

Lighter-than-air craft rise again - duelin_markers
http://www.bbc.com/future/story/20120921-lighter-than-air-craft-rises

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camtarn
If you try and load this page from the UK, you get:

"We're sorry but this site is not accessible from the UK as it is part of our
international service and is not funded by the licence fee. It is run
commercially by BBC Worldwide, a wholly-owned subsidiary of the BBC, the
profits made from it go back to BBC programme-makers to help fund great new
BBC programmes."

O.o

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terhechte
This is offtopic but, for precisely this reason I recently bought vpn access
to a provider that has severs in all major countries. I'm living in Germany,
and here, YouTube is almost unusable because everything music or somehow
copyrighted can't be accessed. Also, I like to watch BBC programmes or Hulu,
again impossible from here. VPN has been a great investment so far.

~~~
kirubakaran
Name of the said VPN provider please.

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bduerst
I used Astrill when I was in China - they are pretty reliable and have server
locations across the globe.

Make sure you get a dedicated IP address though.

Edit: Link for the lazy - <https://www.astrill.com/>

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lutusp
The good news is that blimps rely passively on the relationship between their
overall density and that of the atmosphere to stay aloft. That's also the bad
news.

In some future, more rational society, blimps would be tested for their
resistance to a microburst, and if they failed, they would not be allowed to
carry passengers. It's not true now, and every famous lighter-than-air
disaster except Hindenburg involved the craft being pushed down to the surface
entirely out of control.

<http://en.wikipedia.org/wiki/Microburst>

Picture of a microburst:
<http://en.wikipedia.org/wiki/File:Microburstnasa.JPG>

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tisme
That's not a picture of a microburst, that's an artists rendering.

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lutusp
I would have used "photograph" if I had meant a literal recording of nature.
This reminds me of the conversation between an artist and a critic, who
complained about his distorted woman on display. He replied, "madam, that's
not a woman, it's a picture of a woman."

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zachrose
Metonymy!

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lutusp
> Metonymy!

Perfect word. It's not an exaggeration to say that most of our conversations
about (a given topic) "A" aren't about "A" at all, but its symbolic or
metaphysical version.

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arturadib
> _When the pilot wants to descend, the vehicle needs to be heavier, so the
> helium in the main body of the craft is compressed and put into storage
> chambers._

Ha, it's an inverted submarine!

[http://en.wikipedia.org/wiki/Submarine#Submersion_and_trimmi...](http://en.wikipedia.org/wiki/Submarine#Submersion_and_trimming)

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tocomment
This idea seemed obvious too me. In fact that's how I've assumed blimps worked
since I first heard about them.

How would they descend otherwise, release helium and reload before taking off?

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lutusp
> How would they descend otherwise, release helium and reload before taking
> off?

Too wasteful, and uneconomic. The way they control their buoyancy is by
compressing the helium to reduce buoyancy, then later releasing it from a
special storage tank to increase buoyancy. BTW this is how submarines control
their buoyancy -- they displace water with air in set-aside volumes made
available for this purpose, which increases the craft's overall buoyancy.
Then, when they want to descend, they recompress the air and allow water back
into the set-aside areas.

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bduerst
Helium is expensive, and is only going to get more so in the coming decade or
so.

They mention that on the descent, they mix outside air with the remaining
helium in the ballasts.

Aren't you going to lose a lot of the helium in this process?

Wouldn't it be easier to have a sealed bladder that inflates/deflates with
pressure changes?

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fab13n
They obviously considered the bladder option when designing the craft, which
means that: \- either air and He separate fast and well enough to make it
unnecessary; \- or there are big problems which make the bladder impractical.
I have no idea what these problems might be.

Anyway you're right: a scientifically literate journalist would probably have
explained the rationales behind this non-obvious choice.

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PaperclipTaken
This is a concept that I find myself continuously in love with. As ahi points
out, it comes up every few years and never seems to go anywhere, but something
like an airborne luxury craft sounds like a fun vacation. You couldn't have
all of the grandness of a cruise ship, but you could find several ways to take
recreational advantage of being several thousand feet in the air. For example,
a rock climbing wall outside of the ship. And instead of having a ship
designed for a 2 week journey, maybe only 3 days (or one day), because there
is inherently less room for things like spas and casinos and restaurants.

I also like the transportation focus presented by this article. Perhaps having
a useful application (IE retrieving large things that are difficult for
helicopters to retrieve) will help to encourage the market for all types of
lighter-than-air craft.

Would cruise ships have happened without cargo ships first being designed? My
guess is no, because cruise ships largely piggyback off of a technology that
is industrially very useful. I do not think that a recreational company would
dump so much money into finding ways to make ships more economically feasible.
That takes industry, where the need is more obvious, and the potential demand
is much easier to predict.

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TylerE
The problem with lighter than air craft is that the payload fraction is
minimal - you need a big craft to get a fairly small useful load. This problem
is worse if you don't use hydrogen.

