From: ganderson@force.decnet.lockheed.com
Newsgroups: sci.space
Subject: SSF Progress
Date: 14 Dec 92 18:03:48 GMT
Article-I.D.: cs.Bz9H23.9FM.1
Distribution: sci
Organization: [via International Space University]
X-Added: Forwarded by Space Digest
Original-Sender: isu@VACATION.VENARI.CS.CMU.EDU

I have to comment on the dialog between Allan S. and L.W. on the relative
progress of MacDonnell Douglas' WP-02.  I have missed some of the
conversation but having read many of Alan's past missives and can't 
surmize the general bent of his comments.  

First of all, I agree with the rebultal that the Space Station budget and
design has been enything but stable.  NASA received "almost" full funding
this year for the first time in about 4 years.  The pertinent point is 
that "full" funding is determined AFTER NASA has squeezed their contractors
to the wall as to schedule and budget.  So, ANY reduction in the proposed
budget value will have some effect (there is no breathing room).  As an
example, WP-04 was asked to quote (right after restructure) to a "Just
in Time" building schedule.  To anyone who knows anything about designing
and building a spacecraft, JIT principles do not mean anything except that
you are accepting more schedule risk.  In the case of the Solar Arrays, of
which I have very intimate knowledge, this has meant implementing a very
cost ineffecient subcontractor delivery schedule of solar cells, bypass
diodes, motor drive assemblies, etc.  It has also meant greater and greater
schedule risk as the design process has been delayed by relatively minor
glitches in the development test process as can be expected with any
development program (but which Alan tends to ignore when he cites costs
of developing new launch systems.)

Second, I would like to comment on the question of CDR design maturity.  It
is true that it is a guideline that 90% of all drawings be complete by the 
time of the CDR but, at least in the case of WP-04, there is nothing written
into LMSC's subcontract requiring this value.  The 90% is an industry rule
of thumb that must be tempered by two factors;  1)  Customer restraint in
changing requirements and 2)  the relative number of structural vs. 
mechanism drawings.  The second item is common sense.  You can sketch the
cross-sections of major structural elements and describe their material
make-up and most engineers and analysts can verify the strcture will do
what is required (and of course, the fastening methods), however, 
mechanisms must be scrutinized carefully for lubricants, surface finishes, 
tolerances, meterial compatablity, etc.  Therefore, a mechanisms intense
program will need to have a greater number of design drawings complete by
CDR to "adequately disclose the design" as the phrase usually is place
into contracts says.

Customer restraint in changing requirements is where NASA is falling down
very heavily (the bigger they are, the harder they fall.)  It is not that
NASA is changing their minds as to what they want, it is that NASA is just
now getting together to find out whatthey require.  As an example, take
plume loading on the Solar Arrays (again, a subject that I am very familiar
with.)  The actual loads due to pluming were formally placed on out contract
in January.....of 1992!!!  This is 3 years into the design process and
after ALL the PDRs and some of the subcontract CDRs.  It is not that no
one knew that plume loads were going to happen (we'd been screaming about
not having a requirement for years) but it took that long for Mission Ops,
(JSC) and Power Systems (NASA Lewis) to come up with numbers.  I have often
heard the arguement that designers should have "put more margin" into the
design to envelope this load case.  If you really want to be flamed, state
that arguement....

Anyway, the bottom line is, when you are faced with multiple redesigns that
effect most of the design drawings that are required, the number of 
drawings that are "complete" at CDR can be compromised if the schedule of
the CDR (and first element launch) is critical.  Again, it just assumes
more risk to schedule when problems are discovered downstream of the
CDR and after production has begun.

A final comment to my second point:  NASA has still not settled requirements. 
At the Soalr Array Wing CDR which took place December 1-4, 1992, NASA Lewis
and NASA JSC and Rocketdyne (WP-04 prime contractor) were still in disagree-
ment over the plume loading and other shuttle induced loads on the array
(docking, berthing, Asronaut induced truss oscillations...)  The "on
contract" solution is to retract the arrays during all early mission (pre-
permanently manned capability: PMC) shuttle docking proceedures.  NASA JSC is
very much against this approach and I believe NASA REston is in agreement
with them, for obvious reasons of practicality.  As of today, there are NO
contractural requirements for dockingor bething loads on the solar arrays
but there are studies going on about how to make the array mast withstand
these loading scenarios.

My third and final point is about the integration of the station.  A very
telling point was a converstation that accured during the Solar Array Wing
CDR.  During discussions about what configuration the station is in
during the second shuttle assembly flight, it was revealed that both
arrays are deployed partially in what is called a "ready to deploy"
configuration.  Unfortunately this is not how the thermal analysis
was done as both Rocketdyne and LMSC had a different configuration in 
which one array was fully stowed and the other in this "ready to deploy"
configuration.  When asked by Rocketdyne how NASA intended to flow down
this requirement to its contractors, NASA's response was that the new
configuration was in the TOS (I later found out that this is a Technical
Operation Support document).  Unfortunately the TOS is not on Rcoketdyne's
contract.  When I enquired of JSC representatives as to who had 
juresdiction over this TOS, he said that it was not an official document
buut something that a few concerned JSC engineers put together because 
they did not see the needed work being down as to the piece by piece
analyssis of the on orbit configuration as the buildup progresses
(remember, every element left up there has to act like a controllable
spacecraft.)  So the bottom line is that their seems to be a very large
lack of "big picture" work fromthe station system design standpoint.  If
consolidating everything at JSC will fix this, then more power to it all.

Now that I have provided more fodder to Allan to call for the concellation
of space Station, I might as well sign off.  Feel free to respond to
my address below.

Grant Anderson
Ganderson@jedi.decnet.lockheed.com
Design Project Leader
Space Station WP-04
Lockheed Missiles and Space Co.
Sunnyvale, CA
All oppinions expressed are my own.  Facts speak for themselves.  Fools 
speak for each other.  
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