High strength fibers for hydrogen storage on the VentureStar.
Robert Clark
VentureStar/X-33, a single-stage to orbit vehicle:
Lockheed Martin X-33.
http://en.wikipedia.org/wiki/Lockheed_Martin_X-33
X-33/VentureStar - What really happened.
http://www.nasaspaceflight.com/content/?id=4180
Interestingly the main problem was making the liquid hydrogen tanks
light enough, certainly not a high tech problem. I wonder if
lightweight storage could be achieved by storing the hydrogen in very
many micron-scale hollow fibers. See the table of tensile strengths
listed here:
Tensile strength.
http://en.wikipedia.org/wiki/Tensile_strength
The solutions investigated for the hydrogen tanks for VentureStar
included using high strength aluminum alloys or composite fiber tanks.
The composite tanks were lighter but had a problem of debonding under
high pressure. Note in the table of tensile strengths carbon fiber has
a better strength to weight ratio than the aluminum alloy listed by a
factor of 19 to 1. And the high strength glass fibers known as S-glass
is better than the aluminum alloy by 10 to 1. There is also a special
steel fiber known as scifer steel not listed in the table that has a
tensile strength of 5500 MPa at a density of 7.8 g/cc. That is better
than aluminum alloy by a factor of 4 to 1. It might even be for the
carbon fibers and the S-glass fibers their strength to weight ratios
are so high you wouldn't need to store the hydrogen in liquid form.
You could store it as high density gas. That would eliminate the
weight of the cryogenic systems for the hydrogen.
However, a key question here is whether this strength will be
maintained in the radial direction. All the strengths listed for the
fibers are for pulling along their lengths, i.e, their longitudinal
tensile strength. But to use the fibers as thin hollow pressure tubes
will require their strength to hold in the radial direction. After
investigating this question before for hydrogen storage, I know that S-
glass and scifer steel fibers do retain that strength in the radial
directions. I'm not sure if this is true for the carbon fiber. (BTW,
the high strength polymer fibers listed in the table such as Kevlar,
Dyneema, or Spectra are unsuitable because their strength only holds
in the longitudinal direction, not radially.)
Another key problem for using high strength fibers as hollow tubes is
that they are only about 10 microns wide. So millions to billions of
them would be needed to form sizable storage tanks. You would need a
method of opening and closing these microscopically thin tubes at the
same time for a throttleable engine. Perhaps one solution would be to
have only a small portion of them being used at any one time and
letting those completely empty out, then open another portion, and so
on until all the fuel is used up. This would be an easier solution
than having so many precisely controlled valves at the micro-scale
that operated all in unison.
Bob Clark
BradGuth
> Nice articles here on the problems that led to the cancellation of the
> VentureStar/X-33, a single-stage to orbit vehicle:
>
>
> X-33/VentureStar - What really happened.http://www.nasaspaceflight.com/content/?id=4180
>
> Interestingly the main problem was making the liquid hydrogen tanks
> light enough, certainly not a high tech problem. I wonder if
> lightweight storage could be achieved by storing the hydrogen in very
> many micron-scale hollow fibers. See the table of tensile strengths
> listed here:
>
How about instead of LH2, using h2o2 at 98% purity. 100% h2o2 is
essentially a crystal like solid.
How about using a basalt fiber and micro-balloon composite as the
primary structural shell or containment vessel on behalf of whatever
fluid storage tank? (it can even be plasma metallic coated on the
inside)
h2o2 along with a little synfuel is actually offering a better
volumetric density worth of stored energy in a fluid format that's not
the least bit cryogenic or even all that vapor prone.
- Brad Guth Brad_Guth Brad.Guth BradGuth
D. Orbitt
the heavier foam insulation?
I like to think that the air force and DOD/CIA took all the parts and
made something anyway, something that's flying right now, probably
unmanned.
BradGuth
DARPA does whatever they want and whenever they want, without asking
or telling. (it's a Zionist/Nazi kind of New World Order thing, that
we're not supposed to understand)
* Brad Guth Brad_Guth Brad.Guth BradGuth
Jeff Findley
"D. Orbitt" <msu10...@aol.com> wrote in message
news:109c0c64-a6ab-403d...@k30g2000hse.googlegroups.com...
That would be a neat trick, considering the tanks failed during testing.
And we're not talking a little failure here. We're talking about big time
structural failure.
Jeff
--
A clever person solves a problem.
A wise person avoids it. -- Einstein
charlie...@yahoo.com
>
> I like to think that the air force and DOD/CIA took all the parts and
> made something anyway, something that's flying right now, probably
> unmanned.
Not really possible. Can't hide operations of a vehicle that size
Robert Clark
> Nice articles here on the problems that led to the cancellation of the
> VentureStar/X-33, a single-stage to orbit vehicle:
>
>
> X-33/VentureStar - What really happened.http://www.nasaspaceflight.com/content/?id=4180
>
> Interestingly the main problem was making the liquid hydrogen tanks
> light enough, certainly not a high tech problem. I wonder if
> lightweight storage could be achieved by storing the hydrogen in very
> many micron-scale hollow fibers. See the table of tensile strengths
> listed here:
>
Another possible solution to having so many tubes release the
hydrogen in unison might be to have them bound together with one end
closed and the other end left open but with a cap over the open end of
all of them made of a high strength material to which would be
connected the controlling valve. Since the end cap would have a much
smaller size than the full tank you could afford to have it be thicker
so as to withstand the pressure of the fuel without it taking up too
much weight. You would need though to have a strong bond between the
material of the end cap and the material composing the separate
microtubes.
Bob Clark
Bret Cahill
volume increases with the square of diameter. High volume/weight
pressurised gas storage would, therefore, favor a bigger cylinder.
Bret Cahill
David M. Palmer
<c124c484-1fef-4386...@p10g2000prf.googlegroups.com>,
Bret Cahill <BretC...@aol.com> wrote:
That's a wash. Container weight scales with area times thickness, and
thickness scales with hoop stress, so the weight scales as
(diameter*length) * diameter, just as volume does.
(Neglecting minimum gauge and other non-theoretical effects.)
--
David M. Palmer dmpa...@email.com (formerly @clark.net, @ematic.com)
BretC...@peoplepc.com
> > volume increases with the square of diameter. �High volume/weight
> > pressurised gas storage would, therefore, favor a bigger cylinder.
. . .
> Container weight scales with area times thickness, and
> thickness scales with hoop stress,
But the area and volume increase with the diameter _squared_.
Bret Cahill
Robert Clark
> ...
>
> Another possible solution to having so many tubes release the
> hydrogen in unison might be to have them bound together with one end
> closed and the other end left open but with a cap over the open end of
> all of them made of a high strength material to which would be
> connected the controlling valve. Since the end cap would have a much
> smaller size than the full tank you could afford to have it be thicker
> so as to withstand the pressure of the fuel without it taking up too
> much weight. You would need though to have a strong bond between the
> material of the end cap and the material composing the separate
> microtubes.
>
This article claims a solution to the composite tank problem for the
Venture Star/X-33 :
New Composite Hydrogen Fuel Tank For RLVs Successfully Tested.
Fuel tank problems on the X-33 Venture Star project were crtitical to
ending what was the last major new space transportation R&D program at
NASA.
Huntsville - Dec 22, 2003
http://www.space-travel.com/reports/New_Composite_Hydrogen_Fuel_Tank_For_RLVs_Successfully_Tested.html
This is after the 2001 program cancellation that was due to a
failure of those tanks so I assume this addressed the debonding
problems that weren't solved then.
