Reply
 
Thread Tools Search this Thread Display Modes
 
Old 08-20-2004, 05:29 PM   #57
Moderator
 
jcanavera's Avatar

 
2004 30' Classic Slideout
Fenton , Missouri
Join Date: Mar 2002
Posts: 9,002
Images: 143
Send a message via AIM to jcanavera Send a message via Skype™ to jcanavera
I'm a little puzzled at this point also. I think there is a missing piece to the puzzle since I have seen other vehicles bearing white rooftops to reflect the sun. I can't believe that there isn't something else we should be looking at other than the temp of the metal itself.

I know my first outing with my new '01 Safari' pointed out something. We camped out in an open field, full sun in Hannibal Mo. in 100+ degree heat. Next to me was my 28' white SOB which had a 13,500 BTU Duo-Therm Brisk Air unit. My Safari was a 27' with a 13,500 Penguin. Both trailers had a curb side awning. Both had the same exact exposure. My SOB was extremely comfortable in the high 70's. The Safari was in the mid 80's and we were sweating. Power was checked and we each had the same voltage available.

The Penguin was checked once by my dealer and once at Jackson Center. Everything was found to be operating to specs. Bottom line I was told was my shiney trailer absorbed more heat than my white SOB. Obviously this led me to upgrade the air conditioner on my Classic to the 15,000 BTU unit.

So what are we missing here in this test?

Jack
__________________

__________________
Jack Canavera
STL Mo.
AIR #56
'04 Classic 30' S.O.,'03 GMC Savana 2500,'14 Honda CTX 700
jcanavera is offline   Reply With Quote
Old 08-20-2004, 06:26 PM   #58
Rivet Master
 
3Ms75Argosy's Avatar
 
1975 Argosy 26
1963 24' Tradewind
Seattle , Washington
Join Date: Aug 2002
Posts: 2,341
Images: 7
SOB vs. Airstream - maybe the fiberglass of the SOB doesn't transfer heat in as "well" as aluminum? That's my guess.
Marc
__________________

__________________
3Ms75Argosy is offline   Reply With Quote
Old 08-20-2004, 08:21 PM   #59
Rivet Master
 
1973 31' Sovereign
Portland , Oregon
Join Date: May 2004
Posts: 1,245
Images: 22
Some heat transfer information...

Determining the efficienciency of any wall construction/insulation combination is more complicated than just measuring the temperature of the skin in sunlight. Let me offer some information about heat transfer that I think is correct information:

Three types of heat transfer:

1.) Radiation (Infra-red) - heat transfer directly from one entity to another by means of direct energy transfer in the infra-red spectrum. A good example of this type of heat transfer is what happens to the skin of an AS sitting in the sun. The source of the heat is, of course, very far away. This type of energy will cause the skin of the AS to warm up depending on how much of the energy is absorbed vs. how much is reflected away. The principle reason that the plain aluminum in Andy's experiment does not rise in temerature as much as the aluminum with the other coatings is exactly because shiney aluminum is a better reflector than even the white surface.

2.) Conduction - energy transfer directly through a given material. Aluminum is a very good conductor and foam insulation is a very bad conductor. When you hear about the "R" value of a particular type of insulation this is referiing to the materials ability to transfer heat by convection. In the case of typical insulation materials you want the "R" value per inch of material to be as high as possible so that heat flows through the material as slowly as possible.

3.) Convection - heat tranfered from entity to another by means of the movement of air. The heat source warms the air and the warm air transfers some of its heat to the things it is in direct contact with. A good example of this type of heat transfer occurs between the hot air outside of an AS and the surface of the skin. Another good example is the type of heat transfer that occurs between the heating element in a typical AS heater and the air that flows through the heating ducts. The air is warmed and the things inside of the trailer that the warm air comes in contact are warmed.

Heat always transfers from hotter things to colder things:

Pretty much all of the objects around us are warm to one degree or another (pardon the pun). A warm object always trys to transfer energy to colder objects nearby. The sun is obviously a lot warmer than an AS so the flow of radiant energy is always from the sun to the AS during the daytime. Radiant energy transfer is by far the way that most heat transfers from one object to another. I have read statistics that indicate that 65% to 85% of the heat that passes from a warm wall surface to a cold wall surface or through an attic is by radiation.

Anatomy of an AS:

The factory original construction of an AS with regard to heat transfer works something like the following when it is hotter outside than inside:

1.) The reflective aluminum surface on the outside turns back a lot but not all of the radiant energy from the sun.

