For your reference, records indicate that
Fred J. McCall wrote:

Doc O'Leary wrote on Fri, 8 Jun
2018 13:10:48 -0000 (UTC):

What are the actual numbers when it comes to savings from a reusable
rocket?


That depends on a lot of things.

Well, sure, but it always helps to have some data to work with before
beginning an optimization process. Best/worst cases or averages or
whatever. What the savings is related to the total cost of the launch
is going to be guiding factor on how much effort it makes sense to
expend to re-use different parts of the system.

It’d also be interesting to know how new technologies might
impact the economics of launching items into space (including just making
disposable launch vehicles much cheaper).


Real reuse will always be cheaper. If you can make disposable launch
vehicles much cheaper, the same technologies allow making reusable
launch vehicles much cheaper.

That is non-obvious. Ideally, I would think a “zero waste” system
would be cheapest; every kg of mass that gets sent up either stays up
(doing something useful) or was the fuel. All this booster landing
(and subsequent refurbishing for relaunch) we’re seeing, while cool,
is definitely *not* the most efficient use of resources.

Once you start to contemplate
the need for multiple daily launches, even recovering boosters to reuse
them seems like a slow and labor-intensive process.


But orders of magnitude faster than throwing them away and building a
new one.

But that’s still assuming old technologies rather than new ones. You
don’t “throw away” a space elevator. Nor a mag-lev cannon. I’m not
sure how viable a high-altitude balloon launch would be, but it may
also be cheaper than traditional first-stage rockets.

On the path to a
space elevator, it seems like there should be many more ways to reach
escape velocity that do a better job than what Musk is doing today.


You've discovered a good supply of unobtainium, have you? Otherwise,
rockets are your man for getting stuff to orbit for the foreseeable
future.

It’s always a good idea to noodle around with other technologies, no
matter how impossible they appear to be today. Because, yes, rockets
are the way to get to orbit, but I’m most interested in the
*unforeseeable* future that has humans on other planets around other
stars. Just being satisfied with rockets is not going to make that
happen.

--
"Also . . . I can kill you with my brain."
River Tam, Trash, Firefly