[VAC] Re: Windows and metal fatigue

["Wayne A. Moore" <wam52@xxxxxxxxxxx>]

Hey Chris,
    I hate to tell you, that what you see is what you get inside all
Airstreams of that vintage. The only full ribs from one side to the other
are the ones at the edges of the front and rear curved end caps. All the
rest are half ribs. The main carrying members are the two aluminum channels
that extend the length of the straight section of the trailer. These are
usually reinforced between the Hehr Vents with scrap sheets of exterior
shell Aluminum 2024T3 or 2030T3 prior to the installation of the interior
panels.
    I have a 61 Flying Cloud 22' that has yet to show even a trace level of
stress in the area mentioned however that is not to say that it doesn't
happen. Many items on these trailers were under-designed for strength in
favor of their lightweight characteristics. In some cases only time tested
elements show failures while others built at a different time with slightly
different material and a different assembler show no signs of fatigue. I
have had a number of these apart and the one constant that I have run into
is that they are all slightly different. It shows just how variable the
production processes were back in the 50's and 60's. Even the same models
have variations from unit to unit. I'm not talking Decor, I'm talking about
how the units were framed inside and the methods of bending and cutting ribs
to fit in places where a full framing member will not.

That is why 50' and 60's trailers are so much lighter that the 70's and 80's
trailers. Their is less aluminum structure, lighter weight frames, and less
interior components.

It truly is a trade off, lightweight vs strength. Airstream has been making
the choice for 70 years.
Sometimes they succeeded sometimes they didn't.

Have fun with your teardown!

Later

WAM