Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!wasatch!utah-gr!uplherc!sp7040!obie!wes
From: wes@obie.UUCP (Barnacle Wes)
Newsgroups: sci.space.shuttle
Subject: Re: shuttle computers; big solids
Summary: Well, you're sort of right...
Message-ID: <212@obie.UUCP>
Date: 7 Oct 88 05:06:41 GMT
References: <6689@nsc.nsc.com> <1543@hp-sdd.HP.COM> <1988Oct1.230542.11512@utzoo.uucp>
Organization: the Well of Souls
Lines: 53

In article <1988Oct1.230542.11512@utzoo.uucp>, henry@utzoo.uucp (Henry Spencer) writes:
> The filament-wound boosters developed with USAF funding were segmented,
> just like the existing ones.  Their only real advantage was that the
> filament-wound cases were lighter.  Their big disadvantage, which is why
> you don't hear about them now, was that the actual joints still had
> to be metal, meaning that each filament-wound segment had a composite
> center bonded to two metal joint rings, i.e. still more joints to fail.

USAF has a large, segmented solid-fuel booster being fielded as we type
:-).  It has had 17 successful launches, and not one of the 17 flights
has blown up, intentionally or not.  But then again, they were never
left out in the cold, either :-).  As a matter of fact, the Shuttle
SRBs are basically derivatives of this motor; they are approximately the
same size, and according to a book Thiokol published as a promo item a
few years ago, the fuel compounds are very similar.  This booster is, of
course, the 1st stage of the Peacekeeper missile.  Remember good ol' MX?

> There was also some (unofficial) skepticism about how reusable they would
> be.  NASA is now concentrating on improved metal casings for a higher-
> performance SRB, and the filament-wound casings seem to have been forgotten
> completely.

A reusable ICBM?  That's funny!

> Large one-piece solids were built and fired a number of years ago -- by NASA
> in fact!

Well, actually, it was Aerojet Corp., during the design & analysis phase
of the MX contract award.  They demonstrated the capability to create a
solid-fuel booster that fit the MX specs, with one single pour of the
fuel, and one solid wound-fiber exterior.  God and Jake Garn only know
why Aerojet didn't win the contract, and the contract for the SRBs as
well.

> The reason for not taking that approach immediately was the desire
> to get the shuttle flying again without waiting several years to develop a
> new SRB.  The reasons for not taking that approach in the long run are a
> combination of NASA inertia and legitimate worry about the problems of
> casting that big a lump of propellant in one piece.  (Cracks in propellant
> are very bad news in any solid rocket.)

If you read the accounts around here, the reason is that the Director of
NASA at the time was a Mormon, and Jake Garn was one of the bigwigs on
the Senate committe allocating funds for the Shuttle.  They apparently
decided Utah could use the jobs, the tax revenues, and the "glamour" of
developing one of the more visible portions of America's Space Station
Wagon.  Too bad they did such a crummy job, both on the boosters and on
the advertising!
-- 
                     {hpda, uwmcsd1}!sp7040!obie!wes

         "How do you make the boat go when there's no wind?"
                                 -- Me --