(Derek Lyons) wrote:
LooseChanj wrote:

My opinion is still do at least Orbiter Mark II. Start with a design for
which we know what's good, bad, and ugly. Or 30 years from now we'll be
saying what a shame...the Saturn V never really got refined, nor did the
shuttle orbiters.

nods There's been rumbles of that now and again in these NG's, but
folks rarely want to address it directly.

There is a gospel/dogma that Apollo was near perfect, and thus all
capsules are near perfect, and that since the Shuttle is flawed, all
descendants thereof are irredeemably flawed as well.


Actually, Derek, many of those who have been shuttle supporters for a
long time have been slowly picking up on what the capsule people have
been saying: winged designs are hard, so lets put off doing another
winged design for a while, pick an easy design and see if we can get
the flight rate up. Have the research centers continue to work on TPS
designs, let DOD do a scram jet, and then revisit winged vessels when
we have better materials and/or design.

Seperately, many of us who have been reusable space craft supporters
for a long time have been slowly picking up on what the expendable
people have been saying: reusable designs require high flight rates
to avoid being expensive (and worse, expensive up front), so lets
concentrate on making reliable expendables that can get the flight
rate up on a pay-as-you go basis, and then use those reliable
components in steps to getting back to reusable craft.

The shuttle is sexy, major impressive, and has done things that Apollo
designers would give right arms for. But it requires heroic efforts
to be usable. Apollo required heroic efforts. But the route to CATS
requires something where heroic is too much. The fabled "airliner
flight-line turnaround" is part of the discussion, and EELVs are a
step closer; DC-X was a step closer; Falcon-V and Spaceship One are
steps closer. Maybe Kliper is a step closer.

200-series orbiters are possible. But they would be only an
incremental improvement in design, and Big Bucks items as much as Buck
Rogers. Capsules designs on make significant advances over Apollo for
better bang for the Big Bucks.

/dps

P.S. For Ray, here's a question: why would a capsule version of OSP
or CEV require as many lines of code as a shuttle? The GNC should be
a lot simpler, especially on a LEO-version (start with a modest
computer for CEV-L, replace the Pentium with a Pentium Pro for CEV-S
(S=Selene for the moon shots), and go with an Itanium for CEV-M
(Mars); processor names chosen for familiar analogy rather than as an
actual design point). In addition, many of those lines of code should
already exist (GEO transfer stage guidance, for instance).

ELCSS should also be closer to "off the shelf" now that we have
experience with Soyuz, Apollo, and Shuttle designs; the ISS designs
are also useful input, but would be overkill on a 4-day flight. Space
suit designs might also have given us engineering data that would help
with a compact modular unit (here's an opportunity for a reusable
component in an expendable airframe).

Modelling a capsule's aerodynamics and heat transfer should be simpler
than a winged design, thus saving CFD and wind tunnel costs.

So many systems should be easier to design and/or manufacture on a
capsule CEV that I would expect to see big savings from adding up all
the smaller savings. Do we lose all that in system integration costs?
Would they really be as bad or worse than the SI for the shuttle?

Tnx

/dps