🚀 go-pugleaf

Geez Phil, you make it sound like I _oppose_ the DC-X program, when I am
actively supporting it.  My basic opinion is that there are some risks
involved that need proper assessment and management.  The taxpayers
should be informed as to the risks (and the rewards) and not just
presented with rosy promises.

In article <C0B93G.Ksx.1@cs.cmu.edu> 
     pgf@srl03.cacs.usl.edu ("Phil G. Fraering") writes:
>\2. There is limited experience with composite airframes in routine
>/operational use.  

>Actually, you forgot the F-22/F-23 program as well. And the F-20.

Please note the qualifiers aboove - "limited" and "routine".  None of
those are operational.  I did forget the F-117, which has a significant
composite %, but it is unclear if any load bearing members are
composite.

>I would also note that the kitplane market bit seems to indicate
>that composites are *better* understood than you think, and aren't
>being used more widely because of stodgy industry. It sounds like
>they're more innovative than Boeing/MacDac et al. Perhaps they are.

Actually, the kiplane market uses (mainly) the epoxy/fiberglass types of
composites for wings, etc.  The major objections to composites (as I
have been told) is the increased cost compared to Al and Steel.  There
are also problems with assembly and repair of composite structures that
increase costs.  The major programs that use composite structural
members that I am familiar with are the fleet ballistic missiles such as
Trident.  The aircraft industry is well aware of the potential of
composites and will use them if they are cost effective.

>After all, who flew around the world unrefuelled first?
>
>THANKFULLY _someone_ had the presence of mind to get Scaled Composites
>involved on DC-X...
>

>\3. The throttled RL-10 with nozzle extender is a new and essentially
>/untried engine. Engine development is more art than science and has a
>\history of being subject to delays.
>
>I don't think so. There were no changes in any of the "wet" parts of
>the engine, just the uncooled part of the nozzle. 

From what AvLeak reported, the throttling mechanism is not a trivial
change to the engine and has had (thanks to an old Air Force contract)
only a limited test series.  The AF tests are what made the engines possible
for this program.  (That and some innovative financial deals - i.e. DC-X
is leasing, not buying the engines.)

>The stupid part
>of the nozzle, as it were. If we can't do that, we should stay on
>the ground.

I would hardly call a deploying nozzle extender trivial either.  It
should be as simple as landing gear deployment, but it is a set of
moving parts that need to work, will need inspection, repair, etc.
>
>\4. The servicing goals and rapid turnaround requirements of the vehicle
>/are doable on paper, but have been held out as very risky by an
>\independent study.
>
>An independent study which apparently had an axe to grind of its own,
>if you're talking about the TAC study.

Yes, this was the TAC study, which seemed to be unbiased.  I read a two
page executive summary that was done of it, so maybe the complete report
was not unbiased.  The conclusion of the report was that the SSX program
could probably be done with some risk.
>
>\5. The weight margins on the vehicle are very tight, a historical source
>/of problems in spacecraft and aircraft design.
>
>Hmmph. Maybe you should repeat this a couple more times for the people
>who started this, you'll help them make everyone else think it's true.

This has been a problem even for the "success oriented" Apollo program.
Great work had to be done to get the LM down to reasonable weight.  (I
may be wrong, but I recall that Apollo had two LM contractors and one
was eliminated due to design and weight problems.  Henry or others
probably remember.)  Other aircraft have had this problem - my employer,
Lockheed, had to take a $700 million writeoff on the P-3 Orion replacement 
program when it was cancelled, in part, due to weight growth.  In a systems 
engineering class I attended, a "model" systems engineering organization
for spacecraft and aircraft design (DOD model procurement) showed a
position for a person to keep track of weight and balances. 

>
>\Even given all that, the DC-X, DC-Y, DC-1 progression is a valid and
>/prudent way to develop this class of vehicle.  There is one other source
>\of risk that is hard to quantify at this point: MacDac is an ailing
>/company, in substantial risk of major cutbacks.  Given that the company
>\is throwing a lot of IR&D money into the project, it could founder on
>/the rocks of a major financial crisis in the company.  I also give
>\MacDac high marks for the management approach, which I have heard the
>/project manager give a talk on.  It is modeled on the Lockheed "Skunk
>\Works" approach.
>
>I think people were saying the same thing about Apple at about the time
>they were developing the Mac. Everyone was talking about how they were
>going to lose out to IBM. But who's in financial trouble now?

The PC division of IBM is doing quite well - the trade press indicates
that they have 2 major problems - the parent organization is in
financial straits and they can't build enough product to meet demand.
Apple was not particularly unstable financially when the Mac was in R&D
(although the Apple III and the Lisa would have killed anyone else in
the business).  MacDac has had to be bailed out by DOD at least once in
the last two years and the C-17 project is in mega trouble, SSF may be
in trouble again this year, etc.
>
>Also, "we better not give them the project, they're a troubled
>company" is the sort of self-fufilling prophecy that's kept many
>many many good alternatives from being tried.

Be that as it may, it is still a risk.  I didn't say that they shouldn't
get the work, just that the financial condition of the company could
threaten the project, espcially since they are using IR&D funds.
>
>\Hopefully, the incoming administration will see the value of the
>/vehicle, there will be a safe and successful flight test this summer and
>\it will proceed with the DC-Y.  I consider the DC development program a
>/prudent use of the government's risk capital.  However, we need to keep
>\an eye on alternatives in case the DC program stubs its toe.
>
>You say that as if DC isn't one of the alternatives instead of one of
>the 200-million-a-year-on-design CAD queens.

I meant that there ought to be some fallback from DC-X, as it seems to
be the only existing booster development program for medium payloads.
DC-Y, et.al. are certainly viable vehicles if the program goes well.

-- 
Edmund Hack - Lockheed Engineering & Sciences Co. - Houston, TX
hack@aio.jsc.nasa.gov - I speak only for myself, unless blah, blah..
"You know, I think we're all Bozos on this bus."
"Detail Dress Circuits" "Belt: Above A, Below B" "Close B ClothesMode"