
Beyond Helium  - judegomila
http://www.judegomila.com/post/55386351452/beyond-helium
======
jakobe
The author doesn't understand the concept of a blimp. The only reason for
filling it with helium (or hydrogen) is to counter the atmospheric pressure.
Since aerographite doesn't do that (it would just collapse under the pressure)
there is absolutely no point in filling a blimp with aerographite.

If you found a way to create a hull that withstand the pressure, and prevents
the aerographite from being compressed, why fill it with that stuff in the
first place? Just use a vacuum inside your superstrong hull!

~~~
bayesianhorse
I don't have a lot of engineering knowledge, but I believe they said when
evacuated it is about as strong as styrofoam. The latter is able to withstand
air pressure. Wouldn't that mean that if you put an airtight hull around it,
this stuff would actually hold it up? But yes, probably it will be tricky to
evacuate and expand it at the same time...

~~~
maaku
Styrofoam doesn't "withstand" air pressure, it has pockets of air inside.

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ggreer
I'm pretty sure aerographite is porous, and the numbers you're quoting don't
count the mass of the air permeating the aerographite. You could wrap it in
something like mylar, but it'd be less safe than helium. Any break in the skin
would be like a hole in a space capsule. This could be ameliorated with
smaller cells, but that cuts into your lift. It's also not clear if
aerographite is strong enough for the job.

To make something as safe and reliable as you describe, you'd have to build an
evacuated closed-cell foam. That material would have to be extremely light
while also being able to withstand being crushed by the atmosphere. It's not
clear if anything is up to the task.

Sorry to dash your hopes.

~~~
marshray
Perhaps you could fill it with hydrogen? I'm not sure if that's a joke or not.
Hydrogen in a closed-cell matrix seems like it would be a lot better contained
and stable than in a bag-of-gas like the Hindenberg.

But this stuff is open-cell, so perhaps seal it into manageable-size beads?
Looks like it might hold up to temperature pretty well.

Alternatively, this stuff could be used to produce a lighter-than-air
structure in a process that somehow consumes it.

~~~
lmm
You don't _want_ your hydrogen contained, you want to be able to vent it
quickly in case of fire.

~~~
lostlogin
Wow - I would have thought that risked an even more exciting event with rocket
propulsion. Is venting really the standard way?

~~~
marshray
During the whole hydrogen car discussion, it was said that hydrogen contained
in a matrix was much safer because it would burn in a controlled fire rather
than an explosion.

Venting hydrogen quickly into an oxygen-rich atmosphere would be silly.

------
ChuckMcM
This is a great idea except for this tricky bit (which they even mention in
the article)

 _" One other limitation will be creating aerographites that can support
themselves with the air inside the material “pumped" out of it."_

I really can't complain too much though as I too was pretty taken with the
idea after reading Diamond Age (which has a variant of this). At some point we
might be able to assemble dodecahedrons out of small diamond pentagon sheets
while in a vacuum and thus create small, lighter than air, "bubbles". But that
time is still quite a ways off. After researching a bit the forces on the
materials relative to the amount of air they would have to displace in order
to achieve a net density lower than air, at volume. It doesn't look
particularly doable yet (perhaps ever but I'm not willing to completely rule
it out.)

The idea though is very alluring.

~~~
wikiburner
Hey Chuck, I actually replied to your comment on the "Human-Powered Helicopter
Wins the $250,000 Sikorsky Prize" thread about a more conventional way we
could achieve "permanent points of presence in the air" before we enter the
"Diamond Age" :) - and I was curious about your thoughts on it, given that I'm
not anything close to an engineer. Anyway, sorry to bug you, just curious if
there's anything to it.

=========

I've often wondered if a balloon-based system might be the way that this
("permanent" points of presence in the air) is eventually achieved. As solar
energy becomes more and more efficient every year (apparently it's on an
exponential price/performance growth curve), you coat the balloon with a
light-weight, flexible solar array, and either heat the air like a hot air
balloon, or as it becomes cheaper and more efficient to extract hydrogen from
water, fill the balloon with hydrogen, and constantly replace the hydrogen
that leaks out with hydrogen extracted from water vapor in the air:
[http://www.technologyreview.com/view/512996/a-cheaper-way-
to...](http://www.technologyreview.com/view/512996/a-cheaper-way-to..).

You could use low powered propellers (like a blimp), and take advantage of
weather patterns (like Google's Loon project) in order to maintain position or
to slowly travel.

~~~
ChuckMcM
The general challenge with balloons is drag, or specifically their response
(or lack thereof) in the presence of winds so staying in one place can be
problematic. I like the idea of cracking water to get hydrogen to replenish
your lift bags, but if you are to fly this over the flyways (say at 60,000')
you're not going to get a lot of moisture in the air. The old Zeppelins had
gas generators which, while they had to be replenished, could supply plenty of
hydrogen during the journey.

Google's balloon system [1] is apparently using quantity to cover holes that
appear when winds blow them down range. Also if they get caught in the jet
stream the can leave the area in a hurry.

