From: Henry Spencer <henry@zoo.toronto.edu>
Newsgroups: sci.space.science
Subject: Re: Lifting Shuttle External Fuel Tank into Orbit
Date: Fri, 22 Mar 1996 15:40:44 GMT

In article <4irpsb$hec@knot.queensu.ca> 3cdk2@qlink.queensu.ca (Kossowski Craig D) writes:
>: Without the mass of the shuttle, the tank, SRBs and SSMEs make a pretty
>: terrific launch system.  In fact, you can put a shuttle+full-cargo-bay
>
>I'm surprised that folks at NASA aren't active about this, or at least 
>the companies that build shuttle hardware... Would seem to me they could 
>put together a very capable unmanned heavy launch system with essentially 
>off-the-shelf components.

This has been proposed.  Repeatedly.  Endlessly, in fact.  Once or twice
it has come close to being built.  The basic problem is:  what are the
payloads?  Off-the-shelf though the components are, full development and
testing of such a system would be a substantial effort, and it's not going
to be undertaken without specific need.  NASA has no specific requirement
for heavylift launches.  Oh, there are a few things it would help with,
like the space station, but nothing that just *can't be done* without it. 
-- 
Americans proved to be more bureaucratic           |       Henry Spencer
than I ever thought.  --Valery Ryumin, RKK Energia |   henry@zoo.toronto.edu

From: ederd@bcstec.ca.boeing.com (Dani Eder)
Subject: Re: Shuttle-C cost? (was: Shuttle vs SSTO)
Date: Jun 30 1995
Newsgroups: sci.space.policy,sci.space.shuttle

mancus@bnr.ca (Cathy Mancus) writes:

>	This was proposed in at least one version of Shuttle-C; the
>entire "boat-tail" with the engines in it would be recoverable.  Someone
>else will have to comment on whether this is still considered feasible.

Having worked for 6 years on Shuttle-derived cargo vehicles, I think I
can comment on this subject.

SHUTTLE DERIVED CARGO VEHICLES

by Dani Eder

Cargo versions of the Space Shuttle have been studied almost from the
inception of the Shuttle program (at least from 1976).  Payloads ranging
from 80,000 lb to 350,000 lb to 160 NM altitude are possible.  The
payload you get depends on the number of SSME's you choose to use,
ranging from 1 to 4+1 (2nd & 3rd stages), and the number of segments
in the SRBs (from 3 to 5).  To be described as a Shuttle-derived cargo
vehicle we assume the basic design of the SSME and SRBs are retained,
and the External Tank diameter is kept the same.

An installed SSME weighs about 10,000 lb (including things like the fuel
lines leading to it).  To recover an SSME from orbit requires an overhead
of about 80% in recovery systems (heat shield, parachutes, air bags for
landing, extended battery life, support structure, deorbit propellant, etc.)
and 100% in cost.  Electronics and engines (~$10,000/lb) are worth about
an order of magnitude more than tankage (~$1000/lb), so there is a wide
range of circumstances where it makes sense to reover the former but
not the latter.  We call them Propulsion/Avionics modules (P/A for
short), since that is what you are reovering.

A complete 2-SSME P/A module was estimated to weigh 45,000 lb.  It
included the equivalent of a Shuttle OMS and RCS system.  It was 
designed to re-enter using an ablative heat shield (like Apollo), 
parachutes, then air-bag for final landing.

Given that the complete module costs about twice what the bare SSMEs
cost, as long as you recover the module more than 50% of the time, it
is cheaper in the long run.

Placing the P/A module directly underneath the External tank makes the
engine thrust go into the tank directly, rather than through a side
as in the Shuttle Orbiter.  This saves you about 12,000 lb of structure,
which translates into payload.  For a similar reason, you want to place
the payload directly above the External tank.  When you do that you
get a rocket that looks a lot like the Japanese H-2 or the Ariane 5, but
bigger.

Re-entry has not been a problem since the early ballistic missiles and
manned capsules demonstrated that technology.  Landing a 45,000 lb 
object by parachute is not a problem since the SRBs regularly land
350,000 lb objects via parachute.

Dani Eder