Bob Clark
David M. Palmer
<63f106f3-c598-4caa...@w24g2000prd.googlegroups.com>,
<BretC...@peoplepc.com> wrote:
> > > Hoop stresses of a tube under pressure increase with the diameter but
> > > volume increases with the square of diameter. ?High volume/weight
> > > pressurised gas storage would, therefore, favor a bigger cylinder.
>
> . . .
>
> > Container weight scales with area times thickness, and
> > thickness scales with hoop stress,
>
> But the area and volume increase with the diameter _squared_.
Assuming you are not talking about a squat cylinder with length much
less than diameter, no.
For a long cylinder, ignoring the endcaps and keeping the length the
same, the area is proportional to the diameter and the volume to the
diameter squared. Letting the length be proportional to the diameter
gives an area of diameter squared and a volume of diameter cubed.
Looking just at spherical endcaps, their volume goes as diameter cubed
and area as diameter squared.
Bret Cahill
thickness is greater with a larger dia tube at the same pressure.
These cancel so the diameter doesn't matter as far as weight/volume is
concerned.
Bret Cahill
Robert Clark
> Nice articles here on the problems that led to the cancellation of the
> VentureStar/X-33, a single-stage to orbit vehicle:
>
>
> X-33/VentureStar - What really happened.http://www.nasaspaceflight.com/content/?id=4180
>
> Interestingly the main problem was making the liquid hydrogen tanks
> lightweight storage could be achieved by storing the hydrogen in very
> many micron-scale hollow fibers. See the table of tensile strengths
> listed here:
>
>
> The solutions investigated for the hydrogen tanks for VentureStar
> The composite tanks were lighter but had a problem of debonding underhighpressure. Note in the table of tensile strengths carbon fiber has
> a betterstrengthto weight ratio than the aluminum alloy listed by a
> factor of 19 to 1. And thehighstrengthglass fibers known as S-glass
> is better than the aluminum alloy by 10 to 1. There is also a special
> steel fiber known as scifer steel not listed in the table that has a
> than aluminum alloy by a factor of 4 to 1. It might even be for the
> carbon fibers and the S-glass fibers theirstrengthto weight ratios
> You could store it ashighdensity gas. That would eliminate the
> weight of the cryogenic systems for the hydrogen.
> maintained in the radial direction. All the strengths listed for the
> fibers are for pulling along their lengths, i.e, their longitudinal
> will require theirstrengthto hold in the radial direction. After
> investigating this question before for hydrogen storage, I know that S-
> directions. I'm not sure if this is true for the carbon fiber. (BTW,
> Dyneema, or Spectra are unsuitable because theirstrengthonly holds
> in the longitudinal direction, not radially.)
> that they are only about 10 microns wide. So millions to billions of
> them would be needed to form sizable storage tanks. You would need a
> method of opening and closing these microscopically thin tubes at the
> same time for a throttleable engine. Perhaps one solution would be to
> have only a small portion of them being used at any one time and
> letting those completely empty out, then open another portion, and so
> on until all the fuel is used up. This would be an easier solution
> than having so many precisely controlled valves at the micro-scale
> that operated all in unison.
>
> Bob Clark
Another solution for releasing the hydrogen in unison comes from the
method of storing hydrogen in glass microspheres:
A future for glass in a hydrogen economy?
Researchers envision tiny spheres storing the gas in cars.
http://www.msnbc.msn.com/id/5343023/
These glass microspheres, about 50 microns across, can store hydrogen
at high pressure. They can be made to release the hydrogen on demand
by exposure to high intensity light. It might be the method of using
very many of the microspheres can itself be used for the hydrogen
tanks on the VentureStar. However, I prefer the method of many glass
microtubes since it would be easier to release the hydrogen in one
direction by illuminating just the front ends of the tubes that are
connected to the fuel lines that are connected to the engine.
This paper shows the possible strength of the microspheres:
Advancing the Hydrogen Infrastructure Using Stronger Glass.
http://www.gmic.org/Student%20Contest%20Entries/2007%20Contest%20Entries/38-Mike%20Hartel%20&%20John%20Rich%20-%20Advancing%20Hyrdrogen%20Infrastructure%20Using%20Stronger%20Glass.doc
This page gives the dimensions of the hydrogen and LOX tanks on the
X-33:
X-33 Program in the Midst of Final Testing and Validation of Key
Components.
http://www.xs4all.nl/~carlkop/x33.html
The twin hydrogen tanks weigh 4,600 pounds each and the single LOX
tank weighs 6,000 pounds. Since the X-33 is a 1/2-scale version of the
VentureStar, the VentureStar tank dimensions would be twice as large
so their mass would be 8 times as great, so 73,800 pounds total for
the two liquid hydrogen tanks and 48,000 pounds for the liquid oxygen
tank. That's a mass of 121,600 pounds for the empty tanks alone. Using
the S-glass fibers that has a 10 to 1 better strength to weight ratio
for the tanks, the weight would be reduced to 12,000 pounds. That's a
more than 100,000 pound saving in weight. That saving in weight could
go to extra payload. The stated payload for VentureStar was 45,000
pounds. Then with these lighter tanks its payload could be increased
to 145,000 pounds.
However, the estimate I gave for the weight of the VentureStar tanks
(I wasn't able to find the exact values) was based on their thickness
increasing in the same proportion as the other dimensions over those
of the X-33, i.e., by a factor of 2. This would mean the pressure the
VentureStar tanks would be able to withstand would be the same as
those of the X-33. However, the weight being increased by a factor of
8 and the surface area being increased by a factor of 4 means the
pressures involved would actually be greater than those of the X-33 by
a factor of 2. Then an additional factor of 2 in thickness may be
required. Still this would only give a total mass of the tanks with
the stronger S-glass material of 24,000 pounds. Then the payload could
still be increased to be more than 130,000 pounds.
Bob Clark
Robert Clark
>
> Another solution for releasing the hydrogen in unison comes from the
> method of storing hydrogen in glass microspheres:
>
> A future for glass in a hydrogen economy?
>
> These glass microspheres, about 50 microns across, can store hydrogen
> at high pressure. They can be made to release the hydrogen on demand
> by exposure to high intensity light. It might be the method of using
> very many of the microspheres can itself be used for the hydrogen
> tanks on the VentureStar. However, I prefer the method of many glass
> microtubes since it would be easier to release the hydrogen in one
> direction by illuminating just the front ends of the tubes that are
> connected to the fuel lines that are connected to the engine.
> This paper shows the possible strength of the microspheres:
>
>
> This page gives the dimensions of the hydrogen and LOX tanks on the
> X-33:
>
> X-33 Program in the Midst of Final Testing and Validation of Key
I don't like the estimate of the empty weight of the tanks for the
VentureStar of 121,600 lbs. This page compares the specifications of
the X-33 and the VentureStar:
MILNET: X-33 Aerospace Test Bed for VentureStar.
http://www.milnet.com/x-33.htm
It gives the fully fueled weight of the VentureStar as 2,186,000 lbs.
and the weight of the fuel alone as 1,929,000 lbs. So the empty weight
of the vehicle would be 257,000 lbs. This only a factor of 4 greater
than the empty weight of the X-33.
If the VentureStar tanks are 4 times as heavy as those of the X-33,
that would give them a total empty weight of 60,000 lbs. So if they
could be made 1/10th as heavy, the payload could be increased by
54,000 lbs. to about 100,000 lbs. If the tank thickness had to be
increased by an additional factor of 2, then the payload could still
be increased to about 90,000 lbs. Note also that lighter tanks would
mean lighter support structures for them so the increase in payload
might be more than this.
Bob Clark
BradGuth
At the 1e-21 bar vacuum of our Selene/moon L1, the volume and/or
tonnage of that hydrogen gas storage is unlimited.
