High strength fibers for hydrogen storage on the VentureStar.

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

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 ahightech 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 he

Tensilestrength.http://en.wikipedia.org/wiki/Tensile_strength

The solutions investigated for the hydrogen tanks forVentureStar
included usinghighstrengthaluminum alloys or composite fiber tanks.
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
tensilestrengthof 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 theirstrengthto weight ratios
are sohighyou wouldn't need to store the hydrogen in liquid form.
You could store it ashighdensity gas. That would eliminate the
weight of the cryogenic systems for the hydrogen.
However, a key question here is whether thisstrengthwill be
maintained in the radial direction. All the strengths listed for the
fibers are for pulling along their lengths, i.e, their longitudinal
tensilestrength. But to use the fibers as thin hollow pressure tubes
will require theirstrengthto hold in the radial direction. After
investigating this question before for hydrogen storage, I know that S-
glass and scifer steel fibers do retain thatstrengthin the radial
directions. I'm not sure if this is true for the carbon fiber. (BTW,
thehighstrengthpolymer fibers listed in the table *such as Kevlar,
Dyneema, or Spectra are unsuitable because theirstrengthonly holds
in the longitudinal direction, not radially.)
Another key problem for usinghighstrengthfibers 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

*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 theVentureStar. 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%20Contes...Contest%20Entr...

* 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 theVentureStar, theVentureStartank 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 forVentureStarwas 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 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
of the X-33, i.e., by a factor of 2. This would mean the pressure theVentureStartanks 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

*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, 1994http://www.springerlink.com/content/t7u643052q1865q6/

What's this going to cost?


Bret Cahill

On Sep 2, 2:38 pm, Robert Clark wrote:
...

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...l/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, 1994http://www.springerlink.com/content/t7u643052q1865q6/


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/Hydroge...torage_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)PVñ/ó, whe

M is mass
P is the pressure difference from ambient, i.e. the gauge pressure
V is volume
ñ is the density of the pressure vessel material
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
density ñ_g: dividing both sides by m_g, the formula becomes:

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:

M/m_g =(3/2)(P/ó)(ñ/ñ_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

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.

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.

DB wrote
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.

On Aug 19, 12:21 pm, 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

On Sep 6, 4:26 am, Robert Clark wrote:
On Aug 19, 12:21 pm, 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

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 ****-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?

~ Brad Guth Brad_Guth Brad.Guth BradGuth

On Aug 17, 4:42 pm, Robert Clark wrote:
On Jul 29, 12:59 pm, Robert Clark 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

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 ahightech 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 he

Tensilestrength.http://en.wikipedia.org/wiki/Tensile_strength

The solutions investigated for the hydrogen tanks for VentureStar
included usinghighstrengthaluminum alloys or composite fiber tanks.
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
tensilestrengthof 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 theirstrengthto weight ratios
are sohighyou wouldn't need to store the hydrogen in liquid form.
You could store it ashighdensity gas. That would eliminate the
weight of the cryogenic systems for the hydrogen.
However, a key question here is whether thisstrengthwill be
maintained in the radial direction. All the strengths listed for the
fibers are for pulling along their lengths, i.e, their longitudinal
tensilestrength. But to use the fibers as thin hollow pressure tubes
will require theirstrengthto hold in the radial direction. After
investigating this question before for hydrogen storage, I know that S-
glass and scifer steel fibers do retain thatstrengthin the radial
directions. I'm not sure if this is true for the carbon fiber. (BTW,
thehighstrengthpolymer fibers listed in the table such as Kevlar,
Dyneema, or Spectra are unsuitable because theirstrengthonly holds
in the longitudinal direction, not radially.)
Another key problem for usinghighstrengthfibers 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

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%20Contes...Contest%20Entr...

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

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

On Sep 5, 8:32 pm, Robert Clark wrote:
On Sep 2, 2:38 pm, Robert Clark wrote:

...

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...l/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, 1994http://www.springerlink.com/content/t7u643052q1865q6/

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/Hydroge...torage_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)PVñ/ó, whe

M is mass
P is the pressure difference from ambient, i.e. the gauge pressure
V is volume
ñ is the density of the pressure vessel material
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
density ñ_g: dividing both sides by m_g, the formula becomes:

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:

M/m_g =(3/2)(P/ó)(ñ/ñ_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

Why not simply use h2o2 plus a little fossil or synfuel?

~ BG

On Sep 6, 10:26 am, BradGuth wrote:


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

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 bull****, 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