Cheap Realistic Space Flight

I'm trying to imgaine cheap space flight. I'd also like to see it
sooner rather than later. Given this I believe we are limited to
chemical rockets.

What's the cheapest cost to orbit a chemical rocket is likely to
yield in the next fifty years? Will we see $100/pound to orbit?
How about $10/pound? And what underlying technology will
this rocket use?

Note: Please avoid the use of wormholes and unobtanium. Please
don't say "carbon nanotubes will solve everything" unless you also
believe that we will build 50,000 lbs structures in carbon nanotubes
sometime in the next 50 years. We're looking reasonably far into
the future (50 years or less) but trying to limit ourselves to chemical
rockets and things that can actually be built and used.

"Charles Talleyrand" wrote in message ...
I'm trying to imgaine cheap space flight. I'd also like to see it
sooner rather than later. Given this I believe we are limited to
chemical rockets.

If you are talking about cheap, but politically unrealistic
spaceflight, I don't think anything could beat Orion. More politically
plausible would be NTR , I think still cheaper then chemical (without
development cost).

In article , says...
What's the cheapest cost to orbit a chemical rocket is likely to
yield in the next fifty years? Will we see $100/pound to orbit?
How about $10/pound? And what underlying technology will
this rocket use?


NASA was talking a few years ago of getting it to $1000/pound in the
future. No way will they achieve it soon.

But you need to specify more details.

Say it costs you $X to develop the rockets
Say you build a launch pad for $Y
Say each rocket costs $Z
Say each rocket carries P pounds

and use it to fire N rockets

Then your cost per rocket per pound = (x+y+z) * P / N

N at present is probably the most disappointing figure.

--
I hope that God's behaviour improves in the future?

What's the cheapest cost to orbit a chemical rocket is likely to
yield in the next fifty years? BRBR


The trouble is that there's no simple answer. "It depends" sounds like a cop
out, but it's true. The market demand, and thus the flight rate, are as or
more important than the vehicle design and operation in determining cost per
pound to orbit of the system. For example, the Pegagus guys say their cost
would be about 1/3 what it is now if the flight rate was 4x higher, so the
fixed infrastructure could be spread over more flights.

Assuming a robust market, the likely low-cost approach is a mix of dumb simple
ELVs for medium and heavy lift and TSTO RLVs for specialty missions like
shuttling humans to LEO. (An SSTO RLV should be cheaper to operate but will
take more upfront investment than TSTO, and again, the market wil ldetermine
which approach would produce the lowest cost.)

Confusing enough? It gets a lot worse in practice


Matt Bille
)
OPINIONS IN ALL POSTS ARE SOLELY THOSE OF THE AUTHOR

Charles Talleyrand wrote:

What's the cheapest cost to orbit a chemical rocket is likely to
yield in the next fifty years? Will we see $100/pound to orbit?

Sure.

How about $10/pound?

Probably not.

And what underlying technology will
this rocket use?

High flight rates. No reason we couldn't achieve $100/lb using 1960's
tech. Just need to build in numbers and fly a lot.


--
Scott Lowther, Engineer
Remove the obvious (capitalized) anti-spam
gibberish from the reply-to e-mail address

Charles Talleyrand wrote:
I'm trying to imgaine cheap space flight. I'd also like to see it
sooner rather than later. Given this I believe we are limited to
chemical rockets.

What's the cheapest cost to orbit a chemical rocket is likely to
yield in the next fifty years? Will we see $100/pound to orbit?
How about $10/pound? And what underlying technology will
this rocket use?

Note: Please avoid the use of wormholes and unobtanium. Please
don't say "carbon nanotubes will solve everything" unless you also
believe that we will build 50,000 lbs structures in carbon nanotubes
sometime in the next 50 years. We're looking reasonably far into
the future (50 years or less) but trying to limit ourselves to chemical
rockets and things that can actually be built and used.



This is frequently discussed on sci.space.policy.

Some believe if rocket engines were massed produced economies of scale
would make launch expense much less.

They are hoping the X-prize contenders will open a new industry of space
tourism, and that many would pay to enjoy sub orbital flight into near
earth space just as people paid to enjoy rides with barn stormers in the
early days of aviation.

It's argued that a free market could make rockets common just as it has
done for motor cars, airplanes, and computers.

If rocket engines become very affordable, the expense may be dominated
by fuel. I believe your fuel to payload ratio is e^(Vf/Ve) where Vf is
final velocity and Ve is exhaust velocity. IIRC 4 km/sec is good exhaust
velocity for chemical rockets. And 8 km/sec is an orbital velocity. So
e^(8/4) = e^2 = about 7.4. So you'd need more than 7 times the mass of
your payload in fuel.

Another obstacle is government regulation. I can see the need for
regulation but some sci.spacers argue that existing regulations will
smother the space tourism industry before it's born.

--
Hop David
http://clowder.net/hop/index.html

In article ,
Charles Talleyrand wrote:
I'm trying to imgaine cheap space flight. I'd also like to see it
sooner rather than later. Given this I believe we are limited to
chemical rockets.

There are actually a number of alternatives that would be realistic on
a timescale of a few decades, e.g. laser launchers. However, taking the
question as read...

