Desert Sailplane storage

A somewhat easier solution is to get a "black light" out of your attic from
when you had all of those black light posters in high school..

Can't do that...I still use mine! Hendrix rules, dude!

Jim Vincent
N483SZ
illspam

Hi,

Are there UV-meters?

There is a very crude method using test-strips that are sometimes
distributed in pharmacies here in germany, especially in the summer
holiday season. These strips are meant to help people avoid sunburn
by indicating a safe time to spend in the sun.

They are made of cardboard and some UV-sensitive paint covered in
some kind of goo. You are supposed to rub off the goo when you go
out. Put the strip next to you on the beach and when it has
changed color according to a scale and instructions printed next
to it you better get out of the sun.

One could use two of these: Put one on the outside of the trailer
and one inside. Time how long it takes the one on the outside to
discolor to a certain degree. Wait until the one on the inside has
taken the same amount of UV. Divide the times and you should arrive
at a rough estimate of how much UV gets through the trailer.

I do not know of anyone who has made such an experiment on a glider
trailer. I did it for car windows a few years ago.

Ciao, MM
--
Marian Aldenhövel, Rosenhain 23, 53123 Bonn. +49 228 624013.
http://www.marian-aldenhoevel.de
"Flying an An-2 is like making love to a fat lady who's had too much to drink:
there's a lot to work with, it's unresponsive, you're never quite sure when
you're there, and it's big-time ugly."

somewhat easier solution is to get a "black light" out of your attic from
when you had all of those black light posters in high school...they transmit

I don't think that would work. A black light transmits both in the visible
light and UV frequency spectrums. Each frequency is attenuated, reflected, or
absorbed differently by a material.

If you see light coming through the trailer when shining the black light, all
you can deduce is that the visible light transmitted through the trailer,
nothing about whether the UV.

Jim Vincent
N483SZ
illspam

Jim Vincent wrote:
somewhat easier solution is to get a "black light" out of your attic from
when you had all of those black light posters in high school...they transmit


I don't think that would work. A black light transmits both in the visible
light and UV frequency spectrums. Each frequency is attenuated, reflected, or
absorbed differently by a material.

If you see light coming through the trailer when shining the black light, all
you can deduce is that the visible light transmitted through the trailer,
nothing about whether the UV.

You have to bring your Metallica black light poster with you and see if
it glows.

Shawn

I called around to some testing labs. I spoke first to a local company in the
Philly area, but the guy was not willing to do a freebie...Philly Attitude.

I then spoke with a company in Plainfield, IL that is willing to spend a few
minutes on the project!

If there is someone on this group that lives near Plainfield, IL (north of
Juliett) and is willing to drive their trailer for some testing, please
contact me directly for the company contact.

Or maybe someone out west could pursue this with a local company there.

With a little planning, we could test a few different materials. Go out on a
sunny day, get a reference reading, then test in the trailer. Perhaps also
make a small box on which we can put different covers such as tin foil, paint,
wood, etc and measure the UV ingress.

Let me know!

Jim Vincent
N483SZ
illspam

What about a Cobra owner contacting Herr Spindelberger
to ask what information he has on the subject?

John Galloway


At 16:30 28 December 2004, Jim Vincent wrote:
I called around to some testing labs. I spoke first
to a local company in the
Philly area, but the guy was not willing to do a freebie...Philly
Attitude.

I then spoke with a company in Plainfield, IL that
is willing to spend a few
minutes on the project!

If there is someone on this group that lives near Plainfield,
IL (north of
Juliett) and is willing to drive their trailer for
some testing, please
contact me directly for the company contact.

Or maybe someone out west could pursue this with a
local company there.

With a little planning, we could test a few different
materials. Go out on a
sunny day, get a reference reading, then test in the
trailer. Perhaps also
make a small box on which we can put different covers
such as tin foil, paint,
wood, etc and measure the UV ingress.

Let me know!

Jim Vincent
N483SZ

UV-A and UV-B light penetrates poorly through anything that is tinted. Also
tightly woven materials do not allow penetration. Most of us have had "tan
lines" at some point with your skin being pasty white under your bathing
suit or shirt while the exposed areas are tan or burned.

With a reflective white coating on the outside and the opaque nature of
fiberglass it is highly unlikely that any substantial amount of UV light
gets to the inside of anyones trailer. If anyones wishes to have references
for the science of it all just let me know.

Casey Lenox
KC
Phoenix

If anyones wishes to have references
for the science of it all just let me know.

Casey,

I for one would much appreciate a link to a site listing the transmissivity of
frp. I agree with you that UV transmits minimally if at all through a trailer,
but would love some emperical numbers.

Jim Vincent
N483SZ
illspam

Hi Jim-

Try this one for starters:

This page discusses the penetration of UV light in plastics:
http://www.newton.dep.anl.gov/askasc...9/eng99272.htm

Also for those of you who seriously wish to do your own experiment re UV
penetration into your trailer (or whatever else you can think of) here is a
site that sells UV sensitive beads for cheap...$7 (US). The cheapest UV
meters are around $150 (US).
http://www.stevespanglerscience.com/product/1350

I have no financial interest in any of this BTW. I am thinking that I just
might put up a few posters again...chalk it up to midlife crisis. Not so
sure that the wife will tolerate it though.

Casey

We have a fair amount of research available on the effects of UV on gel coat,
including some just completed work that will be presented at the SSA
convention. Here are some of the pertinent facts:

Light energy (radiation) varies throughout the spectral band, from ultraviolet,
to visible, to infrared. The most energetic region of the spectrum is the UV
range (400 nm)) - potentially the most damaging to polymer surfaces… not to
mention one's skin. For study proposes the UV range of the spectrum is divided
into three categories - UV-A, UV-B, and UV-C.

The UV-A region (wavelengths 400-315 nm) has an affect on polymers. These
wavelengths will transmit through window glass (used as a benchmark). UV-B
(315-280 nm) is highly energetic and will result in degradation of polymers.
UV-B is the shortest wavelength to reach the earth's surface, however it is
effectively filtered out by window glass. UV-C (280 nm) is the most energetic
UV band, however it is filtered out by the atmosphere and is only found in
space.

So, UV-C is a non-issue. UV-B is potentially harmful but is easily absorbed by
window glass and to a much higher degree by gel coat. The titanium dioxide
(TiO2) pigment in white gel coat is particularly good at mitigating UV-B
penetration. UV-A is the least energetic within that portion of the spectrum.
While it will transmit through window glass, again the TiO2 pigment in white
gel coat is particularly effective at absorbing and limiting the transmission
of this wavelength.

While UV exposure impacts the photo-aging of the gel coat surface, UV
penetration through the gel coat and into the laminate substrate is not an
issue. The end result is that UV damage to the underlying laminate does not
occur. Taking this a step further there is little cause for concern with UV
penetrating a trailer - the wavelengths are simply too short to make it through
a gel coated laminate. The idea of painting the inside of a trailer reduces
the penetration of longer wavelengths that are not harmful to polymers, but
rather contribute to solar heating inside the trailer.

Bob Lacovara
American Composites
Manufacturers Association