"Rolling reuseability"

"Bob Martin" wrote in message ...
Instead of building a fleet of 3-4 reuseable vehicles and then trying to
make them last a long time, maybe we should go with what I call "rolling
reuseability". You use a craft designed for 12 flights, at the end of which
it is retired. ...
With this system, your fleet is never more than 3 years old, and changes or
upgrades could be done on the production line instead of more costly
retrofitting. It also keeps your production line open, maintaining skill in
LV manufacturing and meaning that you could be flying vastly improved
vehicles after only a few years. ...

I like this idea. Until the Palmdale orbiter rebuild factory
was closed down a couple of years ago, NASA almost had such a
capability (though at a smaller scale). The problem that such
an arrangement might face is the same problem that shut down
Palmdale - a slow-rate production program like this is vulnerable
to stretch-outs, interruptions, and shutdowns by short-horizon
budget planners.

How would your plan compare, cost-wise, with an initial full
fleet run consisting of sufficient vehicles to fly for the life
of the program (say 20 years), assuming that each vehicle is
retired after three-years worth of flights. Instead of a
production facility, you would need a long-term storage and
maintenance facility for the yet-to-fly vehicles.

- Ed Kyle

(Alan Anderson) wrote in message ...
(ed kyle) wrote:

Instead of building a fleet of 3-4 reuseable vehicles and then trying to
make them last a long time, maybe we should go with what I call "rolling
reuseability". You use a craft designed for 12 flights, at the end of
which
it is retired. ...
With this system, your fleet is never more than 3 years old, and changes or
upgrades could be done on the production line instead of more costly
retrofitting. It also keeps your production line open, maintaining skill in
LV manufacturing and meaning that you could be flying vastly improved
vehicles after only a few years. ...

How would your plan compare, cost-wise, with an initial full
fleet run consisting of sufficient vehicles to fly for the life
of the program (say 20 years), assuming that each vehicle is
retired after three-years worth of flights. Instead of a
production facility, you would need a long-term storage and
maintenance facility for the yet-to-fly vehicles.

That completely loses the advantage of ongoing (albeit slow) production.
You get a one-shot batch of identical vehicles, which doesn't let you
improve later models as you learn from the earlier ones.

True, but wouldn't it cost less to produce everything in one big
batch, maximizing worker productivity during that time? That is
how most military aircraft are produced. They aren't, for example,
building new B-2s, B-52s, Harriers, or A-10s, but they are still
flying them.

- Ed Kyle

True, but wouldn't it cost less to produce everything in one big
batch, maximizing worker productivity during that time? That is
how most military aircraft are produced. They aren't, for example,
building new B-2s, B-52s, Harriers, or A-10s, but they are still
flying them.

But aircraft fly much more often. It doesn't cost too much more to make a
plane have a long life than a short one--unlike spacecraft.

Also, aircraft are always being built--manned spacecraft aren't (at least
not here in the US). You don't lose worker ability and infrastructure
building one vehicle a year, at least if it's a large and complicated system
(like a spacecraft). Trying to satisfy safety constraints and such would
drive the production of a large reuseable spacecraft out to at least a year,
anyways.

"Bob Martin" wrote in message ...

The annual flight rate would be once per
month after the first year.

Once a month. Even the idea of it is exciting. Of course the current
way flights are prepared, you wouldn't have enough pads at KSC to
manage this, as launch delays would inevitably pile up... you be lucky
to fly once every three months :-

The first two vehicles would only fly 11 times
each instead of twelve, so as to maintain the 12 flights/year pattern. At
the end of the fourth year, vehicle #3 (which entered service at the end of
year 1) would be retired. And the pattern would continue.
With this system, your fleet is never more than 3 years old, and changes or
upgrades could be done on the production line instead of more costly
retrofitting. It also keeps your production line open, maintaining skill in
LV manufacturing and meaning that you could be flying vastly improved
vehicles after only a few years.

I think that this step, (almost) no matter the extra cost, is the most
crucial step towards seriously improving our launch vehicles. It gives
you the best of both worlds: reusable equipment is used frequently
enough to establish a baseline for durability, and keeping the
production lines open allows for continual tweaking and improvement.
And at the end, they still have to have a flying vehicle (unlike
x-33/34/SLI), so it avoids the "next generation technology" syndrome
that now has our shuttles in a permanent state of backfit (as opposed
to improvement.)

Tom Merkle