(Derek Lyons) wrote:
[...]
Putting it off won't make it easier, especially considering that the
real problems have nothing to do with TPS designs or scram jets.

So what are the real problems with winged vehicle design, and how can
we address them in a timely manner? [Also, don't be lead astray by my
mentioning scram jets -- in this context, they are just a way to test
TPS]

[...]
The key to lowering expenses is reducing the standing army, which
applies regardless of winged or not, expendable or not. The next key
is lowering capital expenses, which is difficult to do with
expendables unless you have a fairly high flight rate resulting in
mass production.

Which is the point about buying LVs that other people are buying;
Ariane and Semayorka aren't currently acceptable answers when NASA
pitches to Congress, but we do have a couple choices.


Ultimately, achieving CATS isn't about engineering, it isn't about
cheap spacecraft. It's about managing capital, it's about designing
systems and processes, it's about a metric buttload of things that
have nothing to do with bending metal or pumping fuel. CATS
supporters ignore this at their peril.


Indeed.

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;

[...]

Look up above, where you said

The key to lowering expenses is reducing the standing army, which
applies regardless of winged or not, expendable or not.

Compared to the Shuttle, and probably to S-V, you'll find D4 and A5
are way ahead on this. And the Shuttle's standing army goes to
reusable components (TPS, SSMEs, and SRBs).


And in the end, you wrap up with the same statement you started.
Apollo was cool, therefore capsules are cool, the Shuttle sucks,
therefore winged vehicles suck.

No, I think the Shuttle is cool, and I'd join the ride to HST if I
could.

The Shuttle's ability to Bring Things Back is unparalled, and I'm
watching to see how this problem gets solved in the next generation.
It *will* be an important issue for serious Moon work, not to mention
sample returns from Mars.

The Problem with the Shuttle is that it is at the edge of things that
we know how to do, especially in terms of reentry, and (possibly from
being at the edge) requires a huge standing army.

A CEV using a capsule would have a much smaller standing army, part of
which would be shared by DOD and other customers, and the LV is much
closer to mass production.

Actually, I'd be interested in hearing how a lifting body CEV might
measure up, like some of the Kliper-related pics, or HL-20. It seems
that the TPS issues are more manageable there because LBs have fewer
hot spots than winged vehicles do.

I'm definitely not having a knee-jerk reaction against WVs; it took a
lot of persuasion to get me to see the above viewpoint. It is true
that one design or the other goes in or out of fashion at various
times. In the long run, I think we need to do both (though not always
at the same time) in order to actually get past our current
limitations.

/dps