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12-18-2007, 03:08 PM
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#1
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3 Rivet Member
1968 26' Overlander
Ann Arbor
, Michigan
Join Date: Oct 2007
Posts: 117
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68 Overlander Restoration/Mod
Hey All. I am about knee deep in my restoration/modification project.
Today, I have taken off the streetside interior panel.
I dont understand what I see.
First...I thought that when I saw the main ribs of the inside that the full end would be sitting in the c chanel...it is not. It looks to be cut to a 45 degree angle and the only side that is in the chanel so to speak is the on facing the exterior skin.
Second...I removed the furnace and it looks like one of the ribs were cut to install the furnace.
It also looks like the cross bars do not connect to the main ribs.
The windows dont seem to be attatched to the main ribs either...I could not tell because I did not go that far up the wall.
The C Chanel does not connect
The "insulation" is taped in place
What gives?
With all this said...where does the structure come from.
It seems solid, but when I took the panel off...I can wiggle the main ribs a bit.
Is this normal?
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12-18-2007, 03:37 PM
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#2
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Rivet Master
1971 21' Globetrotter
Currently Looking...
Currently Looking...
Currently Looking...
Arvada
, Colorado
Join Date: May 2006
Posts: 3,530
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Yep, thats how they are made. Mine frame to "C" channel WAS that way at first, they are tied together now. I,m still working on the stringer to frame attachments
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12-18-2007, 03:43 PM
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#3
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3 Rivet Member
1968 26' Overlander
Ann Arbor
, Michigan
Join Date: Oct 2007
Posts: 117
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So where does the strength come form? Is the All Clad aluminum structural aluminum?
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12-18-2007, 03:44 PM
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#4
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3 Rivet Member
1968 26' Overlander
Ann Arbor
, Michigan
Join Date: Oct 2007
Posts: 117
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Quote:
Originally Posted by Aerowood
Yep, thats how they are made. Mine frame to "C" channel WAS that way at first, they are tied together now. I,m still working on the stringer to frame attachments
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Is that the original aluminum beam you have anchored?
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12-18-2007, 03:45 PM
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#5
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Retired.
Currently Looking...
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, At Large
Join Date: Jun 2003
Posts: 21,276
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Basically, all the parts work together as a unit that is strong, but will flex with movement and expansion and contraction from heat and cold. If you make it too stiff, you will do more harm than good.
__________________
Meddle not in the affairs of dragons, for you are crunchy, and taste good with ketchup.
Terry
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12-18-2007, 03:50 PM
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#6
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Rivet Master
1967 26' Overlander
Huntsville
, Alabama
Join Date: Dec 2003
Posts: 3,018
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Quote:
Originally Posted by Aluminati
So where does the strength come form? ...
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Terry made a good post.
If you want more detail, Google keywords "unibody", "monocoque", and "semi-monocoque". An Airstream utilizes "semi-monocoque" construction.
Tom
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12-18-2007, 04:11 PM
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#7
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Rivet Master
1967 28' Ambassador
1963 19' Globetrotter
1970 29' Ambassador
Waukesha
, Wisconsin
Join Date: May 2007
Posts: 1,180
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The strength comes from the skins. The ribs are only there to hold the two skins in relation to each other. You do not want to create a point load at the ribs because that will transfer a point load to the skin. The system relies on the loads being spread over a large area. Point loads will cause rivet pops and tearing of the skins.
Just focus on repairing what is broken. The system has been proven by a half century trailers. Damage is normally caused by inadequate maintenance... as Inland Andy has pointed out many times.
Happy to see you are into the "fun" part!
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12-18-2007, 04:53 PM
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#8
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Rivet Master
1971 21' Globetrotter
Currently Looking...
Currently Looking...
Currently Looking...
Arvada
, Colorado
Join Date: May 2006
Posts: 3,530
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Quote:
Originally Posted by Aluminati
Is that the original aluminum beam you have anchored?
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Yes that is the original frame that is now tied to the "C" channel. The channel was attached with pop rivets on the flanges of the frame but all the original rivets had failed some time in the past. Attaching the stringers to the frames will not cause the shell to become any stiffer or cause any point loads. There are more point loads now in the structure at the first and last rivet in each stringer then there will be with the stringers attached to the frame. The shell and frame work will still have the ability to flex plus giving the AS a more true semi-monocoque structure. The Airstream construction as from the factory is more of a reinforced shell then a true semi-monocoque structure.
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12-18-2007, 06:29 PM
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#9
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3 Rivet Member
1968 26' Overlander
Ann Arbor
, Michigan
Join Date: Oct 2007
Posts: 117
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Quote:
Originally Posted by Aerowood
Yes that is the original frame that is now tied to the "C" channel. The channel was attached with pop rivets on the flanges of the frame but all the original rivets had failed some time in the past. Attaching the stringers to the frames will not cause the shell to become any stiffer or cause any point loads. There are more point loads now in the structure at the first and last rivet in each stringer then there will be with the stringers attached to the frame. The shell and frame work will still have the ability to flex plus giving the AS a more true semi-monocoque structure. The Airstream construction as from the factory is more of a reinforced shell then a true semi-monocoque structure.
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Stringers Point Loads O.K...please slow down...This is all new terminology for me. What by gum is a stringer and a point load. Looking at it from the outside...it looks like the window is riveted to the rib...at least I thought...is this correct. I searched for simi-monocoque but did not find anything...I will search again. Sorry for sounding like a dimwit but I am only familiar with beams, crossmembers. I have built a few residential walls, so it just threw me off when I pull the panel back and saw what I saw.
