Bring back hydrogen lifting gas(thecgo.org)
thecgo.org
Bring back hydrogen lifting gas
https://www.thecgo.org/news/bring-back-hydrogen-lifting-gas/
348 comments
Even that wouldn't be such a big issue, if the flammability limit of hydrogen is from 4% to 74% in air (~20x). For comparison gasoline vapor is 1.4% to 7.6% (~5x)
In an open space that's not so bad since the flammable material literally floats away (while gasoline vapor settles), but it's still an issue in any contained area.
In an open space that's not so bad since the flammable material literally floats away (while gasoline vapor settles), but it's still an issue in any contained area.
oops that was supposed to be a wouldn't/wasn't construction. The is doesn't make sense.
Yeah it kind of defeats the point when your definition of 'doesn't burn' covers every single substance.
Except Li-ion batteries, which burn with their own oxidizer.
Well there's plenty of monoprops that supply their own oxidizer, and oh boy are they absolutely dangerous as hell. https://en.wikipedia.org/wiki/Monopropellant
And rocket fuel? Technically
Rocket fuel is more of a "pre-mixed with oxidizier" sorta thing.
Although I am enjoying the side discussion about monopropellants.
Although I am enjoying the side discussion about monopropellants.
Most modern rockets are liquid and mix the fuel and oxidizer only at the point of combustion, burning H2/O2, Kerosene/O2 or more recently CH4/O2.
Mono-propellant, and solid (not hybrid) rocket fuel fits the description though
Mono-propellant, and solid (not hybrid) rocket fuel fits the description though
> Mono-propellant, and solid (not hybrid) rocket fuel fits the description though
Decomposition doesn’t count as “burning” which means combustion. Fusion and fission release energy as well, but I don’t think anyone calls fusion “burning” hydrogen.
Decomposition doesn’t count as “burning” which means combustion. Fusion and fission release energy as well, but I don’t think anyone calls fusion “burning” hydrogen.
Generally I don't think this type of language debate is useful, we aren't debating what is happening, just what to call it, and that's pretty boring. If you want to call it not burning, ok, be my guest. Hopefully my answer is still an interesting point about the kinds of violent chemical reactions that exist and could make a substance dangerous to work with in an environment without (outside, in the case of solid rocket fuel) oxidizing agents.
I'll make an exception and reply about the language in this case because I there's a broader point I want to make:
English isn't a language defined based of "X happens if chemical reactions Y happens behind the scenes", because we didn't even know about chemical reaction Y when English was invented. Moreover if you tried to define it as oxidation you'd fail, rust isn't burning, meanwhile (non-oxidizing) chemical burns, sunburns, etc all exist because they were just analogous enough to the concept of fire. If people knew about some chemical that decomposes into plasma in the 1600s, they definitely called it burning even if there was no oxidation.
Meanwhile people definitely refer to fusion as "burning", e.g. see this stackexchange question with lots of links to wikipedia and the like which refer to different kinds of fusion as burning [1] or ctrl-f burning in this wikipedia article [2] (which is linked from [1]).
[1] https://astronomy.stackexchange.com/questions/43907/hydrogen...
[2] https://en.wikipedia.org/wiki/Stellar_nucleosynthesis
I'll make an exception and reply about the language in this case because I there's a broader point I want to make:
English isn't a language defined based of "X happens if chemical reactions Y happens behind the scenes", because we didn't even know about chemical reaction Y when English was invented. Moreover if you tried to define it as oxidation you'd fail, rust isn't burning, meanwhile (non-oxidizing) chemical burns, sunburns, etc all exist because they were just analogous enough to the concept of fire. If people knew about some chemical that decomposes into plasma in the 1600s, they definitely called it burning even if there was no oxidation.
Meanwhile people definitely refer to fusion as "burning", e.g. see this stackexchange question with lots of links to wikipedia and the like which refer to different kinds of fusion as burning [1] or ctrl-f burning in this wikipedia article [2] (which is linked from [1]).
[1] https://astronomy.stackexchange.com/questions/43907/hydrogen...
[2] https://en.wikipedia.org/wiki/Stellar_nucleosynthesis
I don’t really take this as a language debate though. It clearly is about the fact that people don’t understand what an oxidizer is at a chemical level.
Someone who says the following isn’t just using language inaccurately, it actually shows a fundamental misunderstanding of combustion:
> pure hydrogen doesn’t burn. It needs an oxidizer—like the oxygen in air.
That statement, no matter how you take it, leaves an assumption that other gases might burn like hydrogen without oxygen, which is again a fundamental misunderstanding of chemistry.
In addition calling something “self oxidizing” doesn’t make sense. There are always mixtures of fuel and oxidizers… whether those are gas and fuel, solid and fuel, mixed in gunpowder form, mixed as gasoline and air in a carburetor, etc. So if I supply you a balloon with the proper stoichiometric ratio of gasoline and air, is that “self-oxidizing”? If so then everything is self oxidizing.
And while I would agree that people do refer to fusion as “burning” I actually think this is a again a prime example of people not understanding the underlying physics. Most people don’t understand how fusion works, so calling it “burning” is a lazy way to conceptualize what the sun is doing. Scientists will sometimes use “burning hydrogen” when talking about nucleosynthesis, but they assume the audience of other scientists understand the difference between combustion and fusion.
When articles like the original post are talking to the layperson in this manner however, it does nothing but lead to more scientific illiteracy. A perfect example is one of the above comments:
> There are rumours that because of this fact, that the Hindenburg disaster was not from natural causes.
If we don’t communicate science effectively then we end up with conspiracies and pseudoscience. Words are tools. They should be used wisely.
Someone who says the following isn’t just using language inaccurately, it actually shows a fundamental misunderstanding of combustion:
> pure hydrogen doesn’t burn. It needs an oxidizer—like the oxygen in air.
That statement, no matter how you take it, leaves an assumption that other gases might burn like hydrogen without oxygen, which is again a fundamental misunderstanding of chemistry.
In addition calling something “self oxidizing” doesn’t make sense. There are always mixtures of fuel and oxidizers… whether those are gas and fuel, solid and fuel, mixed in gunpowder form, mixed as gasoline and air in a carburetor, etc. So if I supply you a balloon with the proper stoichiometric ratio of gasoline and air, is that “self-oxidizing”? If so then everything is self oxidizing.
And while I would agree that people do refer to fusion as “burning” I actually think this is a again a prime example of people not understanding the underlying physics. Most people don’t understand how fusion works, so calling it “burning” is a lazy way to conceptualize what the sun is doing. Scientists will sometimes use “burning hydrogen” when talking about nucleosynthesis, but they assume the audience of other scientists understand the difference between combustion and fusion.
When articles like the original post are talking to the layperson in this manner however, it does nothing but lead to more scientific illiteracy. A perfect example is one of the above comments:
> There are rumours that because of this fact, that the Hindenburg disaster was not from natural causes.
If we don’t communicate science effectively then we end up with conspiracies and pseudoscience. Words are tools. They should be used wisely.
Another relevant example of the English language referring to burning that doesn't involve oxidation is "flaming", as referenced in the guidelines:
https://news.ycombinator.com/newsguidelines.html
>Eschew flamebait. Avoid unrelated controversies and generic tangents.
But who am I to throw water on your fire?
;)
https://news.ycombinator.com/newsguidelines.html
>Eschew flamebait. Avoid unrelated controversies and generic tangents.
But who am I to throw water on your fire?
;)
> I don’t really take this as a language debate though.
It is when "burning" just means "fast reaction that creates something like a flame"... the vast majority of your post relies on a definition where it does not.
> That statement, no matter how you take it, leaves an assumption that other gases might burn like hydrogen without oxygen,
There are at least two ways to read this statement where that is incorrect.
One is to use the merriam-webster definition (see another one of my comments in this thread where I tracked that down) of burning (which includes things like H2O2 decomposing) instead of your definition.
The other is to include non-pure gasses, like a mixture of H2 and O2. Or if you somehow managed to vaporize gunpowder without it igniting.
A potential third is if you managed to make a chemical with an oxidizing agent on one end, and a reducing agent on the other... which now that I think about it sounds technically possible (if very difficult).
> And while I would agree that people do refer to fusion as “burning” I actually think this is a again a prime example of people not understanding the underlying physics.
Fusion researches call it burning, so with respect I think you're just wrong, they just understand the word burning to mean something other than what you do.
Consider also that things "burn up" upon re-entry from space (I'm sure anything oxidizable oxidizes, but mostly that means they vaporize), that you get rope burn, that ablative heatshields burn up, ... (I'm sure I could come up with more given some time)
> If we don’t communicate science effectively then we end up with conspiracies and pseudoscience. Words are tools. They should be used wisely.
I agree, but I think you are doing the exact opposite of what you want to to achieve this goal.
Redefining words so that they have a cleaner scientific definition makes it easier to talk about things precisely within the "in-crowd" who have accepted your redefinition. It confuses, annoys, and generally makes the "out" crowd feel stupid. That confusion makes it easier to get them to accept conspiracies and pseudoscience, making them feel stupid makes them less likely to listen to you (as a whole group) when you try and show them why they are wrong. This is counter-productive.
This is a common trend in "academic language", and I really think it does untold damage in peoples trust in these illiterate experts who keep insisting on facts that are simply wrong in the language called English that everyone else speaks (Peanuts are in fact nuts, Tomatoes are in fact vegetables and not fruits, and so on and so forth).
It is when "burning" just means "fast reaction that creates something like a flame"... the vast majority of your post relies on a definition where it does not.
> That statement, no matter how you take it, leaves an assumption that other gases might burn like hydrogen without oxygen,
There are at least two ways to read this statement where that is incorrect.
One is to use the merriam-webster definition (see another one of my comments in this thread where I tracked that down) of burning (which includes things like H2O2 decomposing) instead of your definition.
The other is to include non-pure gasses, like a mixture of H2 and O2. Or if you somehow managed to vaporize gunpowder without it igniting.
A potential third is if you managed to make a chemical with an oxidizing agent on one end, and a reducing agent on the other... which now that I think about it sounds technically possible (if very difficult).
> And while I would agree that people do refer to fusion as “burning” I actually think this is a again a prime example of people not understanding the underlying physics.
Fusion researches call it burning, so with respect I think you're just wrong, they just understand the word burning to mean something other than what you do.
Consider also that things "burn up" upon re-entry from space (I'm sure anything oxidizable oxidizes, but mostly that means they vaporize), that you get rope burn, that ablative heatshields burn up, ... (I'm sure I could come up with more given some time)
> If we don’t communicate science effectively then we end up with conspiracies and pseudoscience. Words are tools. They should be used wisely.
I agree, but I think you are doing the exact opposite of what you want to to achieve this goal.
Redefining words so that they have a cleaner scientific definition makes it easier to talk about things precisely within the "in-crowd" who have accepted your redefinition. It confuses, annoys, and generally makes the "out" crowd feel stupid. That confusion makes it easier to get them to accept conspiracies and pseudoscience, making them feel stupid makes them less likely to listen to you (as a whole group) when you try and show them why they are wrong. This is counter-productive.
This is a common trend in "academic language", and I really think it does untold damage in peoples trust in these illiterate experts who keep insisting on facts that are simply wrong in the language called English that everyone else speaks (Peanuts are in fact nuts, Tomatoes are in fact vegetables and not fruits, and so on and so forth).
All I can say is that your scientific knowledge on the subjects are incorrect.
I’m not trying to put down anyone in the “out crowd”. It’s simply that if we want to talk about scientific subjects, then we need to use precise language. Math has its own language. Science uses math in many areas, which removes ambiguity. Unfortunately English and other languages are the best we have when communicating other topics, which is why it’s best to be very precise.
I understand all the points you make and I agree with some of them in many respects (I was an undergraduate English major)
It’s simply that the use of imprecise English terms when talking about science specifically with the general public often does more harm than good. For instance:
> A potential third is if you managed to make a chemical with an oxidizing agent on one end, and a reducing agent on the other... which now that I think about it sounds technically possible (if very difficult).
This lacks an understanding of redox reaction chemistry, since it’s not possible. Salt is NaCl, the Cl being an oxidizer and the Na being a reducer. You can’t cause salt to self combust. It’s just not possible. In this case we need to turn to more precise language, and the use of chemical formulas to explain why. It’s the perfect example of how in plain English something like you described sounds possible, but comes from a confusion introduced by the language. As a further example let’s say you mean that the oxidizer is on a remote far end of the molecule. Then what your are again talking about is that molecule acting as an oxidizer. If you want to imagine some large molecule with a strong reducing component on one end and a strong oxidizing component in the other, that also can’t “self oxidize” because it would be in constant reaction with itself. (To be even more specific requires even more specific language that is too much for one reply.. for example you can have molecules that get reduced and oxidized in something called a disproportionation reaction, but you’ve basically got multiple reactions happening with multiple products)
> I really think it does untold damage in peoples trust in these illiterate experts who keep insisting on facts that are simply wrong in the language called English that everyone else speaks.