2.) The highly conduction aluminum surface of the AS conducts some heat from the warm air outside of the AS into the wall cavity and through the wall framing to the inner aluminum surface of the AS.

3.) The fiberglass insulation in the wall cavity resists the flow of heat by conduction through the wall cavity to the inner skin of the wall.

Why an SOB might be better insulated:

Other brands of trailers may very well be better insulated than the factory original AS is. While I do think that a polished alumuminum skin will do much better in the direct sun than a white fiberglass skin relative to reflecting radiant energy from the sun the story does not stop there. Here are some reasons the rest of the trailer might perform better:

1.) Fiberglass skins most likely do not conduct heat as readily as aluminum skins do.

2.) Many of the other brands have a wooden frame which also does not conduct heat as well as the aluminum frame on an AS.

3.) It is becomming increasingly common for other brands to use solid foam insulation instead of fiberglass hence better results.

4.) The roof framing of a typical SOB is usually thicker than te 1-1/2" we have on our AS's. Ther is more room for solid insulation in there.

5.) The inner skin of most other brands of trailers is typcially not aluminum. These other types of skins generally do not conduct heat as well as the aluminum skins of our AS's.

Possible changes and their effect:

1.) Any additional coating on the outside of the outer aluminum skin will help block the flow of heat by conduction to the wall cavity and to the frame members. Unfortunately it may also reduce the ability of the skin to reflect away radiant energy from the Sun as evidenced by Andy's test results. Rubber roof coating would block more heat flow by conduction than paint would both because it is thicker and probably has a higher R value.

2.) Any additional coating on the inside of the outer aluminum skin will also help reduce the flow of heat by conduction to the wall cavity but not so much to the frame members. Any vulkem between the body panels and the frame will help block heat flow to the frame. Rubber roof coating for example can help here. I think this explains why panel 4 in Andy's experiment is slightly hotter than panel 1. The extra coating prevents some of the heat from bleading off the bottom side of the aluminum panel into the foam insulation.

3.) Different types of solid insulation in the wall cavity can help reduce the flow of heat if they have a higher "R" value than fiberglass insulation does. Foam insulation, for example, has an "R" value in the neighborhood of about R4 to R7 per inch depending on the type of foam while fiberglass is more in the range of R3. This means that the R value for 1-1/2" of AS wall can be in the range of R5 to maybe R10 maximum.

4.) Using radiant foil insulation between the inner and the outer skins of the trailer instead of solid insulation can dramatically reduce the amount of radiant energy that still manages to transfer through the walls by radiation. Supossedly a single layer of rlective foil insulation spaced between the inner and the outer wall surfaces has an effective R value of R16. For more informaion about how foil insulation works check out the following site:

http://www.tvmi.com/rfoil/physics2.htm

I also wrote up some things about reflective foil insulation in the thread titled "What should I use to insulate the floor?".

The bottom line:

For tests about the relative merits of the different types of AS surface treatments (and insulation types) to be entrirely valid they must measure the amount of heat that actually gets all the way through the wall to the other side.

It is my intent to modify my AS as follows:

1.) Add a rubber roof coating to the inside of my outer skin while I have the inner skins off. I would really like to know how effective this would be at reducing the amount of heat flow from the outer surface to the inner surface. If Andy could put his heat gun on the bottom side of the test panels this might help me know that.

2.) Use reflective foil insulation in the walls and roof spaced between the skins so that there is an air gap on both sides of the reflective foil. I have in mind to use narrow strips of foam insulation around the edges to help center the foil in the middle of the cavity. I would really like to do a heat flow test on complete wall panels of different construction styles (orginal and with my modifications). I may very well put such a test together myself just so I can find out for sure if what I am proposing will work effectively.

Would anyone else interested in the results of such a test?

Malcolm
__________________
malconium is offline   Reply With Quote
Old 08-21-2004, 10:26 AM   #60
Moderator
 
jcanavera's Avatar

 
2004 30' Classic Slideout
Fenton , Missouri
Join Date: Mar 2002
Posts: 9,002
Images: 143
Send a message via AIM to jcanavera Send a message via Skype™ to jcanavera
Wow, great post Malcolm. That answers a lot of questions. My SOB did not have fiberglass walls and had an aluminum frame construction. I think the white rubber roof which covered a wood underlayment and the lack of metal inside walls accounts for a lot of the difference. The SOB by the way used batting for insulation.