~ Brad Guth Brad_Guth Brad.Guth BradGuth
BretC...@peoplepc.com
> > volume increases with the square of diameter. �High volume/weight
> > pressurised gas storage would, therefore, favor a bigger cylinder.
> At the 1e-21 bar vacuum of our Selene/moon L1, the volume and/or
> tonnage of that hydrogen gas storage is unlimited.
Several times I tried to design a lighter than air vacuum structure --
a _really_ worthless project -- but no material was strong/light
enough except maybe C nanotubes. All three times I determined that
there was no advantage either in scaling up or down. I somehow forgot
my own conclusion. Again.
Bret Cahill
Robert Clark
> VentureStar of 121,600 lbs. This page compares the specifications of
> the X-33 and the VentureStar:
>
>
> It gives the fully fueled weight of the VentureStar as 2,186,000 lbs.
> and the weight of the fuel alone as 1,929,000 lbs. So the empty weight
> of the vehicle would be 257,000 lbs. This only a factor of 4 greater
> than the empty weight of the X-33.
> If the VentureStar tanks are 4 times as heavy as those of the X-33,
> that would give them a total empty weight of 60,000 lbs. So if they
> could be made 1/10th as heavy, the payload could be increased by
> 54,000 lbs. to about 100,000 lbs. If the tank thickness had to be
> increased by an additional factor of 2, then the payload could still
> be increased to about 90,000 lbs. Note also that lighter tanks would
> mean lighter support structures for them so the increase in payload
> might be more than this.
>
> Bob Clark
At the bottom of this page are given some images for the 3 competing
proposals for NASA's reusable launch vehicle:
NASA Dryden X-33 Advanced Technology Demonstrator Photo Collection.
http://www.dfrc.nasa.gov/gallery/photo/X-33/
The Rockwell proposal was quite similar to the Space Shuttle without
the external tank and solid rocket boosters. The McDonnell Douglas
proposal was the DC-X. And the Lockheed proposal was the VentureStar
which won the competition.
It is quite likely that for all the proposals the mass of the tanks
alone was a significant portion of the mass of the empty vehicle,
about 1/4 for the Space Shuttle and also for the half-scale Lockheed
X-33 suborbital test vehicle.
Then decreasing the weight of the tanks by 1/10th might make all three
proposals feasible.
Bob Clark
BradGuth
Would you care to try again, on behalf of creating a composite rigid
airship intended for safely cruising about Venus?
Either a vacuum and/or a hydrogen displaced composite hull interior
would do rather nicely. A series of rigid spheres forming an airship
would become truly impressive, especially since the volumetric size
and mass are not the least bit significant factors.
Even that of a 99% hydrogen and 1% O2 cabin interior would become
entirely human survivable while parked near or on the surface of
Venus. A terrestrial application of 4% O2 and 96% H2 is perfectly
safe and sane, as having been more than proven to sustain human life
while under terrific pressure as is. France has for decades had a 68
bar (1000 psi) habitat chamber for further testing of such humanly
survivable environments.
Don’t forget that Venus also offers roughly 10% less gravity, and
there’s unlimited local energy to burn (so to speak), as well as
countless local minerals that are continually getting geothermally
contributed to that toasty surface and robust atmospheric environment.
btw, there’s already a complex tarmac of absolutely terrific size,
along with a substantial township of highrise structures and multiple
nearby reservoirs, plus a downright nifty bridge, not to mention that
nearby rigid airship and of its mostly underground facility, and
otherwise that rather nifty looking fluid arch that’ll knock your
socks off.
Would you care to review and deductively interpret the radar obtained
image, on behalf of any of this?
Robert Clark
> On Jul 29, 12:59 pm, Robert Clark <rgregorycl...@yahoo.com> wrote:
>
>
>
> > Nice articles here on the problems that led to the cancellation of the
> >VentureStar/X-33, a single-stage to orbit vehicle:
>
> > Lockheed Martin X-33.http://en.wikipedia.org/wiki/Lockheed_Martin_X-33
>
>
> These glass microspheres, about 50 microns across, can store hydrogen
> at high pressure. They can be made to release the hydrogen on demand
> by exposure to high intensity light. It might be the method of using
> very many of the microspheres can itself be used for the hydrogen
> microtubes since it would be easier to release the hydrogen in one
> direction by illuminating just the front ends of the tubes that are
> connected to the fuel lines that are connected to the engine.
> This paper shows the possible strength of the microspheres:
>
>
> This page gives the dimensions of the hydrogen and LOX tanks on the
> X-33:
>
> X-33 Program in the Midst of Final Testing and Validation of Key
>
> The twin hydrogen tanks weigh 4,600 pounds each and the single LOX
> so their mass would be 8 times as great, so 73,800 pounds total for
> the two liquid hydrogen tanks and 48,000 pounds for the liquid oxygen
> tank. That's a mass of 121,600 pounds for the empty tanks alone. Using
> the S-glass fibers that has a 10 to 1 better strength to weight ratio
> for the tanks, the weight would be reduced to 12,000 pounds. That's a
> more than 100,000 pound saving in weight. That saving in weight could
> pounds. Then with these lighter tanks its payload could be increased
> to 145,000 pounds.
> However, the estimate I gave for the weight of theVentureStartanks
> (I wasn't able to find the exact values) was based on their thickness
> increasing in the same proportion as the other dimensions over those
> those of the X-33. However, the weight being increased by a factor of
> 8 and the surface area being increased by a factor of 4 means the
> pressures involved would actually be greater than those of the X-33 by
> a factor of 2. Then an additional factor of 2 in thickness may be
> required. Still this would only give a total mass of the tanks with
> the stronger S-glass material of 24,000 pounds. Then the payload could
> still be increased to be more than 130,000 pounds.
>
> Bob Clark
New synthetic diamond particles might also be a good choice as
microspheres:
Brief Communications
Nature 421, 599-600 (6 February 2003)
Materials: Ultrahard polycrystalline diamond from graphite.
"Polycrystalline diamonds are harder and tougher than single-crystal
diamonds and are therefore valuable for cutting and polishing other
hard materials, but naturally occurring polycrystalline diamond is
unusual and its production is slow. Here we describe the rapid
synthesis of pure sintered polycrystalline diamond by direct
conversion of graphite under static high pressure and temperature.
Surprisingly, this synthesized diamond is ultrahard and so could be
useful in the manufacture of scientific and industrial tools."
http://www.nature.com/nature/journal/v421/n6923/full/421599b.html
Since the hardness is superior to natural diamond, the tensile
strength likely would be higher as well, which has been measured to be
up to 60 GPa for natural diamond. These would also be an excellent
choice to investigate for storing hydrogen for the proposed "hydrogen
economy".
And silicon nitride and silicon carbide whiskers have been found to
have tensile strength up to 50 GPa and 20 GPa respectively. In the
case of silicon nitride this remarkable strength extends almost to the
macroscale since they have been found to have this strength at
centimeters lengths though still only at micron wide widths:
A synthesis of mono-crystalline silicon nitride filaments.
Journal of Materials Science.
Volume 29, Number 11 / June, 1994
http://www.springerlink.com/content/t7u643052q1865q6/
Bob Clark
Bret Cahill
What's this going to cost?
Bret Cahill
Robert Clark
> ...
It may be interesting to calculate how much hydrogen could be stored
for example for hydrogen-fueled cars using these high strength
materials as microspheres.