Granted winds are a challenge for any aerial platform but actively flying
shapes, seem to out perform lighter than air ideas when staying on station is
required [2]. So solving the station keeping question would be a big part of
the equation.

That said, the company that proposed the blimp to the Army is continuing to
develop it as far as I can tell from their web site [3]. Perhaps it will get
additional engineering work on those issues.

[1]
[http://www.google.com/loon/#utm_source=google&utm_medium=cpc...](http://www.google.com/loon/#utm_source=google&utm_medium=cpc&utm_campaign=Global_semBK)

[2] [http://www.popsci.com/technology/article/2013-02/army-
cancel...](http://www.popsci.com/technology/article/2013-02/army-cancels-
airship)

[3]
[http://airshipmanufacturing.com/sentinel-2-airship.html](http://airshipmanufacturing.com/sentinel-2-airship.html)

------
abtinf
Can someone explain why the material isn't floating in the air? I watched the
video and it just sits here?

edit: I understand that air is in the space between the nanotube fibers. But I
still don't understand why the material doesn't float. Why doesn't the air
inside the material average out with the material itself to result in a space
with lower density (thus causing it to float) then the surrounding air?

~~~
scarmig
The solid material is denser than air. It does, however, form a structure
which when evacuated of air has a lower average density than air.

Letting the air flow in fills in those gaps, raising the interstitial density
enough that the average is greater than air.

~~~
tempestn
I keep reading this, but I'm missing what makes it special. If you create a
large enough vessel of _anything_ and evacuate all the air, you can make it
lighter than air. Is it just that it's rare to find a material strong enough
with respect to its density to withstand the necessary vacuum? (ie: would a
titanium bubble with a sufficient volume to thickness ratio to be lighter than
air implode? Or would it just be too expensive?)

~~~
dsr_
Buckminster Fuller thought that if you built a large enough geodesic dome out
of normal midcentury materials, you could get enough lift from sunlight-driven
thermal expansion of air to float it.
[http://www.thirteen.org/bucky/cities.html](http://www.thirteen.org/bucky/cities.html)

------
joshu
Physics doesn't work that way. The "6x lighter than air" doesn't include the
air inside the material.

I'm not sure that "if law of physics X were repealed, we could..." stuff is
anything more than science fiction: see the multiple comparisons to Diamond
Age in this thread.

~~~
kamkazemoose
They mention that at the end of the article

>One other limitation will be creating aerographites that can support
themselves with the air inside the material “pumped" out of it (to truly
achieve being lighter than air). In practice, getting a real blimp to work
will probably be made out of a future version of aerographite or another
aerogel that is super strong and light, one that could self support itself
without collapsing in on itself if the air between the meshes of nanotubes is
pumped out. A partial vacuum will have to be created inside the aerographite
structure without crushing the aerogel. This may be the fatal flaw to the idea
or at least the next problem to solve (i.e. given that the material is
superhydrophobic, maybe a thin shell of water could be put around the aerogel
or some similar exotic solution).

~~~
IsometricAI
"pumped"

Ionize the air?

------
gojomo
Other than giant airships: how about just novelty/party balloons that never
out-gas & sink? Re-positionable ceiling decorations? Indoor microblimps?

If such things escape into the atmosphere, you've got a floating-garbage
problem... as described in Stephenson's _Snow Crash_.

------
knome
> You might ask yourself, how are you going to come back down to earth if you
> cannot release some of the hydrogen/helium?

If the material can be compressed to 95% it's size and reexpands, you just
compress your tanks and lower back down, expand tanks to rise. ( all concerns
of other comments having been solved with the standard wave of the hand )

~~~
geon
Or you just make it slightly heavier than air, and use it as a very fuel
efficient airplane.

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Aardwolf
The article somehow seems to have a misconception that if you bring material
lighter than air aboard, you will float up... Then you could as well just take
some vacuum with you.

Maybe that would be even more useful than this material: a balloon filled with
vacuum! And some support structure to make it keep its shape :)

------
stonemetal
Helium 0.1786 g/L

Hydrogen 0.08988 g/L

Air 1.275 g/L

This stuff is six times lighter than air so 0.2 g/L or there about. Both
Helium and Hydrogen are lighter than this stuff. Considering the explosive
reintroduction of air thing being pretty equivalent to the other two what
makes this theoretically better?

~~~
DanBC
Helium is non-renewable and in limited supply.

------
davvydavy
There's also a greater potential health risk posed by carbon nanotubes. I am
completely guessing, but I feel as though the risk of dispersed airborne
nanotubes (in this model) would be greater than dispersed helium (from a
current blimp.)

------
kens
The article mentions this would be safer than flammable hydrogen, but wouldn't
this stuff burn really well being carbon with a whole lot of surface area?

------
6ren

      how are you going to come back down to earth if you cannot release some of the
      hydrogen/helium?
    

You compress it.

~~~
rdtsc
As others mentioned it, wouldn't air pressure compress it as well and thus
make it not be able to take off.

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Gravityloss
You have to take into account two things:

1\. the porosity, meaning air fills the cavities. Can you really talk about
open structures and say they're really light? Make an aluminum balloon filled
with air and it's probably lighter than air as well.