Peanuts are legumes in a biological sense. It’s an important distinction because it matters about the types of proteins that peanuts contain (and tree nuts do not). This is due to bacteria in the roots that are able to fix nitrogen. So again, this is not about academic language… it’s about being clear and precise when it matters to talk about how the world actually is rather than how we perceive it.
Edit:
> It confuses, annoys, and generally makes the "out" crowd feel stupid. That confusion makes it easier to get them to accept conspiracies and pseudoscience, making them feel stupid makes them less likely to listen to you (as a whole group) when you try and show them why they are wrong. This is counter-productive.
I think there are many reasons for this, but I don’t think using clear and precise language is to blame. I think for one our society puts a stigma on saying “I don’t know”. No one should feel stupid for saying that, since it’s the start of all knowledge, and as a society we need to teach that.
I also think that the education system still does a poor job on science education in general. So very smart people end up unable to decide between “purveyors of knowledge”. If we judge arguments solely on their oratorical value, it’s easy to be mislead.
A great change to our education system would be better teaching of logic and biases, something like the following:
https://yourlogicalfallacyis.com/
I’m not trying to put down anyone in the “out crowd”. It’s simply that if we want to talk about scientific subjects, then we need to use precise language. Math has its own language. Science uses math in many areas, which removes ambiguity. Unfortunately English and other languages are the best we have when communicating other topics, which is why it’s best to be very precise.
I understand all the points you make and I agree with some of them in many respects (I was an undergraduate English major)
It’s simply that the use of imprecise English terms when talking about science specifically with the general public often does more harm than good. For instance:
> A potential third is if you managed to make a chemical with an oxidizing agent on one end, and a reducing agent on the other... which now that I think about it sounds technically possible (if very difficult).
This lacks an understanding of redox reaction chemistry, since it’s not possible. Salt is NaCl, the Cl being an oxidizer and the Na being a reducer. You can’t cause salt to self combust. It’s just not possible. In this case we need to turn to more precise language, and the use of chemical formulas to explain why. It’s the perfect example of how in plain English something like you described sounds possible, but comes from a confusion introduced by the language. As a further example let’s say you mean that the oxidizer is on a remote far end of the molecule. Then what your are again talking about is that molecule acting as an oxidizer. If you want to imagine some large molecule with a strong reducing component on one end and a strong oxidizing component in the other, that also can’t “self oxidize” because it would be in constant reaction with itself. (To be even more specific requires even more specific language that is too much for one reply.. for example you can have molecules that get reduced and oxidized in something called a disproportionation reaction, but you’ve basically got multiple reactions happening with multiple products)
> I really think it does untold damage in peoples trust in these illiterate experts who keep insisting on facts that are simply wrong in the language called English that everyone else speaks.
Peanuts are legumes in a biological sense. It’s an important distinction because it matters about the types of proteins that peanuts contain (and tree nuts do not). This is due to bacteria in the roots that are able to fix nitrogen. So again, this is not about academic language… it’s about being clear and precise when it matters to talk about how the world actually is rather than how we perceive it.
Edit:
> It confuses, annoys, and generally makes the "out" crowd feel stupid. That confusion makes it easier to get them to accept conspiracies and pseudoscience, making them feel stupid makes them less likely to listen to you (as a whole group) when you try and show them why they are wrong. This is counter-productive.
I think there are many reasons for this, but I don’t think using clear and precise language is to blame. I think for one our society puts a stigma on saying “I don’t know”. No one should feel stupid for saying that, since it’s the start of all knowledge, and as a society we need to teach that.
I also think that the education system still does a poor job on science education in general. So very smart people end up unable to decide between “purveyors of knowledge”. If we judge arguments solely on their oratorical value, it’s easy to be mislead.
A great change to our education system would be better teaching of logic and biases, something like the following:
https://yourlogicalfallacyis.com/
> All I can say is that your scientific knowledge on the subjects are incorrect.
I doubt that, at least to the extent it's been used in this discussion.
> This lacks an understanding of redox reaction chemistry, since it’s not possible. Salt is NaCl, the Cl being an oxidizer and the Na being a reducer. You can’t cause salt to self combust. It’s just not possible.
I agree it doesn't occur with salt, that doesn't mean it can't happen. 2 Sn2+ → Sn4+ + Sn looks to be an example.
I was actually imagining something more along the lines of H3C-CH2-CH2-CF3 managing to have the F3 end oxidize the H3 end (I strongly suspect that specific example doesn't work) - I'll ask the chemists in the house if they know of any such reactions tomorrow since Google isn't being much use... but it's certainly seems like it should be able to.
> Peanuts are legumes in a biological sense. It’s an important distinction because it matters about the types of proteins that peanuts contain (and tree nuts do not). This is due to bacteria in the roots that are able to fix nitrogen.
Agreed
> So again, this is not about academic language
Choosing to try and label "peanuts" as not "nuts" is. Introducing the phrase "tree nuts" is a much better way to be clear and precise, because you aren't trying to declare things that use to be nuts, not nuts anymore, and hoping that everyone will go along with it.
I doubt that, at least to the extent it's been used in this discussion.
> This lacks an understanding of redox reaction chemistry, since it’s not possible. Salt is NaCl, the Cl being an oxidizer and the Na being a reducer. You can’t cause salt to self combust. It’s just not possible.
I agree it doesn't occur with salt, that doesn't mean it can't happen. 2 Sn2+ → Sn4+ + Sn looks to be an example.
I was actually imagining something more along the lines of H3C-CH2-CH2-CF3 managing to have the F3 end oxidize the H3 end (I strongly suspect that specific example doesn't work) - I'll ask the chemists in the house if they know of any such reactions tomorrow since Google isn't being much use... but it's certainly seems like it should be able to.
> Peanuts are legumes in a biological sense. It’s an important distinction because it matters about the types of proteins that peanuts contain (and tree nuts do not). This is due to bacteria in the roots that are able to fix nitrogen.
Agreed
> So again, this is not about academic language
Choosing to try and label "peanuts" as not "nuts" is. Introducing the phrase "tree nuts" is a much better way to be clear and precise, because you aren't trying to declare things that use to be nuts, not nuts anymore, and hoping that everyone will go along with it.
Re your edit
> but I don’t think using clear and precise language is to blame
It's not the use of clear and precise language which is to blame, it's the attempt to redefine existing imprecise language in an incompatible way to make it precise that is to blame.
I'm all for adding a discussion of logic to math, and fallacies/biases to some sort of civics/philosophy style course. I don't think that's going to solve the problem that trying to redefine words out under people doesn't go very well though. It's not a logic problem, because logic relies on the definitions being agreed upon, and what you have here is one group trying to change the definitions in a way that makes everyone else wrong.
> but I don’t think using clear and precise language is to blame
It's not the use of clear and precise language which is to blame, it's the attempt to redefine existing imprecise language in an incompatible way to make it precise that is to blame.
I'm all for adding a discussion of logic to math, and fallacies/biases to some sort of civics/philosophy style course. I don't think that's going to solve the problem that trying to redefine words out under people doesn't go very well though. It's not a logic problem, because logic relies on the definitions being agreed upon, and what you have here is one group trying to change the definitions in a way that makes everyone else wrong.
> 2 Sn2+ → Sn4+ + Sn
This isn’t a redox reaction though. Those are tin ions in equilibrium with each other.. so no combustion.
> I'll ask the chemists in the house if they know of any such reactions tomorrow since Google isn't being much use
I’d be interested what you find out, my chemistry knowledge has aged… theres always stuff I don’t know!
Edit: Yep you’re correct it is considered a redox, but not combustion.
This isn’t a redox reaction though. Those are tin ions in equilibrium with each other.. so no combustion.
> I'll ask the chemists in the house if they know of any such reactions tomorrow since Google isn't being much use
I’d be interested what you find out, my chemistry knowledge has aged… theres always stuff I don’t know!
Edit: Yep you’re correct it is considered a redox, but not combustion.
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Self oxidizing mixtures exist. Gun powder is probably the classic example.
Monopropellants, that aren't mixtures, exist and "burn" too, high concentration H2O2 for instance.
Monopropellants, that aren't mixtures, exist and "burn" too, high concentration H2O2 for instance.
T-Stoff/High-Test Peroxide doesn't actually burn, but rather decomposes into water and oxygen.
They can still burn in the presence of an oxidiser. They don't need it, but that won't stop them from burning, or blowing up, or doing whatever they want to do, as monopropellants are really (no pun intended) impulsive.
Gunpowder still requires an oxidizer, it just happens to be mixed in. The potassium nitrate is the oxidizer, KN03, whereas the sulphur and charcoal are the fuels that burn.
Pretty much any combustion requires a molecule with oxygen to accept the electrons: exceptions exist with halogens like chlorine… but these are still called “oxidizers”
So saying hydrogen doesn’t burn without an oxidizer still makes little sense. Hydrogen will combust with either oxygen or chlorine for example, both oxidizers. Without those then nothing happens because nothing can combust without an oxidizer… You may just not realize the oxidizer is mixed with the fuel.
Pretty much any combustion requires a molecule with oxygen to accept the electrons: exceptions exist with halogens like chlorine… but these are still called “oxidizers”
So saying hydrogen doesn’t burn without an oxidizer still makes little sense. Hydrogen will combust with either oxygen or chlorine for example, both oxidizers. Without those then nothing happens because nothing can combust without an oxidizer… You may just not realize the oxidizer is mixed with the fuel.
Technically speaking, sulfur is an oxidizer in gunpowder, not fuel. Sulfur is even in the same elemental group as oxygen.
Sulfur is commonly used as an oxidizer for metal fuels. In the case of gunpowder, that would be the potassium in potassium nitrate.
Sulfur is commonly used as an oxidizer for metal fuels. In the case of gunpowder, that would be the potassium in potassium nitrate.
That’s not correct. (Sulfur can be an oxidizer in some reactions as you mention, but not in gunpowder where it acts as the fuel)
https://www.wikipedia.org/wiki/Gunpowder#Components
Potassium nitrate is the most important ingredient in terms of both bulk and function because the combustion process releases oxygen from the potassium nitrate, promoting the rapid burning of the other ingredients
Sulfur's main role in gunpowder is to decrease the ignition temperature. A sample reaction for sulfur-free gunpowder would be:
https://www.wikipedia.org/wiki/Gunpowder#Components
Potassium nitrate is the most important ingredient in terms of both bulk and function because the combustion process releases oxygen from the potassium nitrate, promoting the rapid burning of the other ingredients
Sulfur's main role in gunpowder is to decrease the ignition temperature. A sample reaction for sulfur-free gunpowder would be:
6 KNO3 + C7H4O → 3 K2CO3 + 4 CO2 + 2 H2O + 3 N2Nothing you’ve stated contradicts my point. You are also misunderstanding the chemistry in the passage you quoted.
Sulfur is commonly used to bootstrap exothermic reactions, largely based on its strong affinity for oxidizing metals with relatively low activation energy. In gunpowder, you need the potassium nitrate to release the “nitrate” part so that it can oxidize the carbon but for that to happen you need to offer potassium something more thermodynamically attractive to bind to. Charcoal (carbon) cannot serve that purpose. Sulfur provides that thermodynamically attractive outlet for potassium such that it will happily release the nitrate. Sulfur, in this case, would be termed a “sensitizer” but the mechanism of action is as a metal oxidizer. Sulfur/metal complexes are often used to bootstrap hard-to-ignite things such as thermites.
There are many metal oxidizer salts that become so sensitized in the presence of sulfur that they become dangerously unstable. In the case of potassium nitrate, it becomes more sensitized but still stable enough to be useful. For most real industrial applications, metal oxidizer salts have long been replaced with ammonium oxidizer salts which don’t have any metals to worry about.
The “sulfur-free” formulation uses an organic fuel (gunpowder does not), which provides alternative potassium sinks thereby obviating the need for sulfur.
Sulfur is commonly used to bootstrap exothermic reactions, largely based on its strong affinity for oxidizing metals with relatively low activation energy. In gunpowder, you need the potassium nitrate to release the “nitrate” part so that it can oxidize the carbon but for that to happen you need to offer potassium something more thermodynamically attractive to bind to. Charcoal (carbon) cannot serve that purpose. Sulfur provides that thermodynamically attractive outlet for potassium such that it will happily release the nitrate. Sulfur, in this case, would be termed a “sensitizer” but the mechanism of action is as a metal oxidizer. Sulfur/metal complexes are often used to bootstrap hard-to-ignite things such as thermites.
There are many metal oxidizer salts that become so sensitized in the presence of sulfur that they become dangerously unstable. In the case of potassium nitrate, it becomes more sensitized but still stable enough to be useful. For most real industrial applications, metal oxidizer salts have long been replaced with ammonium oxidizer salts which don’t have any metals to worry about.