Bottom line Airstream does provide an better line of insulation on their Limited models (as was told to me during my Jackson Center tour). I wonder if that could be requested on any trailer if you order a new build unit?

Secondly Duo-Therm finally has got a decent sized Penguin airconditioner unit available (15,000 BTU) as an option. Anyone ordering any Airstream 30' or more or needing an upgrade should consider taking this option.

Jack
__________________
Jack Canavera
STL Mo.
AIR #56
'04 Classic 30' S.O.,'03 GMC Savana 2500,'14 Honda CTX 700
jcanavera is offline   Reply With Quote
Old 08-21-2004, 11:36 PM   #61
Tom, the Uber Disney Fan
 
Minnie's Mate's Avatar
 
2006 30' Safari
Orlando , Florida
Join Date: Aug 2004
Posts: 4,693
Images: 7
Quote:
Originally Posted by mandolindave
I am surprized that the white was that much hotter too. Could it be that the
the reflection was adding to the temperature reading? I am wondering why
none of you tried the experiment with painted beer cans. ( just kidding )

P.S. Use the hot beer to boil hot dogs when you are finished ( to avoid
being accused of alcohol abuse ).
I'm no physisist or infrared thermographer, but I think mandolindave might have hit on the reason for the white having the high temperature but keeping the interior cooler. Airstream claims the white roof lowers the interior temperature by 7 degrees vs. mill finished aluminum. Infrared thermometers measure the radiant heat of an object by measuring the infrared heat being radiated or given off by that object. Since white reflects all light, including the light we cannot see, which includes the infrared spectrum, I believe the white paint is also reflecting the infrared heat of the sun and that it is being measured as part of the temperature the infrared thermometer "sees" on the white painted aluminum.

I know if you stand on a typical black built-up roof you get hot, but if you stand on a white PVC roof you get even hotter even though less heat is reaching into the interior of the building. The sun's heat is reflecting off of the roof and hitting you along with the direct sunlight from above so you get a compound heat effect. As far as the black rubber coating being cooler, you got me on that one!
__________________
Minnie's Mate is offline   Reply With Quote
Old 08-22-2004, 01:14 PM   #62
Rivet Master
Airstream Dealer
 
Inland RV Center, In's Avatar
 
Corona , California
Join Date: Feb 2002
Posts: 16,499
Images: 1
Further study

Who wants to further the study I started?

Surely, there must be someone that has different test instruments than I do.

At this point, I can't offer any more information than previously posted.

If someone, who has additional test equipment, wants to continue the study, please let me know and I will send you the metal plates that I used.

Andy
__________________
Inland RV Center, In is offline   Reply With Quote
Old 08-22-2004, 02:11 PM   #63
Rivet Master
 
pinkflamingoes's Avatar
 
1967 24' Tradewind
Alameda , California
Join Date: Feb 2004
Posts: 1,569
Images: 38
Blog Entries: 3
Send a message via AIM to pinkflamingoes Send a message via Yahoo to pinkflamingoes
This whole thread was worth the Partridge Family airstream alone! Thanks Bredlo!
__________________
"Let's look Death in the face and say, 'Whatever man.'"
~ Hurley

ingrid
1967 24' Tradewind #19104 ~ Forums #4449
pinkflamingoes is offline   Reply With Quote
Old 08-22-2004, 02:32 PM   #64
Rivet Master
 
1973 31' Sovereign
Portland , Oregon
Join Date: May 2004
Posts: 1,245
Images: 22
Different test is all that is needed...

Andy,

I don't think that additional test instrumentation is needed. I really think all that is needed is to measure the temperature from the back side using an infrared thermometer like what you already have. If you don't have the time to do that my offer earlier in this post still stands. If you will send me your panels and a little bit of the 2" fiberglass (I tossed out all of mine) I will do some additional testing. I found that I can buy an inexpensive infrared thermometer at radio shack that should be sufficient and I am willing to do that.

Here is what I am prepared to do:

1.) Create a ladder like framework to mount the panels on out of 2x lumber. I can easily support the framework on some saw horses. The 2x lumber will create wall cavities that are 1-1/2" thick like on an AS.

2.) Attach the test panels to the top of framework.

3.) Add fiberglass insulation to all of the panels between the 2x lumber to represent the correct AS wall thickness. Add plain aluminum to the bottom side to represent the interior of an AS.

