On Oct 22, 8:08 pm, BradGuth wrote:
On Oct 21, 5:33 pm, wrote:
On Oct 21, 1:21 am, BradGuth wrote:
On Oct 20, 7:58 pm, wrote:
On Oct 20, 4:18 pm, BradGuth wrote:
On Oct 20, 9:00 am, wrote:
More information on this hypthetical moonship.
http://en.wikipedia.org/wiki/Gas_core_reactor_rocket
A gas core nuclear rocket sustainer with chemical rocket boosters for
take off and landing built out of Apollo era hardware, to build and
sustain a moonbase.
600,000 lbs lift-off weight
360,000 lbs propellant
180,000 lbs lox
180,000 lbs lh
30,000 lbs booster
150,000 lbs sustainer
150,000 lbs payload weight
90,000 lbs structural weight
45,000 lbs of this is the gas core nuclear fission engine
900,000 lbs thrust at lift off
(2x 400,000 lbs - lox/lh liquid fuele booster - J2)
(1x 300,000 lbs - lh fueled gas core fission rocket)
(8x 15,000 lbs - lox/lh liquid fueled maneuvering rockets - RL10)
Chemical booster 450 sec Isp
Gas core nuclear susteainer 4,000 sec Isp
Top speed;
Booster: Vf = 450*9.82*LN(600,000/(600000-210000))
=1,910 m/sec (4,256 mph)
Sustainer Vf = 4000*9.82*LN(390,000/(390,000-150,000))
= 19,070 m/sec (45,642 mph)
Combined: 20,980 m/sec (49,898 mph)
The volume of hydrogen is 1,168 cubic meters (41,277 cf)
The volume of oxygen is 68 cubic meter (2,386 cf)
total propellant volume is 1,236 cubic meters (43,663 cf)
This is about the same volume as the S-II second stage.
http://en.wikipedia.org/wiki/S-II
So, one can imagine a reduced oxygen tank size for the SII, and
increasing the hydrogen tank by moving the bulkhead between the two -
which achieves the 405,000 lb mass with the appropriate mass ratios.
Remove the centrally located J2 and add the 45,000 lb weight and
300,000 lb thrust gas core nuclear sustainer in its place. Drop 2 of
the 4 remaining J2 engines, keep 2 J2s at boosters at lift off from
Earth. Add 4 RL10S clusters (8 total) at 2 of the of old J2
locations
for take off landing and meneuvering around the moon.
The SIVB is configured for a moonbase module similar to skylab for for
operations at 1/6 gee instead of zero gee..
To deploy the SIVB modules on the lunar surface equip the SII with a
simple
loading crane to erect on the lunar surface and then to lift the SIVB
out of its position atop the SII and put it in place near the landing
point. Apollo 14 landing next to the Surveyor spacecraft on the moon
shows that even in Apollo days you could land pretty accurately on
the
moon. With a radio transponder the SII-GC version could land at the
same point precisely each time. So, the crane could be erected after
each landing to remove an additional payload bay. After a half dozen
flights a base would be established and the personnel carrier version
of the SIVB large enough to carry a crew of 30 - or 10 plus supplies
- for crew rotations - would maintain the base after it was
completed.
http://www.astronautix.com/lvs/wintu....nasaspaceflig...
The Model 979 flyback booster for the Saturn SIC - the first stage,of
the Saturn V - could easily be adapted for the smaller SII second
stage. A
large nose cone with cargo doors would carry the SIVB inside
.
? 600,000 lbs lift-off weight ?
By your own numbers, it seems as though your 600,000 lbs of lift-off
weight or GLOW is in error, especially if including all the realted
fuel, payload and infrastructure or inert mass. Or, is it just my
having missed something obvious?
- Brad Guth -- Hide quoted text -
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I dunno, did I add it up right?
600,000 lbs lift-off weight
360,000 lbs propellant
that leaves 240,000 lbs everything else
the 360,000 lbs propellant is broken down into
180,000 lbs lox
and
180,000 lbs lh
and the 180,000 lbs lh is broken down to
30,000 lbs booster
150,000 lbs sustainer
The 240,000 lbs everything else is
150,000 lbs payload weight
thet's the SIVB payload configured as a luna-lab
and
90,000 lbs structural weight
everything else. that 90,000 lbs is broken down into;
45,000 lbs of this is the gas core nuclear fission engine
and 45,000 lbs everything else (the SII booster)
So, it all adds up to 600,000 lbs...
We have 1.5 gees at lift off because we have
900,000 lbs thrust at lift off
Broken down as;
(2x 400,000 lbs - lox/lh liquid fuele booster - J2)
(1x 300,000 lbs - lh fueled gas core fission rocket)
(8x 15,000 lbs - lox/lh liquid fueled maneuvering rockets - RL10)
The engines are throttable. The nuclear engine is started midflight
and brought to full throttle during ascent. The RL10s and J2s at 100%
thrust produces 920,000 lbs at lift off - and as propellant is burned
off, and the nuclear engine brought up to full thrust, gees mount to 2
gees - at which point the RL10s and then the J2s are throttled back.
The vehicle ascends directly to lunar injection speed and then shuts
down until it gets to the vicinity of the moon and does its major
delta vee with the sustainer - doing a direct descent. The final
landing is with the RL10s and nuclear engine off. But they account
for only a very small fraction of the total delta vee as indiciated.- Hide quoted text -
- Show quoted text -
240/600 = 40% inert, which seems a wee bit on the high side for
getting 75 tons into leaving Earth behind in its nuclear dust, but
what do I know.