The “sulfur-free” formulation uses an organic fuel (gunpowder does not), which provides alternative potassium sinks thereby obviating the need for sulfur.
> You are also misunderstanding the chemistry in the passage you quoted.
I’m not. I’ll give the benefit of the doubt we have a miscommunication though.
> Technically speaking, sulfur is an oxidizer in gunpowder, not fuel.
This initial statement makes it sound like you were claiming that the potassium nitrate is not the primary oxidizer in the combustion. It is the potassium nitrate’s role which is the oxidizer and not the fuel.
And yes, sulfur attracts the potassium, and aids in the reaction, but it’s role is also as fuel, which you incorrectly stated it was not.
Again, from wikipedia:
sulfur (S), which, while also serving as a fuel, lowers the temperature required to ignite the mixture, thereby increasing the rate of combustion. [1]
[1]https://en.m.wikipedia.org/wiki/Gunpowder#Components
And Fuel:
A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work.
Sulfur itself can be burned. Potassium nitrate cannot. In fact if you add sulfur to potassium nitrate the sulfur can act as the reducing agent and you’ll get sulfur dioxide.
Gunpowder (specifically black powder) works in a vacuum because of the potassium nitrate, not because of the sulfur. You can have gunpowder without sulfur, but it’s not going to work without the potassium nitrate.
I’m not. I’ll give the benefit of the doubt we have a miscommunication though.
> Technically speaking, sulfur is an oxidizer in gunpowder, not fuel.
This initial statement makes it sound like you were claiming that the potassium nitrate is not the primary oxidizer in the combustion. It is the potassium nitrate’s role which is the oxidizer and not the fuel.
And yes, sulfur attracts the potassium, and aids in the reaction, but it’s role is also as fuel, which you incorrectly stated it was not.
Again, from wikipedia:
sulfur (S), which, while also serving as a fuel, lowers the temperature required to ignite the mixture, thereby increasing the rate of combustion. [1]
[1]https://en.m.wikipedia.org/wiki/Gunpowder#Components
And Fuel:
A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work.
Sulfur itself can be burned. Potassium nitrate cannot. In fact if you add sulfur to potassium nitrate the sulfur can act as the reducing agent and you’ll get sulfur dioxide.
4KNO3+5S⟶2K2O+5SO2+2N2
Gunpowder (specifically black powder) works in a vacuum because of the potassium nitrate, not because of the sulfur. You can have gunpowder without sulfur, but it’s not going to work without the potassium nitrate.
Mixtures aren’t single substances. Monopropellants don’t burn, their just one of many exothermic reactions.
> Monopropellants don’t burn, their just one of mangy exothermic reactions.
Gave a fairly full reply to this over here
https://news.ycombinator.com/item?id=28121336
Gave a fairly full reply to this over here
https://news.ycombinator.com/item?id=28121336
No offense intended, but the fact language evolves isn’t an excuse to be imprecise. As arch discharge lighting became popular the idea of burning began to separate from the creation of plasma because nothing was being used up. We still say electrical components “burned out” because of this idea of fire as something that consumes.
Anyway, as long as you understand that’s not what is meant by the term burning I don’t really think there is anything worth arguing about here. And hey in 100 years your definition might win.
Anyway, as long as you understand that’s not what is meant by the term burning I don’t really think there is anything worth arguing about here. And hey in 100 years your definition might win.
I guess I got into this argument, so to be clear, I am not conceding this (nor do I particularly want to continue this part of the argument, so I won't and ask the others do not take a lack of reply as you conceding the opposite)
> that’s not what is meant by the term burning
Monopropellants may not agree with your use of the term burning, but I deny that they do not agree with the majority of english speakers use of the word burning, or the definition of the word burning that you will find in common dictionaries [1].
[1] For example merriam-webster defines "burning" as "being on fire", "fire" as "the phenomenon of combustion manifested in light, flame, and heat" and "combustion" as "a usually rapid chemical process (such as oxidation) that produces heat and usually light".
> that’s not what is meant by the term burning
Monopropellants may not agree with your use of the term burning, but I deny that they do not agree with the majority of english speakers use of the word burning, or the definition of the word burning that you will find in common dictionaries [1].
[1] For example merriam-webster defines "burning" as "being on fire", "fire" as "the phenomenon of combustion manifested in light, flame, and heat" and "combustion" as "a usually rapid chemical process (such as oxidation) that produces heat and usually light".
Fair enough, I will not try and persuade you. I am sure you can find people using the term burning in association with monopropellants.
For anyone reading this I will say Wikipedia and at no point is combustion or burning used do describe them. “Monopropellants[1] are propellants consisting of chemicals that release energy through exothermic chemical decomposition” https://en.wikipedia.org/wiki/Monopropellant
For anyone reading this I will say Wikipedia and at no point is combustion or burning used do describe them. “Monopropellants[1] are propellants consisting of chemicals that release energy through exothermic chemical decomposition” https://en.wikipedia.org/wiki/Monopropellant
[deleted]
But they only burn easily at the interface. The trick would be to control fire there - keep them from mixing, keep the flame, if one were to start, from enlarging the hole.
Good point. I remember a science demonstration where lighting a balloon filled with a mixture of hydrogen and oxygen caused a much more violent eruption compared to a balloon of pure hydrogen.
Both pure hydrogen and a stochiometric hydrogen-oxygen mixture explode (produce a bang, indicating a flame front moving faster than the speed of sound).
The stochiometric mixture explodes more violently, true. But again, both explode.
Periodic Videos, feat. Destin Sandlin: https://youtube.com/watch?v=qOTgeeTB_kA
The stochiometric mixture explodes more violently, true. But again, both explode.
Periodic Videos, feat. Destin Sandlin: https://youtube.com/watch?v=qOTgeeTB_kA
Not only control where the fire is, but do so with materials light enough for an airship. It's a hard problem.
Not necessarily. Remember, you only need to control the interface. A bag, not a wall.
The burning plume escapes upward. It's probably safer than aviation fuel.
The cabin could be made to detach if necessary, with parachutes along with individual parachutes for passengers as a fallback.
Right, seen that in Hindenburg footage.
The Hindenburg was covered in aluminum paint.
Aluminium must be really exotic material in airspace applications?
Also:
The truth is that the dope used on the Hindenburg was specifically chosen for its low flammability, and the composition of the dope had almost nothing in common with the formula used to make rocket fuel.
https://www.airships.net/hindenburg-paint/
Also:
The truth is that the dope used on the Hindenburg was specifically chosen for its low flammability, and the composition of the dope had almost nothing in common with the formula used to make rocket fuel.
https://www.airships.net/hindenburg-paint/
You're trying to be witty but the crashing airframe of a lighter than air craft is very likely to do less damage mainly due to its slower speed and the fact most flammable material escapes upwards.
Have you thought through this at all?
Have you thought through this at all?
It is well established that a burning dirigible incident is not very survivable. I'm not sure why am the one being unreasonable here.
I could understand if hydrogen balloons were never tried before tech, but you're just gaslighting now.
I could understand if hydrogen balloons were never tried before tech, but you're just gaslighting now.
Even the non-burning ones aren't especially survivble. The UK R-101 which first crashed, then burned (48 souls), and US Navy Macon (2 souls), Akron (73 souls), and Shenandoah (14 souls).
Have you compared those to contemporary plane crashes? Even today plane crashes are quite bad.
Simo K.Ekman, Michel Debacker, "Survivability of occupants in commercial passenger aircraft accidents", Safety Science, Volume 104, April 2018, Pages 91-98
The average survival rate is 86.3%, casualty rate 20.1% and RSF 0.16.
Survival rate increases to 95.6% when accidents with a 100% fatal rate are excluded.
That is, survival rates overall are good, and if there are any survivors, odds are that nearly all passengers will survive.
https://www.sciencedirect.com/science/article/abs/pii/S09257...
Note that this is the result of over a century of incrementally increasing safety measures. I don't have a good chart to show for aircraft, but I strongly suspect the trends are similar to those of the auto industry, where deaths measured in passenger-distance travelled halved about every two decades since 1910, with the exception of the first decade, where it halved in only 10 years.
See this chart (the relevant line is the "Deaths per billion VMT" (vehicle miles travelled), in red, descending left to right): https://upload.wikimedia.org/wikipedia/commons/4/4f/US_traff...
From: https://en.wikipedia.org/wiki/Transportation_safety_in_the_U...
That is: with time, incremental improvements in design, procedures, equipment, training, standardisation, material, responses, and infrastructure add up. This shows up across transporation modes: ships, rail, cars, and aircraft.
This makes direct comparisons to early-20th-century airships difficult, as the entire safety mindset and understanding were different. Even just between the loss of the Akron and Macon, the addition of personal floatation devices (life preservers) decreased deaths from 73 to 2, in identical craft operated by the same organisation with similar crews. (Most of the Akron's crew drowned.) The US also used helium rather than hydrogen (a vast safety improvement itself), though due to the cost and scarcity of helium, limited venting capabilities (this directly contributed to the loss of the Shenendoah).
(I discuss several airship accidents, with links, in this thread: https://news.ycombinator.com/item?id=28126643)
There's a general principle in manufacturing that efficiencies increase in direct proportion to experience (Wright's law, and others, see: https://en.wikipedia.org/wiki/Experience_curve_effects). There's a similar effect in safety, though I'm not aware of a named principle. Effectively, with time, more of the possible things that can go wrong do. In a systematised discipline or craft, these lessons are incoprorated and guarded against.
Airships saw about 20 years of operating history, at relatively low intensity. Jet airliners have been in operation for nearly 70 years, at phenomenal scales of use, and built on earlier propeller-driven experience. There are ten times as many people aloft in airplanes at any moment than travelled by airship in an entire year. Direct safety comparisons are of very different experiences.
That said, I'd tend to suspect that airships would prove less safe on a similar passenger-distance metric (or cargo mass-distance), than powered heavier-than-air craft. Airships simply operate far too close to their safety margins, in a much more hostile environment (lower atmosphere), and with runaway feedbacks (buoyancy decreases with sink and increases with rise), whilst capacity and speed limit scales of operations.
The average survival rate is 86.3%, casualty rate 20.1% and RSF 0.16.
Survival rate increases to 95.6% when accidents with a 100% fatal rate are excluded.
That is, survival rates overall are good, and if there are any survivors, odds are that nearly all passengers will survive.
https://www.sciencedirect.com/science/article/abs/pii/S09257...
Note that this is the result of over a century of incrementally increasing safety measures. I don't have a good chart to show for aircraft, but I strongly suspect the trends are similar to those of the auto industry, where deaths measured in passenger-distance travelled halved about every two decades since 1910, with the exception of the first decade, where it halved in only 10 years.
See this chart (the relevant line is the "Deaths per billion VMT" (vehicle miles travelled), in red, descending left to right): https://upload.wikimedia.org/wikipedia/commons/4/4f/US_traff...
From: https://en.wikipedia.org/wiki/Transportation_safety_in_the_U...
That is: with time, incremental improvements in design, procedures, equipment, training, standardisation, material, responses, and infrastructure add up. This shows up across transporation modes: ships, rail, cars, and aircraft.
This makes direct comparisons to early-20th-century airships difficult, as the entire safety mindset and understanding were different. Even just between the loss of the Akron and Macon, the addition of personal floatation devices (life preservers) decreased deaths from 73 to 2, in identical craft operated by the same organisation with similar crews. (Most of the Akron's crew drowned.) The US also used helium rather than hydrogen (a vast safety improvement itself), though due to the cost and scarcity of helium, limited venting capabilities (this directly contributed to the loss of the Shenendoah).
(I discuss several airship accidents, with links, in this thread: https://news.ycombinator.com/item?id=28126643)
There's a general principle in manufacturing that efficiencies increase in direct proportion to experience (Wright's law, and others, see: https://en.wikipedia.org/wiki/Experience_curve_effects). There's a similar effect in safety, though I'm not aware of a named principle. Effectively, with time, more of the possible things that can go wrong do. In a systematised discipline or craft, these lessons are incoprorated and guarded against.
Airships saw about 20 years of operating history, at relatively low intensity. Jet airliners have been in operation for nearly 70 years, at phenomenal scales of use, and built on earlier propeller-driven experience. There are ten times as many people aloft in airplanes at any moment than travelled by airship in an entire year. Direct safety comparisons are of very different experiences.
That said, I'd tend to suspect that airships would prove less safe on a similar passenger-distance metric (or cargo mass-distance), than powered heavier-than-air craft. Airships simply operate far too close to their safety margins, in a much more hostile environment (lower atmosphere), and with runaway feedbacks (buoyancy decreases with sink and increases with rise), whilst capacity and speed limit scales of operations.
