We Were Promised Airships
March 19, 2016 10:38 AM   Subscribe

 
His parents, civil engineers, thought that he would move on to more practical interests.

I believe this sentence appears in every narrative concerning an obsession with airships.
posted by GenjiandProust at 10:43 AM on March 19, 2016 [18 favorites]


Ok this will sound silly and naive but I don't understand why we can't use hydrogen. The Hindenburg was certainly horrific but fewer lives were lost both in numbers and percentage than the jet this weekend. The real reason is more practical in terms of speed, navigation issues with the wind, probably economic. But with good engineering static can be managed, modern engines are certainly safe and escape strategies should be possible.

Just how pleasant it would be to cross the country at 1500 feet watching all the details below, sipping tea and chatting with friends in the lounge.
posted by sammyo at 11:01 AM on March 19, 2016 [7 favorites]


I went in a hot air balloon once. It's a very uncanny experience, because unlike being in an airplane or even an elevator, there is none of that tug and pull that signals that you are moving upward. Because you aren't making any motions that fight against gravity. You are literally in a situation where gravity is deciding to let you go, so the entire experience is of having the ground move away from you while you just watch it move away.

My main concern with this scheme is that helium is becoming more and more rare on our planet, to the point where I have been reading editorials against filling party balloons with it because it is a vanishing resource. Maybe if we can learn how to manufacture it (which would solve a lot of our other problems, too)...
posted by hippybear at 11:05 AM on March 19, 2016 [6 favorites]


what I want is a residential blimp.

have it park itself somewhere at 2,000' while I work, and at 5PM it comes down to pick me up.

the only way to escape the Monopoly board of our economy is that, or a boat I guess, but the ocean is 150 miles away now, alas.
posted by Heywood Mogroot III at 11:06 AM on March 19, 2016 [5 favorites]


"To be honest I’ve never seen the inside of a public blimp."
posted by percor at 11:07 AM on March 19, 2016 [1 favorite]


"dirigible" shares the same root as "direct" by the way, and means 'steerable'.
posted by Heywood Mogroot III at 11:07 AM on March 19, 2016 [7 favorites]


You want to put a hospital into Africa?” Bruce Dickinson, the company’s lead investor, said to me. “You put the whole hospital in the inside of this—whoosh. Start the generator. ‘Here’s your hospital, buddy!’ Job done. You know?

Me: lol like the Iron Maiden dude

Clean-shaven, with dimples and loosely cropped silver hair, Dickinson is better known to a certain fraction of the world as the lead singer of the heavy-metal band Iron Maiden.

Me: HOLY FUKCKING SHIIT
posted by Greg Nog at 11:12 AM on March 19, 2016 [71 favorites]


The canonical answer regarding using hydrogen is that the Hindenburg disaster provides such sufficiently horrific and spectacular negative publicity that the idea of using hydrogen is a non-starter, and cannot be overcome with regard to passenger-oriented applications.

This is not necessarily inaccurate; the Germans had nearly fifty years of experience providing hydrogen-based passenger flight. Granted, huge chunks of their upper management had been thrown into disarray by the arrival of the Nazis, but the company was confident - and had reason to be - in their ability to fly the ships safely.

Of course, the US Navy was also confident in their ability to operate the huge ships, without hydrogen.

Abandonia has a zeppelin line simulator, by the way!
posted by mwhybark at 11:16 AM on March 19, 2016 [2 favorites]


Me: HOLY FUKCKING SHIIT

Greg, Dickinson also has and flies a Fokker Dr1 replica, which is, of course, painted with the livery of Manfred von Richthofen.
posted by mwhybark at 11:17 AM on March 19, 2016 [7 favorites]


One of several previously links, this one selected for personal reasons. I should maybe check to be sure my blog migration didn't kill the links, but that task will have to wait.
posted by mwhybark at 11:20 AM on March 19, 2016


Growing up asking why the skies are not filled with airships may of course indicate that you are a refugee from another timestream.
posted by Artw at 11:21 AM on March 19, 2016 [9 favorites]


My main concern with this scheme is that helium is becoming more and more rare on our planet

I'd like to see some references here, because I'm pretty confident that's not how physics works.
posted by mhoye at 11:23 AM on March 19, 2016


A simple search for "helium shortage" will give you many articles describing a lot of facets of this issue.

And yes, it is how physics works.
posted by hippybear at 11:29 AM on March 19, 2016 [27 favorites]


Helium floats out into outer space, and it's generated through radioactive decay (α particles).
posted by ambrosen at 11:30 AM on March 19, 2016 [6 favorites]


My idea is a massive graphene aerogel cloud, with loads and loads of tiny chambers which (when a current is applied through them) force out the air, creating a practical vacuum airship.

Combine that with a photovoltaic skin covering the cloud, integrated superconductors to store and direct energy, and maybe some tunnels to accelerate and direct the air for propulsion and steering.

I'm thinking the whole thing could be essentially 3D printed, or condensed out of the carbon in the atmosphere using some kind of fancy sci-fi process.

I'll do a Projects post if I ever get it off the ground.
posted by mrjohnmuller at 11:30 AM on March 19, 2016 [22 favorites]


It's not, of course, how chemistry works, and given that most resource issues are chemistry problems, not physics ones, the confusion's understandable.
posted by ambrosen at 11:31 AM on March 19, 2016 [1 favorite]


I'm pretty confident that's not how physics works.

Oh boy!

Helium is so light so that at atmospheric temperatures, its thermal motion is higher than escape velocity. If you have free helium in the atmosphere, it slowly leaks into space over time.

There is no easy way to make more helium. The stuff we have originated from alpha decay of U-238 in rocks, but that occurs on billion-year timescales and we're using it faster than that.