This page gives the storage goals for hydrogen by the Department of
Energy:
Hydrogen storage.
http://en.wikipedia.org/wiki/Hydrogen_storage#Mobile_storage_targets
If you calculate from the data in the table how much energy they are
assuming you can get from a kilo of hydrogen, it's about 120
megajoules per kilo. This is less than the total energy released by
burning hydrogen in oxygen of 142 megajoules per kilo. Perhaps they
are assuming the hydrogen being used for fuel cells where only 83% of
the energy can be recovered as electricity, the rest going as heat.
However, even in this case much of this heat energy can be recovered.
So I'll assume the full 142 megajoules per kilo of energy can be used
either by just burning the hydrogen in air or by heat exchanger
methods that recover the heat energy released by the fuel cells.
The DOE goals are 3 kWh/kg of total system weight and 2.7 kWh/L of
total system volume by 2015. Using the 142 MJ/kg amount for hydrogen
energy density, this is .076 kg H2/kg total system weight and .068 kg
H2/L total system volume, or 68 kg H2/m^3 total system volume.
This page gives the properties of hydrogen gas at different
temperatures and pressures:
Hydrogen Properties Package.
http://www.inspi.ufl.edu/data/h_prop_package.html
At 300K temperature and 6,000 bar pressure, the density of hydrogen
gas is 72 kg/m^3, about the same as for liquid hydrogen.
This page gives a formula for the mass of a spherical pressure
vessel:
Pressure vessel.
http://en.wikipedia.org/wiki/Pressure_vessel
It gives:
M = (3/2)PVρ/σ, where:
M is mass
P is the pressure difference from ambient, i.e. the gauge pressure
V is volume
ρ is the density of the pressure vessel material
σ is the maximum working stress that material can tolerate.
Rather than using volume V, I'll use the mass of the gas, m_g, and its
density ρ_g: dividing both sides by m_g, the formula becomes:
M/m_g =(3/2)(P/σ)ρ(V/m_g). The term V/m_g is the inverse of the
density of the gas, so the formula becomes:
M/m_g =(3/2)(P/σ)(ρ/ρ_g)
For the diamond microspheres the tensile strength would be 60 GPa =
600,000 bar or higher, and the density that of diamond about 3600 kg/
m^3.
Then storage of hydrogen in the diamond microspheres would give a
ratio of the mass of the containers to the mass of the gas of:
M/m_g = (3/2)(6000/600,000)(3600/72) = .75 so ratio of mass of the gas
m_g to total mass M + m_g would be .57, far above the DOE
requirement .076.
Since these would be thin walled spheres the volume would be about
the same as the volume of the hydrogen itself, so still above the DOE
volume requirement of 68 kg H2 per m^3 total system volume.
For microspheres of silicon nitride, their strength and density are
close to that of diamond so the numbers would be similar.
For the silicon carbide microspheres their strength is about 2/5 that
of silicon nitride but their density about 2/3 that of silicon
nitride, so the amounts would be about 1/2 as good.
However, problems would be finding ways to make the hydrogen
releasable and of making the microspheres reusable.
Bob Clark
DB
>
> It may be interesting to calculate how much hydrogen could be stored
> for example for hydrogen-fueled cars using these high strength
> materials as microspheres.
Not really. Because the premise, 'hydrogen is readably available', is false.
You can not drill for it, you have to produce it. If it were so simple,
the oil sands of Canada would not be sweetened with natural gas.
The hydrogen must come first before worrying how it would be utilized.
It isn't. Back to liquid fuels and batteries......
At that, nothing we have will negate five to eight percent in declines
of conventional liquid production without a radical paradigm change...
Number count, period.
Rod Speed
> Robert Clark wrote
>> It may be interesting to calculate how much hydrogen could be stored
>> for example for hydrogen-fueled cars using these high strength
>> materials as microspheres.
> Not really. Because the premise, 'hydrogen is readably available', is false.
Nope.
> You can not drill for it, you have to produce it.
And its easy to use nukes to produce it.
> If it were so simple, the oil sands of Canada would not be sweetened with natural gas.
> The hydrogen must come first before worrying how it would be utilized. It isn't.
Completely trivial to produce it using nukes.
> Back to liquid fuels and batteries......
Fraid not.
> At that, nothing we have will negate five to eight percent in declines
> of conventional liquid production without a radical paradigm change...
Wrong with hydrogen from nukes.
> Number count, period.
Its more complicated than that.
Robert Clark
> > > Hoop stresses of a tube under pressure increase with the diameter but
> > > volume increases with the square of diameter. High volume/weight
> > > pressurised gas storage would, therefore, favor a bigger cylinder.
> > tonnage of that hydrogen gas storage is unlimited.
>
> a _really_ worthless project -- but no material was strong/light
> enough except maybe C nanotubes. All three times I determined that
> there was no advantage either in scaling up or down. I somehow forgot
> my own conclusion. Again.
>
> Bret Cahill
After a web search I found a report on creating inflatable vacuum
chambers, where the walls are filled with pressurized gas for
strength. Such chambers could even be buoyant if the walls were filled
with a lighter than air gas such as helium:
Stability Analysis of an Inflatable Vacuum Chamber.
http://arxiv.org/abs/physics/0610222v4
In experiments discussed in the report the chamber failed. But the
researchers believe this is because of the failure of the epoxy
joining the separate pressurized tubes that made up the chamber walls.
Bob Clark
BradGuth
> On Aug 19, 12:21 pm, BretCah...@peoplepc.com wrote:
>
> > > > Hoop stresses of a tube under pressure increase with the diameter but
> > > > volume increases with the square of diameter. High volume/weight
> > > > pressurised gas storage would, therefore, favor a bigger cylinder.
> > > At the 1e-21 barvacuumof our Selene/moon L1, the volume and/or
> > > tonnage of that hydrogen gas storage is unlimited.
>
> > Several times I tried to design alighterthanairvacuumstructure --
> > a _really_ worthless project -- but no material was strong/light
> > enough except maybe C nanotubes. All three times I determined that
> > there was no advantage either in scaling up or down. I somehow forgot
> > my own conclusion. Again.
>
> > Bret Cahill
>
> After a web search I found a report on creating inflatable vacuum
> chambers, where the walls are filled with pressurized gas for
> strength. Such chambers could even be buoyant if the walls were filled
> with a lighter than air gas such as helium:
>
>
> In experiments discussed in the report the chamber failed. But the
> researchers believe this is because of the failure of the epoxy
> joining the separate pressurized tubes that made up the chamber walls.
>
> Bob Clark
You are grasping at straws, in much the same way our bipolar William
Mook tries to suggest that going much bigger is always better.
Hydrogen itself offers a fairly piss-poor form of stored energy
density, especially since it requires so much highly insulated and
complex infrastructure plus loads of LOx and turbo-pumps for each in
order to be utilized, and of the makings of LOx while on the fly is
not terribly space efficient or offering low inert mass.
Are you talking about a near zero payload craft?
BradGuth
>
> These glass microspheres, about 50 microns across, can store hydrogen
> at high pressure. They can be made to release the hydrogen on demand
> by exposure to high intensity light. It might be the method of using
> very many of the microspheres can itself be used for the hydrogen
> tanks on the VentureStar. However, I prefer the method of many glass
> microtubes since it would be easier to release the hydrogen in one
> direction by illuminating just the front ends of the tubes that are
> connected to the fuel lines that are connected to the engine.
> This paper shows the possible strength of the microspheres:
>
>
> This page gives the dimensions of the hydrogen and LOX tanks on the
> X-33:
>
> X-33 Program in the Midst of Final Testing and Validation of Key
The all-inclusive X-33 inert mass (including unusable fuels and all
other fluids and those pilots) is what?