> This makes direct comparisons to early-20th-century airships difficult,
This is exactly my point. It's unwise to assume they are worse. If anything, to a first estimation, you can have the passenger cabin disconnect and glide to a controlled crash as we do for planes in certain scenarios.
I'm not seeing how a slower moving, less energetic vehicle is less safe. It's a complete subversion of engineering acumen.
This is exactly my point. It's unwise to assume they are worse. If anything, to a first estimation, you can have the passenger cabin disconnect and glide to a controlled crash as we do for planes in certain scenarios.
I'm not seeing how a slower moving, less energetic vehicle is less safe. It's a complete subversion of engineering acumen.
Lots of energy stored in contained hydrogen, that's before counting the fuel.
[deleted]
https://en.wikipedia.org/wiki/Pomeroy_bullet
The British anti-zeppelin forces researched this problem and were unable to come up with a method of reliably igniting the hydrogen gas.
The British anti-zeppelin forces researched this problem and were unable to come up with a method of reliably igniting the hydrogen gas.
Crashing aircraft into them was quite reliable, it just wasn’t cheap.
"Floating in oxidizer" doesn't matter - airships are under such low pressure that leaks are too slow to maintain a flame front. I researched this quite a bit for the Army back in the day, even worked with a vendor who fired 50 caliber tracer rounds through an airship to try to get it to catch on fire, and it did not.
There are rumours that because of this fact, that the Hindenburg disaster was not from natural causes.
[deleted]
Do you mean that it was sabotaged?
There are also rumours along those lines. Not entirely unfounded as incendiary bullets were available by the 1930s
Okay, what’s the alternative scenario and how do we ensure that doesn’t happen?
IIRC something about the pain used on the aerodynamic outer shell (the gas cells inside were separate gas tight balloons made from processed cattle stomach tissue (!)). This paint apparently turned out to be highly flammable and/or explosive and could be activated by dischrges of static electricity.
I think there was static discharge involved, and thermite paint. And of course a giant bag filled with hydrogen, surrounded by oxygen.
Iirc there is a great YouTube video with Bill Hammack about this. Highly recommended. https://youtu.be/ixxXhZVFXxQ
He also wrote a book.
He also wrote a book.
Rips along the seams of the fabric siding causing large surface areas of hydrogen to be mixed, I think?
German Zeppelins were essentially invincible until the British invented incendiary ammunition. Their conventional rifle rounds would harmlessly punch through the gasbag.
https://en.wikipedia.org/wiki/Pomeroy_bullet
https://en.wikipedia.org/wiki/Pomeroy_bullet
In this doco they run through the ammunition types they tried and actually fire some from WW1 and they still worked.
https://www.pbs.org/wgbh/nova/video/zeppelin-terror-attack/
https://www.pbs.org/wgbh/nova/video/zeppelin-terror-attack/
Why could an airship not be made using a vacuum instead of a lifting gas?
A quick google reveals that someone has thought of this before: https://en.wikipedia.org/wiki/Vacuum_airship and it seems like it might not be possible with currently available materials.
Would it be possible to reduce the density of helium for the same pressure by electrostatically charging it to make the molecules repel, effectively turning the airship into a giant capacitor with alternating +ve and -ve sections?
A quick google reveals that someone has thought of this before: https://en.wikipedia.org/wiki/Vacuum_airship and it seems like it might not be possible with currently available materials.
Would it be possible to reduce the density of helium for the same pressure by electrostatically charging it to make the molecules repel, effectively turning the airship into a giant capacitor with alternating +ve and -ve sections?
SF author Fritz Leiber wrote an alternative history short story called "Catch That Zeppelin!", which won the 1975 Nebula Award for Best Short Story and the 1976 Hugo Award for Best Short Story.
https://en.wikipedia.org/wiki/Catch_That_Zeppelin!
>When Fritz Leiber sees a Zeppelin moored at the Empire State Building one afternoon in 1973, he realizes that he has shifted into another timeline — one where a more decisive defeat of Germany at the end of the First World War led to greater international prosperity and a deeper, more acceptable peace, with the result that America was willing to sell Germany helium for use in airships, thereby preventing the Hindenburg disaster. Also, the year has changed from 1973 to 1937, and Leiber has become a patriotic-but-peaceful German airship engineer named Adolf Hitler.
https://www.goodreads.com/book/show/40626645-catch-that-zepp...
https://en.wikipedia.org/wiki/Catch_That_Zeppelin!
>When Fritz Leiber sees a Zeppelin moored at the Empire State Building one afternoon in 1973, he realizes that he has shifted into another timeline — one where a more decisive defeat of Germany at the end of the First World War led to greater international prosperity and a deeper, more acceptable peace, with the result that America was willing to sell Germany helium for use in airships, thereby preventing the Hindenburg disaster. Also, the year has changed from 1973 to 1937, and Leiber has become a patriotic-but-peaceful German airship engineer named Adolf Hitler.
https://www.goodreads.com/book/show/40626645-catch-that-zepp...
Airships are a concept which is inherently attractive given their theoretical simplicity, but highly impracticle on closer examination. They're not impossible, but they're far less viable than would first appear.
Heavier-than-air powered aircraft were largely a result of powerful engines and energy-dense fuels. Emergence of mass-produced automobiles and the first aircraft occurred within a few years of each other. Materials science (duraluminium) was another major factor. Aeronautical engineering was largely secondary and likely would have emerged with experience regardless.
For airships, the key enabling factors are lifting gases and materials, in this case the gas-bag envelopes. For early-20th-century airships, the material of preference was ox intestines, glued together. One airship required the entrails of ~800,000 oxen.
See EngineerGuy’s video (accompanies his book) on the doomed British Airship R-101:
https://youtube.com/watch?v=ixxXhZVFXxQ
There are some factors which might help, and others which still work against, airships.
Rather than hydrogen, a "hot helium" design might offer greater flexibility. There's actually some research of such concepts: https://ui.adsabs.harvard.edu/abs/1987STIA...8748646R/abstra...
Materials science might allow for improvements in gas-bag design. Plastics made mid-century blimps possible, and modern Zeppelin semi-rigid airships rely on PVF (polyvinyl fluouride), principally. Graphene or other monatomic sheet materials might allow for thinner and/or stronger designs. Similarly structural components (frames, guy-wires) might benefit by both materials and computer-aided design and improve mass:volume ratios, safety margins, maintenance requirements, or other factors.
Improved lifting gas properties or mixes might also be an option, though here chemistry is fundamentally limiting.
Integrating PV capabilities into an outer skin might reduce fuel requirements, though even covering all the top surface of a USS Los Angeles sized airship (200m x 30m) would provide less than 300 kW of power. The Zeppelin NT (70m x 14m) has 3x 150 kW engines (450 kW total). Routing electricity next to hydrogen gas bags might prove problematic.
https://en.wikipedia.org/wiki/Zeppelin_NT
In all, I expect materials innovation might contribute to fractional improvements in airship capabilities or aspects, but not improvements of multiples.
Note that airships also have the submariner’s problem concerning buoyancy: lift is proportional to volume, but volume varies with pressure. As a submarine descends, there’s additional pressure on its buoyancy tanks, compressing the gas within them, reducing buoyancy further. As a submarine sinks, it wants to sink further, which may prove interesting if crush depth is exceeded. (Destin Sandlin’s recent “Smarter Every Day” series aboard the USS Toledo is pretty fascinating in this regard.) By contrast, in an airplane, lifting forces increase as one descends, and decrease as one ascends.
For airships and balloons, you’ve got the reverse problem: as they rise, the lifting gas expands. After a point one of three things must occur: the gas is vented (and lost forever), the envelope expands, or the gas is pressurised (meaning carrying the additional mass of compressors and pressure vessels).
One of the biggest disadvantages of airships compared to jet aircraft is that jets fly above the weather, at 30k--40k feet, whilst airships fly in it, often at only a few hundred feet altitude. The Hindenberg’s cruise altitude was 200m (650 ft), see: https://www.airships.net/hindenburg/flight-operations-proced... Operating and flight ceilings of 16k and 21k feet were apparently possible. Passenger Zeppelins were unpressurised. Note that this makes crossing even relatively low mountain ranges a challenge. Given the large number of airship failures in which wind and weather were primary or contributing causes, this is a major handicap.
The altitude record for an airship is 95,000 ft, though that’s for an unmanned system consisting of little more than the lifting balloons, frame, and propulsion. https://newatlas.com/highest-airship-flight-record/20379/
High-altitude flight requires a pressurised passenger compartment (increasing costs and risks), supplemental oxygen (the jet airliner's air-bleed pressurisation system is not available), and other factors.
The other massive disadvantage is that airships serve a limited number of roles and compete poorly against alternatives. They're highly intermediate between heavier-than-air airplanes and ships. They lack the former's speed (115 kph vs. 1,000 kph), and the latter's cargo capacity (160 tonne vs. 210,000 tonne for a Triple E-class Maersk container ship). Overland, airships would have to compete with river and canal traffic, rail, and trucking. The remaining remote-location work is likely of relatively limited economic value.
https://en.wikipedia.org/wiki/Triple_E-class_container_ship
That leaves the prospect of intercontinental trans-oceanic voyages, probably largely passenger and high-value cargo. Airships are likely to be limited to ~100 -- 200 kph. A transatlantic trip (NYC-LON) would take 1dy 4h to 2dy 8h. A Los Angeles -- Shanghai trip would be 2--4 days. Los Angeles to Sydney, 2.5--5 days. Given no other options, I could see that happening, but even a drastically curtailed fuel-based airliner industry would likely be preferable. Given either a carbon offset, synthetic hydrocarbon analogues, or carbon-neutral fuels, this seems more likely.
Heavier-than-air powered aircraft were largely a result of powerful engines and energy-dense fuels. Emergence of mass-produced automobiles and the first aircraft occurred within a few years of each other. Materials science (duraluminium) was another major factor. Aeronautical engineering was largely secondary and likely would have emerged with experience regardless.
For airships, the key enabling factors are lifting gases and materials, in this case the gas-bag envelopes. For early-20th-century airships, the material of preference was ox intestines, glued together. One airship required the entrails of ~800,000 oxen.
See EngineerGuy’s video (accompanies his book) on the doomed British Airship R-101:
https://youtube.com/watch?v=ixxXhZVFXxQ
There are some factors which might help, and others which still work against, airships.
Rather than hydrogen, a "hot helium" design might offer greater flexibility. There's actually some research of such concepts: https://ui.adsabs.harvard.edu/abs/1987STIA...8748646R/abstra...
Materials science might allow for improvements in gas-bag design. Plastics made mid-century blimps possible, and modern Zeppelin semi-rigid airships rely on PVF (polyvinyl fluouride), principally. Graphene or other monatomic sheet materials might allow for thinner and/or stronger designs. Similarly structural components (frames, guy-wires) might benefit by both materials and computer-aided design and improve mass:volume ratios, safety margins, maintenance requirements, or other factors.
Improved lifting gas properties or mixes might also be an option, though here chemistry is fundamentally limiting.
Integrating PV capabilities into an outer skin might reduce fuel requirements, though even covering all the top surface of a USS Los Angeles sized airship (200m x 30m) would provide less than 300 kW of power. The Zeppelin NT (70m x 14m) has 3x 150 kW engines (450 kW total). Routing electricity next to hydrogen gas bags might prove problematic.
https://en.wikipedia.org/wiki/Zeppelin_NT
In all, I expect materials innovation might contribute to fractional improvements in airship capabilities or aspects, but not improvements of multiples.
Note that airships also have the submariner’s problem concerning buoyancy: lift is proportional to volume, but volume varies with pressure. As a submarine descends, there’s additional pressure on its buoyancy tanks, compressing the gas within them, reducing buoyancy further. As a submarine sinks, it wants to sink further, which may prove interesting if crush depth is exceeded. (Destin Sandlin’s recent “Smarter Every Day” series aboard the USS Toledo is pretty fascinating in this regard.) By contrast, in an airplane, lifting forces increase as one descends, and decrease as one ascends.
For airships and balloons, you’ve got the reverse problem: as they rise, the lifting gas expands. After a point one of three things must occur: the gas is vented (and lost forever), the envelope expands, or the gas is pressurised (meaning carrying the additional mass of compressors and pressure vessels).
One of the biggest disadvantages of airships compared to jet aircraft is that jets fly above the weather, at 30k--40k feet, whilst airships fly in it, often at only a few hundred feet altitude. The Hindenberg’s cruise altitude was 200m (650 ft), see: https://www.airships.net/hindenburg/flight-operations-proced... Operating and flight ceilings of 16k and 21k feet were apparently possible. Passenger Zeppelins were unpressurised. Note that this makes crossing even relatively low mountain ranges a challenge. Given the large number of airship failures in which wind and weather were primary or contributing causes, this is a major handicap.
