Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!cs.utexas.edu!uunet!mitel!sce!cognos!geovision!gd
From: gd@geovision.uucp (Gord Deinstadt)
Newsgroups: sci.space.shuttle
Subject: Re: Orbiter tiles affected by rain?
Summary: Coating burns off on reentry
Keywords: Scotchguard
Message-ID: <651@geovision.UUCP>
Date: 25 May 89 02:54:48 GMT
References: <1015@syma.sussex.ac.uk>
Reply-To: gd@geovision.UUCP (Gord Deinstadt)
Organization: GeoVision Corp, Ottawa, Canada
Lines: 28

In article <1015@syma.sussex.ac.uk> andy@syma.sussex.ac.uk (Andy Clews) writes:
>In an article about the adapted Boeing 747 shuttle-transfer aircraft in
>the June '89 issue of Spaceflight News, I read that there are a number
>of constraints governing the ferry-flights.  One of these constraints is
>that the flights cannot take place when there is danger of rain because
>this apparently is bad for the thermal-protection tiles on the orbiter. 

>If this is so, what happens to the tiles if the orbiter is sitting on
>the launch pad and there's a rainstorm? How does rain affect the tiles?
>Or is it because flying through rain at high velocity (up to 250mph in
>the case of the STA) would act like a high-pressure hose on the tiles
>and damage them? Surely 250mph rain can't be as bad as 17000mph air
>which the orbiter meets on re-entry?

The tiles are coated before launch.  I'm not sure what they use now, but
it used to be plain old 3M brand Scotchguard!  (No smiley, I read
it in Av Leak so it MUST be true.  They had pictures 'n everything.)

Anyhow, the coating burns off during reentry.  They don't spray the
tiles again before return to Florida because 1) it's time consuming,
and 2) it would get in the way of tile refurbishment.

I don't know what happens to the tiles if they get wet.

--

Gord "water proof is ok, but I'd rather have 100 proof" Deinstadt
gd@geovision