Cheap Realistic Space Flight

In article ,
Oren Tirosh wrote:
...(b) innovative engine designs with rather better
performance than conventional approaches,

For what definition of "performance"? Energy efficiency is already
fantastic in today's rockets.

Well, no, it's not all that terrific... but it is probably about as good
as it is going to get, aside from the question of altitude compensation.

Thrust/Weight? Performance in the atmosphere?

Yes, and some other things -- see previous posting.
--
MOST launched 30 June; first light, 29 July; 5arcsec | Henry Spencer
pointing, 10 Sept; first science, early Oct; all well. |

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?
How about $10/pound? And what underlying technology will
this rocket use?

Depends on what you're planning to send. For example, if your payload is
capable of withstanding, say, 50 gravities, you could launch via a railgun
(a la Jules Verne). You'd only need a 60 km long rail. Cost to orbit
would be just about nothing; the main expense would be amortizing the
railgun cost, and the technology is basically "off the shelf." There's
been talk of building a prototype along Mauna Loa (nice, tall mountain near
the equator and in the middle of the ocean so neighbor's don't complain
about the noise).

You could use the railgun to cheat a little; at a modest 3 gravities, that
60 km railgun would get you up to about 2 km/sec. Not sure how much that
would cut your cost-to-orbit, but it would probably be a significant
amount.

Jeffs

Jeff Suzuki writes:

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?
How about $10/pound? And what underlying technology will
this rocket use?

Depends on what you're planning to send. For example, if your payload
is capable of withstanding, say, 50 gravities, you could launch via a
railgun (a la Jules Verne). You'd only need a 60 km long rail.

Two problems:

1.) A railgun basically can only be used =ONCE=. After each firing, it needs
to be almost completely rebuilt, as the "rails" pretty much destroy themselves.
This is =NOT= a recipe for "cheap."

1.) You =CANNOT= build a 60 km long railgun, as they don't scale up well;
high-performance railguns are intrinsically ultra-high acceleration devices.
Your railgun will have to be MUCH shorter, and your payload will need
to be able to tolerate MUCH higher gees.

Hence, I strongly suggest you look at other types of "guns" or accelerators.


-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'

Jeff Suzuki wrote:

Depends on what you're planning to send. For example, if your payload
is
capable of withstanding, say, 50 gravities, you could launch via a
railgun
(a la Jules Verne). You'd only need a 60 km long rail.

You're still going to need an orbital insertion burn when you get up
there, though granted it can be made much smaller.

Cost to orbit
would be just about nothing; the main expense would be amortizing the
railgun cost, and the technology is basically "off the shelf."

I'm not sure where you get "off the shelf," since no one's managed to
make a railgun that doesn't melt itself to slag each time it's used.

--
Erik Max Francis && && http://www.alcyone.com/max/
__ San Jose, CA, USA && 37 20 N 121 53 W && &tSftDotIotE
/ \ I want to know God's thought; the rest are details.
\__/ Albert Einstein

You could use the railgun to cheat a little; at a modest 3 gravities, that
60 km railgun would get you up to about 2 km/sec. Not sure how much that
would cut your cost-to-orbit, but it would probably be a significant
amount.

2000 m/s muzzle velocity looks a bit low to me. I like 2500 m/s.

Here are the results from a simulation of various single-stage propane-LOX
rockets fired from guns at the equator. The payload masses rise with launch
velocity so fast because the thing being held constant is the engine thrust.

