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Cargo airships could be big

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Re: Cargo airships could be big

#171

Post by chatmasta »

stopping wrote: post #158
padobson wrote: post #93

Earlier quoted context omitted.

Massive airships flying 90/km an hours are LESS susceptible to blockades than cargo ships? I think I'll need a little more explanation than that. Seems like a shoulder-mounted rocket launcher would be more than enough to bring one down.

Or a single tracer bullet, if it's filled with hydrogen.

Surely you could design some redundancy into the hull? It's not like the ship needs to be one giant gas bubble. It can be a mesh of a few hundred bubbles that could each pop without bringing the whole thing down.

Re: Cargo airships could be big

#172

Post by LarryMullins »

coryrc wrote: post #164
LarryMullins wrote: post #132

Earlier quoted context omitted.

The really rich private plane owners all have planes that burn jet fuel, which is always unleaded. The piston planes are generally owned by "doctor rich" upper-middle class people, who have political influence to be sure but they're hardly the billionaires that might be known by name to politicians. I think it's more likely that the FAA protects general aviation because general aviation is part of the professional pi…

[flagged]

> Ah, if you're only "doctor rich" then it's okay to poison children!

That's not what I said and you know it.

> GA is responsible for 50% of lead emissions!

Little lead is emitted at all these days, because leaded gasoline was banned in almost all circumstances. So you're talking about 50% of "not much". I'd be happy to see it banned completely since there are now viable alternatives, but I think you're going a little bit too hard with this class war narrative.

Re: Cargo airships could be big

#173

Post by jerf »

triceratops wrote: post #120
jodrellblank wrote: post #90

Earlier quoted context omitted.

Helium is a non-renewable resource drilled out of the ground, of which there is a global 'crisis' shortage[1]. Hydrogen is easy to make in vast quantities and cheaper. But more importantly, while they have similar lift capacities on paper (Helium ~90% of Hydrogen), in practice they don't - https://www.airships.net/helium-hydrogen-airships/ has an explanation and calculations. Hydrogen lift airships set off fully infl…

If fusion power takes off, could you produce helium as a by-product?

Basically, no: https://www.jerf.org/iri/post/2922/

And that assumes perfect capture, too.

If you're going that route it'd probably be better to just use hot air with the energy.

Re: Cargo airships could be big

#174

Post by credit_guy »

BeefySwain wrote: post #91
credit_guy wrote: post #77

Earlier quoted context omitted.

There's actually no need for hydrogen. Helium would do just fine. From the blog post, filling the hypothetical airship with helium would cost $8 MM, while filling it with hydrogen would cost only $100k. Sounds like a no brainer. But, the overall cost of the airship would be at $100 MM. Hydrogen would result in a less than 10% cost reduction. Now, the FAA approved unleaded jet fuel in 2022. Yes, that's how conservativ…

You may have overlooked the part where filling the quantity of airships that would (theoretically) be used would represent over half of the KNOWN quantity exploitable on earth, and would take decades to produce at current production rates. Also, they would need topped up over time. Compared to hydrogen, which is cheap, available, and renewable.

> KNOWN quantity exploitable on earth

It's great that you emphasized "known".

Knowledge is not a static thing. Also what's economically exploitable is a variable thing.

Currently, the US produces 40% of the world's helium, despite producing only 25% of the world's natural gas. Is it because the US has drawn a lucky lottery ticket for helium?

That's very unlikely. Helium is being produced continuously inside Earth as the alpha particles generated during the radioactive decay of some elements (mainly Uranium and Thorium, but Radon too). It seeps upward, and it generally escapes in the atmosphere, but some of it gets trapped in the same geological formations that trap natural gas.

In most places people don't bother to see how much helium there is in natural gas. They just sell the gas and take the money. Separating helium can increase the profitability a bit, but it depends on how cheaply you can do the separation. It's very likely that the US has better technology than the rest of the world, and because of that it separates more helium for the same quantity of natural gas.

As the technology will spread out, more helium will become recoverable.

Also, it may come as a tautology, but more helium is economically recoverable if its price goes up.

Re: Cargo airships could be big

#175

Post by kurthr »

LarryMullins wrote: post #139
kurthr wrote: post #117

Earlier quoted context omitted.

So, if filling your gas tank cost 8% of the price of your car... you'ld think nothing of it? Lift gas leaks (esp He) and gets vented. So this seems odd to me. It's kinda like buying your car again every few months to a year or paying $250/gal to fill up. Now 80x lower at 0.1% of the car price you're in the regime where it's negligible like an EV.

> Lift gas leaks (esp He) Hydrogen more than helium, I believe.

Each Hydrogen molecule is more reactive, but actually a larger molecule (less leaky) because there are two (it's diatomic H2 rather than monoatomic He).