- Brad Guth -- Hide quoted text -
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Indeed, one wonders what you know given all that you post.
You would do well to learn the rocket equation
Vf = Ve * LN(1/(1-u))
where Vf = final velocity
Ve= exhaust velocity
LN( = natural logarithm
u = propellant fraction
And Ve = g0 * Isp
g0 = acceleration at Earth's surface = 9.82 m/s/s
Isp = specific impulse in sec
A gas core nucleer rocket if one were built would likely have a
pitiful thrust to weight ratio compared to a chemical rocket. So, you
would expect the propellant fraction to be dismal as well.
However, on the plus side, exhaust speeds would be astronomical. A
4,000 sec Isp means exhaust speeds approach 40 km/sec. Which means
with a 60% propellant fraction you can achieve;
Vf/Ve = LN(1/(1-0.6)) = 0.916
or 91.6% exhaust speeds. So, with an exhaust speed something like 10x
that of chemical rockets, final speeds even with dismal propellant
fractions approach 36 km/sec - 7x the stage speeds of chemical
rockets.
Unlike our NASA/Apollo (aka Saturn V) fiasco of having merely a 60:1
ratio of rocket per payload that was nearly 30% inert to start off
with, there's no doubt that via applied nuclear energy it's all
perfectly doable. So, when are those fully 3D interactive simulations
as easily created and thus virtual proof-tested by way of those public
supercomputers, as already programmed with all the known laws of
physics, going to knock our fly-by-rocket socks off?
As I'd said, your gas-core thruster should have easily become one of
those nifty supercomputer proof-tested items. Is there a problem with
that?
- Brad Guth -- Hide quoted text -
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Brad, its hard to tell what you're going on about. We've known that
gas core reactors would be an interesting development in rocketry
since the 1940s. We either haven't done the research, or haven't done
the research publicly. And anyone competent in nucleonic and thermal
transfer calculations can estimate what a gas core rocket would look
like. Details of course can vary.
http://www.inspi.ufl.edu/research/gcr/index.html
Nuclear pulse propulsion and nuclear thermal solid core rockets are at
either end of a continuum that includes liquid core rockets and gas
core rockets.
The working codes and actual technical details obviously have
significant weapons applications - so any work which might have been
completed over the past 60 years most likely has been completed in
secrecy.
But add eletromagnetic and dynamic flow calculations to the nucleonic
and thermal diff eq, and its easy to show a toroidal scheme is likely
possible, and is well within the capacity of 1950s or 60s technology -
with a dedicated effort. The ratio of gas pressure to external
pressure to hold a gas core in place - a factor called beta in fusion
research must be far less than 1 for a reactor to work. Its quite
easy to show that a counterflow toroidal system that makes use of the
charged fissile plasma as a current that produces a large external
magnetic field - as well as using the centripetal acceleration of the
this flow - produces beta well below one with very simple designs -
and has good thermal transfer properties.
If sucy programs were carried out in secret and resulted in rocket
engines that have 4,000 sec Isp or more - its too damn bad they
weren't made public because our nation is involved in a war that at
its core is an argument over the availability of fossil fuels and how
the profits earned by the owners of those fuels will be spent. I
think it ironic that in the name of national security we ignored the
very technology that if widely available to qualified commercial
vendors would make us more secure not less. And as a side benefit
would answer Tito's complaint about Clarke's prediction in 1968 - that
a ticket to orbit would be $200 by 2001.
Humanity uses energy at a rate of 10 trillion watts. One moderately
sized gas core reactor could produce ALL this energy at a very low
cost. 'Putting a gas core reactor as the energy producing portion of
a magneto-hydrodyamic generator would make containment even simpler,
and provide a compact world energy source. Such a source could
produce fresh water on a massive scale from sea water,process the
salts that are left behind into industrial chemicals, take a small
portion of the water and electrolyze it into hydrogen and oxygen, take
a portion of the hydrogen and combine it with atmospheric CO2 to
produce methane, polyermize the methane into higher alkanes like
octane (gasoline) nonane (diesel fuel) unadecane (jet fuel) - and
dominate the world's energy and fresh water and food markets.
Most people don't have a clear idea of the importance of lift capacity
to sustaining and building offworld assets. And they don't have a
clear idea of how important exhaust speed is to making practical
rocket systems. with significant lift capacity.
Laser thermal and nuclear thermal rockets are one answer to this issue
- and with significant laser capacity, laser based mirror lift
surfaces. The nuclear basis can get us started since that's 1950s era
technology. Its also a good use for our weapons grade fissile
materials now housed in nuclear weapons. I proposed 20 years ago with
the fall of the Soviet Union eminent that we enter an age of enhanced
non-proliferation using nuclear materials to mount a manned grand tour
of the solar system. That along with a global power network that
would set the stage for strong growth in the world economy - ending
our age of artificial disparity - would have avoided both the capacity
and willingness for those outside the US to attack the US and would
have avoided 9/11/01.
Its not too late to recognize that the containment policies of the
cold war are no loonger operative after the fall of the Soviet Union
and that new policies are needed for the US to maintain its global
position in the world,by using its technical know-how to lead the
world into a better richer and more interesting age