payload_mass delta_v drag_loss gravity_loss throw_mass muzzle_vel gun_elev
kg m/s m/s m/s kg m/s degrees
1803.00 1600.00 2086.93 497.44 3576.36 8223.86 12.05
1314.63 1900.00 2073.22 515.91 2870.77 7931.33 13.73
996.89 2200.00 2016.40 535.96 2398.07 7597.79 15.42
776.89 2500.00 1929.73 557.93 2060.36 7236.58 17.16
618.42 2800.00 1821.94 582.01 1809.70 6856.80 18.97
501.27 3100.00 1700.54 608.29 1619.85 6466.46 20.87
411.62 3400.00 1570.54 637.28 1470.42 6070.84 22.88
341.88 3700.00 1436.82 669.24 1351.50 5675.41 25.02
286.69 4000.00 1299.67 704.56 1255.60 5281.03 27.33
241.92 4300.00 1171.67 744.15 1175.64 4900.97 29.85
205.70 4600.00 1045.85 788.06 1110.65 4529.21 32.59
175.91 4900.00 927.11 837.17 1056.97 4171.61 35.60
151.13 5200.00 816.74 892.42 1012.39 3830.68 38.91
130.30 5500.00 715.68 955.04 975.15 3508.91 42.59
112.83 5800.00 625.00 1025.58 945.31 3208.76 46.65
97.97 6100.00 544.87 1105.86 921.24 2932.44 51.15
85.28 6400.00 475.52 1197.42 902.49 2682.24 56.11
74.43 6700.00 416.92 1301.54 889.08 2459.81 61.51
65.07 7000.00 368.78 1420.52 880.35 2267.05 67.33
57.00 7300.00 329.92 1555.42 876.67 2103.48 73.43
50.01 7600.00 300.71 1707.65 878.01 1969.71 79.65
43.90 7900.00 280.17 1878.94 884.15 1864.60 85.76

This is effectively a two stage to orbit design, with the gun acting as
the first stage. There are a number of constants for this simulation:

thrust2mass 500.00 m/s^2 tank2fuel 20.00 m -
exhaust_v 3300.00 m/s motor_thrust 5000.00 N
pointing 1000.00 m - fuel_density 1222.00 kg/m^3
fuel_price 7000.00 m $/kg length2diam 10.00 -
cd 150.00 m - collar_mass_fraction 200.00 m -
final_orbit_alt 360.00 K m muzzle_alt 0.00 m
orbit_vel 7692.43 m/s

Like most orbital insertion rockets, this one has a short high
acceleration stage (the gun) followed by a long low acceleration
stage. The short high acceleration stage is not a cheat -- it
accomplishes three important objectives:

(a) it gets the upper stage into thin air, where a high-expansion
high-ISP LOW-PRESSURE engine can operate (no turbopumps),
(b) it eliminates the need for an upper stage that can lift its own
weight, and
(c) it sharply reduces the gravity losses from a low-acceleration
upper stage.

Guns are particularly nice for first stages, since they have gigantic
reaction masses that give them high energy efficiency. I like simple
chemical guns, either gunpowder or maybe LOX-propane, as they are
generally reusable and don't have anything as expensive and development-
intensive as turbopumps or railguns. They also won't deliver muzzle
velocities over 3 km/s, and 2500 m/s is a bit of a stretch.

My particular favorite above is the delta-v=6700, muzzle_v=2460 point.
Note that the rocket, when it lights up, masses 889 kg and has 5000 N
of thrust. That's just over a half G of acceleration -- the thing
loses speed for a good chunk of its flight, and gets to orbit anyway.

Nothing like this is ever going to be man rated or even useful for
most satellites. With some ingenuity, you might be able to launch
some sturdy satellite bits -- perhaps the RCS system and fuel, and
perhaps the solar arrays, folded up to fit inside the propane fuel
tank of the launched rocket, with a foamed silicon carbide backing to
give it neutral buoyancy to survive the launch.

(Iain McClatchie) wrote in message . com...

Guns are particularly nice for first stages, since they have gigantic
reaction masses that give them high energy efficiency. I like simple
chemical guns, either gunpowder or maybe LOX-propane, as they are
generally reusable and don't have anything as expensive and development-
intensive as turbopumps or railguns. They also won't deliver muzzle
velocities over 3 km/s, and 2500 m/s is a bit of a stretch.


This is an interesting idea that I'm surprised has not received more
attention: a combustion-driven single-stage gas gun as a
"zeroth-stage" booster using combustible gases as the propellant.

This is probably the most low-tech boost-assist device you can
imagine: no moving parts, low tolerances on barrel design, low
pressure loads on barrel, and principles of operation that are
completely understood. Also, a dirt-cheap fuel that is logistically
trivial to handle. Being gaseous-based, it also scales up nicely
(designing and fabricating large-bore powder charges is a demanding
art with not many practioners left).