4.) Put the whole assembly out in the sun and measure the temperature from the bottom side of the panels as though it was inside of the AS.

5.) Change all of the insulation in all of the panels to foil insulation and take the readings again.

6.) Publish my findings.

What do you think?

Malcolm
__________________
malconium is offline   Reply With Quote
Old 08-22-2004, 03:17 PM   #65
Rivet Master
Airstream Dealer
 
Inland RV Center, In's Avatar
 
Corona , California
Join Date: Feb 2002
Posts: 16,499
Images: 1
Malcomb.

They will be on their way, tomorrow, via UPS.

Same address as before?

Andy
__________________
Inland RV Center, In is offline   Reply With Quote
Old 08-22-2004, 04:57 PM   #66
2 Rivet Member
 
Join Date: Jan 2004
Posts: 52
Images: 5
RED, red red ! has anyone besides me ever thought about having the exterior of ther airstream engraved? ENGRAVED- scenes permanently scratched ( artisticly of course ) into the exterior ! angels , eagles , wolves and little deer frolicking ? mountains , praries ,deserts and of course an amber wave of grain ! just wondering, i guess paint would be easyier to remove if you didnt like it !
roger
__________________
roger n cindy is offline   Reply With Quote
Old 08-22-2004, 08:11 PM   #67
Rivet Master
 
norbert's Avatar
 
1993 30' Excella
chicagoland , north of cheddar curtain
Join Date: Jun 2003
Posts: 1,258
Images: 24
Quote:
Originally Posted by roger n cindy
RED, red red ! has anyone besides me ever thought about having the exterior of ther airstream engraved? ENGRAVED- scenes permanently scratched ( artisticly of course ) into the exterior ! angels , eagles , wolves and little deer frolicking ? mountains , praries ,deserts and of course an amber wave of grain ! just wondering, i guess paint would be easyier to remove if you didnt like it !
roger
only if you have teresa kerrys money....
__________________
Illegitimous noncarborundum(dont let the bastards wear you down)

The only true nobility is found through giving good food to your friends- Anton Careme

beauty is in the eye of the beerholder-cosmo fishhawk

if something is too good to be true, its usually gone before i get there-mister boffo
norbert is offline   Reply With Quote
Old 08-22-2004, 10:43 PM   #68
Rivet Master
 
Join Date: Mar 2004
Posts: 2,183
I have an Argosy Minuet that I need to paint sometime soon. I am going to try that PaintShop thing.
I do have to say that I have always been an Airstream purist. I have camped in nothing but Airstreams from the time I was born. My dad didn't even like the Argosys. When I would mention that I want one he would ask me why I wanted a an imitation Airstream.
Now you guys got me thinking! I was gonna paint it using the same DuPont Imron paint codes. Now I may change my mind!
Oh dear, what will happen when I join the WBCCI? I will have to be on the look-out for those scooters!
__________________
Anon is offline   Reply With Quote
Old 08-23-2004, 01:21 PM   #69
Rivet Master
 
1973 31' Sovereign
Portland , Oregon
Join Date: May 2004
Posts: 1,245
Images: 22
Same address...

Andy,

My address is the same as for my orders. Please be sure to include some of the 2" fiberglass if you would please. As I mentioned I don't have any on hand and the 2" stuffs seems a little hard to find around here.

Thanks,

Malcolm
__________________
malconium is offline   Reply With Quote
Old 08-23-2004, 07:53 PM   #70
Site Team
 
, Minnesota
Join Date: Aug 2003
Posts: 6,940
Images: 59
Malcolm,

I see a problem with your test protocol.

Step 4. . . . . where are you going to find sunshine in Portland?

LOL. I applaud you efforts to move forward the boundaries of Airstream technology.
__________________

__________________
markdoane is offline   Reply With Quote
Reply


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
Painting Walls of Bambi Marshall44 Upholstery, Blinds, Walls & Interior Finishes 13 04-19-2010 02:25 PM
Painting Airstream Roswell Clearcoat, Exterior Paint & Trim 14 09-01-2004 01:04 PM
Painting the Exterior of an A/S Navigator Clearcoat, Exterior Paint & Trim 25 08-06-2004 09:16 AM
Red plastic trim insert for 1978 International... drboyd Clearcoat, Exterior Paint & Trim 2 09-17-2003 01:47 PM
Red Planet in August COArgosy78 Our Community 6 08-10-2003 01:09 PM


Virginia Campgrounds

Reviews provided by




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 10:10 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.

Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.