Michael Walsh wrote in message ...
Len wrote:


I realize that the context has been in terms of SE--
however, John O.'s recurring theme is that there are
no launch concepts that can reduce costs without
new "technology."

This is a place where I part company with John Ordover.

I do believe that a government financed "proof of concept"
small, completely reusable space vehicle would be a step
in the right direction. I see a problem with a commercial
organization having to demonstrate a capability that has
not so far been demonstrated by anyone. That is recovering
and reusing an upper stage, complete with propellant tanks
and all that goes with them. The fact that the Shuttle solved
the problem by dumping the propellant tanks makes that
a continuing region of uncertainty.

Mike Walsh

Your point (I think) that government has far more
resources than a commercial organization is well taken.
However, IMO, commercial entrepreneurs have a huge
flexibilty advantage when it comes to defining real
requirements and allowable design paths.

With respect to an example of "real" requirements, the
mass and size of the Shuttle payload requirement is moot.

As an example of design flexibility, let me cite the
external tank--as you have cited it as a "solution."
As project engineer for space transportation systems
at the LA sister division at North American Aviation,
I had come to the conclusion a decade before the
Shuttle program started that the volume of internal
propellants could relieve reentry heating by providing
lower planform loading; moreover, my tradeoffs indicated
that this benefit could counter the performance advantages
of dropping an external tank. As for economics, an
expendable tank kills any potential for the type of
cost effectiveness I was looking for. As for safety,
I fail to see why an adjacent external tank with
disconnectable propellant transfer was going to be
so much safer than carrying propellants internally in
a design that could take full advantage of not having
to disconnect propellant lines in flight.

At the time that North American--Rockwell by that time
--won the Shuttle Program, I was head of tactical systems
at the LA Division, with a conflict of interest agreement
with respect to commercial space transportation. When
Rockwell won the Shuttle program, I quit Rockwell--partly
because of conflict of interest, but also because of the
sheer absurdity of the Shuttle program.

Best regards,
Len (Cormier)
PanAero, Inc. and Third Millennium Aerospace, Inc.
( http://www.tour2space.com )