The altitude record for an airship is 95,000 ft, though that’s for an unmanned system consisting of little more than the lifting balloons, frame, and propulsion. https://newatlas.com/highest-airship-flight-record/20379/
High-altitude flight requires a pressurised passenger compartment (increasing costs and risks), supplemental oxygen (the jet airliner's air-bleed pressurisation system is not available), and other factors.
The other massive disadvantage is that airships serve a limited number of roles and compete poorly against alternatives. They're highly intermediate between heavier-than-air airplanes and ships. They lack the former's speed (115 kph vs. 1,000 kph), and the latter's cargo capacity (160 tonne vs. 210,000 tonne for a Triple E-class Maersk container ship). Overland, airships would have to compete with river and canal traffic, rail, and trucking. The remaining remote-location work is likely of relatively limited economic value.
https://en.wikipedia.org/wiki/Triple_E-class_container_ship
That leaves the prospect of intercontinental trans-oceanic voyages, probably largely passenger and high-value cargo. Airships are likely to be limited to ~100 -- 200 kph. A transatlantic trip (NYC-LON) would take 1dy 4h to 2dy 8h. A Los Angeles -- Shanghai trip would be 2--4 days. Los Angeles to Sydney, 2.5--5 days. Given no other options, I could see that happening, but even a drastically curtailed fuel-based airliner industry would likely be preferable. Given either a carbon offset, synthetic hydrocarbon analogues, or carbon-neutral fuels, this seems more likely.
This is really interesting... I am suspicious of fossil fuel based hydrogen, but as electrolyzed hydrogen gets cheaper, this could be very useful for some applications.
There are some really interesting chemical methods of creating hydrogen gas using like, aluminum and sodium ( or potassium? ) in water that might be able to allow for on demand gas generation with otherwise solid/condensed fuel sources;
it's "simple" enough of a concept that creators[1] are doing it to power their own systems, though I imagine scaling it up carries its own set of difficulties ( e.g., using aluminum nanoparticles for greater surface area to more rapidly generate gas, but keeping it cool enough to avoid problematic side effects, or like, you know, exploding in general )
Edit: it looks like MIT is actually actively working[2] on this type of clean hydrogen production from the viewpoint of creating a scalable system!
1: https://youtu.be/LKfbZvpoQ0g?t=5m23s
2: https://energy.mit.edu/news/using-aluminum-and-water-to-make...
it's "simple" enough of a concept that creators[1] are doing it to power their own systems, though I imagine scaling it up carries its own set of difficulties ( e.g., using aluminum nanoparticles for greater surface area to more rapidly generate gas, but keeping it cool enough to avoid problematic side effects, or like, you know, exploding in general )
Edit: it looks like MIT is actually actively working[2] on this type of clean hydrogen production from the viewpoint of creating a scalable system!
1: https://youtu.be/LKfbZvpoQ0g?t=5m23s
2: https://energy.mit.edu/news/using-aluminum-and-water-to-make...
Interesting. I did some back of the envelope calculations.
A 100% efficient electrolyser requires 39 kWh of electricity to produce 1 kg of hydrogen. Best practical ones need about 50 kWh [1].
Hinderburg had about 18 metric tons of hydrogen [2], filling it would require about 1 GWh of energy. The good thing is - it could be used as a way to balance the electric network because we don't particularly care when we fill it as long as it's done. So we can do it when there's overproduction only. The energy would be quite cheap - in some cases you can get paid for using energy when electrical network needs balancing. Same thing is done with other energy-intensive industrial processes like smelting.
In Germany (not particularly sunny but a lot of solar panels so effects of scale are there) the low bounds for price of 1 MWh of solar energy in 2018 was about 37 euro [3], let's round that up to 50 - filling Hindenburg would require about 50 000 euro of renewable energy.
Additionally it would require about 9 * 18 ~= 162 tons of water and some additives to make it conductive. Maybe sea water could be used as is?
[1] http://www.renewableenergyfocus.com/view/3157/hydrogen-produ... [2] https://www.history.com/news/the-hindenburg-disaster-9-surpr... [3] https://en.wikipedia.org/wiki/Cost_of_electricity_by_source#...
A 100% efficient electrolyser requires 39 kWh of electricity to produce 1 kg of hydrogen. Best practical ones need about 50 kWh [1].
Hinderburg had about 18 metric tons of hydrogen [2], filling it would require about 1 GWh of energy. The good thing is - it could be used as a way to balance the electric network because we don't particularly care when we fill it as long as it's done. So we can do it when there's overproduction only. The energy would be quite cheap - in some cases you can get paid for using energy when electrical network needs balancing. Same thing is done with other energy-intensive industrial processes like smelting.
In Germany (not particularly sunny but a lot of solar panels so effects of scale are there) the low bounds for price of 1 MWh of solar energy in 2018 was about 37 euro [3], let's round that up to 50 - filling Hindenburg would require about 50 000 euro of renewable energy.
Additionally it would require about 9 * 18 ~= 162 tons of water and some additives to make it conductive. Maybe sea water could be used as is?
[1] http://www.renewableenergyfocus.com/view/3157/hydrogen-produ... [2] https://www.history.com/news/the-hindenburg-disaster-9-surpr... [3] https://en.wikipedia.org/wiki/Cost_of_electricity_by_source#...
Current cost of electrolyzed hydrogen is €2.5-€5.5/kg, and the EU hopes to get that to less than half by 2030:
https://about.bnef.com/blog/liebreich-separating-hype-from-h...
$100k for a filling, with many many re-uses, could maybe be feasible today, and $20k should definitely be.
One note about hydrogen production, as I understand it, is that electrolyzers are enough of a capital expense that you want to be running them at fairly high capacity factors. Cheaper energy helps, but cheaper electrolyzers would probably help more.
https://about.bnef.com/blog/liebreich-separating-hype-from-h...
$100k for a filling, with many many re-uses, could maybe be feasible today, and $20k should definitely be.
One note about hydrogen production, as I understand it, is that electrolyzers are enough of a capital expense that you want to be running them at fairly high capacity factors. Cheaper energy helps, but cheaper electrolyzers would probably help more.
I've been thinking of it the same way since I learned that helium is a non-renewable fossil resource. Once it's gone, it's gone.
Only on earth. Helium is the 2nd most abundant element in the universe.
You’ll have a hard time extracting it from the sun, though.
But an easier time from the Moon. The Moon's soil is apparently lousy with Helium.
There was a movie named Moon about a decade back where that was the main character's job, helium mining on the Moon.
That's not to say it would be easy, but it's closer than the Sun. Because it is everywhere.
In the various Star Trek shows, ships are made with something called "Bussard collectors" which basically scoop up particles like helium and hydrogen from space for use in the ship.
Obviously both of those example are fiction. We don't have the capability to mine on the Moon or catch elements free floating in space. But those fictions are based on the fact that those elements are that abundant.
There was a movie named Moon about a decade back where that was the main character's job, helium mining on the Moon.
That's not to say it would be easy, but it's closer than the Sun. Because it is everywhere.
In the various Star Trek shows, ships are made with something called "Bussard collectors" which basically scoop up particles like helium and hydrogen from space for use in the ship.
Obviously both of those example are fiction. We don't have the capability to mine on the Moon or catch elements free floating in space. But those fictions are based on the fact that those elements are that abundant.
>"Bussard collectors"
I think I read somewhere that despite this being a science fiction trope forever, there may not be a region between "too thin to produce net power" and "thick enough to blow up a spaceship at relativistic speeds". And in practice, the interstellar medium turned out to be the former, too thin.
In fact, I'm not sure but what someone may have calculated drag would exceed power generated, regardless of density.
I think I read somewhere that despite this being a science fiction trope forever, there may not be a region between "too thin to produce net power" and "thick enough to blow up a spaceship at relativistic speeds". And in practice, the interstellar medium turned out to be the former, too thin.
In fact, I'm not sure but what someone may have calculated drag would exceed power generated, regardless of density.
Length contraction should also increase the apparent density for a ship travelling at relativistic speeds.
The Busard collectors in Star Trek are based on a real theoretical design; The Busard ramjet. I can't comment on its feasiblilty, but it would've actually captured elements free floating in space.
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as an aside: a "fossil" resource implies the feedstock is decayed organic matter. Trapped helium is finite, but it's much more like a metal or ore than oil, LNG, or coal, which all were formed from living things under time and pressure.
Actually ... I just looked up the etymology in yesterday's discussion of whether or not petroleum is dinosaurs.
Fossil means "dug up". So both fossil remains (remnents of ancient plants and animals) and fossil fuels are called that because they are dug (or drilled) from the ground. As opposed to harvested fuels (wood, dung, etc.).
https://www.etymonline.com/word/fossil
The popular meaning of "fossil" has somewhat orbited around the usage such that we associate "fossil fuels" with "fossil remains" rather than "dug from the ground".
I don't know if that makes helium a "fossil" resource, though I could see the argument for that. We don't refer to other minerals (e.g., iron, much of which comes from banded iron formations, or limestone, from seashells), as "fossil" resources, despite both being dug from the earth and biological in origin.
Fossil means "dug up". So both fossil remains (remnents of ancient plants and animals) and fossil fuels are called that because they are dug (or drilled) from the ground. As opposed to harvested fuels (wood, dung, etc.).
https://www.etymonline.com/word/fossil
The popular meaning of "fossil" has somewhat orbited around the usage such that we associate "fossil fuels" with "fossil remains" rather than "dug from the ground".
I don't know if that makes helium a "fossil" resource, though I could see the argument for that. We don't refer to other minerals (e.g., iron, much of which comes from banded iron formations, or limestone, from seashells), as "fossil" resources, despite both being dug from the earth and biological in origin.
> I learned that helium is a non-renewable fossil resource
It is renewed, by radioactive decay within the Earth, but very, very slowly.
It is renewed, by radioactive decay within the Earth, but very, very slowly.
Helium is sort of renewable in that it's continuously produced by radioactive decay underground. That will continue effectively forever. But we're using the easily accessible helium far faster than it's being produced. Much of the helium we capture as part of natural gas extraction is totally wasted, just vented into the atmosphere.
As we necessarily transition away from fossil fuels we also transition away from our primary source of helium.
TLDR:
> With modern engineering standards, there is no doubt that hydrogen could be made a safe lifting gas.
Disadvantages of hydrogen:
* burns (but only with sufficient oxygen, eg a mixture of air and 4% up to 75% hydrogen)
Advantages of hydrogen:
* lifts 8% more than helium (per volume). Not a huge difference, but not trivial for an airship
* costs 98.5% less than helium (!) (Airships have crashed because helium was too expensive to vent: safety valves on the USS Shenandoah were capped, 14 crew members lost their lives.)
> Airships are too slow for human travel
Too slow for transportation, maybe. But leisure travel? Imagine a one week air safari from Kilimandjaro and the Serengeti to Kruger Park. It could be awesome.
Edit to add:
(Leisure air travel/Safari is my own pipe dream. The article suggests cargo):
> If airships were to make a major comeback, it would be in cargo service.
> Cargo airships would need to be big—bigger than the Hindenburg. [...] ”’the lift-to-drag ratio, a critical parameter in aircraft performance, gets better as the airship gets bigger)
> Ginormous airships require a lot of lifting gas—perhaps a million cubic meters
> FAA has discouraged the return of the airship in the use case that makes the most sense
> With modern engineering standards, there is no doubt that hydrogen could be made a safe lifting gas.
Disadvantages of hydrogen:
* burns (but only with sufficient oxygen, eg a mixture of air and 4% up to 75% hydrogen)
Advantages of hydrogen:
* lifts 8% more than helium (per volume). Not a huge difference, but not trivial for an airship
* costs 98.5% less than helium (!) (Airships have crashed because helium was too expensive to vent: safety valves on the USS Shenandoah were capped, 14 crew members lost their lives.)
> Airships are too slow for human travel
Too slow for transportation, maybe. But leisure travel? Imagine a one week air safari from Kilimandjaro and the Serengeti to Kruger Park. It could be awesome.
Edit to add:
(Leisure air travel/Safari is my own pipe dream. The article suggests cargo):
> If airships were to make a major comeback, it would be in cargo service.
> Cargo airships would need to be big—bigger than the Hindenburg. [...] ”’the lift-to-drag ratio, a critical parameter in aircraft performance, gets better as the airship gets bigger)
> Ginormous airships require a lot of lifting gas—perhaps a million cubic meters
> FAA has discouraged the return of the airship in the use case that makes the most sense
Once internet comes from satellites as a matter of course, I have little doubt we'll all be living in airships.
Airships are being investigated as a method of shipping to remote locations without ship, train, or truck access.
Airships would be good for freight. Far less carbon footprint than airplanes.
There's more to compete with though: train and ship. Both have severely lower carbon footprint than airplane as well. Ship might seem terrible at first glance, but the amount of tonnes being transported is so huge that it outweighs the fuel.
