Go Back   iRV2 Forums > MOTORHOME FORUMS > Class C Motorhome Discussions
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
 
Thread Tools Search this Thread Display Modes
 
Old 06-16-2015, 08:44 PM   #1
Member
 
Ford Super Duty Owner
Join Date: May 2014
Posts: 49
Class C Aerodynamics

I have looked at airtabs to add to my 2007 Jayco 31SS. I don't think it would improve gas mileage much but might help handling in wind. Conceptually, eliminating or reducing drag makes sense when travelling over 45 mph. Wondering if other class c owners have them installed.

Also, my suv has an air dam over the rear window. Theoretically, this helps keep the back cleaner. Is should also help reduce drag. Would that work on a class c? I know there are a lot of smart experienced people on the forum. Does someone have a thought on this? Thanks, Larry
__________________

__________________
ledoylefcco is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 06-16-2015, 09:00 PM   #2
Senior Member
 
Ford Super Duty Owner
Join Date: Apr 2012
Location: Austin, TX
Posts: 1,885
Larry, I had an 05 Granite Ridge, which is basically the same model. It's pretty tall for a class-C and had great basement storage. However, short of cutting the thing down to a B+, I don't know how much various do-dads are going to do for aerodynamics. I just kept it at 65...

What I don't know about the V10 is at what point they start getting better mileage in terms of cutting them down and making them more aerodynamic like a Class-B+ or actually shortening them up and removing the weight...
__________________

__________________
cb1000rider is offline   Reply With Quote
Old 06-16-2015, 11:13 PM   #3
Senior Member
 
Join Date: Jun 2010
Location: Anacortes, WA (Stick & Brick)
Posts: 2,623
There is no way to make one of our dearly-loved big boxes "aerodynamic". Even if it were possible, the cost would be outrageous. Just accept 8 mpg and enjoy the lifestyle.

Cutting down on how much stuff you carry might make a difference (maybe 0.2 mpg) or keeping your foot off the gas pedal a bit might do a bit more.

If gas consumption is a major issue, maybe the RV lifestyle isn't for you.
__________________
Frank Damp -Anacortes, WA,(DW- Eileen)
ex-pat Brits (1968) and ex-RVers.
frankdamp is offline   Reply With Quote
Old 06-17-2015, 05:23 AM   #4
Senior Member
 
Join Date: Jun 2013
Location: Calabash, NC
Posts: 123
in my two years with that engine on a BT Cruiser, 24', there makes little difference between going 50 or 55 or 60 or 65, loaded or unloaded, 10 mpg is about it. We never did any mountain climbing but would expect 8 mpg based on past experiences.
__________________
Dan_Johnston is offline   Reply With Quote
Old 06-17-2015, 08:45 AM   #5
Senior Member
 
Join Date: Jun 2015
Location: The hilly part of Texas
Posts: 355
Probably would not make a statistical difference in MPG unless you are driving 100s of thousands a year. Reduced idling, Moderate acceleration & speeds, trailing throttle and coasting as much as possible may make a small improvement. I.E., drive it like a hybrid.

Not much you can do to improve the aerodynamics of a shed.
__________________
Old Crows is online now   Reply With Quote
Old 06-21-2015, 11:03 PM   #6
Senior Member
 
Dan Wong's Avatar
 
Fleetwood Owners Club
Join Date: Nov 2013
Location: phoenix, Arizona
Posts: 124
Send a message via AIM to Dan Wong Send a message via Yahoo to Dan Wong
I agreed with what everyone said above.

I would like to know; has anyone done any statistical comparison between old style (boxy) V.S. new modern curvy style? (aerodynamically speaking)
__________________
Dan Wong is offline   Reply With Quote
Old 06-22-2015, 08:48 AM   #7
Senior Member - DIYer
 
Waiter21's Avatar


 
Ford Super Duty Owner
Join Date: Nov 2014
Location: NW Ohio
Posts: 3,366
I wouldn't spend my money on them.

The airflow problem exist in the back end. Basically, you have a square parachute that 6 ft wide by 8 ft tall.

If you could fill that area with something, i.e. air, or solid, that would significantly reduce the drag associated with the trailing edge (back end).

You may see many 18 wheeler trailers with the new flap things that open up on the back of the trailers. PERFECT (well almost), They do reduce the back end drag area by about 1/2.
__________________
1999 Fleetwood Southwind 35S (Ford F53 6.8L V10) - Toad 2003 Saturn Vue.
(www.1999Southwind.com)

It won't do MACH 2, but I can get a sandwich and take a pee.
Waiter21 is offline   Reply With Quote
Old 06-23-2015, 05:27 PM   #8
Senior Member
 
Join Date: Jun 2015
Location: The hilly part of Texas
Posts: 355
Quote:
Originally Posted by Dan Wong View Post
I agreed with what everyone said above.

I would like to know; has anyone done any statistical comparison between old style (boxy) V.S. new modern curvy style? (aerodynamically speaking)
Dont know of any studies on RVs. Lots on box trucks and semis.


What Waiter said... About the only practical and cost effective changes would be to wide radius the square edge corners (top and sides) to "fool" the airflow into smoothly turning into the the reduced pressure area. Even a small radius is better than a 90* corner. What you look for on a new RV.