Can they safely burn 95% of their total fuel supply? (I don't think
so)
~ BG
BradGuth
>
> If you calculate from the data in the table how much energy they are
> assuming you can get from a kilo of hydrogen, it's about 120
> megajoules per kilo. This is less than the total energy released by
> burning hydrogen in oxygen of 142 megajoules per kilo. Perhaps they
> are assuming the hydrogen being used for fuel cells where only 83% of
> the energy can be recovered as electricity, the rest going as heat.
> However, even in this case much of this heat energy can be recovered.
> So I'll assume the full 142 megajoules per kilo of energy can be used
> either by just burning the hydrogen in air or by heat exchanger
> methods that recover the heat energy released by the fuel cells.
> The DOE goals are 3 kWh/kg of total system weight and 2.7 kWh/L of
> total system volume by 2015. Using the 142 MJ/kg amount for hydrogen
> energy density, this is .076 kg H2/kg total system weight and .068 kg
> H2/L total system volume, or 68 kg H2/m^3 total system volume.
>
> This page gives the properties of hydrogen gas at different
> temperatures and pressures:
>
>
> At 300K temperature and 6,000 bar pressure, the density of hydrogen
> gas is 72 kg/m^3, about the same as for liquid hydrogen.
>
> This page gives a formula for the mass of a spherical pressure
> vessel:
>
>
> It gives:
>
> M = (3/2)PVñ/ó, where:
>
> M is mass
> P is the pressure difference from ambient, i.e. the gauge pressure
> V is volume
> ó is the maximum working stress that material can tolerate.
>
> Rather than using volume V, I'll use the mass of the gas, m_g, and its
>
> M/m_g =(3/2)(P/ó)ñ(V/m_g). The term V/m_g is the inverse of the
> density of the gas, so the formula becomes:
>
>
> For the diamond microspheres the tensile strength would be 60 GPa =
> 600,000 bar or higher, and the density that of diamond about 3600 kg/
> m^3.
> Then storage of hydrogen in the diamond microspheres would give a
> ratio of the mass of the containers to the mass of the gas of:
>
> M/m_g = (3/2)(6000/600,000)(3600/72) = .75 so ratio of mass of the gas
> m_g to total mass M + m_g would be .57, far above the DOE
> requirement .076.
> Since these would be thin walled spheres the volume would be about
> the same as the volume of the hydrogen itself, so still above the DOE
> volume requirement of 68 kg H2 per m^3 total system volume.
>
> For microspheres of silicon nitride, their strength and density are
> close to that of diamond so the numbers would be similar.
> For the silicon carbide microspheres their strength is about 2/5 that
> of silicon nitride but their density about 2/3 that of silicon
> nitride, so the amounts would be about 1/2 as good.
> However, problems would be finding ways to make the hydrogen
> releasable and of making the microspheres reusable.
>
> Bob Clark
Why not simply use h2o2 plus a little fossil or synfuel?
~ BG
Robert Clark
>
> Why not simply use h2o2 plus a little fossil or synfuel?
>
> ~ BG
For getting to orbit you want the propellant that gives the greatest
thrust for the weight. This is measured by the Isp (specific impulse).
The amount of fuel needed to shows a exponential dependence on the
Isp, though in an inverse fashion: if your Isp is smaller there will
be an exponential increase in the fuel required.
The Isp of hydrogen/oxygen engines is about 450 s, while that for
hydrogen peroxide as a monopropellant it's about 150 s, and for use as
an oxidizer with another fuel such as kerosene it's about 320 s.
Bob Clark
Uncle Al
[snip crap]
> It may be interesting to calculate how much hydrogen could be stored
> for example for hydrogen-fueled cars using these high strength
> materials as microspheres.
[snip rest of crap]
Calculate the (hydrogen atoms)/cm^3 in a open bucket of diesel. When
you can equal that with engineered bullshit, come back.
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/lajos.htm#a2
BradGuth
But h2o2 plus a little synfuel is by far the best ratio, of the least
amount of inert mass.
Doesn't inert mass (including unusable fuel) mean anything?
From the time of toping off those tanks, how long does LOx and LH2
last within your inert massive storage tankage?
What tonnage of inert GLOW in ice loading are we speaking of?
Can either LOx and LH2 be efficiently stored for any length of time,
such as for future usage? (I didn't think so)
Can LOx and LH2 be effectively made from solar or other forms of
energy while on the fly in outer space? (I didn't think so)
~ BG
BradGuth
> Robert Clark wrote:
>
> [snip crap]
>
> > It may be interesting to calculate how much hydrogen could be stored
> > for example for hydrogen-fueled cars using these high strength
> > materials as microspheres.
>
> [snip rest of crap]
>
> Calculate the (hydrogen atoms)/cm^3 in a open bucket of diesel. When
> you can equal that with engineered bullshit, come back.
Actually, of hydrogen stored as hydrides isn't half bad, although h2o2
and aluminum is still offering way better energy density. Perhaps
h2o2 and a good hydride is even better, and even better yet if that
was of a triple fuel arrangement or formulation that included a little
liquid fossil/synfuel in order to obtain the absolute most rocket
thrust per kg/s.
~ BG
Robert Clark
> Robert Clark wrote:
>
> [snip crap]
>
> > It may be interesting to calculate how much hydrogen could be stored
> > for example for hydrogen-fueled cars using these high strength
> > materials as microspheres.
>
> [snip rest of crap]
>
> Calculate the (hydrogen atoms)/cm^3 in a open bucket of diesel. When
> you can equal that with engineered bullshit, come back.
>
> --
> (Toxic URL! Unsafe for children and most mammals)http://www.mazepath.com/uncleal/lajos.htm#a2
Hydrogen has three times the energy per weight than diesel or
gasoline.
It's the weight advantage that's key.
However, you, no doubt, are very fond of the U.S. dependence on
foreign oil and want to continue it as long as possible.
Bob Clark
Robert Clark
H2O2 and other monopropellants are used for station keeping on
satellites because they have to be stored long periods. Here of course
you don't need a large velocity change, as required to get to orbit,
so the amount of fuel required is much less and you can make do with a
lower energy fuel.
However, the weight penalty would be too large if you wanted to use
it as propellant for a reusable launch vehicle where you can just
barely make it with a high energy fuel like hydrogen.
Bob Clark
N:dlzc D:aol T:com (dlzc)
"Robert Clark" <rgrego...@yahoo.com> wrote in message
news:3880acc7-3c5d-4b98...@34g2000hsh.googlegroups.com...
> On Sep 6, 12:35 pm, Uncle Al <Uncle...@hate.spam.net> wrote:
>> Robert Clark wrote:
>>
>> [snip crap]
>>
>> > It may be interesting to calculate how much
>> > hydrogen could be stored for example for
>> > hydrogen-fueled cars using these high strength
>> > materials as microspheres.
>>
>> [snip rest of crap]
>>
>> Calculate the (hydrogen atoms)/cm^3 in a open
>> bucket of diesel. When you can equal that with
>> engineered bullshit, come back.
>
> Hydrogen has three times the energy per weight
> than diesel or gasoline.
Which is why the Space Scuttle requires the external tank be 80%
devoted to hydrogen storage. It is light but not compact. The
enclosure costs too...
> It's the weight advantage that's key. However, you,
> no doubt, are very fond of the U.S. dependence on
> foreign oil and want to continue it as long as
> possible.
Hydrogen is currently "mined" from those same fossil fuels. Or
the power to "electrolyze" it comes from those same sources. Or
perhaps you want us to stay dependent on foreign oil?
David A. Smith
Robert Clark
wrote:
> Dear Robert Clark:
...