Here is Popular Mechanics article.

On preview, aw man, not fast enough.
posted by officer_fred at 11:31 AM on March 19, 2016 [3 favorites]


I'd like to see some references here, because I'm pretty confident that's not how physics works.

It's been pretty big news. And it's basically exactly because physics works - really light stuff gets up to the edge of the atmosphere and some bleeds off (and becomes difficult to recapture).

It's not so much that there's a shortage of helium so much as a shortage of usable helium. We get a certain amount cheap from natural gas but if we want a lot more of it, it's going to cost us.

article one
article two
posted by Candleman at 11:32 AM on March 19, 2016 [1 favorite]


There is no easy way to make more helium.

Sure there is -- in 20 years we'll have fusion reactors and can make as much of the stuff as we want.
posted by nathan_teske at 11:33 AM on March 19, 2016 [8 favorites]


His parents, civil engineers, thought that he would move on to more practical interests.

Peggy, that boy ain't right.
posted by Behemoth at 11:39 AM on March 19, 2016 [1 favorite]


" It took two hundred and fifty thousand cows to make one airship. During the First World War, Germany and its allies ceased production of sausages so that there would be enough cow guts to make zeppelins from which to bomb England."

Okay, yeah, but we have progressed since then. We've transcended the cow-gut gap. I believe we have enough party balloons to last decades.

Aside from the absolutely marvelous travel experience afforded by these vehicles as passenger airships, the ability to move--literally--a boatload of cargo without having to deal with an infrastructure of roads, railroads, bridges, or similar support facilities, is a paradigm-shifting development.
posted by mule98J at 11:53 AM on March 19, 2016 [1 favorite]


A few years back I was a passenger in Airship Ventures' dirigible in California. Pictures here. It was a marvelous way to travel, serene and gentle. Sadly they went out of business, tourist flights and the occasional low-vibration sensor flight wasn't enough to make it work. I think the company in Germany that made the zeppelin is still operating though. For more on the majesty of airships, the round-the-world documentary is very entertaining. It's not quite a truthful documentary but is about 90% accurate, and has great vintage footage.

But this article is about cargo flying. And that makes a little more sense to me than passenger flight, where time is more critical. I can't do the economic math to understand if it would really work though. The problem with helium isn't just that it's scarce, but that the market in it is so small and specialized the pricing is particularly unpredictable.
posted by Nelson at 11:55 AM on March 19, 2016 [3 favorites]


Ctrl-F "Helium Reserve" but nothing. How can you talk about blimps without discussing our STRATEGIC RESERVES of the stuff?!? That's almost as good as the strategic maple syrup reserve in Canada.

(Also relevant: domestic demand is decreasing, and BLM is moving to a international production model and giving up the strategic reserve and socialized production of helium business.)
posted by anotherpanacea at 12:04 PM on March 19, 2016


Not only is Zeppelin NT still operating at Freidrichshafen, Goodyear has built two NTs here in the US as well. The second one has not yet been christened, if I recall correctly.

Nelson, I was also pleased to fly in the Eureka. In fact, in an hour, I'm driving north to Paine Field to gawk at Paul Allen's toy box, and that's where Airship Ventures flew her out of when she was up here.
posted by mwhybark at 12:07 PM on March 19, 2016 [1 favorite]


Growing up asking why the skies are not filled with airships may of course indicate that you are a refugee from another timestream.

Yeah, one of the good ones.


So less a refugee and more a dystopia-tourist.
posted by Ray Walston, Luck Dragon at 12:09 PM on March 19, 2016 [10 favorites]


Airships will never be a viable proposition; trucks and ships are always cheaper, winged planes are always faster. They're exceptionally vulnerable to weather conditions and difficult to land even at prepared sites.

They do seem to have a strange appeal though.
posted by Segundus at 12:10 PM on March 19, 2016 [4 favorites]


Both nitrogen and hydrogen are lift gasses. Hydrogen is dangerous, but could you dilute it with nitrogen to reduce the danger of an explosion or fire?
posted by rustcrumb at 12:11 PM on March 19, 2016


Oh, I'll be back in here to chatter about the economics of LTA cargo flight, like, maybe Sunday? There's a reason these guys want military contracts, and there's a reason the military pushes back after a while, and it's not hydrogen volatility.
posted by mwhybark at 12:11 PM on March 19, 2016


Per Wikipedia, rustcrumb:
Nitrogen gas (density 1.251 g/L at STP, average atomic mass 28.00 g/mol) is about 3% lighter than air, insufficient for common use as a lifting gas.
(You may be aware of this, and I'd still be curious to hear whether mixing nitrogen with hydrogen would be useful to still provide lift but also defuse some of the explosiveness.)
posted by limeonaire at 12:23 PM on March 19, 2016


Also: I laughed at the dirigibles in Earth 2100, but maybe this is the wave of the future.
posted by limeonaire at 12:47 PM on March 19, 2016


Hydrogen is dangerous, but could you dilute it with nitrogen to reduce the danger of an explosion or fire?

I wouldn't have thought so. Hydrogen/air mixes will ignite with as little as 4% hydrogen. To render a hydrogen-based lift gas non-inflammable, you'd need to use so much diluent as to ruin the lift completely.

You'd be better off building your balloon envelope in ways that tolerate fires. In hindsight, there were probably safer choices for the skin of the Hindenburg than solid rocket fuel and thermite.
posted by flabdablet at 12:52 PM on March 19, 2016 [7 favorites]


in 20 years we'll have fusion reactors and can make as much of the stuff as we want.

I really wish I could find a more credible source, but a back of the envelope calculation from Reddit suggests we'd be off by several orders of magnitude.

Not to mention (assuming you're serious), if scientists had a dollar for every time someone dismissed a problem by saying that future research could solve it, none of us would have to apply for grant funding.

