Thanked 6 Times in 3 Posts
Kind of like this additional area I added.
Attached Thumbnails
Click image for larger version

Name:	image.jpg
Views:	105
Size:	42.8 KB
ID:	15510  
  Reply With Quote
Old 08-08-2014, 01:34 AM   #3 (permalink)
EcoModding Lurker
 
Join Date: Aug 2012
Location: El Cerrito, CA
Posts: 76
Thanks: 3
Thanked 6 Times in 3 Posts
Or would there be a way to extend something off the front and still have it be somewhat aero....maybe a wedge like those newer trailers?
  Reply With Quote
Old 08-08-2014, 05:52 PM   #4 (permalink)
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 11,087
Thanks: 17,532
Thanked 5,916 Times in 3,585 Posts
roof

*Hucho's recommendation is to never do anything to add frontal area.
*The added frontal area adds drag arithmetically.
*If you add 10% frontal area,your drag increases 10%,all else being equal.
--------------------------------------------------------------------------
*Don Bur,in the UK has been able to add frontal area to create roof camber on his '18-wheelers' ,and realize a net drag reduction.
*If you're absolutely committed to the roof addition,you should study their work closely.
http://www.fdcholdings.co.uk/wp-cont...rop-tunnel.jpg
--------------------------------------------------------------------------
*Having roof camber,without side camber is a setup for creation of vortices if not integrated perfectly.
--------------------------------------------------------------------------
Also,you owe your self a look at 'NOSECONE' fairings.These are undisputedly the best solution for the front of the box.Truck salvage yards might provide you with a used one which would fit the truck.I worked for a local moving company and we added a nosecone to a 35-ft, Ford chassis,gasoline-powered, moving van and realized 8-mpg with it.Something otherwise impossible without it.
-------------------------------------------------------------------------
I've been working on commercial vehicle stuff during the heat of the day and will try and post some truck aero stuff Saturday (tomorrow).
If you haven't seen the NASA truck aero link yet,check it out.It's way out ahead of nothing.
__________________
Photobucket album: http://s1271.photobucket.com/albums/jj622/aerohead2/

Last edited by aerohead; 08-08-2014 at 06:17 PM.. Reason: add link
  Reply With Quote
Old 08-08-2014, 05:55 PM   #5 (permalink)
I got ideas
 
Join Date: Aug 2014
Location: Georgia, United States
Posts: 115

Beast - '97 Mercury Mountaineer
Thanks: 29
Thanked 23 Times in 15 Posts
If you mean a wedge off the front of the box (above the cab and not connected to it), then I would assume that would lead to a lot of wind resistance if not done correctly. It's an issue that overland and expedition guys face when building their campers. And if those DIY guys notice an issue, with their blatant disregard for FE, then I can only assume it most be bad I would think raising the roof of the cab idea would be better. Then again, I might be misunderstanding what you are referring to by "wedge".

Also, I can't tell in the photo... But if the cab isn't attached to the box, and you create this high cab extension that is molded the length of the box, you are in for some serious issues due to body/frame flex. You might be even if the cab is already attached. I know this is a consideration/issue when designing campers/RV's on medium and light duty trucks. I'm not an expert on ANY of this though.

~C
  Reply With Quote
Old 08-08-2014, 06:39 PM   #6 (permalink)
Master EcoModder
 
jedi_sol's Avatar
 
Join Date: Mar 2009
Location: Tustin, CA
Posts: 929

2013 STi *SOLD* - '13 Subaru Impreza WRX STi
Subaru
Sports Cars
Team Turbocharged!
90 day: 26.59 mpg (US)

1996 Geo Metro *RETIRED from Ecomodding* - '96 Geo Metro Base
90 day: 58.68 mpg (US)
Thanks: 368
Thanked 378 Times in 236 Posts
http://ecomodder.com/forum/showthrea...ics-29659.html
__________________







See the rest of the Sti project log:
http://ecomodder.com/forum/showthrea...log-26612.html
  Reply With Quote
The Following 2 Users Say Thank You to jedi_sol For This Useful Post:
aerohead (08-09-2014), chillsworld (08-09-2014)
Old 08-08-2014, 09:44 PM   #7 (permalink)
I got ideas
 
Join Date: Aug 2014
Location: Georgia, United States
Posts: 115

Beast - '97 Mercury Mountaineer
Thanks: 29
Thanked 23 Times in 15 Posts
Aerohead, that stuff by Don Bur is phenomenal! I had never seen his work before.


capturedbyrobots, I was sitting here watching netflix and I was wondering if it wouldn't perhaps be easier to build on to the rear of the box as opposed to building up for a sleeper birth. Rather than adding frontal mass, use the idea of the tear drop shape to build an aero unit on the back to hold a bunk and your personal gear. Figures below, design 1 and 2, from the NASA link provided by jedi_sol. Design of the sleeping quarters would be dependent upon the adoption of egg or aero back... Then it would be a simple matter of accounting for the space above the cab from an aero standpoint rather than the addition of space standpoint. One could heat/cool the whole box since it's small, or simply control the back add on. The unit could hinge, allowing it to swing out of the way for loading and unloading. Or one could cut a door in the side of the box allowing the rear unit to be more permanent and allow for easier design and installation.

One need only look to small teardrop campers and overland/expedition resources for ideas on small and efficient sleeping quarters. Better yet, boat design!

~C

Design 1:


Design 2:
  Reply With Quote
The Following User Says Thank You to chillsworld For This Useful Post:
aerohead (08-09-2014)
Old 08-08-2014, 10:35 PM   #8 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 15,832
Thanks: 4,127
Thanked 5,294 Times in 4,215 Posts
Embrace the box—and then think outside it. These exist, or you could make your own.



As chillsworld, says, boattail it. Here's a sketch I did for my VW van. It has a vertical tail in the back and an horizontal wedge in the front to lower tha stagnation point.



You could hinge the tail at the top and have power jacks. Then it would open up into an 8' long Gothic roof over a fold-down floor section.
  Reply With Quote
The Following 3 Users Say Thank You to freebeard For This Useful Post:
aerohead (08-09-2014), Cd (08-09-2014), chillsworld (08-09-2014)
Old 08-08-2014, 11:09 PM   #9 (permalink)
Cyborg ECU
 
California98Civic's Avatar
 
Join Date: Mar 2011
Location: Coastal Southern California
Posts: 5,610

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: 2,068
Thanked 1,773 Times in 1,202 Posts
Quote:
Originally Posted by capturedbyrobots View Post
Kind of like this additional area I added.
That seems like it will add a lot more frontal area than it is worth. Tapering is a good idea. Rear wheel well covers would be good too. And there are many other suggestions in the links jedi-sol provided via aerohead.
__________________


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 (08-09-2014)
Old 08-08-2014, 11:10 PM   #10 (permalink)
Master EcoModder
 
skyking's Avatar
 
Join Date: Apr 2011
Location: Tacoma WA
Posts: 1,295

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: 603
Thanked 468 Times in 303 Posts
The money is all in the tail. Add a foldable tail and you will get the most gain possible.

__________________




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 User Says Thank You to skyking For This Useful Post:
Cd (08-09-2014)
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