Spaceship One stepping-stone or dead-end?

Jeff Findley wrote:
While the design may need to be completely different, SS1 did what it was
supposed to do. It showed that you can build and fly an actual spaceship
for far less than NASA cost models would predict. Far, far less money was
spent on SS1 than was spent on Mercury Redstone, and Mercury Redstone didn't
enter orbit either.

I don't think that's a valid comparision. MR were testflights of a
spaceflight-capable capsule, the Mercury. Comparing it with the X-15
comes to mind, but that's also not valid as it was a program of much
larger scale and goals.

In article ,
"Jeff Findley" wrote:

"Greg Kuperberg" wrote in message
...
In article ,
jacob navia wrote:
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.

Except that twice as fast isn't twice as expensive. In practice twice as
fast is usually between 4 and 8 times as expensive (*). If you multiply
Rutan's $20+ million by 9^2, you get more than $1.6 billion.

I'm not sure if this metric is true, but even if it is, this would still be
far less than NASA spent to develop the shuttle.

That's hardly a fair comparison. In its day what the designers &
engineers did with the shuttle was cutting edge.

Not only was it the first spacecraft to be reusable (they were hoping
for 100 flights apiece) it was the first able to come down from orbit
nose first and glide to a runway rather than come down tail-first on a
suite of parachutes and land in either the ocean or some wind-swept
steppe.

Plus the part which returned was the size of a small jetliner. As
opposed to a comparatively tiny capsule capable of carrying three men
and a few kilos of moon rocks, but not much more.

Something like that was always going to cost serious money.

Those who want to emulate what it did will either need to use the
technologies it pioneered or some derivative or develop better ones; and
better ones seem unlikely to come cheaply, especially if you want to
build something similar in size to the shuttle & able to carry several
dozen passengers at a time into orbit rather than a mere handful, which
will eventually need to happen for a commercial manned spaceflight
industry to be viable.

--
Stephen Souter

http://www-personal.edfac.usyd.edu.au/staff/souters/

"jacob navia" wrote in message
...
MichaelJP wrote:
Was wondering after watching the webcast yesterday, obviously relatively
cheap sub-orbital flights are now a reality once they get the bugs
ironed
out...

But does the development of Spaceship One help with the much more useful
goal of cheaper access to orbit? As a non-expert, I understand that a
spacecraft capable of low earth orbit requires a velocity of at least
18,000mph compared to SS1's 2000mph, which is obviously a massive
difference.

So would an orbital design have to be totally different and we'd end up
back
with multi-stage expendable rockets?

- MP


Cheap access to space needs new technology. 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...


There's no breakthrough technology in the pipeline AFAIK so waiting for it
will keep us stuck on the mudball for a very long time. I think it's more
prudent to develop current technology so that it becomes safe and routine.
Unless someone can prove that a space elevator will work with current (or
very near) technology I think cheap, safe rockets in combination with rugged
capsules are our best bet.

"Jeff Findley" wrote in message
...

"jacob navia" wrote in message
...
Jeff Findley wrote:
"jacob navia" wrote in message
...

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.


But the U.S. Space Shuttle has definitively show that reusable craft aren't
really cheaper and definitely more fragile and therefore dangerous, as the
death of 14 astronauts has demonstrated. The Shuttle is a marvelous piece of
engineering, but too fragile to work reliably in the rigours of orbital
flight.

"Harald Kucharek" wrote in message
...
MichaelJP wrote:
Was wondering after watching the webcast yesterday, obviously relatively
cheap sub-orbital flights are now a reality once they get the bugs
ironed
out...

But does the development of Spaceship One help with the much more useful
goal of cheaper access to orbit? As a non-expert, I understand that a
spacecraft capable of low earth orbit requires a velocity of at least
18,000mph compared to SS1's 2000mph, which is obviously a massive
difference.

So would an orbital design have to be totally different and we'd end up
back
with multi-stage expendable rockets?
I don't think we will ever go into orbit with something that is very
similar to SS1. But I also don't think we will do it with multi-staged
expendable rockets.
If there is a market for the flights the SS1-class offers, I'm sure they
will continue development to push the envelope of current designs
further and try out new designs to add every now and then some zero-g
time to the flights, as this and the sight is what the people want.
At one point, they may develop some suborbital transportation system
which does intercontinental jumps, thus also open the market for this
kind of transport (New York - Sydney in one hour or something like
this). And then, one day, it will only be a final small step to get into
orbit from this point.