(As someone who uses superconducting magnets for a living, I may be slightly biased. A few years back, helium was being triaged -- we had a system we'd purchased we couldn't use for several months because there was a wait list for non-critical uses of liquid helium. IMHO, blimps are at the bottom of the list.)
posted by steady-state strawberry at 1:02 PM on March 19, 2016 [2 favorites]


Not to mention (assuming you're serious), if scientists had a dollar for every time someone dismissed a problem by saying that future research could solve it, none of us would have to apply for grant funding.

Given that "20 years" and "fusion" were used in the same sentence, I think we can assume it was a joke.
posted by Ickster at 2:01 PM on March 19, 2016 [6 favorites]


A few years back I was a passenger in Airship Ventures' dirigible in California.

I got to ride in one of the zeppelins in Friedrichshafen!

We had this amazing woman pilot who trained in the US and went there after that facility shut down IIRC, Nelson. She was so passionate about airships; she was a Brit who had gone through this amazing journey all over the world in order to learn how to fly them and keep doing it. Her name was Kate Board (I talked about her here before). I'll never forget her.

But yeah, if you ever get a chance to go to Friedrichshafen for zeppelin action, do it. It was totally worth it just to go there for the Zeppelin Museum, which is on my top-5-museums-I've-ever-visited list.
posted by barchan at 2:03 PM on March 19, 2016 [7 favorites]


I am working on a fantasy trilogy and one night decided airships would be a good idea. Oh jebus, too much time spent on research and while I'm no scientist it seemed that everything I read stipulated hydrogen or helium to do the lifting. I've already had to invent one element. I balk at creating another because I want a fair amount of this moored to reality. Plus at this point the way hydrogen blows up is actually good. It blows up real good.
posted by Ber at 2:07 PM on March 19, 2016 [1 favorite]


I've already had to invent one element. I balk at creating another because I want a fair amount of this moored to reality

heh, I'm in the same boat with one of my decades-old game design ideas.

Airships are simply too cool to not exist. The anime Last Exile had some good aerial battle scenes showing what should be.

I've played with negative gravity ideas, special rocks that float a la Avatar. So much fun here.
posted by Heywood Mogroot III at 2:21 PM on March 19, 2016 [2 favorites]


'Master of the World'
posted by clavdivs at 2:29 PM on March 19, 2016 [2 favorites]


Couldn't we have a design where there's a core alpha emitter in the middle of the airship envelope? That could both produce the helium for the lift and heat it up to increase buoyancy. Admittedly, I don't know of any radioactive element that could produce enough helium to be useful in this role, but it's a nice idea. Providing you don't crash, and the daughter products aren't too unpleasant.

Because the only thing cooler than an airship is a nuclear-powered airship.
posted by Devonian at 2:37 PM on March 19, 2016


I was under the impression that helium is a dwindling resource. Should we really be counting on it to fuel vehicles?
posted by constantinescharity at 2:38 PM on March 19, 2016 [1 favorite]


It is NOT a fuel!

There is plenty of free helium is sight most days.!
posted by Burn_IT at 2:43 PM on March 19, 2016


Maybe we just need to focus on finding a way to safely make the atmosphere denser, so we'd need less helium? Plus, we'd all sound like cartoon devils!
posted by mccarty.tim at 3:10 PM on March 19, 2016 [3 favorites]


Ber, why not have some kind of lightweight gizmo that just creates a vacuum and contains it? No gas at all is even lighter than helium.
posted by Segundus at 3:20 PM on March 19, 2016


To get an idea of the scale of the ML86X, imagine a flying, elongated Houston Astrodome hauling a hundred and fifty elephants.

To be fair he was ready to do this back in 2005, but as Kanye West pointed out, the President back then didn't let the paperwork go through the FAA because he didn't care about the plight of Africans in the Astrodome.
posted by Nanukthedog at 3:30 PM on March 19, 2016


They're exceptionally vulnerable to weather conditions and difficult to land even at prepared sites...
This.
Windage - projected area.
The entire New Yorker article never mentioned wind or ice, which are the real obstacles to lighter than air flight.
posted by Abinadab at 3:34 PM on March 19, 2016 [1 favorite]


Everyone knows I hate to be contrarian. But we were promised flying cars and jetpacks and (some film) hoverboards. And a buncha other shit (see: World Fair). But Not dirigibles. After Hindenburg (sp?) nobody promised dirigibles.

That said, they're great. They're the gentle, laid-back, shy giants of the sky ... like whales only higher. Jetting all over the world at breakneck speed is fine for your average coke freak, but some of us prefer soaring slowly over magnificent landscapes, closer to the surface, sipping wine or tea or nostalgically chatting about the good old days while seagulls and eagles and large horseflies skim past us.
posted by Twang at 3:37 PM on March 19, 2016 [1 favorite]


and the daughter products aren't too unpleasant.

A strong alpha emitter in enough quantity to generate a non-trivial amount of helium gas sounds unpleasant enough all on its own, thanks.
posted by ctmf at 3:38 PM on March 19, 2016 [2 favorites]


Since helium is the least reactive gas possible, why not include a small percentage of hydrogen bladders inside? I'm going to say bladders with a ten per cent hydrogen/ninety per cent helium component have zero chance of exploding. This will add to the lift and cost less than the expensive helium.
Alternatively, we could superheat a vacuum providing the lift of hot air and emptiness. (j/k)
posted by dances_with_sneetches at 3:44 PM on March 19, 2016


Why not hot air, or even better: hot nitrogen?
posted by Joe in Australia at 3:47 PM on March 19, 2016 [1 favorite]


Nathan said: in 20 years we'll have fusion reactors and can make as much of the stuff as we want.

