Plexiglass II UVA has been around for decades! It filters out UV A,
but
I don't know about UV B. It is the stuff from which aircraft canopies,
windows, windshields, etc. have been made for at least the past 45
years.

The only reference I could find was 280 to 400 nonometers, on the
RPlastics.com web page. According to the ThermoTecUSA.com web page,
that
looks like the bottom third of UVB and all of UVA.

But, all of that brings up an ... umm ... interesting ... umm
....question
...
(Considering that I wasn't the only one on the NG who didn't know this)
Do you suppose ... presuming that your timeline is correct ... that OEMs
for
both civil and military aicraft have been using the "right stuff" ...
and
that Homebuilders may have been using whatever happened to be lying
around
at the local plastic distributor?

Peter

YUP!

It certainly looks like you are correct.

I found a little more information, although some of the Plexiglas
nomenclature is slightly different, on another vendor page at
http://www.plexiglas.com/literature/pdf/81.pdf and that one includes
graphical presentation of the solar sprectral distribution as well as
transmittance of several types of Plexiglas.

At the moment, I have not found much on the IR side for Plexiglas, aside
from the assertion that coatings exist--and of course the obvious that
tinting does reduce overall heating.

And, of course, there is also the Solar Control Lexan--which has both the
fault and feature that it is not intended to be frangible. That is a
feature in the event of bird strikes and also regarded as a fault in some
excape situations where a canopy can not be readily opened. BTW, some of
the Plexiglas formulations are also asserted to be either non frangible or
less frangible.

Clearly, more research is indicated and some volunteers are needed.

Peter