Plastic ships - flights of fancy ?

Greetings everyone,

This may seem a rather stupid question to some, so please indulge
my ignorance or the possibility it's been discussed here before.

I was thinking the other day about the possibility of using plas-
tics in the construction of starships, that is the external hull.
Given the weight ratios between "standard" metal  structures  and
their  plastic  counterparts, would it not be more fuel-efficient
to use plastics and thus benefit from  any  weight  savings  that
might accrue ?

I then thought to myself, "Well, what would happen upon free-fall
re-entry  ?  Fried  plastic  blob  hits deck at G ?" Perhaps not.
Wouldn't it be possible to shield the ship using good ol' ceramic
tiles a la Space Shuttle ?

Then the problem of aging occurred to me.  Plastics  age  through
photo-chemical  reactions  caused  by  the interaction of natural
phenomena (sun, wind, rain, local soil etc.) with  the  plastic's
own  atomic  structure  (plastics-  or  organic chemists - please
shoot me down in flames if this is a misconception on  my  part).
This  can  be  useful,  for example when designing bio-degradable
plastics,  but would surely be an undesirable trait in  plastics-
for-space-vehicles  purposes.  Given that UV light (which clearly
lends a hand in the aging process) is shielded  somewhat  by  our
atmosphere (unless you live in Antarctica, that is), wouldn't the
situation be that much worse in vacuum where  no  such  shielding
takes place ? I suppose solving this problem might help solve the
next ...

I remember hearing years back that all plastics are, to a greater
or  lesser extent, porous.  Is this true ? How could this be com-
pensated for or, preferably, eliminated when considering  plastic
vehicles ?

Note that I didn't consider strength as a factor in my reasoning.
Why  not  ? Well, I reckon that a ship-asteroid collision at some
of the speeds frequently discussed on the TML will turn both ship
and  contents  into  so  much blackberry jelly no matter what the
ship's made of. Comments ?

If these thoughts aren't pure fancy, it gives rise to the follow-
ing possible scenario :-

Punter enters local branch of "Spaceships R Us". Asks  about  the
possibility of purchasing a brand new 1,000 ton trader. Slick and
somewhat greasy salesman says, "Certainly, sir. You need the  La-
zlar  Lyricon  (sp ?) model. Only 17 zillion credits or $ 1.98 in
Revell kit form".

Looking forward to some replies.

All the best, everyone.

Hugh.
- - -----

P.S. Apologies to Douglas Adams and the  Hitchhiker's  Guide  for
misusing the Lazlar Lyricon bit. H.

| Hugh P. Schoenemann     | "Hey sonny - haven't you  got an  | *  * ***   *** |
| Pyramid Technology Ltd. |  FGMP  15 to play with or what ?" | *  * *  * **   |
| ..[email removed]       |                                   | **** ***    ** |
| Tel : [phone removed]   |  ***** FIZZZZZZZZZZZZZZZ ! *****  | *  * *    ***  |