2\. the buoyancy, meaning that the fibers displace air. If a light material is
weighed in air, the result does not give the mass of the object.

With normal solids, this does not matter since they are heavy compared to air.

For example, you can weigh wood with a volume of 1 liter in normal air
pressure, and get a mass result of 0.500 kg. Then weigh it in a vacuum, you
should get a 1 gram difference (air density is about 1 gram per liter) - a
weight of 0.499 kg. In practice this is in the noise for normal materials.

Cloced cell extruded foam is about 30 kg per cubic meter. So here the air mass
1 kg per cubic meter already has a 3% effect. I don't know if the weights are
usually quoted with buoyancy or not. But this is closed cell, I don't know how
well it stands up to a vacuum.

One example of structures that can have a lot of mass but little weight is
inflated ones. There have been some human powered aircraft that are really big
but light on the scale. Yet they take a lot of time and energy to accelerate
since all the air mass inside must be brought up to speed.

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faddotio
Imagine having a landfill of this stuff, blanketing the Earth at 10,000 feet.

Hmmm. :|

~~~
Groxx
Sort of like we have now with satellites + the ISS, which has to move
occasionally to avoid the pieces of junk we can track?

------
dhughes
How about flying cars?

I've always thought a great idea for a flying car was a van-like vehicle that
is either filled with helium or a vacuum, maybe a combination.

A blimp-like vehicle that won't deflate or leak would be even better since it
won't need lift to stay up and wouldn't require much power to propel.

~~~
galaxyLogic
That's the point! We don't need materials that are lighter than Helium. We we
need nano-materials that are strong enough to keep the vacuum in. Thanks ...

~~~
dhughes
Then suck in air for ballast, it may be similar to ocean going vessels they
float when idle but need power or wind for propulsion plus ballast to
stabilize.

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babebridou
I'm not too sure if I interpret these right, but wouldn't this material be
tailor-made for a weightless sail that can compress itself 20 times?

Wouldn't this be a revolution for boats, lifebuoys or seaplanes?

Also, wouldn't this allow human-size people to carry around weightless wings
on their back that expand 20 times from 50cm to 10 meters in span, letting
them fly like birds?

Edit: I know these ideas have no scientific basis. I'm just surprised that the
only mentioned applications of this material are lithium batteries, waterproof
clothing and the likes. Surely there would be a lot of things to create out of
an essentially weightless solid.

------
galaxyLogic
Cover this new stuff with a balloon and then fill it with helium. Is there any
difference to a balloon filled with helium?

I suppose it could keep its shape, which would be a benefit.

When the shape doesn't change there is less wear and tear and tension on the
"skin". It could be made of a light, inflexible but strong material, because
the shape of "Beyond Helium" unlike with a balloon would not continuously
change due to altitude and weather.

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tzs
> You might ask yourself, how are you going to come back down to earth if you
> cannot release some of the hydrogen/helium?

So if the aircraft loses power, or loses its hydraulics, the failure results
in the aircraft getting stuck in the air? I can see that being promoted as a
feature.

~~~
jlgreco
On airships of old, this was actually a potential problem as well. They tried
to avoid venting lifting gas whenever possible and investigated several
techniques to avoid it as much as possible.

Extracting water from the air or weather to use as ballast as your airship
becomes lighter and lighter (by consuming fuel for instance) is a particularly
clever idea I think.

[http://en.wikipedia.org/wiki/Buoyancy_compensator_(aviation)](http://en.wikipedia.org/wiki/Buoyancy_compensator_\(aviation\))

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tocomment
I've wondered if we could fill a sealed ballon with thin wires. Then put a
large electric charge on all the wires so they repel each other and expand the
balloon with vacuum.

Why do you guys think?

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hcarvalhoalves
Actually, I would be more excited about it replacing the non-biodegradable
styrofoam. Since it's a simple carbon composite it should be more
environmental friendly, no?

------
Tharkun
What about the effect of 15nm carbon fibres entering your lungs? Are we
setting ourselves up for another asbestos-like scenario? Or is this stuff
somehow safer?

------
dmritard96
seems to me like a good styrofoam alternative/competitor, but for floating
like properties, it to have vacuums in the tubes right? That is certainly the
difficult problem to make this truly be better than helium for some
applications. On the other hand, maybe with the structure each small tube is
under or is a vacuum.

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cookingrobot
Idea: how about super-heated air in a balloon lined with aerogels to act as an
insulator.

Air at 1000f is a third as dense as air at 200f.

------
twic
How did this get voted up this high? What? WHAT?

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rorrr2
Aerographite is NOT lighter than air. What they mean is that a vacuum-filled
cubic cm of aerographite is lighter than a cubic cm of air.

A piece of that material will NOT float up on its own, because it's heavier
than air.

~~~
JoeAltmaier
Right. Its density that matters, not weight. And as the top posting says, the
ability to withstand atmospheric pressure. Since this aerographite stuff
actually compresses 20X quite willingly, its useless for balloons etc. because
pumping out the air would result in the envelope collapsing.