>
> > It's the weight advantage that's key. However, you,
> > no doubt, are very fond of the U.S. dependence on
> > foreign oil and want to continue it as long as
> > possible.
>
> Hydrogen is currently "mined" from those same fossil fuels. Or
> the power to "electrolyze" it comes from those same sources. Or
> perhaps you want us to stay dependent on foreign oil?
>
> David A. Smith
Obviously it's not *only* from fossil fuels. Expect the production
from alternative sources to increase.
Bob Clark
N:dlzc D:aol T:com (dlzc)
"Robert Clark" <rgrego...@yahoo.com> wrote in message
news:523529cf-e75a-428b...@e53g2000hsa.googlegroups.com...
> On Sep 6, 2:01 pm, "N:dlzc D:aol T:com \(dlzc\)"
> <dl...@cox.net>
> wrote:
>> Dear Robert Clark:
> ...
>>
>> > It's the weight advantage that's key. However, you,
>> > no doubt, are very fond of the U.S. dependence on
>> > foreign oil and want to continue it as long as
>> > possible.
>>
>> Hydrogen is currently "mined" from those same
>> fossil fuels. Or the power to "electrolyze" it comes
>> from those same sources. Or perhaps you want us
>> to stay dependent on foreign oil?
>
> Obviously it's not *only* from fossil fuels.
Obviously *now* it is.
> Expect the production from alternative sources to
> increase.
As soon as someone figure out how to store it without being a
danger. Oh, wait, someone already did... in hydrocarbon chains.
How about that?
David A. Smith
BradGuth
You use funny math, and the avoidance and/or exclusion of whatever
rocks your boat.
Why do you and William Mook continually insist upon strictly a mono
propellant usage of h2o2? (are you related to one another?)
You’re saying we can forget about whatever’s the all-inclusive GLOW
inert mass (just like in those good old DARPA Apollo days of hocus-
pocus science as based upon conditional physics), including ice
loading and of whatever becomes unusable or evaporated fuel.
It seems without all the LOx, your LH2 is downright wussy as all get
out, not to mention extremely volumetric consuming and thus
unavoidably inert.
Using imported energy that’s extremely spendy in order to offset the
process of creating those horrific volumes of LOx and LH2, are not
exactly insignificant factors.
How much global energy for creating LH2 and LOx can we afford to burn
off as rocket fuel, and otherwise for sustaining the all-inclusive
infrastructure that you’d like to greatly expand upon?
Are millions of tonnes worth of LH2 and LOx per year all that
sustainable, as yourself and that of our resident bipolar wizard
William Mook might suggest?
Do you not care about global inflation and the subsequent
environmental as well as human trauma and wars such creates?
Why is bigger and of more energy demanding applications always better?
What’s the true birth-to-grave (meaning all-inclusive which includes
all things terrestrial) accounting per kg placed in LEO or worse GSO?
(and don’t leave out all the R&D plus mission failures)
Do you honestly think it’s much less than a million dollars per kg?
How much more debt can humanity and that of our frail environment
afford?
BradGuth
That's still loads of energy diverted away from humanity, of which
clearly sets well within your lack of consequence and remorseless
mindset.
~ BG
BradGuth
wrote:
> Dear Robert Clark:
>
> "Robert Clark" <rgregorycl...@yahoo.com> wrote in message
Hydrides are a darn good thing, as solids they store rather nicely.
Too bad h2o2 can't be utilized along with such hydrides. (only
kidding)
~ BG
Robert Clark
> On Sep 6, 10:51 am, Robert Clark <rgregorycl...@yahoo.com> wrote:
> > H2O2 and other monopropellants are used for station keeping on
> > satellites because they have to be stored long periods. Here of course
> > you don't need a large velocity change, as required to get to orbit,
> > so the amount of fuel required is much less and you can make do with a
> > lower energy fuel.
> > However, the weight penalty would be too large if you wanted to use
> > it as propellant for a reusable launch vehicle where you can just
> > barely make it with a high energy fuel like hydrogen.
>
> > Bob Clark
>
> You use funny math, and the avoidance and/or exclusion of whatever
> rocks your boat.
>
> Why do you and William Mook continually insist upon strictly a mono
> propellant usage of h2o2? (are you related to one another?)
>
> You’re saying we can forget about whatever’s the all-inclusive GLOW
> inert mass (just like in those good old DARPA Apollo days of hocus-
> pocus science as based upon conditional physics), including ice
> loading and of whatever becomes unusable or evaporated fuel.
>
A nice retrospective article here discussing the DC-X attempt at a
reusable launch vehicle:
The legacy of DC-X.
by Jeff Foust
Monday, August 25, 2008
http://thespacereview.com/article/1196/1
The progenitors of the DC-X project would dearly have loved to have
some higher energy fuel than LH2/LOX to allow them to succeed with
their single stage to orbit proposal but it's the highest one
practical. These propulsion experts are well aware of H2O2 as a
propellant and that it takes up much less volume than LH2 and that
it's simpler to store. But having to wring every last bit of weight
saving including the amount of required propellant to get to orbit
they were led to using LH2/LOX, as was every other proposal for using
rocket propulsion for a single stage to orbit vehicle. It's not
because they have some fixation on hydrogen as a fuel and they never
heard of other kinds.
Bob Clark
Pat Flannery
Robert Clark wrote:
> For getting to orbit you want the propellant that gives the greatest
> thrust for the weight. This is measured by the Isp (specific impulse).
> The amount of fuel needed to shows a exponential dependence on the
> Isp, though in an inverse fashion: if your Isp is smaller there will
> be an exponential increase in the fuel required.
> The Isp of hydrogen/oxygen engines is about 450 s, while that for
> hydrogen peroxide as a monopropellant it's about 150 s, and for use as
> an oxidizer with another fuel such as kerosene it's about 320 s.
>
Still, with H2O2 you save a lot of tankage weight versus LH2/LOX due to
the low density of LH2, and avoid the possible need to insulate the
propellant tanks, with that added weight on the vehicle.
I was always amazed by the small size of the Black Arrow launch vehicle
(it wasn't much bigger than a V-2), which used H2O2 and kerosene for
propellants, but was capable of putting a satellite into polar orbit.
It also had about the cleanest burning exhaust I ever laid eyes on:
http://www.geocities.com/CapeCanaveral/Launchpad/6133/arrow.jpg
Pat
BradGuth
Very good feedback, not to mention the lower aerodynamic drag, lack of
ice loading and the nearly 100% fuel burn that only further reduces
inert mass.
h2o2 along with a better than kerosene synfuel can kick serious rocket
butt.
~ BG
BradGuth
>
> The progenitors of the DC-X project would dearly have loved to have
> some higher energy fuel than LH2/LOX to allow them to succeed with
> their single stage to orbit proposal but it's the highest one
> practical. These propulsion experts are well aware of H2O2 as a
> propellant and that it takes up much less volume than LH2 and that
> it's simpler to store. But having to wring every last bit of weight
> saving including the amount of required propellant to get to orbit
> they were led to using LH2/LOX, as was every other proposal for using
> rocket propulsion for a single stage to orbit vehicle. It's not
> because they have some fixation on hydrogen as a fuel and they never
> heard of other kinds.
>
> Bob Clark
STTO is not a very practical alternative for accomplishing the most
payload to orbit, especially when those reusable boosters are clearly
the way to go, and even of those reusable boosters could be h2o2/
synfuel configured.
~ BG
Robert Clark
Yes, all kinds of fuels can be used for staged, disposable rockets,
as the Black Arrow was. The first stage engines of the Saturn V also
used kerosene, with LOX as the oxidizer.
