Xref: utzoo sci.space.shuttle:3932 sci.space:15022
Newsgroups: sci.space.shuttle,sci.space
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: Space Shuttle SRB exhaust gas makeup.
Message-ID: <1989Oct26.052801.22642@utzoo.uucp>
Organization: U of Toronto Zoology
References: <1989Oct26.025442.17842@agate.berkeley.edu>
Date: Thu, 26 Oct 89 05:28:01 GMT

In article <1989Oct26.025442.17842@agate.berkeley.edu> gwh@typhoon.Berkeley.EDU (George William Herbert) writes:
>>And don't sneer at the idea of doing without the aluminum, because the
>>rubber is also a fuel; similar combinations without aluminum have almost
>>as high a specific impulse...
>
>...	As for the 'no aluminum' bit, it really was described as making
>most of the difference.  There's a whole lot more energy in Al than rubber...

I confess I was a bit surprised myself, but Sutton lists a PVC/AP combination
as having only about 10% less exhaust velocity than PVC/AP/Al.  Aluminum is a
lot more energetic, but it also exacts a price:  aluminum oxide has a very
high molecular weight, and it tends to condense out to complicate things
further.  I'm not up enough on the fine points of solids to really assess
the tradeoffs.
-- 
A bit of tolerance is worth a  |     Henry Spencer at U of Toronto Zoology
megabyte of flaming.           | uunet!attcan!utzoo!henry henry@zoo.toronto.edu