by mezmo » Fri May 24, 2013 2:16 am
General consensus was tall and narrow 'not ideal'.
Low and wide is 'better'. Try to keep CG low. Do not
tow in high winds. [Obviously easy to say, but you can get caught
unawares when you are out on the road, as she was.]
From what I recall, the winds were very high in speed and
when they turned into a crosswind vector, the very light, high
and narrow TTT keeled over - so-to-speak. But with minimal
actual damage to the foamy body other that a case of "road-
surface-grater effect" on a front corner and the bent frame.
Any vehicle with a similar profile and surface area will be
affected similarly, but most commercially built vehicles are
more likely to have had their suspensions designed to help
deal with such conditions, but very few would be considered
'immune' to them.
I would say that it'd probably be a good rule of thumb to say to
"don't build higher than wide" or maybe "not higher than wide +
a 'reasonable' road clearance". And it's the best idea to, again,
keep the CG as low as possible and to balance the built-in features
weight as much as possible. Remember to concentrate your 'portable'
loads, if possible, along fore-to-aft and side-to-side center lines and
as close to the axle as possible. [I.E., don't cantilever a heavy load
off of the back or pack everything up in the front. [One needs to pay
attention to where you locate the axle too - see angibs work-up on
that, as well as the tongue weight work-up he did - both in the TD
plans area on here.]
I don't consider Foamies inherently unstable. Environmental and
design considerations need to be considered in the build. It is a vehicle,
so we need to remember to consider what that means when we are
designing. A dynamic moving "room" is built differently than an always
stationary "room". Look around and read all the various approaches
that have been taken in constructing a TD/TTT. You'll get an appreciation
for what will work, which methods you think are 'better' or 'best' [Everything is
'relative' to its circumstances IMHO.] for you. The good weight savings
Foamies allow has a great benefit in positively affecting towing costs.
[But remember too, that weight is one of many considerations in those.]
And the quantity [And its inherent weight.] of personal equipment you can
include in your camping trips can be increased when the structure itself
has a lower weight when using the same chassis's capacity.
Just some rambling thoughts on it...
Cheers,
Norm/mezmo
If you have a house - you have a hobby.
Good judgement is far better than any design considerations, and if you do find yourself in a dangerous situation , it’s Wise to stop and seek some type of shelter from the wind , or at least park the vehicle and trailer INTO the wind ... Much like being in a boat ... some days it’s just not advisable to travel ... 
That being said , it was the
