Corky Scott wrote:

...... How much change in
temperature occurs overnight during the summers there? Here in New
England, we can, and often do, see a 30 to 40 degree swing from the
cold of night to the warmest part of the day.

Another data point, as long as we're throwing them out - I park my COZY
MKIV outside at KFIT in MA. It lives outside throughout the whole year,
and sees large temperature swings (daily, usually). The fuel tanks are
integral with the strakes and made from fiberglass/epoxy - no bladders
or "wrinkles" in the bottom to trap water. The drains are at the lowest
point of the tanks. I rarely top up after a flight, and regularly leave
the tanks 1/10 - 1/2 full. I always sump the tanks first thing when
approaching the plane, before I move it or top it off. I have seen
water in the tanks exactly once, and that was after a very heavy rain.
I tightened the O-ring seal on the gas cap, and have never seen water
again in over 1.5 years.

The fiberglass is a good insulator, and as the temperature changes, I
see lots of condensation on the OUTSIDE - if it was going to condense on
the inside to any appreciable degree, it's got it's chance with the
materials at hand. It doesn't do so.

Personally, I think this condensation thing is a crock - if you've got
water in your tanks, it's because your caps leak in the rain.

--
Marc J. Zeitlin
http://marc.zeitlin.home.comcast.net/
http://www.cozybuilders.org/
Copyright (c) 2004