Now it does get complicated, because the simple atomic radii aren't sufficient when you start bouncing around and leaking through other materials, but suffice it to say that He is still smaller once you look at the Vander Walls attraction and everything. It may only be 10% smaller, but that leads to at least a 20% lower leak rate.

https://bbblimp.com/2021/09/17/helium-vs-hydrogen-atom-size/

Re: Cargo airships could be big

#176

Post by LarryMullins »

criddell wrote: post #167
worik wrote: post #148

Earlier quoted context omitted.

> But even with helium, airships are still very fragile and dangerous. True. But with high speed landing and takeoff aeroplanes are extremely dangerous too. Thousands of gallons of high octane fuell in the tanks on board does not help

> high octane fuel Doesn’t jet fuel have a relatively low octane rating compared to most liquid fuels?

Yes, but I think he's using it in the colloquial sense that means "highly energetic".

Re: Cargo airships could be big

#177

Post by jasamer »

triceratops wrote: post #120
jodrellblank wrote: post #90

Earlier quoted context omitted.

Helium is a non-renewable resource drilled out of the ground, of which there is a global 'crisis' shortage[1]. Hydrogen is easy to make in vast quantities and cheaper. But more importantly, while they have similar lift capacities on paper (Helium ~90% of Hydrogen), in practice they don't - https://www.airships.net/helium-hydrogen-airships/ has an explanation and calculations. Hydrogen lift airships set off fully infl…

If fusion power takes off, could you produce helium as a by-product?

Probably, but the amount would be tiny. ITER is trying to generate 500 megawatt from a half-gram of hydrogen.

Re: Cargo airships could be big

#178

Post by jcranmer »

worik wrote: post #165
0xffff2 wrote: post #138

Earlier quoted context omitted.

Not very well. [0] [0]: https://en.wikipedia.org/wiki/USS_Akron

An extreme example. One extraordinary event is not very good evidence. The safety record of the Zepplin company in Germany is very impressive They had many failures, no fatalities. Until the Hindenburg

The USS Akron, USS Shenandoah, and USS Macon all failed due to bad weather. That's 3 of the US's 4 operational airships. (Another airship was constructed for the US, but was destroyed by poor handling before it was delivered to the US.)

Of the British experience with airships, R101 outright failed due to bad weather, and three more were scrapped after suffering accidents during bad weather, out of a total of 16 completed.

I don't feel like totting up the record of the Zeppelins, but the Wikipedia page does indicate that several of them failed due to weather incidents. One of the big lessons from the most notable airship failures is that airships don't really work in poor weather, and safety in such conditions means "don't even attempt to fly," which is a pretty different rule than the one for airplanes or other modes of transportation.

Re: Cargo airships could be big

#179

Post by hnarn »

If something doesn't exist, especially when it's something that has existed in the past but no longer does, there's usually a good reason for it. It's not a natural law, but it's a good rule of thumb to use to initially question and defend a "groundbreaking" idea.

A quick search online tells me that ocean freight is about $1.3/lbs and air freight is about $5.3/lbs. Since we already know that "airships" would likely never be more convenient than existing air cargo, their only way of succeeding is if they found a place between 1.3-5.3 where the cost savings felt motivated to sacrifice regular air freight, while being many orders of magnitude better than ocean freight for that use case.

Even if we're nice and call this a "new" technology rather than what it actually is -- a tried and failed technology -- this "new" technology needs to be many times better than existing options either for cost or convenience (preferably both) to offset the major penalty you will have initially due to the lack of existing infrastructure; and we're not just talking about airports and runways, we're talking about the entire network of optimizations in logistics, maintenance and everything else that have occurred during a century of practice.

I'm just a guy with an opinion, but I very much doubt cargo airships even have a small chance of being "big", unless someone builds something absolutely groundbreaking that leapfrogs existing air cargo solutions entirely -- for example in areas like fuel efficiency, autonomy, or something else.

Nothing is impossible, but if I was a very technical and entrepreneurial person, this isn't where I would put my time.

Re: Cargo airships could be big

#180

Post by bruce511 »

criddell wrote: post #167
worik wrote: post #148

Earlier quoted context omitted.

> But even with helium, airships are still very fragile and dangerous. True. But with high speed landing and takeoff aeroplanes are extremely dangerous too. Thousands of gallons of high octane fuell in the tanks on board does not help

> high octane fuel Doesn’t jet fuel have a relatively low octane rating compared to most liquid fuels?

It depends on the plane, but both your point and the parent point are correct.

Piston engines run on high octane gasoline (Avgas) . This is the stuff that powered planes up to, and just past, ww2. Today it's still used in planes from that era, and some smaller general aviation planes.

Jet fuel (jet a1) is basically paraffin. All turbine engines (think "jets", but also turbofan etc) run on this. It's a lot less flammable than Avgas, but, well, still makes a big bang if you fly it into a mountain.

In short both are dangerous because they are high-density liquid energy. Hydrogen is also dangerous, and there does appear to be a double standard here.

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