I've toyed with the idea of a "diffuser" under the rear end. Some work to smooth the turbulent air flow and to reenergize it while directing it upward toward the low pressure area behind the RV.

Probably would not significantly reduce drag compared to just reducing your speed.

Removing the "elephant ear" mirrors would be make the biggest reduction in the front. Illegal, of course until video cameras become do.

Reducing the front openings to the engine compartment and venting engine compartment to front wheel wells to draw high pressure air from engine compartment into the low pressure wells.

We're talking tiny percentages of improvement. Again slowing down is the biggest, cheapest, most effective tool in the long haul.

For sure...the "school solution" to keeping the rear end clean by installing a skirt under the rear end is not good. It will greatly increase the drag.
__________________
Old Crows is online now   Reply With Quote
Old 06-24-2015, 01:28 PM   #9
Member
 
Ford Super Duty Owner
Join Date: May 2014
Posts: 49
Great discussion. Any more ideas? What about a delector at the top like some SUV'S have? It would not be expensive but would it help?
__________________
ledoylefcco is offline   Reply With Quote
Old 06-24-2015, 04:19 PM   #10
Member
 
Ford Super Duty Owner
Join Date: May 2014
Posts: 49
yyo kok knnef c un dfi hnz
__________________
ledoylefcco is offline   Reply With Quote
Old 06-25-2015, 08:12 AM   #11
Senior Member
 
Join Date: Jun 2015
Location: The hilly part of Texas
Posts: 355
Quote:
Originally Posted by ledoylefcco View Post
Great discussion. Any more ideas? What about a delector at the top like some SUV'S have? It would not be expensive but would it help?
A "deflector" kicking the air upward would not be helpful as it would make the air "think" the rear was taller than it is and, depending on size, add downforce to the rear of the RV which is already heavy. The taller and wider the "deflector" the more aero drag ... meaning more power and fuel burn. Look at a Formula 1 car. Big, fat rear wing with big fat end plates to stick the rear wheels to the ground. Drag is huge... And they use a "drag reduction system" built into the wing that can be opened under certain conditions to enable a passing speed differential for the passing car.


What might work would be subtle "turning vanes" (top & sides) that would smooth the airflow into a laminar flow and reduce turbulence without increasing drag. You want the air to "think" the box is not a box but a gently sloped incline extending many feet behind the box and join again with its mates from both sides smoothly and gently. The laminar airflow essentially becoming extended sides & top of the RV..... (Google Kamm Back) this is why drag reduction systems on semis age growing tail feathers! Look,at the shape and envision the air flow coned down to a smaller, less draggy, square shape.


There are really not good solutions...
__________________
Old Crows is online now   Reply With Quote
Old 06-25-2015, 10:20 AM   #12
Senior Member
 
Timon's Avatar
 
Join Date: Jul 2014
Location: Tustin, CA
Posts: 981
Isn't that basically what the AirTabs do? I agree they are not the most wonderful looking, better if you paint them to match the coach, but they do work. Maybe not as much as one would like but something is better than nothing. As far as the toad I think you'd just have to depend on it's aerodynamics.

One other side benefit is they keep the back of your coach cleaner
__________________
John (N6BER), Joyce, Lucas (Golden Retriever mix), Bella (Great Pyrenees) and Lance (Great Pyrenees).
Tustin, CA
Timon is offline   Reply With Quote
Old 06-25-2015, 01:55 PM   #13
Senior Member
 
Join Date: Jun 2010
Location: Anacortes, WA (Stick & Brick)
Posts: 2,623
A toad can help some by breaking up the big low-pressure bubble behind the back wall. A neighbor with a 43' DP says he gets about 1 mpg better when he tows his boat and trailer than when he just takes the RV out.
__________________
Frank Damp -Anacortes, WA,(DW- Eileen)
ex-pat Brits (1968) and ex-RVers.
frankdamp is offline   Reply With Quote
Old 06-25-2015, 02:17 PM   #14
Senior Member
 
Dan Wong's Avatar
 
Fleetwood Owners Club
Join Date: Nov 2013
Location: phoenix, Arizona
Posts: 124
Send a message via AIM to Dan Wong Send a message via Yahoo to Dan Wong
Quote:
Originally Posted by frankdamp View Post
A toad can help some by breaking up the big low-pressure bubble behind the back wall. A neighbor with a 43' DP says he gets about 1 mpg better when he tows his boat and trailer than when he just takes the RV out.
Great posting. It answered my nagging question.
Years ago; I pull a utility trailer and sometimes my boat behind my service van.
I found that that MPG is nearly the identical; with or without the trailer. Never did figure out "why", but I think you just answered my "why".
__________________

__________________
Dan Wong is offline   Reply With Quote
Reply

Tags
class c



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Texas Class A Exempt (Non Commercial) License Requirements C130 Trailer Towing and Tow Vehicles Discussion 47 12-21-2016 09:12 PM
Class A DP or Gas Bunkhouse with 2 pocket doors? peteavery247 Class A Motorhome Discussions 10 07-20-2015 10:09 AM
I am Torn Between Class A Gasser and Class C NerdyNomad MH-General Discussions & Problems 41 06-16-2014 07:33 AM
RV of the Year Awarded to Thor Motor Coach Class A RUV Motorhomes DriVer RV Industry Press 0 12-12-2013 01:00 PM

» Virginia Campgrounds

Reviews provided by


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 09:59 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.