One suggestion would be to consider using methane (or even natural
gas) as opposed to propane. The lower molecular weight products would
translate into a higher muzzle velocity (as you mentioned, 2.5 km/s is
probably stretching it). Also, methane is much less detonable than
propane, and you probably would want to avoid detonation as the
combustion mode. Very rich methane with oxygen would be optimal for
low detonability and high sound speed products.

Also, note you want to use *gaseous* oxygen in breech, not LOX. LOX +
hydrocarbon fuel = very sensitive high explosive!
--
Andrew J. Higgins Mechanical Engineering Dept.
Assistant Professor McGill University
Shock Wave Physics Group Montreal, Quebec CANADA
http://www.mcgill.ca/mecheng/staff/academic/higgins/

"Gordon D. Pusch" wrote in message ...
Scott Lowther writes:

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.

...Kind of like the Russions do with their "Proton" booster...


You people are either being sarcastic or silly. Getting $100/pound using
1960's technology requires building thinsg like the Titan and Saturn for
around $5,000,000 per copy, which seems wildly unlikely.

And the Proton is no where near $100/pound to orbit. And there labor
is much cheaper than ours.

In article , says...
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?
How about $10/pound? And what underlying technology will
this rocket use?

Depends on what you're planning to send. For example, if your payload is
capable of withstanding, say, 50 gravities, you could launch via a railgun
(a la Jules Verne). You'd only need a 60 km long rail. Cost to orbit
would be just about nothing; the main expense would be amortizing the
railgun cost, and the technology is basically "off the shelf." There's
been talk of building a prototype along Mauna Loa (nice, tall mountain near
the equator and in the middle of the ocean so neighbor's don't complain
about the noise).

You could use the railgun to cheat a little; at a modest 3 gravities, that
60 km railgun would get you up to about 2 km/sec. Not sure how much that
would cut your cost-to-orbit, but it would probably be a significant
amount.


Do you have any further details on this railgun.

--
It is amazing how complex a simple machine is when you try to fix it.

10th saying of Bernard

"Charles Talleyrand" writes:

"Gordon D. Pusch" wrote in message ...
Scott Lowther writes:

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.

...Kind of like the Russions do with their "Proton" booster...


You people are either being sarcastic or silly. Getting $100/pound using
1960's technology requires building thinsg like the Titan and Saturn for
around $5,000,000 per copy, which seems wildly unlikely.

And the Proton is no where near $100/pound to orbit. And there labor
is much cheaper than ours.

The Proton's $700/lb is closer to $100/lb than it is to the Space Scuttle's
$30,000/lb --- even on a logarithmic scale. The Russians acheived this
lower cost primarily by using a _SIMPLER DESIGN_ (the cost of a rocket
tends to be proportional to the number of components it has, not its size),
and by good old fashioned capitalistic _ECONOMIES OF SCALE_, amortizing
its design and tooling costs over a large number of manufactured units ---
=NOT= by "lower labor costs."


-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'

In article ,
Charles Talleyrand wrote:
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.
...Kind of like the Russions do with their "Proton" booster...

You people are either being sarcastic or silly. Getting $100/pound using
1960's technology requires building thinsg like the Titan and Saturn for
around $5,000,000 per copy, which seems wildly unlikely.

It has been reported that Proton costs less than $1M to build, although
such numbers are notoriously dependent on the assumptions made. The
Russians invested heavily in automated production for operational
launchers -- none of this business of building each one by hand in a
cleanroom -- and in automated pad operations.

And the Proton is no where near $100/pound to orbit.

The *price* of a Proton is far above $100/lb, but that says little about
their *costs*. They are politically required to set their prices not too
much lower than Western launchers.

And there labor is much cheaper than ours.

Quite true, but they also need much less of it. The same principle could
be applied here.
--
MOST launched 30 June; first light, 29 July; 5arcsec | Henry Spencer
pointing, 10 Sept; first science, early Oct; all well. |