What is the best lifting gas for an airship?

Technical discussions regarding LTA-technology.

What is the best lifting gas for an airship?

Hydrogen
10
34%
Helium
11
38%
Methane
0
No votes
Hot Air
0
No votes
A combination of one/more of the above
8
28%
Other
0
No votes
 
Total votes: 29

Sean
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Re: What is the best lifting gas for an airship?

Postby Sean » Fri Aug 26, 2016 4:34 pm

Hiroshi wrote:I say both helium and hydrogen. Helium for outer cell surrounding inner cell with hydrogen.


This may actually be the best option for current airships if helium becomes too expensive to use.
It should be very safe, as the helium would create an inert barrier. I think this conclusion is a good middle-ground for both helium and hydrogen advocates.

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Re: What is the best lifting gas for an airship?

Postby Airshipcenter » Sat Aug 27, 2016 8:13 am

I personally would have no trouble travelling on an airship that has an inner hydrogen cell and a surrounding helium cell.

To my knowledge, this is what the Germans planned to do, until the angry man with the funny mustache screwed it all up.

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Re: What is the best lifting gas for an airship?

Postby pyronaught » Sun Aug 28, 2016 8:03 pm

Ideally the inner hydrogen cell would be centered so that there is a buffer of helium all around it, but the hydrogen cell would want to rise to the top of the helium cell due to being lighter. So you would actually have to tether the hydrogen cell to the bottom to keep it centered. The hydrogen cell could just be a sphere too, since that is easier to fabricate and gives you the most volume for the least surface area.

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Re: What is the best lifting gas for an airship?

Postby Sean » Mon Aug 29, 2016 6:35 pm

Are there even businesses/scientists actively searching for helium?

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Re: What is the best lifting gas for an airship?

Postby turtleairships » Tue Aug 30, 2016 12:51 am

The nation of Qatar has been active in developing helium extraction from their huge natural gas production reserves, with the intent of becoming the #2 world supply.

Recently, a major helium field was discovered in Tanzania. It is believed that this supply could outstrip the historic sources in USA.

of course, in Russia, much work has been done to develop helium from natural gas in the areas surrounding the north of Caspian Sea, and Lake Baikal.......

helium from natural gas under Timor Sea is rapidly becoming available.

bottom line.........there is enough helium to sustain an airship industry for a while yet.
( but, so much more WILL BE be done when flammable gasses are considered and permitted)

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Re: What is the best lifting gas for an airship?

Postby Sean » Tue Aug 30, 2016 8:20 am

Thank you for the informative reply @turtleairships.
Then there must be enough helium for a niche market or a few airship liners to be built, but I also consider the chance of it happening very low. It would cost hundreds of millions alone to redesign and build an airship like the Hindenburg to 21st century standards not to mention the construction of a few gigantic hangars around the world. Although I think the Zeppelin company would be more than happy to do it if they got the money somehow!

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Re: What is the best lifting gas for an airship?

Postby meme » Fri Sep 02, 2016 11:12 pm

For the people recommending the classic solution of a helium outer cell, what is your solution to prevent / reverse hydrogen permeation into the helium cell and accumulation at the top? How do you control buoyancy? If it's via venting, do you vent helium (the pricey one) or hydrogen (the one that burns very aggressively when mixed with air, with a tiny ignition energy)? How do you prevent double puncture (lightning, etc)? What do you to do to reduce the risks of hydrogen handling on the ground, not just in the air? In places that handle hydrogen (refineries, rocketry, etc) it's always a major safety risk.

Why do you find the extra weight and complexity (of a double envelope approach) / risk to be worth using hydrogen? Surely not lift, the difference isn't that great. If the answer is price, why do you find that superior to solutions to prevent the venting of helium (and thus having it more as a capital cost, not a recurrent operations cost), such as hybrid airships, and modern permeation-resistant fabrics such as vectran? This seems to be where the market is headed instead.
Last edited by meme on Fri Sep 02, 2016 11:23 pm, edited 1 time in total.

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Re: What is the best lifting gas for an airship?