Ah ha ha. 50 years ago the experts agreed that fusion was 25 years away. So, according to your figure, we've shaved off 5 years in 50 years. So the function is
yearsToGoTilFusion = prediction x 10
Which means we've got 200 years to go. Only THEN does everyone get to do the "funny voice" stuff all they want.
posted by Twang at 3:48 PM on March 19, 2016


It's 20 years and always will be!
posted by Artw at 3:52 PM on March 19, 2016 [6 favorites]


Why not hot air..? The relative density of hot air to cold air is rather small, so the size of the envelop for a given lift capacity is much larger than for Helium or hydrogen.

I am interested in vacuum. A vacuum container must support atmospheric pressure on the outside, 14.7 pounds per square inch at sea level, it's possible recent advances in materials have produces a plastic light enough to make a pressure vessel that can float in air when evacuated.
posted by Abinadab at 3:55 PM on March 19, 2016


I like the idea in the article of delivering tons and tons of fresh water. Sky aqueduct! Problem: requires a donor. Also, it turns your airships into an existential-level security problem. Once you start depending on that, you have to prevent disruption of delivery.
posted by ctmf at 3:56 PM on March 19, 2016 [1 favorite]


"Luckily, in the history of humanity, nothing bad has ever happened from lighting hydrogen on fire." /The Martian
posted by Eyebrows McGee at 4:07 PM on March 19, 2016 [7 favorites]


I'm going to say bladders with a ten per cent hydrogen/ninety per cent helium component have zero chance of exploding.

You don't need to dilute the hydrogen with anything. Pure hydrogen gas will not explode. It can only catch fire when it leaks out and mixes with air.

On the other hand, if you properly mix hydrogen with oxygen, you can use it to put out fires.
posted by JackFlash at 4:36 PM on March 19, 2016 [3 favorites]


What about methane?
posted by Ray Walston, Luck Dragon at 4:44 PM on March 19, 2016


Explain to me the vacuum idea? Can a complete vacuum be contained without collapsing the container?
posted by SecretAgentSockpuppet at 4:48 PM on March 19, 2016


I'm going to guess the vacuum idea violates physics somehow, because the ability for helium or hydrogen to lift things is based on there being a substance that has less gravitational pull on it than the surrounding atmosphere. A vacuum won't be lighter than air -- it will simply be the weight of whatever is containing it.
posted by hippybear at 4:59 PM on March 19, 2016


Can a complete vacuum be contained without collapsing the container?

If I were going to be nit-picky, I'd say that a complete vacuum isn't contained; rather, everything else has been excluded. Very pure vacuums are hard to obtain in our atmosphere, but that's not because the containers collapse; it's because at some point you're working harder and harder to remove less and less, and things like lubricants and gases trapped in the walls of the container keep boiling out to spoil the purity of your vacuum. That being said, I can't imagine any way to make a large and light container that wouldn't collapse when evacuated, even if you supported it internally with something like aerogel.
posted by Joe in Australia at 5:08 PM on March 19, 2016 [1 favorite]


It doesn't violate physics. Just like a less dense material floats in air, so something less dense than air floats. So a volume of hydrogen might be 1/14th as dense as air or whatever the value is and so rises. Vacuum is 0% as dense as air, so even better!

The problem is pressure. Hydrogen or helium can inflate a lightweight membrane because the net force on it is close to 0 - the gas inside exerts as much (or slightly more) pressure as the air outside.

Vacuum, being a lack of stuff, doesn't. So instead of a membrane, you need a rigid wall that can withstand the 14 lbs/in^2 (at sea level, less higher) that the atmosphere imposes. Anything we have that can handle that is too heavy to lift.

For readability, I've been talking about our contained volume lifting, but that's wrong. It's our atmosphere doing the lifting.
posted by The Gaffer at 5:13 PM on March 19, 2016 [2 favorites]


'Master of the World'

Oh my goodness. I am a better, wiser person for having seen that trailer. Thank you.
posted by officer_fred at 5:53 PM on March 19, 2016


Segundus, you may have just given me a very dangerous idea...
posted by Ber at 5:56 PM on March 19, 2016


The Diamond Age uses vacuum airships to great effect.

Still, I figure hydrogen or bust. You can make it from water! It's good at lifting! The slight risk of fiery death just keeps you on your toes.

It's less that we'll run out of helium, but that we might make helium so expensive that it will make using it economically impossible.
posted by BungaDunga at 6:11 PM on March 19, 2016 [1 favorite]


Airships will never be a viable proposition; trucks and ships are always cheaper, winged planes are always faster.

Radio New Zealand's Sunday Morning: James Higham - the Mythical Solutions To Aviation Emissions
posted by XMLicious at 6:25 PM on March 19, 2016


Perhaps the hydrogen risk is overstated. Hell, the Hindenberg had a smoking cabin for the passengers.
posted by Nelson at 7:17 PM on March 19, 2016


It is NOT a fuel!

There is plenty of free helium is sight most days.!
Collection & cooling, however, remain problems…
posted by Pinback at 7:51 PM on March 19, 2016


You can limit the fire risk of hydrogen but cannot eliminate it. You could build a lighter than air vehicle more like a balloon with hydrogen and propulsion up top with passengers hanging below divided by fire resistant shielding.

However, if the hydrogen ends up bonding with oxygen and producing water with some excess energy, the lighter than air vehicle quickly becomes just a vehicle . . . a few hundred feet above ground level.
posted by cmfletcher at 7:54 PM on March 19, 2016


So... printable diamond?
posted by Artw at 8:36 PM on March 19, 2016 [1 favorite]


I've been a light-weight airship enthusiast (heh) for about 7 years now. The two main things I've learned are:

1. There are always new airship facts, and they are always fantastic. A great example from this article: It took 250,000 cows intestines to build a WWII Zeppelin, so the Germans and their allies quit eating sausages during the war in order to build more Zeppelins.

