Hello
I have long felt that the best way to lower the cost to orbit is to
construct a ground based launch system that can accomodate most
existing launch vehicles. I mean some sort of launch rail system that
either via EM or jets or rockets or rubber bands can accelerate a
launch vehicle to near escape velocity.

Hear me out. Such a system would be complex and costly but none of it
would have to be flight worthy so steel and concrete could be used.
Development would be simplified since failures could be repaired or
modified rather than exploding and requiring a new launcher as a new
rocket would require.

What do you think?

> Hello
> I have long felt that the best way to lower the cost to orbit is to
> construct a ground based launch system that can accomodate most
> existing launch vehicles. I mean some sort of launch rail system that
> either via EM or jets or rockets or rubber bands can accelerate a
> launch vehicle to near escape velocity.

Since there are no existing launch vehicles capable of taking the
stresses of being launched to near escape velocity in any reasonable
distance (say a few kilometers), nor are there any capable of handling
the aerodynamic stresses of escape velocity within the atmosphere, I
think this idea pretty much dies on the drawing board. The thermal
loads are pretty horrific, too. There is no way to do this with
existing launchers, and designing a launcher for it is likely to be
nearly impossible. Certainly you can't launch humans on it (which is a
*big* deal, IMO, since humans are the killer app for opening the high
frontier).

> Hear me out. Such a system would be complex and costly but none of it
> would have to be flight worthy so steel and concrete could be used.
> Development would be simplified since failures could be repaired or
> modified rather than exploding and requiring a new launcher as a new
> rocket would require.

A fixed structure capable of giving a modest boost to a purpose
designed launcher might turn out to be worth it if the flight rate was
high enough. There have been various proposals to run magnetic
launchers up the sides of e.g. Kilimanjaro, or one of the Hawaiian
Volcanos, or a peak in the Andes. Not totally nuts, but you really need
a guaranteed high flight rate in order to justify engineering on that
scale.

All the schemes for making orbit need high flight rate in order to
bring down costs. The dirty little secret of spaceflight is that it
really isn't that hard to make orbit. It's been known how to do it for
50 years, and the available materials and design tools just keep
getting better and better. O'Neill understood this, which is why he
pushed SPS in order to get flight rates up and get infrastructure built
in space. By 1965 the basic problems of spaceflight had been solved,
and by 1975 we knew how to perform relatively complex tasks in space.

The reason NASA keeps bolloxing up X-programs is that they are focused
on technology development (and pork) - this means they have absolutely
the wrong mindset for bringing down costs. Low costs are best achieved
by small refinements on known-good systems, not by starting from a
blank slate each time. The other part of the equation is flight rate:
much of the cost of a launch system (the pads, the production lines,
the design process, handling infrastructure) is independent of flight
rate, so adding another launch is only a modest expense. In order to
pay for the whole thing, you need to get the total number of launches
up, so you amortize the infrastructure and development investment over
many launches.

......Andrew

>What do you think?

I think you've been mainlining Heinlein. Which is not at all a bad thing :)

This is precisely the plan he so effectively novelized in his now-classic
libertarians-in-space opera, "The Moon Is A Harsh Mistress."

Ad astra per aspera -- spike

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