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12-18-2007, 06:33 PM
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#10
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3 Rivet Member
1968 26' Overlander
Ann Arbor
, Michigan
Join Date: Oct 2007
Posts: 117
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...and I cant believe that they "taped" the isulation in place...
So if ai am understanding you correctly...the outter skin is where alot of the strength comes from. If that is true then wow...my hat's off to the guys who built this thing and that it has lasted so long.
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12-18-2007, 06:36 PM
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#11
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3 Rivet Member
1968 26' Overlander
Ann Arbor
, Michigan
Join Date: Oct 2007
Posts: 117
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Quote:
Originally Posted by Aerowood
Yep, thats how they are made. Mine frame to "C" channel WAS that way at first, they are tied together now. I,m still working on the stringer to frame attachments
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Your floor looks great...what did you treat it with?
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12-18-2007, 06:39 PM
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#12
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3 Rivet Member
1968 26' Overlander
Ann Arbor
, Michigan
Join Date: Oct 2007
Posts: 117
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Quote:
Originally Posted by TomW
Terry made a good post.
If you want more detail, Google keywords "unibody", "monocoque", and "semi-monocoque". An Airstream utilizes "semi-monocoque" construction.
Tom
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Sorry...My brain popped a bad rivet...you said Google the keywords. Me getting is bass ackwards just searched thoes words at this site.
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12-18-2007, 06:42 PM
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#13
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3 Rivet Member
1968 26' Overlander
Ann Arbor
, Michigan
Join Date: Oct 2007
Posts: 117
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Missing Rivet
Can water come through a hole where a rivet used to be...on the side of the trailer. I remember seeing some water track marks from a location on the side of the trailer. There is a rivet missing.
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12-18-2007, 06:42 PM
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#14
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Retired.
Currently Looking...
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, At Large
Join Date: Jun 2003
Posts: 21,276
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Quote:
Originally Posted by Aluminati
Stringers Point Loads O.K...please slow down...This is all new terminology for me. What by gum is a stringer and a point load. Looking at it from the outside...it looks like the window is riveted to the rib...at least I thought...is this correct. I searched for simi-monocoque but did not find anything...I will search again. Sorry for sounding like a dimwit but I am only familiar with beams, crossmembers. I have built a few residential walls, so it just threw me off when I pull the panel back and saw what I saw.
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Stringers are analogous to crossmembers, they extend out to the bow (another term) and support them through the floor. Bows are the vertical crossmembers that start at the floor, and go up to the center. And yes, the insulation is taped in place, otherwise it would fall down the inverted curve to the ceiling.
__________________
Meddle not in the affairs of dragons, for you are crunchy, and taste good with ketchup.
Terry
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12-18-2007, 06:57 PM
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#15
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3 Rivet Member
1968 26' Overlander
Ann Arbor
, Michigan
Join Date: Oct 2007
Posts: 117
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Quote:
Originally Posted by overlander63
Stringers are analogous to crossmembers, they extend out to the bow (another term) and support them through the floor. Bows are the vertical crossmembers that start at the floor, and go up to the center. And yes, the insulation is taped in place, otherwise it would fall down the inverted curve to the ceiling.
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So the ribs that I am seeing are what is called formers ( forming the basic shape of the AS)...in Semimonocoque terms? and the crossmembers that are horizontal are stringers?
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12-18-2007, 06:58 PM
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#16
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a.k.a. Ambassador Tim
1960 28' Ambassador
Northern
, California
Join Date: Jun 2003
Posts: 1,921
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Shameless plug.
We talked about Airstream construction a long time ago on theVAP.
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12-18-2007, 06:59 PM
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#17
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Retired.
Currently Looking...
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, At Large
Join Date: Jun 2003
Posts: 21,276
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Quote:
Originally Posted by Aluminati
So the ribs that I am seeing are what is called formers ( forming the basic shape of the AS)...in Semimonocoque terms? and the crossmembers that are horizontal are stringers?
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Yes.
__________________
Meddle not in the affairs of dragons, for you are crunchy, and taste good with ketchup.
Terry
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12-18-2007, 07:50 PM
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#18
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Rivet Master
1971 21' Globetrotter
Currently Looking...
Currently Looking...
Currently Looking...
Arvada
, Colorado
Join Date: May 2006
Posts: 3,530
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Quote:
Originally Posted by Aluminati
Your floor looks great...what did you treat it with?
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I had several partial cans of poly that I mixed all together. semi gloss ,satin, gloss, indoor, outdoor. some tinted maple, you name it , it all went into a large can and I squeegeed it on,three coats worth. After everything is done I will most likely put some epoxy down that I have.
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12-18-2007, 07:53 PM
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#19
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Rivet Master
1971 21' Globetrotter
Currently Looking...
Currently Looking...
Currently Looking...
Arvada
, Colorado
Join Date: May 2006
Posts: 3,530
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Quote:
Originally Posted by Aluminati
Can water come through a hole where a rivet used to be...on the side of the trailer. I remember seeing some water track marks from a location on the side of the trailer. There is a rivet missing.
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Yes
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12-18-2007, 08:46 PM
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#20
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Rivet Master
1967 28' Ambassador
1963 19' Globetrotter
1970 29' Ambassador
Waukesha
, Wisconsin
Join Date: May 2007
Posts: 1,180
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Quote:
Originally Posted by Aerowood
Attaching the stringers to the frames will not cause the shell to become any stiffer or cause any point loads.
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True... but bearing the rib on the "C" channel/floor will. There is a reason they stop the ribs above the floor.
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