Competition is always a problem. Trains cannot compete with trucks in most cases because logistics are dirt cheap and trucks are more flexible.
Oh, but they can - and they do. It is really common for freight to go the distance it can by rail and then the last miles by truck - they load the entire semi trailer onto the train and only have to load the trailer once.
Trains aren't as flexible as trucks, true. But a train can go hundreds of miles with only two dedicated people - the engineer and the conductor - and they pull hundreds of trucks (and more). A lot of trains in the US are more efficient: They have a diesel generator that runs the electric motors on the wheels.
Even better: In the US, the tracks prioritize freight trains. Amtrak usually rents the space, and you get stuck waiting for freight to pass (at least in Indiana).
I have relatives that work as engineers and conductors for a freight train company, by the way.
Trains aren't as flexible as trucks, true. But a train can go hundreds of miles with only two dedicated people - the engineer and the conductor - and they pull hundreds of trucks (and more). A lot of trains in the US are more efficient: They have a diesel generator that runs the electric motors on the wheels.
Even better: In the US, the tracks prioritize freight trains. Amtrak usually rents the space, and you get stuck waiting for freight to pass (at least in Indiana).
I have relatives that work as engineers and conductors for a freight train company, by the way.
Depends on the airplane. An electric touring motorglider would be extremely efficient and could give zeppelins a run for the money.
... as long as you don't need that freight while the weather is even slightly bad.
Just like shipping things doesn't work because of storms, right?
Airships just don't work in strong winds, no need for a storm. And a plane can quickly move out of a hazardous location. An airship cannot move quickly.
Is that true even if it has a large mass from cargo?
Yes. It always has to have a much larger surface area in proportion to the weight it is carrying than any heavier than air craft, by definition.
That means it has to have more volume to lift more weight. More volume means more surface area (though not linearly!). More surface area means more impact from strong winds, updrafts, downdrafts.
And we haven’t figured out any plausible sort of propulsion that can even momentarily provide enough force to counteract something like a strong sudden downdraft without being too bulky to be practical.
That means it has to have more volume to lift more weight. More volume means more surface area (though not linearly!). More surface area means more impact from strong winds, updrafts, downdrafts.
And we haven’t figured out any plausible sort of propulsion that can even momentarily provide enough force to counteract something like a strong sudden downdraft without being too bulky to be practical.
I think they still have a point though:
Let X be any linear measurement of the airship (like length). The forces on the airship are proportional to X^2, and the max mass is proportional to X^3. Consequently, acceleration from wind and whatnot tends to 0 as the airship size increases (when fully loaded).
Moreover, the necessary propulsion similarly scales with X^2 (which is convenient, because that's the amount of space you have to place the propulsion), while requiring increasingly negligible fractions of the ship's carrying capacity as the ship size increases.
Let X be any linear measurement of the airship (like length). The forces on the airship are proportional to X^2, and the max mass is proportional to X^3. Consequently, acceleration from wind and whatnot tends to 0 as the airship size increases (when fully loaded).
Moreover, the necessary propulsion similarly scales with X^2 (which is convenient, because that's the amount of space you have to place the propulsion), while requiring increasingly negligible fractions of the ship's carrying capacity as the ship size increases.
Nice!
Any chance you’d be interested in doing the math to figure out power to surface area ratios and what it would have to be to have the maneuvering capabilities of say a Cessna 172 in something like a blimp?
Any chance you’d be interested in doing the math to figure out power to surface area ratios and what it would have to be to have the maneuvering capabilities of say a Cessna 172 in something like a blimp?
If I'm not mistaken that's impossible as the size of the blimp increases (similar idea -- X^2 max power, X^3 mass, consequently acceleration and maneuverability are poor).
The point was more that heavy winds aren't an issue for a sufficiently large blimp, even without maneuverability, because the impact of the storm on a blimp is negligible.
The point was more that heavy winds aren't an issue for a sufficiently large blimp, even without maneuverability, because the impact of the storm on a blimp is negligible.
That doesn't make sense though - if the entire air mass is moving, and there is insufficient propulsion to go faster than the airmass is moving - then that airmass will carry the blimp into whatever that airmass hits? There is too much surface area for much else to happen right?
Microburst wind speeds can hit 270km/h or more. Updrafts can hit 10,000 ft/minute or more [https://en.wikipedia.org/wiki/Downburst][https://www.britann...
Microburst wind speeds can hit 270km/h or more. Updrafts can hit 10,000 ft/minute or more [https://en.wikipedia.org/wiki/Downburst][https://www.britann...
A few points:
- The O(1/X) acceleration property prevents a 300km/h wind from getting the blimp to speed quickly. The "entire air mass moving" doesn't change that; you'll see wind flowing around the blimp, wind becoming turbulent and reversing directions, wind losing velocity and converting to heat and sound, local portions of the blimp temporarily deforming, potential blimp damage, and all kinds of other effects from a microburst, but you won't see a high mass-to-surface-area-ratio object have its center of mass accelerate quickly from wind drag.
- The blimp _would_ need to have sufficient propulsion to counteract average wind forces over some time period. If you had a sustained downdraft with squared velocity averaging 270^2km/h over the surface of the blimp for any substantial length of time then the blimp would need equivalent upward propulsion to avoid _eventually_ crashing into the ground. For a sufficiently large blimp though, "eventually" can be extended as far as you'd like by reducing the acceleration induced by such forces and allowing you to average external forces over a longer time period before experiencing any negative repercussions.
- The O(1/X) acceleration property prevents a 300km/h wind from getting the blimp to speed quickly. The "entire air mass moving" doesn't change that; you'll see wind flowing around the blimp, wind becoming turbulent and reversing directions, wind losing velocity and converting to heat and sound, local portions of the blimp temporarily deforming, potential blimp damage, and all kinds of other effects from a microburst, but you won't see a high mass-to-surface-area-ratio object have its center of mass accelerate quickly from wind drag.
- The blimp _would_ need to have sufficient propulsion to counteract average wind forces over some time period. If you had a sustained downdraft with squared velocity averaging 270^2km/h over the surface of the blimp for any substantial length of time then the blimp would need equivalent upward propulsion to avoid _eventually_ crashing into the ground. For a sufficiently large blimp though, "eventually" can be extended as far as you'd like by reducing the acceleration induced by such forces and allowing you to average external forces over a longer time period before experiencing any negative repercussions.
I'd think the forces would still be formidable. But yes, assuming the airship withstands the forces, it would not be thrown around as much (specifically: the accelerations and displacements would be lower) as it gets bigger. That seems plausible to me, by your x^2/x^3 argument.
> Yes. It always has to have a much larger surface area in proportion to the weight it is carrying than any heavier than air craft, by definition.
What do you mean 'by definition'?
A heavier than air craft lifts with its surface. It has a relatively fixed surface area to weight ratio, no matter how big it gets.
A lighter than air craft lifts with its volume. The bigger you make it, the less surface area you have per weight.
What do you mean 'by definition'?
A heavier than air craft lifts with its surface. It has a relatively fixed surface area to weight ratio, no matter how big it gets.
A lighter than air craft lifts with its volume. The bigger you make it, the less surface area you have per weight.
Heavier than air craft can be denser than air, by definition, and therefore have a lower ratio of surface area to weight - and hence less drag. This allows them to go fast (potentially), and power through problematic air turbulence with minimal impact.
Lighter than air craft must (by definition), have an overall density less than the surrounding gas. This means their surface area and volume for any notable weight must always be quite large, and the corresponding influence from the surrounding air mass is always much, much higher, and their ability to fight any change in direction is always much less.
Imagine what it would take to get a blimp to go the cruising speed of an airliner, and it might make more intuitive sense.
And even those airliners avoid storms when they can.
It might not be impossible - but it would require a degree of engineering not even considered here.
Lighter than air craft must (by definition), have an overall density less than the surrounding gas. This means their surface area and volume for any notable weight must always be quite large, and the corresponding influence from the surrounding air mass is always much, much higher, and their ability to fight any change in direction is always much less.
Imagine what it would take to get a blimp to go the cruising speed of an airliner, and it might make more intuitive sense.
And even those airliners avoid storms when they can.
It might not be impossible - but it would require a degree of engineering not even considered here.
The mistake you're making is to assume the two types of craft have similar-enough shapes that you can mix up surface area and volume. But even though a heavier than air craft has a lot less volume, it doesn't have to have less surface area. Planes are pretty flat, and have a much higher ratio of surface area to volume.
A small delicate plane can weigh less than 50 grams per square meter.
Or we could look at planes designed for human-powered flight. Those are ruthlessly optimized so you know they have no more surface area than necessary, and they weigh well under a kilogram per square meter, even if you added a motor on top.
The balloons google was using to lift mini cell towers, at 50 feet wide, had about 2 cubic meters of helium per square meter of surface area. So about two kilograms of payload per square meter. And if you made it bigger you could turn that into five or ten kilograms per square meter without even trying.
Is it extremely hard for a blimp to beat an airliner, which even for a plane has a small surface area? Yes. But lots and lots of other plane designs lose to a big blimp. Some of them even lose to a small blimp. Especially slow planes. And this is only talking about reasonable plane designs.
A small delicate plane can weigh less than 50 grams per square meter.
Or we could look at planes designed for human-powered flight. Those are ruthlessly optimized so you know they have no more surface area than necessary, and they weigh well under a kilogram per square meter, even if you added a motor on top.
The balloons google was using to lift mini cell towers, at 50 feet wide, had about 2 cubic meters of helium per square meter of surface area. So about two kilograms of payload per square meter. And if you made it bigger you could turn that into five or ten kilograms per square meter without even trying.
Is it extremely hard for a blimp to beat an airliner, which even for a plane has a small surface area? Yes. But lots and lots of other plane designs lose to a big blimp. Some of them even lose to a small blimp. Especially slow planes. And this is only talking about reasonable plane designs.
Is it possible to make a heavier than air aircraft with terrible enough surface area to weight and power ratios that it will make a blimp seem easy to control in bad weather? Sure, I guess. I wasn't saying you couldn't if you read my comment - I was saying you can make a heavier than air aircraft with a LOWER surface area to weight/power, unlike lighter than air aircraft, so you can avoid being knocked around as much, have less drag, etc.
Heavier than air craft are far more versatile in general.
You can never get a lighter than air craft to an overall density higher than air by definition, and that is hugely limiting.
A 50 foot wide balloon (r=25ft), would have a surface area of 7853 square feet (729 m^2) if an ideal sphere. If you add up all of the wing and control surfaces on a 757 [https://www.b757.info/boeing-757-200-specifications/], you get 3992 square feet. Add another several thousand for the fuselage, and you're probably in the same ballpark.
The balloon you're talking about has a volume (assuming a perfect sphere, r=25ft) of 65,449 cubic feet (1853 m^3). Per [https://www.airships.net/helium-hydrogen-airships/], that seems to pencil out at around 4000 lbs of lift for helium, and 4500 lbs of lift for hydrogen (in 'real world' situations), add 20% to be closer to ideal. Or 2.5m^3 of gas per square meter of surface area. But the literal maximum amount of lifting force you can get is 1.01kg/m^3 with helium and 1.2kg/m^3 with hydrogen.
That really isn't much lift for something that big. You could scale it up, but then you're talking more surface area no? a LOT more surface area? We'll figure that out later.
Said 757 weight will vary from 130,000 lbs-255,000 lbs (empty to max takeoff weight), or 59k-72k lbs of payload if configured as a freighter. Each engine produces 36,000-43,000 lbs of thrust depending on model.
So for the 757, it is lifting (payload alone, on top of it's own weight, fuel, etc.) 3.4kg/m^2, and empty, is lifting 7.5kg/m^2. If you look at max takeoff weight, it's hitting 32kg/m^2. Way more if you care about just the airfoils of course. And to hit that takeoff, it is likely going over 200+km/h.
For a balloon to lift the same weight as the 757 at max takeoff weight, you need one with a volume of at least 114520 m^3 (for helium, ideal) or 96388 m^3 (for hydrogen, ideal), which is a minimum of r=30m for helium and r=28m for hydrogen (ideal). That is a sphere approximately 95-100ft in diameter.
That comes out to a surface area of 11309m^2 for helium and 9852m^2 for hydrogen (assuming perfect spheres, which don't happen).
That is 6.1x the surface area for helium, and 5.3x for hydrogen, assuming everything is perfect - and there is zero way you could drag that through the atmosphere or control it in any way like you can a 757 (or a Cessna, even), even if you used the same engines.
And even if you use a balloon big enough to literally lift a 757 at max takeoff weight, you're weight to surface area ratio is just hitting 10kg/m^2. 1/3 of the 757, and that means you have 3x more 'surface' to drag through the air for the same available weight (aka power/airframe) budget.
so you need to be talking multiple max-takeoff-weight-of-a-757 worth of ballon lifting capacity before you start getting in the same ballpark from a raw 'surface exposed vs weight' perspective. If we use weight as a raw proxy for power (roughly probably correct), you get the same setup.
