🚀 go-pugleaf

In article <ewright.725648029@convex.convex.com> 
             ewright@convex.com (Edward V. Wright) writes:
[stuff deleted]
> There is no reason to believe that there will be more practical
>technical problems involved in building DC than in building the B-777,
>except that you *want* to believe that is true.

I think that there are quite a few reasons to believe that an SSTO
vehicle will have more "practical technical problems" than the B-777:

1. The B-777 is one in a series of airliners built by the same
engineering organization.  No one has built a man-rated space vehicle
with the design goals of the DC-1 project, and certainly not at MacDac.

2. There is limited experience with composite airframes in routine
operational use.  Certainly less with composite cryo tanks, if that
route is taken. (The exceptions to this lie in the B-2 program and the
kitplane market, but the B-2 is very early in the flight programs. There
may be some data from "black" programs that MacDac has access to.)

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.

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.

5. The weight margins on the vehicle are very tight, a historical source
of problems in spacecraft and aircraft design.

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.

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.
-- 
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"