What's the cheapest cost to orbit a chemical rocket is likely to
yield in the next fifty years?

That depends enormously on just how things evolve -- it is not primarily a
technological question. To the extent that it is technological, the
technical issues are things like heatshield maintenance requirements,
which are very difficult to predict.

Will we see $100/pound to orbit? How about $10/pound?

The former is very likely. The latter is conceivable but rather a
stretch: a cheap propellant combination like LOX/propane can in theory
put stuff in orbit for $1-2/lb of dry mass, but *payload* will be only a
modest fraction of the dry mass, and getting maintenance and overhead down
to the point where fuel cost is a large fraction of total operating cost
would be challenging.

And what underlying technology will this rocket use?

The best bets, in my opinion, are (a) carbon-fiber or *possibly* nanotube-
composite structures, (b) innovative engine designs with rather better
performance than conventional approaches, and (c) reentry concepts that
unfurl or inflate a large heatshield, much larger than the vehicle proper,
so as to reduce the demands on the heatshield materials. But there are
alternative approaches aplenty; again, much will turn on non-technical
issues.

don't say "carbon nanotubes will solve everything" unless you also
believe that we will build 50,000 lbs structures in carbon nanotubes
sometime in the next 50 years.

I think that's credible, but by no means certain. Making a good composite
structural material using nanotubes as the fiber is much harder than just
making nanotubes. Lots of people are working on it, but it's a difficult
problem and it might not *have* near-term solutions. (People have been
trying for nearly 20 years to make high-power wire using liquid-nitrogen
superconductors, with only the most limited results so far.)
--
MOST launched 30 June; first light, 29 July; 5arcsec | Henry Spencer
pointing, 10 Sept; first science, early Oct; all well. |

"Charles Talleyrand" writes:

I'm trying to imgaine cheap space flight. I'd also like to see it
sooner rather than later. Given this I believe we are limited to
chemical rockets.

What's the cheapest cost to orbit a chemical rocket is likely to
yield in the next fifty years? Will we see $100/pound to orbit?
How about $10/pound? And what underlying technology will
this rocket use?


$10/pound is close to the ultimate limit, barring miracle tech,
of three times the fuel/energy cost. That's where the airline
industry has stabilized after a hundred years of manned airline
flight, and the same economic logic seems to apply.

But it took a hundred years for the airline industry to get where
it is today, and anyone suggesting we've already had fifty years
of actual progress in space launch will be laughed at. Fifty
years from now, we'll probably still be at the $100/pound level
and still trying to figure out the ultimate best way to run the
show.

The underlying technology will be, well, rocketry. Pump liquid
oxygen and probably something hydrocarbonish into a metal chamber,
burn same, and exhaust through a converging/diverging nozzle.
Use some fraction of the propellant that hasn't been burnt yet
to A: regeneratively cool the whole assembly and B: run the fuel
pumps. This works as well as anything that can be expected to;
it converts 95+% of the energy content of the propellant into
kinetic energy at a prodigious rate in an extremely compact
system.

There may be some use of airbreathing engines and wings to augment
rocketry during the early part of the mission, especially if the
best system turns out to be two-staged. I strongly doubt that this
will ultimately be the best, but it makes for an easier introduction
to the field and may still be state-of-the-art in 2053 even if I
expect it to be quaintly archaic by 2103.

The only advanced technology at less than the miracle level that
will really change things is materials science; better structural
materials and better thermal protection systems will be seriously
helpful. What is actually necessary, is better systems engineering,
and that's mostly not a technology issue.


--
*John Schilling * "Anything worth doing, *
*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
*Chief Scientist & General Partner * -13th Rule of Acquisition *
*White Elephant Research, LLC * "There is no substitute *
* for success" *
*661-951-9107 or 661-275-6795 * -58th Rule of Acquisition *

"Henry Spencer" wrote in message ...
The best bets, in my opinion, are (a) carbon-fiber or *possibly* nanotube-
composite structures, (b) innovative engine designs with rather better
performance than conventional approaches, and ...

In what way will these engines be better than the current ones?

I understand that the current engines opperate at a very large fraction of
the theoretical performance. So I assume you're talking about either lower
weight or lower cost. Is that correct?

Is this also correct: you do not believe that concepts like ORTAG are
the way to go? Why? I have to admit the concept appeals to me.

-Curious
-Randy

Charles Talleyrand wrote:
Is this also correct: you do not believe that concepts like ORTAG are
the way to go? Why? I have to admit the concept appeals to me.

Big Dumb Boosters are a strongly viable short term
technology step; credible designs start at around a
thousand dollars a pound for multi-ton payloads and up,
and for high flight rates should drop below $500/lb.

The question is ultimately how cheap can they get.
The studies which have been done so far indicate
that the number is under $500/lb, possibly under $250/lb,
but almost certainly not less than $125/lb.

People are not going to be satisfied in the long
run with dropping costs only to a couple of hundred
dollars a pound or so. Barring magic materials or
fabrication technologies, BDB isn't going to get there.

Though, I have to say, the BDB implications of some of
the composite technologies which are now beginning to
see the light of day have not been openly fully evaluated
to date, and the possible implications for BDBs of cheap
carbon nanotube composites abound as well, so ruling out
magic is perhaps premature ;-)


-george william herbert