2. Anyone who doesn't know the history of airships will be utterly blown away when you fill them in on just a few of the details (unless they are painfully incurious, but I'm not convinced that incurious people actually exist). Did you know that the Hindenburg's sister ship, the Graf Zeppelin, safely ran passenger service across the Atlantic for nearly a decade? Or that those two airships were both almost the same length as the Titanic? Or that the Hindenburg had a frickin' Nazi Swastika on its tail when it hovered over Manhattan, several hours before the fateful crash? Or that there are photos?

(An unfortunate downside of an airship obsession is that you end up pinning photos with Swastikas on Pinterest).

I eagerly await our new airship overlords. The British Airlander 10 (part funded by Iron Maiden) takes flight for the first time on Monday!
posted by simonw at 9:02 PM on March 19, 2016 [6 favorites]


We were a handful of engineers at the pub one night, talking about wild and radical possibilities for inventions and tech that could really do something cool for the world. Barry tells us he's been thinking very intensely about bringing back zeppelins and blimps for transporting goods to remote areas at lowered cost. He was even thinking about the possibility of trans-atlantic shipping.

But, he says, do you know how big one of those zeppelins would have to be, to carry as much as one of those shipping container ships? Just volume-wise (as we argued weight was more appropriate). He took the rate of size of the blimp to its passenger compartment on the bottom, and then determined how long a ship would have to be to take as much compartment volume as the shipping containers on an average ship...

Five miles long, he tells us. Might not work. (sips beer)
posted by lizbunny at 9:28 PM on March 19, 2016 [1 favorite]


Yeah, container ships are unbelievably high capacity and cost efficient. Rail's similar. Replacing them with airships is romantic, but I would not hold my breath.
posted by The Gaffer at 9:43 PM on March 19, 2016 [1 favorite]


The article talks about using airships to take cargo to places that don't have infrastructure in place, because they can be more or less landed anywhere and don't require rails or roads or runways. I don't think airship is going to replace the container ship or rail or the 18-wheeler.
posted by hippybear at 9:51 PM on March 19, 2016


I've already had to invent one element.

"It's called hydroleum! It is only slightly heavier than hydrogen but is particularly non-flammable, especially in airships. It has *cough* 1.5 protons."
posted by sebastienbailard at 9:56 PM on March 19, 2016 [4 favorites]


Metafilter: providing the lift of hot air and emptiness
posted by CynicalKnight at 10:34 PM on March 19, 2016 [2 favorites]


Just like a less dense material floats in air, so something less dense than air floats. So a volume of hydrogen might be 1/14th as dense as air or whatever the value is and so rises. Vacuum is 0% as dense as air, so even better!

The density of gases is, to a good first approximation, proportional to their molecular weights. These are 0, 2, 4, 28 and 32 for vacuum, hydrogen, helium, nitrogen and oxygen respectively. Air is about 4/5 nitrogen and 1/5 oxygen, so the average molecular weight for air is about 29.

The lift you get is not proportional to the density of the floating object, but to the difference between that of the floating object and that of the medium it displaces. So lifts from vacuum, hydrogen and helium respectively are proportional to 29, 27 and 25.

To another good first approximation, the density of gases is inversely proportional to their absolute temperature. Heating air at 20°C to 120°C takes its absolute temperature from (20 + 273 = 293)K to (120 + 273 = 393)K, reducing its density to about 3/4 that of cool air. So on a scale where cool air's density is 29, hot air's would be 22 and its lift would be about 7.

So a hot air balloon needs to be about four times the volume of a hydrogen or helium balloon to generate the same lift force.

For any given shape, the volume of the shape is proportional to the cube of the length, while the surface area is proportional to its square. To get four times as much volume, then, you end up with a balloon about 1.6 times as long, requiring about 2.5 times as much skin material.

That doesn't strike me as outrageous. Certainly looks a lot easier to achieve than trying to construct an evacuated Hindenburg-size structure rigid enough to resist collapse.
posted by flabdablet at 10:38 PM on March 19, 2016 [1 favorite]


Lift for methane (CH4) on that same scale would be (29 - (12 + 4)) = 13, roughly twice that for hot air. But frankly I would rather be suspended below a huge ball of burning hydrogen than a huge ball of burning methane.
posted by flabdablet at 10:57 PM on March 19, 2016


Besides balloon-type vacuum airships, if you could build something really really tremendously big, big enough that it stuck up over the atmosphere, it could be open on top like a boat.
posted by XMLicious at 11:02 PM on March 19, 2016 [2 favorites]


Whoa, XMLicious, did you come up with that one?
posted by Joe in Australia at 11:05 PM on March 19, 2016


Airships already do make sense, for certain markets. As it says in the article, there's quite a bit of demand for surveillance platform dirigibles, by countries or companies that can't afford their own spy satellites. And the mythical cargo airship could work if they can build them really big. Pasternak's biggest design is maybe the smallest cargo airship that would be economically feasible, at a fifty ton cargo capacity. But successful ones will probably have to be bigger than that, if they want to compete against trains and container ships.
posted by Kevin Street at 12:26 AM on March 20, 2016


it could be open on top like a boat
I think my head just imploded.
posted by wilberforce at 12:35 AM on March 20, 2016


I don't feel like I read that anywhere but it seems unlikely no one else has thought of it in the hundreds of years (according to Wikipedia at least) since vacuum airships were conceived of. I think it occurred to me while thinking about Cloud-City-type things floating in the atmospheres of gas giants.
posted by XMLicious at 1:02 AM on March 20, 2016 [1 favorite]


1 atmosphere of pressure is a lot of force when you have the surface area of even a small airship. I don't think we'll ever see a vacuum vessel light enough to float short of some sort of science fiction status/force field reinforced material.
posted by Mitheral at 1:26 AM on March 20, 2016 [1 favorite]


Make a bunch of softball-sized ones, and suspend from them in a handy cotton mesh shopping bag?