And from a air resistance/drag perspective (what we care about here), it still isn't even all that close due to airfoil shape vs giant spheres. If you're using a blimp/zepplin shape, you're trading off airframe weight for aerodynamics, but it doesn't help as much - you end up having to spend a lot of your weight budget structuring it more like an airfoil, because the density still has to be low, so the shape has to be much bigger, and you have less budget for engines - so the heavier than air craft actually have an even bigger advantage. But even doing these very basic comparisons show it pretty clearly enough.
If you need to move through air faster than the air itself is moving, density helps - by reducing the surface area (and hence impact of these winds) and allowing you to have more engines, or a fancier airframe, or whatever. If you need to resist weather and similar forms of strong, high speed wind currents and changes, you need to be able to move through the air fast, and preferably have a strong frame.
Lighter than air craft are hindered in this by having a cap on their density, and for buildable/practical sized craft, high surface areas to weight ratios (which is a proxy for strength of airframes and available power).
Heavier than air craft are far more versatile in general.
You can never get a lighter than air craft to an overall density higher than air by definition, and that is hugely limiting.
A 50 foot wide balloon (r=25ft), would have a surface area of 7853 square feet (729 m^2) if an ideal sphere. If you add up all of the wing and control surfaces on a 757 [https://www.b757.info/boeing-757-200-specifications/], you get 3992 square feet. Add another several thousand for the fuselage, and you're probably in the same ballpark.
The balloon you're talking about has a volume (assuming a perfect sphere, r=25ft) of 65,449 cubic feet (1853 m^3). Per [https://www.airships.net/helium-hydrogen-airships/], that seems to pencil out at around 4000 lbs of lift for helium, and 4500 lbs of lift for hydrogen (in 'real world' situations), add 20% to be closer to ideal. Or 2.5m^3 of gas per square meter of surface area. But the literal maximum amount of lifting force you can get is 1.01kg/m^3 with helium and 1.2kg/m^3 with hydrogen.
That really isn't much lift for something that big. You could scale it up, but then you're talking more surface area no? a LOT more surface area? We'll figure that out later.
Said 757 weight will vary from 130,000 lbs-255,000 lbs (empty to max takeoff weight), or 59k-72k lbs of payload if configured as a freighter. Each engine produces 36,000-43,000 lbs of thrust depending on model.
So for the 757, it is lifting (payload alone, on top of it's own weight, fuel, etc.) 3.4kg/m^2, and empty, is lifting 7.5kg/m^2. If you look at max takeoff weight, it's hitting 32kg/m^2. Way more if you care about just the airfoils of course. And to hit that takeoff, it is likely going over 200+km/h.
For a balloon to lift the same weight as the 757 at max takeoff weight, you need one with a volume of at least 114520 m^3 (for helium, ideal) or 96388 m^3 (for hydrogen, ideal), which is a minimum of r=30m for helium and r=28m for hydrogen (ideal). That is a sphere approximately 95-100ft in diameter.
That comes out to a surface area of 11309m^2 for helium and 9852m^2 for hydrogen (assuming perfect spheres, which don't happen).
That is 6.1x the surface area for helium, and 5.3x for hydrogen, assuming everything is perfect - and there is zero way you could drag that through the atmosphere or control it in any way like you can a 757 (or a Cessna, even), even if you used the same engines.
And even if you use a balloon big enough to literally lift a 757 at max takeoff weight, you're weight to surface area ratio is just hitting 10kg/m^2. 1/3 of the 757, and that means you have 3x more 'surface' to drag through the air for the same available weight (aka power/airframe) budget.
so you need to be talking multiple max-takeoff-weight-of-a-757 worth of ballon lifting capacity before you start getting in the same ballpark from a raw 'surface exposed vs weight' perspective. If we use weight as a raw proxy for power (roughly probably correct), you get the same setup.
And from a air resistance/drag perspective (what we care about here), it still isn't even all that close due to airfoil shape vs giant spheres. If you're using a blimp/zepplin shape, you're trading off airframe weight for aerodynamics, but it doesn't help as much - you end up having to spend a lot of your weight budget structuring it more like an airfoil, because the density still has to be low, so the shape has to be much bigger, and you have less budget for engines - so the heavier than air craft actually have an even bigger advantage. But even doing these very basic comparisons show it pretty clearly enough.
If you need to move through air faster than the air itself is moving, density helps - by reducing the surface area (and hence impact of these winds) and allowing you to have more engines, or a fancier airframe, or whatever. If you need to resist weather and similar forms of strong, high speed wind currents and changes, you need to be able to move through the air fast, and preferably have a strong frame.
Lighter than air craft are hindered in this by having a cap on their density, and for buildable/practical sized craft, high surface areas to weight ratios (which is a proxy for strength of airframes and available power).
> I was saying you can make a heavier than air aircraft with a LOWER surface area to weight/power, unlike lighter than air aircraft, so you can avoid being knocked around as much, have less drag, etc.
You didn't say that you "can" make a heavier than air craft with a better ratio. You said that "by definition" lighter than air craft will have a worse ratio than any heavier than air craft. That's a very different statement! (And I'm being fair, I'm interpreting "any" as "any reasonable".)
> You can never get a lighter than air craft to an overall density higher than air by definition, and that is hugely limiting.
That's true, but the statement I objected to was that weight:surface-area is worse by definition, not any statement about volume.
> 757 stuff
The problem with that chain of logic is that you're starting with some of the best planes around for surface area vs. weight, and then trying to make a blimp that beats them.
Of course that's super hard to do!
But if you take a slow ultralight plane instead, you'll see that it's not very hard to beat with a blimp. The kind of plane that cruises at 35mph and not 500mph.
The truth isn't that [reasonable] planes automatically beat [reasonable] blimps. It's that planes similar to a 757 beat reasonable blimps. That's a much weaker statement.
There are lots of reasonable plane designs that might only hit 5kg/m^2, and it's easy to make a blimp that beats that. Or the 10kg/m^2 in your math, that's not something that takes unreasonable materials to reach in a blimp.
-
tl;dr: If you demand a blimp beat 30kg/m^2, it probably won't happen. But in the 2-10kg/m^2 range, sometimes planes beat blimps and sometimes blimps beat planes, using reasonable designs for both. "[an airship] always has to have a much larger surface area in proportion to the weight it is carrying than any heavier than air craft, by definition." is a false statement.
You didn't say that you "can" make a heavier than air craft with a better ratio. You said that "by definition" lighter than air craft will have a worse ratio than any heavier than air craft. That's a very different statement! (And I'm being fair, I'm interpreting "any" as "any reasonable".)
> You can never get a lighter than air craft to an overall density higher than air by definition, and that is hugely limiting.
That's true, but the statement I objected to was that weight:surface-area is worse by definition, not any statement about volume.
> 757 stuff
The problem with that chain of logic is that you're starting with some of the best planes around for surface area vs. weight, and then trying to make a blimp that beats them.
Of course that's super hard to do!
But if you take a slow ultralight plane instead, you'll see that it's not very hard to beat with a blimp. The kind of plane that cruises at 35mph and not 500mph.
The truth isn't that [reasonable] planes automatically beat [reasonable] blimps. It's that planes similar to a 757 beat reasonable blimps. That's a much weaker statement.
There are lots of reasonable plane designs that might only hit 5kg/m^2, and it's easy to make a blimp that beats that. Or the 10kg/m^2 in your math, that's not something that takes unreasonable materials to reach in a blimp.
-
tl;dr: If you demand a blimp beat 30kg/m^2, it probably won't happen. But in the 2-10kg/m^2 range, sometimes planes beat blimps and sometimes blimps beat planes, using reasonable designs for both. "[an airship] always has to have a much larger surface area in proportion to the weight it is carrying than any heavier than air craft, by definition." is a false statement.
A factor I forgot to mention - heavier than air craft, because of their better surface area to weight ratio (ability to be more dense) can pack in more engines for a given amount of surface area - and go faster, and produce more lift per unit of surface area, due to the reduced drag.
So heavier than air craft do NOT have a fixed surface area to weight ratio, they have a surface area/airfoil to power ratio, which can vary widely depending on the effectiveness of the engine.
So heavier than air craft do NOT have a fixed surface area to weight ratio, they have a surface area/airfoil to power ratio, which can vary widely depending on the effectiveness of the engine.
Cargo mass adds to structural stresses, and subtracts from mass available for increased strength and resilience.
>Is that true even if it has a large mass from cargo?
Nope. It's just plain false.
To wit:
During its career, Graf Zeppelin had flown almost 1.7 million km (1,053,391 miles), the first aircraft to fly over a million miles. It made 144 oceanic crossings (143 across the Atlantic, and one of the Pacific), carried 13,110 passengers and 106,700 kg (235,300 lb) of mail and freight. It flew for 17,177 hours (717 days, or nearly two years), without injuring a passenger or crewman.
It never crashed, and was retired at the dawn of WWII.
The huge airships get a bad rep because the only country which could successfully build and operate them was Nazi Germany.
As for dirigibles operated by the US, the UK, and the USSR... yup, none of them actually worked.
Doesn't say anything about the vehicle type.
Nope. It's just plain false.
To wit:
During its career, Graf Zeppelin had flown almost 1.7 million km (1,053,391 miles), the first aircraft to fly over a million miles. It made 144 oceanic crossings (143 across the Atlantic, and one of the Pacific), carried 13,110 passengers and 106,700 kg (235,300 lb) of mail and freight. It flew for 17,177 hours (717 days, or nearly two years), without injuring a passenger or crewman.
It never crashed, and was retired at the dawn of WWII.
The huge airships get a bad rep because the only country which could successfully build and operate them was Nazi Germany.
As for dirigibles operated by the US, the UK, and the USSR... yup, none of them actually worked.
Doesn't say anything about the vehicle type.
Even the old Zeppelin airships never had a major issue with strong winds - and these days we have satellites and aircraf-based weather radar.
Storms are no danger for airships.
Storms are no danger for airships.
That's not how I remember it from https://en.wikipedia.org/wiki/Slide_Rule:_Autobiography_of_a... though yes we have much better weather forecasting now.
You mean, the book that wasn't about a Zeppelin? As in, an aircraft made by the Zeppelin corporation.
The British never learned how to make dirigibles[1], the Americans never learned how to operate them; all non-German airship projects were failures.
That's why Zeppelin became synonymous with "rigid dirigible airship". Because all other projects failed.
[1] R100 was a good design... but it was scrapped because of politics, and never entered service.
The British never learned how to make dirigibles[1], the Americans never learned how to operate them; all non-German airship projects were failures.
That's why Zeppelin became synonymous with "rigid dirigible airship". Because all other projects failed.
[1] R100 was a good design... but it was scrapped because of politics, and never entered service.
If you look up the ship dispositions several were torn from their moorings and wrecked in storms. And several crashed in thunderstorms.
>Airships just don't work in strong winds
Citation needed, my friend.
Reality check: do you think that the airships which regularly crossed the Atlantic ocean never experienced strong winds? Perhaps a trip to an ocean beach is in order, eh?
Citation needed, my friend.
Reality check: do you think that the airships which regularly crossed the Atlantic ocean never experienced strong winds? Perhaps a trip to an ocean beach is in order, eh?
Crashes of the UK R-101 (48 souls), and US Navy ZR-2 (44 souls), Macon (2 souls), Akron (73 souls), and Shenandoah (14 souls).
Winds and/or handling failures affected all of these airships.
https://en.wikipedia.org/wiki/R38-class_airship
https://en.wikipedia.org/wiki/USS_Macon_(ZRS-5)
https://en.wikipedia.org/wiki/USS_Akron
https://en.wikipedia.org/wiki/USS_Shenandoah_(ZR-1)
https://en.wikipedia.org/wiki/R101
Winds and/or handling failures affected all of these airships.
https://en.wikipedia.org/wiki/R38-class_airship
https://en.wikipedia.org/wiki/USS_Macon_(ZRS-5)
https://en.wikipedia.org/wiki/USS_Akron
https://en.wikipedia.org/wiki/USS_Shenandoah_(ZR-1)
https://en.wikipedia.org/wiki/R101
You might notice that none of them actually crossed the Atlantic, because nobody except Germans knew how to build and operate airships.
None of the airships in your list were Zeppelins. None were ever providing passenger service.
Again, just examine the track record of Zeppelins, and compare it to the track record of contemporary aircraft safety-wise.
None of the airships in your list were Zeppelins. None were ever providing passenger service.
Again, just examine the track record of Zeppelins, and compare it to the track record of contemporary aircraft safety-wise.
The ZR-2 was in fact a Zeppelin, the Macon and Akron were built by the Goodyear-Zeppelin corporation, a joint venture. The Shennendoah (ZR-1) was based on a Zeppelin design (ZL-49) though built in and by the US.