Postby meme » Fri Sep 02, 2016 11:17 pm

Re "helium supply", lifting purposes is a tiny fraction of the total, and will continue to be so even with more widespread adoption of airships. With modern fabrics and techniques to reduce / eliminate venting, that figure becomes even less. I wish people would focus on the real culprits of the waste of helium (industry and medicine) instead.

It's also worth pointing out that it's far from certain that helium is some inexorable trend of increasing scarcity. Compared to resources like oil and gas, helium is rather poorly explored, namely because it used to be so cheap. We don't even really have a good grasp on what determines what becomes a good helium reservoir and what doesn't. Ignoring unexplored natural gas helium sources, there's some new potential helium resources that have thusfar been entirely unutilized (for example, volcanic helium) that could vastly expand the total resource.

Good article here about one of the new volcanic helium deposits discovered - there's been little investigation of that even as a possibility until recently:

https://eos.org/articles/tanzanian-volc ... the-taking

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Re: What is the best lifting gas for an airship?

Postby turtleairships » Sun Sep 04, 2016 7:43 am

@ meme I'd like to read what you might have to say about the Turtle Airship design concerning the above questions re: helium/venting..........

simply, Turtle proposes to build with more robust materials. These include aluminum, carbon fiber, ceramic reinforced aluminum, and some aerogel materials. The entire hull of a Turtle Airship is made of these types of materials...........as well as rigid walled interior compartments for helium, and for gasses that are to be vented.
( yes, we know and accept that the materials will be more expensive.
Yes, we also know that they will add weight.
both of these factors can be worked with.)

Not a primary reason for all this, but a secondary one....is to make the entire craft, as much as possible, "fireproof".......as in, it wouldn't affect the ship much if a gas compartment actually burned off.

re: venting...........we plan to use flammable gasses, yes, but eschew hydrogen for the exact reason you write above; it's too volatile. other gasses such as ammonia, methane, or simply natural gas can be used; and we intend to go that route first. while these are flammable, they are "safer" than hydrogen alone.

there are other considerations....lifting ability, costs, availability, political and environmental issues, etc. but overall, using helium to lift a fully rigid hulled airship; and using flammable gasses to vent.......is our purpose.

I'd welcome a private email discussion....... turtleairships AT hotmail DOT COM

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Re: What is the best lifting gas for an airship?

Postby meme » Sun Sep 04, 2016 11:59 am

Do you have some diagrams for your airship? I'd be quite interested in seeing them. That's an interesting concept - basically an airship "armoured" against damage. I assume you're looking at twinwall CF with the aerogel in the middle (not just for fire resistance, that'd also increase the bending moment of inertia)? Are you looking at internal trusswork as well, or all of the strength in the shell? In a way, you don't want the rigidity to be too great; you need some give in the case of a ground impact. I assume you have some sort of permeation barrier beyond CF? Aluminum is a good gas barrier, so no concerns with that, but CF isn't on its own - CF pressure tanks for hydrogen and helium for example almost always have a liner.

Obviously your scale needs to be large to get a high volume to surface area ratio if you want to have such a reinforced surface. And of course the devil is in the details ;)

I'd have toxicity concerns with ammonia in the event of a ground handling incident if significant quantities are to be used. Methane, however, as you note is not nearly as volatile as hydrogen. The ignition energy required is an order of magnitude higher (0,21mJ vs. 0.016mJ), the flammable fuel-air mixture range is far narrower (5-15% ppv vs. 4-75% ppv), the flamefront propagation rate is much slower, etc. It also doesn't permeate nearly as much as hydrogen or helium. If you're willing to accept the reduced lift and increased envelope volume / cross section / mass, certainly from a safety perspective one could make a very solid argument for it vs. hydrogen.

When I was young, my father was a manager at an oil refinery. Despite the tremendous quantities of hydrocarbons around, one thing that they always worried about burning in particular was the hydrogen used in the hydrocrackers. It was so easy to get a leak, and so easy for that leak to ignite. Even small fires were problematic, particularly because they were hard to see - the teams sent to deal with suspected leaks would wave broomsticks in front of them to make sure that they didn't accidentally lose a limb to a flame that they hadn't noticed ;)


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