(As long as you don't have a chain implosion.)

Besides balloon-type vacuum airships, if you could build something really really tremendously big, big enough that it stuck up over the atmosphere, it could be open on top like a boat.

If you're building that big, just hang a traditional space elevator from a large mass up in space.
posted by sebastienbailard at 3:38 AM on March 20, 2016 [1 favorite]


(Clears throat): The Hindenberg's fiery end was due to two root causes: (a) an inappropriate dopant used on the outer hull ("thermite mixed with rocket fuel" is a good description), and (b) US government policy.

Hindenberg was designed to obtain lift from two gases -- hydrogen and helium. Most of the lift would come from hydrogen-filled spherical lift cells, but to reduce the risk of fire these were to be nested, matroshka-style, inside helium-filled gas cells. This was to provide an anoxic blanket that still produced lift, reducing the risk of a leak allowing air (and oxygen) to get in and mix with the hydrogen. Emergency vent valves in the top of the hydrogen cells, leading to tubes running up to the top of the zeppelin through the helium cells, were designed to vent the hydrogen safely in event of such an emergency.

Unfortunately after WW1 the US government classified helium as a strategic war material and refused to sell it to foreigners; nobody else had enough to inflate the Hindenberg's fire-retardent safety cells, so they ended up being filled with hydrogen (for extra lift) and inspected regularly in order to carry the extra mass of the elaborate and redundant safety system (concentric gas bags come with a weight penalty).

Because helium wasn't inflammable, the outer helium cells didn't have emergency dump vents in the roof, but vented sideways inside the hull of the airship, in the hope that the expensive lift gas could be pumped into cylinders and reused. So the elegant safety mechanism ended up becoming a dangerous liability.

(Zeppelin tech is fascinating, BTW. For fuel, they used Blau gas, a buoyancy-compensating fuel -- gaseous and of the same density as air. One of the inner (hydrogen) gas cells could be filled with blaugas fuel, and burned in the airship's engines in flight: as the fuel was consumed and the gas cell deflated, the outer (helium) cell around it could have air pumped in, thereby maintaining a constant volume of neutral buoyancy gas so that the airship didn't have trim or structural stability issues.)
posted by cstross at 6:27 AM on March 20, 2016 [12 favorites]


Footnote: the surface of Venus is obviously uninhabitable, with surface temperatures around 600+ degrees celsius and around 100 bar pressure (100 times Earth surface atmospheric pressure). Not to mention that the atmosphere is predominantly carbon dioxide.

But the pressure and temperature drop off at altitude, and there's a stratum about 30km up, in the Venusian stratosphere, where the atmospheric pressure is around 1 bar (Earth surface) and the temperature around 35 celsius (about 90-95 fahrenheit).

Now, the interesting thing about a carbon dioxide atmosphere is that an airship can float in it using a breathable gas mix as a lifting gas roughly as efficient as helium. (Air is roughly 80% nitrogen -- dimers of atomic mass ~28 Daltons -- and 20% oxygen -- dimers of atomic mass ~32 Daltons. Carbon dioxide molecules have a mass of 44 Daltons. So breathable air floats in a CO2 atmosphere.)

It has been proposed that astronauts could visit the cloud-tops of Venus for long term research projects, living in a shirt-sleeve environment aboard airships in the stratosphere. And more than that -- Venus might, ironically, be a better target for interplanetary colonization than Mars! And all because of airships.
posted by cstross at 6:35 AM on March 20, 2016 [20 favorites]


Kevin Street's comment reminds me of Google Loon, which is a real project to provide internet access with large balloons. They're not blimps/dirigibles in that they don't have any means of propulsion, just climbing or dropping to catch different winds. The plan is to ride at about 60,000 feet and provide LTE cellular service to the adoring citizens below. Google itself doesn't have anything online about lifting gas I could find, but most discussion I've seen says they're using helium.
posted by Nelson at 8:07 AM on March 20, 2016


...which, given that there are no people on board a loon, strikes me as a waste of resources. Why not hydrogen for uncrewed vessels?
posted by flabdablet at 8:13 AM on March 20, 2016 [1 favorite]


Just how pleasant it would be to cross the

... ocean, spending the one or two nights not in a chair but in bed, in your own private cabin?
posted by Rash at 9:57 AM on March 20, 2016 [1 favorite]


A truck isn't just a truck, and a railway line isn't just freight cars. They are the sum of the infrastructure required to support them, plus the cost of the infrastructure required to make and supply fuel. Ships seem to be more efficient transporters per ton of cargo, however the bottleneck at seaports links them to trucks and railway lines, so, square one.

Fossil fuel is still a dwindling resource. It supplies the fuel to about 100% of our transportation. My stepson's nephew, on his skateboard, sometimes brings me a cold soda from the store, but I'm not so sure he represents a significant alternate energy source when talking about moving cargo around. We have run out of places to put roads in our larger cities. What would a transportation system look like that didn't rely on paved roads and railway lines? I guess airships wouldn't replace local traffic, just the number of vehicles required to bring stuff in and take it out. It could be, once we get over the idea that a delivery system looks a big truck, that we might figure out how local transportation and the distribution of goods can be affected without using shopping centers that need 10 acres of parking lot per 500 customers. My notion is that a paradigm shift can take out the trash when it brings in the new furniture.

