Re: Spaceship One stepping-stone or dead-end?

From: Jeff Findley (jeff.findley_at_ugs.nojunk.com)
Date: 09/30/04 

Date: Thu, 30 Sep 2004 14:41:02 -0400

"jacob navia" <jacob@jacob.remcomp.fr> wrote in message
news:415c4d4f$0$919$8fcfb975@news.wanadoo.fr...
> Jeff Findley wrote:
> > "jacob navia" <jacob@jacob.remcomp.fr> wrote in message
> > news:415bf13d$0$30678$8fcfb975@news.wanadoo.fr...
> >
> >>Cheap access to space needs new technology.
> >
> >
> > Not at all.
> >
> >
> >>None of the commercial
> >>flights for the X prize is showing any breakthrough in propulsion
> >>methods. They are just adapting current technology for people with
> >>100 000 dolars to spend in a flight of a few moments...
> >
> >
> > What leads you to believe that we need a "breakthrough in propulsion
> > methods" to achieve private manned spaceflight?
>
> The difference in speed needed to get in orbital flight. Sub-orbital
> flight is now possible, and it was in 1963, when the X15 record was
> established that SS1 has just broken by a few km/hour.

Then explain to me how the Soyuz launch vehicle was able to put Vostok in
orbit using conventional LOX/kerosene engines.

> SS1 is now at the stage of X15 development.

More or less (if you ignore the high speed X-15 flights).

> Earth orbit however needs substantially (a factor of 9) more speed
> and this means at least a factor of 9 of costs to get it.

I know, I have an Aerospace Engineering degree.

> You mention the russian technology, but consider that each flight
> is much more than a couple of million dollars (at least!)

This is because they throw away the entire vehicle after each flight. Their
only serious attempts at reusability were to "copy" the US shuttle
(reusable) and their own Energia (who's boosters were planned to be
reusable). Otherwise, they keep making the same old Soyuz and Proton launch
vehicles because they don't have the money to develop anything new.

> This means that until humans develop an unexpensive way of getting
> into space, rockets of several stages will be the only solutions.
> And they *are* expensive.

To date, all launch vehicles (except the US shuttle, which is really only
partially reusable) have been expendable. Making them reusable would be a
huge shift in design, but would require no new technology. Large,
lightweight, empty rocket stages should be easier to recover than the large,
heavy US space shuttle.

Jeff 

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