[VAL] Re: VAL Digest V1 #185 - Stiffness, rigidity

[waymark1@xxxxxxxx]

Airstreams and similar trailers such as Avion, Silver Streak, Streamline,
etc., are semi-monocoque construction. The body provides a large part of
the strength of the trailer, especially stiffness.
This kind of trailer does not twist very much even if supported only at
opposite corners as compared to the more common plywood and aluminum foil
and the laminate type trailers, which have very little stiffness in the
body. They rely almost entirely on the underframe for both strength and
stiffness.
There is almost no comparison whatsoever between an Airstream and a
mobile home. The Airstream is a highway vehicle designed to hold up to
hundreds of thousands of miles of high speed towing. The house trailer is
designed to be hauled from the factory to the dealer and then to the
final location where it is used as a permanent dwelling. Most mobiles do
not move again after being set up to be lived in until they are hauled
away to be scrapped. Mobiles are relatively flimsy and are intended to be
fully supported under the sills of their frames on pilings or continuous
foundations before being occupied.
The travel trailer is usable supported by only the wheels and the tongue.
Jacks or stands are only for preventing annoying shaking on the springs
and tires when occupants are moving around. They are not necessary for
keeping the trailer body aligned.
Our old 40' Spartan sat on only its wheels and the tongue jack through a
winter in which the frozen waterlogged snow piled up on its roof about
seven feet thick. The tongue was slightly bent from this tremendous
overload but the roof was not affected at all. Our dump truck's roof and
hood were crushed in. Many cars were badly damaged. Unoccupied mobiles
were destroyed, their roofs caved in. I saw one that even had its walls
buckled in places. Modern houses that were not cared for by having their
roofs cleared also had their roofs collapsed.
The Airstream is a better constructed trailer than the Spartan. It has
double walls where the Spartan has only thin plywood for the interior
wall skin.
Al