But for reusable launch vehicles with rocket propulsion you have to
optimize the energy from the propellants such as by using hydrogen
fuel (an airbreather since it doesn't have to carry the oxidizer could
use a less energetic fuel than hydrogen.)
The reports on the cancellation of the VentureStar suggests it was
only the failure to get the lightweight hydrogen tanks to work that
caused its cancellation, a relatively trivial problem compared to the
complexity of the entire system.
I'm suggesting that storage in the form of numerous containers at the
microscale using high strength materials we already have would solve
this problem. Because of the increase of strength to weight of the
highest strength materials at the microscale you could reduce the
weight of the tanks up to a factor of a 100. The weight of the tanks
would become essentially nothing. It would be comparable to the weight
of the paint on the vehicle. Since the weight of the empty tanks can
be as large as 1/4 of the weight of the empty vehicle this would be a
major weight saving. Quite likely the other reusable launch vehicle
proposals would also become viable.
There has been some discussion on some space forums that the launch
providers have no incentive to produce reusable launch vehicles since
it would cut into their profit margins.
Since use of such high strength microspheres or microfibers might
provide a solution to the problem of storage of hydrogen for the
hydrogen-economy, this might provide a reason to investigate them for
that purpose which would also thereby make possible the goal of
reusable launch vehicles.
Bob Clark
charlie...@yahoo.com
>
> Obviously it's not *only* from fossil fuels. Expect the production
> from alternative sources to increase.
>
> Bob Clark
It is only from fossil fuel. There are no nuclear powered
electrolyzation plants
charlie...@yahoo.com
> You could store it as high density gas.
> Bob Clark
The hydrogen would be too low of density to be of use for launch
vehicles. It has to be liquiefied. Do your research.
On Sep 7, 10:24 am, Robert Clark <rgregorycl...@yahoo.com> wrote:
> I'm suggesting that storage in the form of numerous containers at the
> microscale using high strength materials we already have would solve
> this problem. Because of the increase of strength to weight of the
> highest strength materials at the microscale you could reduce the
> weight of the tanks up to a factor of a 100. The weight of the tanks
> would become essentially nothing.
> Bob Clark
totally nonplausible. This is not a solution. Numerous containers
would have numerous attach fittings and numerous plumbing fixtures and
pipes. This would offset any weight savings (not that the tanks are
viable in the first place) Not to mention dealing with propellant
management.
the tanks were not the only problem with the X-33.
Clark, stick to something that you know (which isn't rocket science)
and leave the engineering to the experts.
Alan Erskine
STOP CHANGING THE SUBJECT LINE!!!
Robert Clark
The failure of the light-weight liquid hydrogen tanks was THE main
reason the VentureStar was canceled:
X-33/VentureStar - What really happened.
http://www.nasaspaceflight.com/content/?id=4180
As I stated in the first posts of this thread, the intent of using
microtubes or microspheres made of high strength materials WAS for the
*liquid* hydrogen and oxygen tanks of the reusable launch vehicles.
The highest strength materials would reduce the weight of the tanks by
a factor of a 100 to 1.
If research into hydrogen gas storage for hydrogen powered cars using
microspheres or microtubes was investigated this would give an
incentive for investigating their use for tanks on reusable launch
vehicles. The reduction in weight of one part of the vehicle's
structure from 60,000 pounds out of a total weight of 250,000 pounds
to only 600 pounds would be a major improvement in weight.
As I mentioned before in the thread there are several different ways
of doing it where you wouldn't have to use separate, individual pipe
fittings or valves for each of the separate micro tubes or spheres.
For instance there is ongoing research on using glass microspheres for
hydrogen storage for cars where obviously the scientists involved
don't intend to attach separate valves to each microsphere only
microns across.
The structure of the tanks consisting of millions of microtubes or
microspheres might appear radical at first but if you think about it
just means you are using a tank whose internal structure is porous
like a sponge and the strength of the tank is coming from the millions
of horizontal and vertical internal layers of the tank rather the
tank's one single outer surface. Indeed there is research on using
sponge-like materials for hydrogen storage:
Press Release 06-043
New "Crystal Sponge" Triples Hydrogen Storage
UCLA, University of Michigan chemists advance hydrogen as fuel for
cars and electronic devices.
http://www.nsf.gov/news/news_summ.jsp?cntn_id=106757
Notably this advance only achieves 7.5 percent hydrogen gas storage
and only at liquid nitrogen temperatures of 77 K. The high strength
materials at the microscale I was suggesting would be able to get 57
percent hydrogen gas storage and at room temperature. If these high
strength microscale materials only had to do the storage at 77 K, then
they would be able to achieve over 90 percent hydrogen storage since
less pressure, and less thickness of the walls, would be required to
get the hydrogen to the density level of the DOE requirements.
Bob Clark
Robert Clark
> "Robert Clark" <rgregorycl...@yahoo.com> wrote in message
>
> news:efe5bc39-ca12-4bc8...@k13g2000hse.googlegroups.com...
>
> STOP CHANGING THE SUBJECT LINE!!!
I'm reading this on groups.google.com where all the responses appear
on the same thread even though you change the subject line. I wanted
to emphasize that this method of storage would make possible all the
different proposals submitted to NASA for reusable launch vehicles not
just the VentureStar. So you would have several different types that
would be flying at the same time thus providing incentive to increase
the innovation in the vehicles and to have competition in lowering the
costs to space.
However, I understand that when reading it on a Usenet news reader
they get separated when you change the subject line so I'll avoid
doing that.
Bob Clark
Robert Clark
The boosters now used to send payloads to orbit are all expendable
not reusable and there are no plans to have staged boosters to reach
orbit where all the stages would be reusable.
As I mentioned before the failure of the VentureStar single stage to
orbit system (SSTO) was because of the relatively trivial problem of
debonding of the composite liquid hydrogen tanks.
Bob Clark
Robert Clark
>
> STTO is not a very practical alternative for accomplishing the most
> payload to orbit, especially when those reusable boosters are clearly
> the way to go, and even of those reusable boosters could be h2o2/
> synfuel configured.
>
> ~ BG
It has been estimated that reusable launch vehicles would reduce the
costs to space from the current $10,000/kilo to $1,000/kilo.
There is a lot of debate on space forums about whether decreasing the
cost to space to 1/10th the current price would increase the market
for launches, but I can give an argument it would increase the market
for passenger flights: at $1,000 per kilo the cost for a 100 kilo
passenger would be $100,000, but at $10,000 per kilo the price would
be $1,000,000. Very many even middle class people could afford to get
a loan for a $100,000 cost, as it is for example comparable to the
cost of buying just an average size home. Very few people on the other
hand could afford to get a loan for $1,000,000. Also very many
universities and colleges could afford to pay a price of $100,000 to
send one of their researchers to space, while few would be willing to
pay $1,000,000 to do so.
There is also the fact that the Bigelow Space Hotels would give the
passengers some place to go to rather than just going to orbit for a
few hours and returning.
Bob Clark
BradGuth
>
> Notably this advance only achieves 7.5 percent hydrogen gas storage
> and only at liquid nitrogen temperatures of 77 K. The high strength
> materials at the microscale I was suggesting would be able to get 57
> percent hydrogen gas storage and at room temperature. If these high
> strength microscale materials only had to do the storage at 77 K, then
> they would be able to achieve over 90 percent hydrogen storage since
> less pressure, and less thickness of the walls, would be required to
> get the hydrogen to the density level of the DOE requirements.
>
> Bob Clark
Such large capacity as hosting volumes of highly insulated tankage,
and of the required structural bindings along with greater flow
capacity of piping infrastructure = inert mass.
Dead or unusable fuel also = inert mass.