For comparison, the S-64 Skycrane (a heavy lift helicopter), weighs 19,000lbs,
can lift 20,000lbs, and is 70ft long.

The Zeppelin NT, a modern semi-rigid airship, has an unloaded weight of
24,000lbs, is almost 250ft long, but only had a payload capacity of 4,200lbs.

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tisme
The good news is that the time that it can stay aloft is substantially longer
than any rotor or prop driven craft.

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ginko
The problem with aircrafts like these is that helium is slowly but surely
becoming a scarce resource on Earth. Here's a somewhat related story about
scientists speaking out about using it in balloons.

<http://www.bbc.co.uk/news/uk-19676639>

We could always use hydrogen, which is even lighter and therefore more
efficient than helium. There's just the problem with it being highly
flammable.

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jakeonthemove
Is hydrogen really that dangerous anymore? I mean, we use bikes that have
highly flammable fuel right under your body, surely it's possible to create
some safety measures to prevent the hydrogen from catching fire.

Not to mention that Hindenburg wasn't that much of a disaster - of 97 people,
61 survived, which is not bad at all for an airship the size of three 747's
(or six if you don't include the wingspan) chockfull of hydrogen.

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sliverstorm
The ignition point of magnesium is fairly high, and its ability to act as a
heat spreader further reduces the risk.

To put it simply, you can set off magnesium with a blowtorch. You can set off
hydrogen with a _match_.

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jakeonthemove
I'm sorry, I don't understand - I was talking about the gas in the tank on
motorcycles (which also ignites from a match and it's pretty damn explosive).
Also, hydrogen does not ignite without air, just like gasoline.

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sliverstorm
Hah! My mistake. Well, thing is with gasoline, is it isn't actually all that
explosive in pure liquid form. Go take a pan with a cup of the stuff outside,
light it with a match. No, seriously! It will just sit there and burn, slowly
and usually with a lot of soot.

Gasoline _vapor_ is a completely different story, and the reason you think of
gasoline as explosive. But, this doesn't generally prove to be a problem, in
part because motorcycles (and just about every type of vehicle) have pressure
vents so that the tank doesn't become dangerously pressurized.

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ahi
This shows up every few years in credulous magazines like Popular Mechanics
and Wired. It is literally vaporware.

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machrider
I was surprised to see the article mention that they'll be going for flight
testing later this year, given that the only picture accompanying the article
is a rendering. However, if you go to their site, they have photos and
videos[1] of working airships. The cabin is tiny though, with room for only
the operators (these may be the cargo ships mentioned in the article, rather
than passenger vehicles).

[1]: <http://www.aeroscraft.com/#/video/4565658106>

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anonymouz
There is also a video accompanying the article which shows a BBC reporter
interviewing an engineer at the hangar. In the video one can clearly see that
at least _some_ rather large airship is well under construction (it's 90m x
27m x 30m, l x w x h). It's frame seems to be finished, and parts of the hull
are installed too.

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bduerst
I guess the only problem this solves is being able to land on the spot?

Even with compressing the helium to land again, I guess it could be more
energy efficient, but it would take forever to reach it's destination. People
typically fly in jets because they are fast, not because they are fuel
efficient.

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andyjsong
I wonder what the costs are to build an airship to the same scale as a
commercial airliner. If speed was not a factor and it seated comparable amount
of people, but it cost significantly less to build and operated there could be
a niche market for the not-in-a-hurry air traveler.

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dangrossman
If you're in California, you can book a zeppelin tour almost any day --
<http://www.airshipventures.com/>

Unfortunately it's quite expensive starting at $375 for a 45-minute flight.

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zefi
Here is a screenshot of the article. <http://i46.tinypic.com/358du2c.png>

Couldn't get the video unfortunately. I'm in the UK, the VPN I used was
Hotspot Shield, it's free.

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troebr
How well does it cope with wind?

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TheSOB88
When I saw the title, I thought they'd figured out a way to make use of
something other than helium, but I guess I was wrong. I was thinking maybe
they built self-resizing vacuum chambers in order to reduce the weight/volume
ratio. Like, there would be two membranes, and between them, supports that can
extend or shorten to change the volume of the vacuum-space, and affect the
overall density that way.

Does anyone know if this has been done, or if it's at all feasible?

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mylittlepony
_“It’s impossible to get into some of the resource rich areas of the world.
Ecologically, you can’t do it. Areas of the far north, or the Amazon are good
examples.”_

Oh great, now we can give the final blow to that annoying Nature!

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JoeAltmaier
Um, the point is, you can get there without building roads and raping the
environment. Its supposed to be kinder to Nature.

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freehunter
"Resource rich" tends to lead me to believe that the reason we want to get
there is to take the resources. Having a road or having a blimp, either way
it's not going to be good.

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JoeAltmaier
Even with a coal mine, the roads do more widespread damage than the actual
mine. Oil derricks in Alaska do minimal damage; its the construction, pipeline
and roads that do it all.

