Newsgroups: sci.space.shuttle
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: Heavylift Boosters
Message-ID: <1988Sep29.172519.25885@utzoo.uucp>
Organization: U of Toronto Zoology
References: <28624@think.UUCP>
Date: Thu, 29 Sep 88 17:25:19 GMT

In article <28624@think.UUCP> craig@think.COM (Craig Stanfill) writes:
>	1.  How much better are SSME's than other liquid-fueled engines?

In terms of performance, they are quite a bit better than the other big
liquid-fueled engines that are in production today.  When you factor in
reliability and cost, the picture may not be quite so rosy, especially
if you are comparing to no-longer-available engines like the F-1.  The
SSMEs win, basically, because they are the only big hydrogen engines you
can get (outside the USSR, anyway).

>	2.  How do the SRB's compare to other large solids in terms
>	    of reliability and cost?

Knowing NASA, the cost is probably a bit on the high side.  Reliability
is okay, given that no solid has exactly a glorious reliability record.

>	3.  How would the cost & lead time for developing a launch vehicle
>	    based on Shuttle components compare with developing one from
>	    scratch?

Depends on who's doing it.  If it's the government, using Shuttle hardware
certainly is a considerable win.

>	4.  How would the cost of developing a family of launch vehicles
>	    (varying the number of SSME's and SRBs) compare with the
>	    cost of independent development efforts?

Not clear exactly what you mean, but varying the number of SSMEs, in
particular, isn't a big deal if you don't want big variations.  Varying
the number of SRBs is a bigger problem because the current launch facilities
are built for exactly 2 SRBs per vehicle.

>	5.  Is it plausible that shuttle-based launch vehicles could
>    	    replace the Titan?

No, because the shuttle and its derivatives are NASA vehicles, and the Titan
is a USAF vehicle, and that alone ensures that the Titan will be continued.
Remember that Titan launches, production, and development went on (albeit
slowly and with some difficulty) even when official government policy was
"all expendable launchers are to be discontinued in favor of the shuttle".
-- 
The meek can have the Earth;    |    Henry Spencer at U of Toronto Zoology
the rest of us have other plans.|uunet!attcan!utzoo!henry henry@zoo.toronto.edu