Hydrogen, the seemingly gold standard of lifting gases, is flammable (and therefore dangerous). I guess we are lucky to have jet fuel, gasoline, propane, and diesel, which aren't.
posted by mule98J at 10:01 AM on March 20, 2016 [1 favorite]


Did you know that the Hindenburg's sister ship, the Graf Zeppelin, safely ran passenger service across the Atlantic for nearly a decade?

I think it would be more accurate to call the original Graf the Hindenburg's older brother -- her sister ship would be the LZ130 aka the Graf Zeppelin II, technologically superior, but never allowed to fly commercially.

Thanks for that link, Nelson. I'll be back in a little while with some more interesting details about that journey.
posted by Rash at 10:10 AM on March 20, 2016


Not sure which link you mean, Rash, but if it's the Round-the-World video always curious to learn more. Wikipedia's entry is pretty good. We know a lot about that flight because Hearst paid an exorbitant sum to have exclusive media rights and had several journalists and cameras aboard. Lady Grace Drummond-Hay's notes are the basis for a lot of the film. The movie is great fun, but beware it's partly fictionalized. For instance it shows the airship going down and needing emergency repairs in the middle of nowhere, an ice field if memory serves right. That never happened. But most of the movie is documentary footage just assembled to make an entertaining story out of it.
posted by Nelson at 10:33 AM on March 20, 2016


force field reinforced material.

You kid, but I wonder what could be done with electromagnetic fields and some kind of electrodynamic material.
posted by Artw at 10:38 AM on March 20, 2016


Re: Hydrogen and the Hindenberg - Possibly making the skin out of the thing out of thermite might have been as much as a problem as the hydrogen, just throwing that out there.
posted by Artw at 10:40 AM on March 20, 2016


What you need is something like an impenetrable force field to make a vacuum airship practical. I recall in the Ringworld RPG had Stasis Field blimps which were made in orbit and towed down to a planet.

Cute another bizarre airhip design, Scott Westfield had the Steampunk Leviathan, a giant bioengineering flying whale. I myself am working on stories about living airships patterned on hugely scaled up Festo Air Ray.

Of course both are impossible, even using hydrogen, the weight of the needed biological systems are too great. But I'm willing to handwave that detail in order to have living zeppelins.

I'm
posted by happyroach at 12:01 PM on March 20, 2016


Wait... Wait... What if we added room temperature superconductors?
posted by Artw at 12:03 PM on March 20, 2016 [2 favorites]


Or unobtainium!
posted by hippybear at 12:10 PM on March 20, 2016


Segundus summarizes the economic critique fairly but doesn't hit on the single most important reason airships are climbing a steep, perhaps impossible, hill to non-experimental non-advertising and leisure use, which is their extreme vulnerability to weather conditions.

The article handwaves that by asserting that these large cargo vessels will simply fly around the storms, which is great and will certainly reduce extreme weather related losses. But neither commerce nor most particularly military applications have a high tolerance for weather related delays; the essence of logistics is scheduling, and this is something that LTA is unlikely to ever be great at.

So part of the reason to pitch these first or second generation heavy cargo ships to the military is specifically to stress test them, given that the military has a built-in tolerance for risk and loss that other forms of organization lack.

In my view, the history of these pitches has a common arc - the proposed LTA vessels are accepted in design and as the project become more mature, more people on the investment side become more skeptical of the ability of the ships to work under heavy weather, and that eventually kills the project for large-scale commercial applications.

The political infighting in the US Navy over airships throughout the Navy's use of LTA, roughly from 1918 to 1960, is fascinating. In effect, it was a battle of lobbyists representing, on the one hand, Goodyear (and to an extent Zeppelin, the company) and on the other the nascent fixed-wing aircraft industry. The Navy also lost significant pro-LTA brass in various dirigible accidents, which did the case to operate LTA no particular good at all.
posted by mwhybark at 12:21 PM on March 20, 2016


But neither commerce nor most particularly military applications have a high tolerance for weather related delays; the essence of logistics is scheduling, and this is something that LTA is unlikely to ever be great at.

When it comes tofictional airships, it's kind of like interplanetary colonization. You just have to handwave some things.

This is why in my "future science-fantasy stories the skywhales were basically a large-scale vanity project. It took a successor civilization to find them useful as relatively fast mail and people delivery devices.

It definitely affected my plotting when I saw how fast an airship could cross a large chunk of Eurasia. I had to include "fueling" stops to enable things to develop between characters. It also made me consider how large empires with moderately low technology could be much more sustainable with rapid message delivery.
posted by happyroach at 2:46 PM on March 20, 2016


If cargo airships ever become A Thing, then I'm totally reinventing myself as the grizzled, hard-drinking captain of a tramp airship plying the most disreputable skylanes with my misfit crew of failed soldiers, failed writers, failed priests, failed - anyhow you get the idea. Until one day a mysterious stranger comes on board and loneliness turns to passion, and passion turns to madness.
posted by um at 2:56 PM on March 20, 2016 [4 favorites]


Until one day a mysterious stranger comes on board and loneliness turns to passion, and passion turns to madness.

