I think that one of the things Elon does well is come up with a development
and production trajectory for things. First he built an electric car with a
really big battery, and a big motor with good acceleration; sold it at a
slight loss, got financing and made a better car, cost reduced it and made
it really good; it sold really well and then he worked on cost reducing it
more after that. Whether that's really going to work out, whether we're all
going to drive his electric cars around is less clear; but it's clearly a
good way to have gone.
And he's doing the same things with rockets. He didn't go for reusability
first, he got a rocket that worked, scaled it up, and sold it, got people
to pay for it as an expendable, and continued to fiddle with it. Even if
the full reusability doesn't work out, he's got a rocket business going,
and the first stage reusability and Dragon capsule reusability is looking
quite promising.
Meanwhile the space shuttle went for full reusability for the Orbiter from
day 1. That does not seem to have worked. It lead to fatal flaws that could
not be fixed. Whereas Soyuz has had loads of different versions. While
nothing is ever infinitely flexible, it can be said that Soyuz is more
flexible and the Space Shuttle less so, so any problems that Soyuz have had
were easier to incrementally remove.
So what? Building even an *expendable* new launcher is almost impossibleto economically justify at current launch rates.
On Mon, 28 Dec 2015, Ian Woollard wrote:
Whereas, the Shuttle *couldn't* change much.
The shuttle hardware changed quite a bit over time. There was a certain
amount of inertia, yes, but that was mostly budgetary limitations, plus an
inefficient organization that made changes very costly. There was a long
list of desired changes, but funding them was always a struggle. Some got
made only when they had become unavoidable, e.g. the cockpit-display
upgrade forced its way into the budget because the old hardware was long
out of production and spares stocks were running out. Some things that
would have substantially reduced ops costs -- notably, a switch to nontoxic
RCS/OMS propellants -- never made it in, not because there was any
fundamental obstacle, but because it was always cheaper to carry on with
the existing design a little longer.
(And if you imagine that such issues never come up for expendables, you're
dreaming. There's a lot of very old hardware and software still in service
on today's expendables.)
...the maximum payload climbed from ~20 tonnes to over 30 tonnes, but IRC
(and I may not) some of that was changes to the external tank- an
expendable part!
It was fundamentally difficult to improve payload mass much by changing
the orbiters, because the orbiter had already been scrubbed thoroughly for
incremental payload improvements, due to weight-growth crises during
development. The original post-Challenger intent was that ASRM -- the SRB
rebuild -- would provide enough performance boost for station launches; the
lighter ET started to feature in plans only when it became clear that ASRM
was in serious budget trouble.
Full reusability, in many ways, is a trap, at the current launch rates.
So what? Building even an *expendable* new launcher is almost impossible
to economically justify at current launch rates. Anyone building even a
partially-reusable launcher is doing it in hopes of new markets and much
higher launch rates.
Henry