I believe that SS1 may well lead to some kind of suborbital business jet
which could wisk bigwigs from New York to London in, say, 30 minutes or so.
But it's still a long way off, a decade at least.

On Fri, 1 Oct 2004 14:13:43 +0200, in a place far, far away,
"BitBanger" made the phosphor on my monitor glow in such a
way as to indicate that:


But the U.S. Space Shuttle has definitively show that reusable craft aren't
really cheaper and definitely more fragile and therefore dangerous, as the
death of 14 astronauts has demonstrated.

It has shown nothing of the kind. All it has shown is that that
particular vehicle didn't live up to its promises.,

This is the fallacy of hasty generalization.

On Fri, 1 Oct 2004 14:09:02 +0200, in a place far, far away,
"BitBanger" made the phosphor on my monitor glow in such a
way as to indicate that:

There's no breakthrough technology in the pipeline AFAIK so waiting for it
will keep us stuck on the mudball for a very long time.

Yes, but fortunately, none is needed.

In article ,
Edward Wright wrote:
No, it hasn't. You're assuming cost squares with the square or cube of
velocity. In reality, it's closer to the square *root* of velocity.

I really don't know what plane of reality you have in mind. You mentioned
some formula from the DAPCA model, but whatever formula it is, it can
be interpreted or misinterpreted in various ways.

What I have in mind is ordinary market reality. For example, the Cessna
Citation Mustang carries 4 passengers and cruises at a maximum 340 knots.
The Cessna Skylane carries 3 passengers and cruises at a below-maximum
140 knots:

http://www.flug-revue.rotor.com/FRTypen/FRCitMt.htm
http://www.flug-revue.rotor.com/FRTypen/FRC182S.htm

So you might suppose by your rule that a Mustang costs about

sqrt(340/140)*4/3 ~ 2

times as much as a Skylane, or on the outside 3 times as much if you
allow the Mustang a fancier interior. Actually a Mustang costs 9 times
as much as a Skylane. The Mustang has an "introductory price" of $2.3
million according to the above, while a new Skylane (according to a
Cessna web page) is $250,000.

Sadly Cessna does not sell a jet that cruises at 700 knots - that would
be more like a fighter jet. Does any company sell new ones for less
than $10 million?
--
/\ Greg Kuperberg (UC Davis)
/ \ Home page: http://www.math.ucdavis.edu/~greg/
\ / Visit the Math ArXiv Front at http://front.math.ucdavis.edu/
\/ * All the math that's fit to e-print *

"Greg Kuperberg" wrote in message
...
Besides, a factor of n^2 in cost for a factor of n in speed is, if
anything, low-balling it.

Speaking as someone with an engineering degree, do you have anything to back
up this assertion?

Cost usually scales strongly with complexity and less strongly with size.
Scaling with speed, if this is a valuable metric, would seem to have a
weaker influence on cost than size.

Bullets, compared to something like an arrow, are quite fast, but are also
very cheap because they are simple and small. Arrows are larger and
generally more complex (more materials, more parts, more assembly, and etc)
and end up costing more, even though they're far slower than a bullet.

I'm curious if you've looked at any of the "big dumb booster" concepts?
These are very simple, very big, use lots of (cheap) fuel, but look like
they could put payloads into LEO. They don't fit in with the typical
"rocket scientist" philosophy of "performance uber alles", so this approach
has never really been tried before.

Jeff
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"BitBanger" wrote in message
...

"Jeff Findley" wrote in message
...
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.


But the U.S. Space Shuttle has definitively show that reusable craft
aren't
really cheaper and definitely more fragile and therefore dangerous, as the
death of 14 astronauts has demonstrated. The Shuttle is a marvelous piece
of
engineering, but too fragile to work reliably in the rigours of orbital
flight.

Perhaps I wasn't clear enough. The US Space Shuttle is not reusable. It's
only partially reusable. The shuttle is reused, but the ET is thrown away
and the SRB's are essentially completely stripped and rebuilt after each
flight.

A fully reusable system with sane propellants ought to be "gas and go" and
ought to be far cheaper than the shuttle.

Jeff
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