Um was last seen updating a Floatr profile.
posted by sebastienbailard at 6:47 PM on March 20, 2016 [2 favorites]


Yeah, that round-the-world video, and I see what you mean about it exaggerating to tell a better story -- I believe the story of the 16-year-old stowaway depicted therein was actually lifted from the first manned flight across the Atlantic, the British dirigible R-34. The reality, from Dr Eckener's Dream Machine, by Douglas Botting (2001):
Lady Hay was no longer alone in her cabin; she had found a new companion who was now sleeping soundlessly on her bed. Though the Graf was searched carefully immediately prior to departure [from Germany], a stowaway of sorts successfully eluded discovery until earlier that day. Hungry, shivering, and distressed. a small black kitten was found in the depths of the ship's vast and complex interior by a rigger on a tour of inspection, and with Dr Eckener's blessing it was brought to the only woman on board for a little necessary care and affection.
posted by Rash at 10:48 PM on March 20, 2016 [1 favorite]


Later,
...there was one unhappy note. The little black cat which had been the ship's mascot on the flight to Tokyo was missing. It had disappeared during the first day at Kasumigaura, and an intensive search had failed to find it. It now seemed likely it had walked off the ship after landing and chosen to take up residence in Japan.
posted by Rash at 11:22 PM on March 20, 2016 [1 favorite]


I went in a hot air balloon once. It's a very uncanny experience, because unlike being in an airplane or even an elevator, there is none of that tug and pull that signals that you are moving upward. Because you aren't making any motions that fight against gravity. You are literally in a situation where gravity is deciding to let you go, so the entire experience is of having the ground move away from you while you just watch it move away.

Poetic, but not strictly true. What you feel in a plane or elevator is just acceleration, and in the case of a hot air balloon you're just accelerating slowly enough that you don't feel it.
posted by vibratory manner of working at 2:45 AM on March 22, 2016 [2 favorites]


What you feel in a plane or elevator is just acceleration, and in the case of a hot air balloon you're just accelerating slowly enough that you don't feel it.

I disagree with you about this but lack the actual physics background to discuss it intelligibly. When you become lighter than air, even if you are accelerating you are doing so at the rate that the force that you would normally fight against (gravity) is letting loose of its grasp. If gravity has decided not to pull on you, you don't feel the tug of fighting against it.

Only been in a balloon once, but it was an outstanding experience I would love to repeat. If nothing else, to get to relive that taking off moment and see how accurate my 20+ year old memories of the experience actually are.
posted by hippybear at 10:06 AM on March 22, 2016


If gravity has decided not to pull on you, you don't feel the tug of fighting against it.

Not to be nitpicky, because you are obviously just sharing a personal experience, but gravity does not change the rate it pulls on you. The upward force of the balloon (from buoyancy) is greater than the downward force of gravity. The only difference is in your body's ability to perceive the (low) acceleration of the balloon as compared to the rapid acceleration of an airplane.
posted by Think_Long at 10:58 AM on March 22, 2016


You don't become lighter than air. It is simply cables exerting force upwards on the whicker basket which in turn presses up on the soles of your feet with a force equal to m*(g+a). Your internal accelerometer feels the same as it would if it were steel cables in an elevator shafts.

Maybe what gives the sublime surreal feeling is that you don't feel the wind because you're moving at the same speed as the wind?

Sounds fun though.
posted by sebastienbailard at 11:00 AM on March 22, 2016


So if you use an airship to bring cargo somewhere without ground infrastructure, how do you unload it?
posted by gottabefunky at 11:27 AM on March 26, 2016


There are two parts to the answer here.

First, much of the technical innovation around these cargo ships has been in the area of ballast and lift management (and I think the article goes into this). That's because is you remove a huge weight from a lift-trimmed ship, the ship will rise. The system referred to in the article compresses the lifting gas and replaces the compressed gas volume with non-bouyant gas, presumably simple air, but possibly something like nitrogen, which is also stored under compression until needed, if I recall.

The older ships relied on water ballast and dumping the water at liftoff, which required a water-delivery infrastructure, and on venting excess gas (if hydrogen) or recompressing the helium (if a US vessel).

With regard to unloading large-scale cargo X in low-infrastructure area Y, I believe the cargo projects generally rely on a somewhat hand wavy conceptualization of having the cargo sufficiently modularized that it is described as being strapped to the belly of the vessel and therefore could be unstrapped in place in the destination - this description is commonly applied to loads intended to convey vastness and immediate utility, such as a hospital.

The objective is to prevent the vessel from needing replenishment in fuel or from seeking shelter at the point of delivery and in theory offers advantages over the requirements of other forms of cargo transport such as trains (railroad required), trucks (roads), and airplanes (runways).

A significant critique of the stated objective is roughly, "What economic justification is there for delivering large cargos to locations that lack infrastructure?" After all, without modern transportation infrastructure, economic activity is likely to be quite limited. Thus, this is typically pitched as a selling point primarily oriented to the military. Such missions could include delivering a bunch of bulldozers, fuel, and seabees to a location intended for development as a runway, for example.
posted by mwhybark at 2:33 PM on March 26, 2016


Of course, C-130s can do that too, with greater scheduling reliability. So here the scale of the loads becomes the selling differentiator. If CargofloatExtreme can move forty dozers at once and it would take ten C-130 overflights to deliver the same material, there is likely both a cost and time savings. As long as C-FloatX doesn't have to fly around a goldurn storm.
posted by mwhybark at 2:37 PM on March 26, 2016


What economic justification is there for delivering large cargos to locations that lack infrastructure?

How else is Elon Musk going to build his base in that hollowed-out volcano?
posted by happyroach at 2:36 AM on March 27, 2016 [2 favorites]


mwhybark: ""What economic justification is there for delivering large cargos to locations that lack infrastructure?""

A big one would be resource extraction. If you could deliver a copper mill in a few huge sub assemblies that essentially just needed bolting together you would save a huge amount paying skilled trades to build a mill from parts in some remote area. Same would apply to a camp; one big block instead of a bunch of trailers hauled over an ice road. And you could ship the ore concentrate out.

Or how about to build infrastructure? You could deliver high tension towers to bases all in one piece instead of having to assemble on site. Drop a bridge onto pylons in a single piece.

There is lots that could be done with super heavy lifters if they were reliable. It's the last bit that seems to be insurmountable by LTA craft.
posted by Mitheral at 12:18 PM on March 28, 2016


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