Newsgroups: sci.space.shuttle
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: SRB solutions
Message-ID: <1989Oct18.173420.23119@utzoo.uucp>
Organization: U of Toronto Zoology
References: <5474@umd5.umd.edu>
Date: Wed, 18 Oct 89 17:34:20 GMT

In article <5474@umd5.umd.edu> rossh@umd5.umd.edu (Hollis "NeXT-Dood" Ross) writes:
>What was the results of the Rogers Commision, ie what did 
>NASA change.  I seem to recall that just another O-Ring was 
>added. 

There were a number of changes, actually.  An extra flange was added to
the joint to reduce flexing ("joint rotation") when the booster ignites.
Another O-ring was added under that flange.  The sealing putty was deleted
entirely in favor of bonding the fuel in adjacent segments together.
Heaters were added to keep the joints warm.  I believe they did something
about better weather protection to make sure that rain didn't get in and
freeze.  Rules for booster assembly were tightened up to ensure that proper
clearances were maintained in the joints.  Those are the high points that
I recall.

>Someone mentioned (in this newsgroup) that he thought that 
>a segmented SRB is a very bad idea.  Is a non-segmented 
>SRB actually feasible without costing 1/2 of the current 
>defense budget? How much more expensive would it be to make 
>a Double wall SRB and would that be too heavy?.  

Double wall would add a lot of weight, I'd say.  But a non-segmented SRB
is quite feasible.  Large non-segmented solid motors were test-fired
successfully in the 60s.  At least one of Thiokol's competitors, Aerojet,
proposed a non-segmented replacement SRB after Challenger.  One practical
problem with non-segmented SRBs is that transporting them is harder, so
manufacturing really needs to be near the launch site.  There is also
some concern about uniformity of casting in such large motors, which
affects things like matching the thrust of the two SRBs (which is critical,
because the shuttle can't handle too much of an imbalance).

>An off the wall question:  If enough fuel were available, 
>would it be possible for the shuttle to make a journey to 
>lunar orbit.  How long can the shuttle stay up, what are 
>the constraints for power, air, ect. 

It would be kind of marginal with a stock orbiter, but with the changes
planned to turn Columbia into an extended-duration orbiter, it would be
practical if propulsion were up to it and things like navigation were
sorted out.  In practice it's a waste, because things like the wings
are dead weight on such a trip.  It's better done with a specialized
vehicle.
-- 
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