A composite formulated tank would tend to minimize such inert mass
considerations.
BradGuth
> On Sep 6, 11:30 pm, BradGuth <bradg...@gmail.com> wrote:
>
> > ...
>
> > STTO is not a very practical alternative for accomplishing the most
> > payload to orbit, especially when those reusable boosters are clearly
> > the way to go, and even of those reusable boosters could be h2o2/
> > synfuel configured.
>
> > ~ BG
>
> It has been estimated that reusable launch vehicles would reduce the
> costs to space from the current $10,000/kilo to $1,000/kilo.
China already offers CATS, at perhaps as little cost as $1000/kg.
> There is a lot of debate on space forums about whether decreasing the
> cost to space to 1/10th the current price would increase the market
> for launches, but I can give an argument it would increase the market
> for passenger flights: at $1,000 per kilo the cost for a 100 kilo
> passenger would be $100,000, but at $10,000 per kilo the price would
> be $1,000,000. Very many even middle class people could afford to get
> a loan for a $100,000 cost, as it is for example comparable to the
> cost of buying just an average size home. Very few people on the other
> hand could afford to get a loan for $1,000,000. Also very many
> universities and colleges could afford to pay a price of $100,000 to
> send one of their researchers to space, while few would be willing to
> pay $1,000,000 to do so.
> There is also the fact that the Bigelow Space Hotels would give the
> passengers some place to go to rather than just going to orbit for a
> few hours and returning.
>
> Bob Clark
I tend to like those Bigelow Space Hotels, especially if a group of
such inflated modules were to cerate POOF City at Venus L2.
Pat Flannery
Robert Clark wrote:
> On Sep 6, 11:30 pm, BradGuth <bradg...@gmail.com> wrote:
>
>> ...
>>
>> STTO is not a very practical alternative for accomplishing the most
>> payload to orbit, especially when those reusable boosters are clearly
>> the way to go, and even of those reusable boosters could be h2o2/
>> synfuel configured.
>>
>> ~ BG
>>
>
> It has been estimated that reusable launch vehicles would reduce the
> costs to space from the current $10,000/kilo to $1,000/kilo.
>
It went a lot further down than that IIRC in the early days of the
Shuttle program; I seem to remember $200.00 per kilo being batted around.
Pat
Odysseus
<f7319d2f-9c35-438d...@a70g2000hsh.googlegroups.com>,
Robert Clark <rgrego...@yahoo.com> wrote:
<snip>
> However, I understand that when reading it on a Usenet news reader
> they get separated when you change the subject line so I'll avoid
> doing that.
Only in some newsreaders; the more capable ones can be configured to
thread articles by reference, more or less the same way that Google does.
--
Odysseus
Robert Clark
> On Aug 19, 12:21 pm, BretCah...@peoplepc.com wrote:
>
> > > > Hoop stresses of a tube under pressure increase with the diameter but
> > > > volume increases with the square of diameter. High volume/weight
> > > > pressurised gas storage would, therefore, favor a bigger cylinder.
> > > At the 1e-21 barvacuumof our Selene/moon L1, the volume and/or
> > > tonnage of that hydrogen gas storage is unlimited.
>
> > Several times I tried to design alighterthanairvacuumstructure --
> > a _really_ worthless project -- but no material was strong/light
> > enough except maybe C nanotubes. All three times I determined that
> > there was no advantage either in scaling up or down. I somehow forgot
> > my own conclusion. Again.
>
> > Bret Cahill
>
> After a web search I found a report on creating inflatable vacuum
> chambers, where the walls are filled with pressurized gas for
> strength. Such chambers could even be buoyant if the walls were filled
> with a lighter than air gas such as helium:
>
> Stability Analysis of an Inflatable Vacuum Chamber.http://arxiv.org/abs/physics/0610222v4
>
> In experiments discussed in the report the chamber failed. But the
> researchers believe this is because of the failure of the epoxy
> joining the separate pressurized tubes that made up the chamber walls.
>
> Bob Clark
The author of that report presents calculations that compressional
strength such as what you would need for the walls of a vacuum chamber
can be obtained by making the walls consist of pressurized tubes with
skin made out of materials with high tensional strength. Then
presumably you could get as high a compressional strength as these
materials have in tensional strength. The idea is similar to the fact
that a basketball will have high compressional strength coming from
the pressurized gas inside and the high strength of the material
against stretching.
Using this method and microtubes of tensile strength as high as 60
GPa, or 600,000 bar, you could get compressional strength this high as
well. This would be over a hundred times the strength to weight ratio
of the steel or aluminum alloys used for the structure of the
spacecraft or of other mostly metal structures.
Imagine the spacecraft instead of weighing 250,000 pounds weighing
only 2,500 pounds. Or a car instead of weighing 2,000 pounds, only
weighing 20.
Bob Clark
BradGuth
Say whatever you may, h2o2+synfuel is still not a bad way to fly-by-
rocket go, and go, and go.
~ BG
Robert Clark
> On Sep 6, 7:26 am, Robert Clark <rgregorycl...@yahoo.com> wrote:
>
>
>
> > On Aug 19, 12:21 pm, BretCah...@peoplepc.com wrote:
>
> > > > > Hoop stresses of a tube under pressure increase with the diameter but
> > > > > volume increases with the square of diameter. High volume/weight
> > > > > pressurised gas storage would, therefore, favor a bigger cylinder.
> > > > At the 1e-21 barvacuumof our Selene/moon L1, the volume and/or
> > > > tonnage of that hydrogen gas storage is unlimited.
>
> > > Several times I tried to design alighterthanairvacuumstructure --
> > > a _really_ worthless project -- but no material was strong/light
> > > enough except maybe C nanotubes. All three times I determined that
> > > there was no advantage either in scaling up or down. I somehow forgot
> > > my own conclusion. Again.
>
> > > Bret Cahill
>
> > After a web search I found a report on creating inflatable vacuum
> > chambers, where the walls are filled with pressurized gas for
> > strength. Such chambers could even be buoyant if the walls were filled
> > with a lighter than air gas such as helium:
>
>
> > In experiments discussed in the report the chamber failed. But the
> > researchers believe this is because of the failure of the epoxy
> > joining the separate pressurized tubes that made up the chamber walls.
>
> > Bob Clark
>
> The author of that report presents calculations that compressional
> can be obtained by making the walls consist of pressurized tubes with
> skin made out of materials with high tensional strength. Then
> presumably you could get as high a compressional strength as these
> materials have in tensional strength. The idea is similar to the fact
> that a basketball will have high compressional strength coming from
> the pressurized gas inside and the high strength of the material
> against stretching.
> Using this method and microtubes of tensile strength as high as 60
> GPa, or 600,000 bar, you could get compressional strength this high as
> well. This would be over a hundred times the strength to weight ratio
> of the steel or aluminum alloys used for the structure of the
> spacecraft or of other mostly metal structures.
> Imagine the spacecraft instead of weighing 250,000 pounds weighing
> only 2,500 pounds. Or a car instead of weighing 2,000 pounds, only
> weighing 20.
>
> Bob Clark
If this method can be made to work then such lightweight vacuum
chambers could be used to maintain the low temperatures required for
liquid hydrogen through the high vacuum as insulation. Then this might
allow the light weight, high density hydrogen storage required for the
hydrogen economy without requiring the complex, expensive systems now
used to keep the hydrogen at the cryogenic temperatures of liquid
hydrogen.
Likewise it would reduce the weight and complexity of the liquid
hydrogen storage for orbital launchers.
Bob Clark
BradGuth
Or you could just as easily use plain old h2o2+synfuel, at least for
the reusable liquid fueled boosters.
~ BG