Only the R-101 and R-38 were entirely independent designs (both UK).
The R-101 was specifically designed for passenger service, and was conducting a demonstration voyage when she crashed with major loss of life. The only reason it didn't enter commercial service was because it didn't survive long enough to do so.
Another British airship, R-100, flew from Britain to Canada.
Airships were built and operated by Germany, the UK, the US, French, Hugarian-Croatians, Brazil, and others.
The Macon, Akron, and Shennendoah were all lost at sea or over water.
There's nothing inherent to nationality, corporate ownership, military vs. civilian use, or passenger travel which changes the laws of physics under which airships operate. The craft are inherently vulnerable, slow, low, and dangerous.
Modern widebody jet aircraft have the highest safety record by passenger-mile travelled of any transportation mode. There are more people aloft at any moment of the day than airships carried in any year of commercial operation.
https://www.travelandleisure.com/airlines-airports/number-of...
Every claim of your comment proves false. A solid record.
Only the R-101 and R-38 were entirely independent designs (both UK).
The R-101 was specifically designed for passenger service, and was conducting a demonstration voyage when she crashed with major loss of life. The only reason it didn't enter commercial service was because it didn't survive long enough to do so.
Another British airship, R-100, flew from Britain to Canada.
Airships were built and operated by Germany, the UK, the US, French, Hugarian-Croatians, Brazil, and others.
The Macon, Akron, and Shennendoah were all lost at sea or over water.
There's nothing inherent to nationality, corporate ownership, military vs. civilian use, or passenger travel which changes the laws of physics under which airships operate. The craft are inherently vulnerable, slow, low, and dangerous.
Modern widebody jet aircraft have the highest safety record by passenger-mile travelled of any transportation mode. There are more people aloft at any moment of the day than airships carried in any year of commercial operation.
https://www.travelandleisure.com/airlines-airports/number-of...
Every claim of your comment proves false. A solid record.
You said a lot of words, and none answered my original question, which was concerning airships on regular trans-Atlantic service.
Again, your list has 0 of those.
My point is that those airships existed; and weather was not a problem for them. That's a counterexample to the claim that inclement issue is necessarily an issue for airships.
The fact that neither the Brits nor Americans could build and operate airships successfully is irrelevant.
Also, you should look up the definition of the word "contemporary". I am obviously not comparing 1920s airships to 2020s jet planes.
Here is a simple claim: airships were the safest way to cross the Atlantic by air during the entire time of their operation.
No other aircraft type even made it across the Atlantic on a regular basis.
Meanwhile, Between 1931 and 1937 the Graf Zeppelin crossed the South Atlantic 136 times.
During its career, Graf Zeppelin had flown almost 1.7 million km (1,053,391 miles), the first aircraft to fly over a million miles. It made 144 oceanic crossings (143 across the Atlantic, and one of the Pacific), carried 13,110 passengers and 106,700 kg (235,300 lb) of mail and freight. It flew for 17,177 hours (717 days, or nearly two years), without injuring a passenger or crewman.
It was retired after the Hindenburg disaster. Notably, Hindenburg has crossed the Atlantic 36 times in passenger service - which is still 36 more than what the airplanes could do. And its destruction 1)had little to do with winds, and 2)was not nearly as deadly as the disintegrations of early jet airliners, like DH Comet, with 100% fatality rate, repeatedly.
OK, tell me again how "airships just don't work in strong winds", I'll listen.
Again, your list has 0 of those.
My point is that those airships existed; and weather was not a problem for them. That's a counterexample to the claim that inclement issue is necessarily an issue for airships.
The fact that neither the Brits nor Americans could build and operate airships successfully is irrelevant.
Also, you should look up the definition of the word "contemporary". I am obviously not comparing 1920s airships to 2020s jet planes.
Here is a simple claim: airships were the safest way to cross the Atlantic by air during the entire time of their operation.
No other aircraft type even made it across the Atlantic on a regular basis.
Meanwhile, Between 1931 and 1937 the Graf Zeppelin crossed the South Atlantic 136 times.
During its career, Graf Zeppelin had flown almost 1.7 million km (1,053,391 miles), the first aircraft to fly over a million miles. It made 144 oceanic crossings (143 across the Atlantic, and one of the Pacific), carried 13,110 passengers and 106,700 kg (235,300 lb) of mail and freight. It flew for 17,177 hours (717 days, or nearly two years), without injuring a passenger or crewman.
It was retired after the Hindenburg disaster. Notably, Hindenburg has crossed the Atlantic 36 times in passenger service - which is still 36 more than what the airplanes could do. And its destruction 1)had little to do with winds, and 2)was not nearly as deadly as the disintegrations of early jet airliners, like DH Comet, with 100% fatality rate, repeatedly.
OK, tell me again how "airships just don't work in strong winds", I'll listen.
I was addressing "Airships just don't work in strong winds".
You subsequently shifted the goalposts.
There was no transatlantic passenger airplane travel until 1939. Two years after Hindenberg disaster. The comparison ... is largely pointless. Though given the lack of heavier-than-air transatlantic commercial passenger flight, and as a consequence, no heavier-than-air commercial passenger fatalities, if you insist on the comparison, airships still lose.
https://www.panam.org/explorations/681-1st-transatlantic-pas...
Passenger liner sea-based travel remained the principle mode of transatlantic crossing until the 1960s, with passenger air travel only becoming significant with the introduction of jet powered aircraft in the 1950s (and late 1950s at that).
You seem bent on insisting you're correct at the cost of denying all contradictory evidence. You fail to even acknowledge the points. Even where you have relevant points, they're lost due to that bias. That's strongly disengenuous, impugns credibility, is a bad look, and is quite frankly exceedingly tedious.
I'm done.
You subsequently shifted the goalposts.
There was no transatlantic passenger airplane travel until 1939. Two years after Hindenberg disaster. The comparison ... is largely pointless. Though given the lack of heavier-than-air transatlantic commercial passenger flight, and as a consequence, no heavier-than-air commercial passenger fatalities, if you insist on the comparison, airships still lose.
https://www.panam.org/explorations/681-1st-transatlantic-pas...
Passenger liner sea-based travel remained the principle mode of transatlantic crossing until the 1960s, with passenger air travel only becoming significant with the introduction of jet powered aircraft in the 1950s (and late 1950s at that).
You seem bent on insisting you're correct at the cost of denying all contradictory evidence. You fail to even acknowledge the points. Even where you have relevant points, they're lost due to that bias. That's strongly disengenuous, impugns credibility, is a bad look, and is quite frankly exceedingly tedious.
I'm done.
I suspect airships are much more vulnerable to bad weather than most other forms of transport.
Well certainly that's an edge case. I don't know anything, honestly, but seems to me TFA is talking about wholesale distributor type cargo, not pizza deliveries. I guess waiting a day for a storm to pass doesn't kill anything, and airships can actually loiter in that time.
I'm trying to think of a (non aquatic) case where rail is worse than airships though. If we were to invest in thousands of vehicles for distributing machinery, I'm guessing the average joe like me would vote rail. Unless we're talking going to a place where the infrastructure isn't good enough to support traditional delivery.
For setting up a base in Greenland or the antarctic, I bet airships are really attractive. Or delivering bulk cargo to hawaii, perhaps.
I'm trying to think of a (non aquatic) case where rail is worse than airships though. If we were to invest in thousands of vehicles for distributing machinery, I'm guessing the average joe like me would vote rail. Unless we're talking going to a place where the infrastructure isn't good enough to support traditional delivery.
For setting up a base in Greenland or the antarctic, I bet airships are really attractive. Or delivering bulk cargo to hawaii, perhaps.
> I'm trying to think of a case where rail is worse than airships though
You can ship non-standard cargo via air easier than rail if its wide. Eg. Moving a wide machinery, or parts to large construction project.
You can ship non-standard cargo via air easier than rail if its wide. Eg. Moving a wide machinery, or parts to large construction project.
Airships are better than trains at crossing the sea
Sure, I was thinking any nation that wants to move cargo over the sea would use ships.
So what conditions other than unestablished areas make airships better than sea ships?
So what conditions other than unestablished areas make airships better than sea ships?
Speed
A cargo airship is slower than a freight jet and only a few times faster than a cargo ship.
Even the relatively "small" PANAMAX container ships can carry 5000TEU. If you had an airship that could carry 50TEU (I'm being extremely generous there) you'd need 100 trips (200 total ocean crossings crossings) to equal a single smaller sized container ship.
If your airships are only four times faster than container ships you'll need 50 of them to carry the same amount of freight as that single ship.
If 20 days is too long a wait air freight (heavier than air) already exists. It also deals with weather by simply flying over it. So you'd need some sort of cargo that was too time sensitive for sea freight but not so sensitive or valuable enough for traditional air freight. But it couldn't be too sensitive or valuable because airships are very sensitive to weather, wind especially, so can only really operate in very clear weather with low winds at departure and arrival.
Even the relatively "small" PANAMAX container ships can carry 5000TEU. If you had an airship that could carry 50TEU (I'm being extremely generous there) you'd need 100 trips (200 total ocean crossings crossings) to equal a single smaller sized container ship.
If your airships are only four times faster than container ships you'll need 50 of them to carry the same amount of freight as that single ship.
If 20 days is too long a wait air freight (heavier than air) already exists. It also deals with weather by simply flying over it. So you'd need some sort of cargo that was too time sensitive for sea freight but not so sensitive or valuable enough for traditional air freight. But it couldn't be too sensitive or valuable because airships are very sensitive to weather, wind especially, so can only really operate in very clear weather with low winds at departure and arrival.
One downside of rail is that new routes seem to always be decade long, multi-billion dollar projects.
If only we had a way to monitor the weather patterns in the entire globe and maybe even predict them...
I’ve been thinking they are a good idea to help with overloaded ports, as they can pick up cargo cans and move them without any of the current bottlenecks.
-The airship would likely be the bottleneck; a 40ft shipping container may weigh anything up to approx. 30 metric tons.
You wouldn't be able to put many of those under an airship, hence you'd need a lot of rather space-hogging airships.
You wouldn't be able to put many of those under an airship, hence you'd need a lot of rather space-hogging airships.
But there are ships moored waiting for their turn for the cranes to unload.
If you have swarms of these unloading, a few cans, it helps right?
I’m sure it would be very handy for edge cases where only a few cans need to be offloaded at a specific port.
You can also setup secondary drop off zones that avoid bottlenecks, like straight transfers from ship to train.
If you have swarms of these unloading, a few cans, it helps right?
I’m sure it would be very handy for edge cases where only a few cans need to be offloaded at a specific port.
You can also setup secondary drop off zones that avoid bottlenecks, like straight transfers from ship to train.
Unlikely to help given how big and slow they are. These cargo ships carry thousands of containers.
Airships would probably be much fast than cargo ships though. Ships cut through the water at like maybe 30 mph in good conditions. Airships could easily keep as they are dealing with so much less drag. In the 1930 they moved at like 70 mph aka 2x the speed of container ships. I mean there cargo space would be like 1/40 but with the difference in speed thats only 1/20 in the rate of moving cargo not to mention that you aren't bound by water which is the major issue with ports. They are just very congested and ships are stuck in ship lanes. The air is much more limitless in terms of shipping paths.
> Ships cut through the water at like maybe 30 mph in good conditions.
Container ships rarely if ever go that fast. Usually it’s in the 15-18 knots range (aka <20mph) from what I’ve seen.
Container ships rarely if ever go that fast. Usually it’s in the 15-18 knots range (aka <20mph) from what I’ve seen.
-It would help; the question is more whether it would be worth it in the grand scheme of things; seeing as the weight differential between air and hydrogen is approximately 1.15kg/cubic meter at sea level, ignoring any weight in the airship itself, you're going to have to displace on the order of 25,000 cubic meters of air to lift one 20/40ft container (the max gross weight is only a couple of tons larger in a 40ft than in a 20ft unit).
This volume of hydrogen is a cube with 30m sides. For one container. Neglecting the weight of the ship itself.
The big container ships can carry upwards of 20,000 20ft units - so you're going to need a lot of airships (which will require a lot of airspace) to make an appreciable dent in the cargo unloading time.
(The main issue really being that container ships are absurdly large!)
This volume of hydrogen is a cube with 30m sides. For one container. Neglecting the weight of the ship itself.
The big container ships can carry upwards of 20,000 20ft units - so you're going to need a lot of airships (which will require a lot of airspace) to make an appreciable dent in the cargo unloading time.
(The main issue really being that container ships are absurdly large!)
> This volume of hydrogen is a cube with 30m sides. For one container
This is actually smaller than i was imagining.
This is actually smaller than i was imagining.
FWIW, the article contemplates cargo airships with a million m^3, which would carry around 40 containers. That would be a cube with 100m sides, and you'd need 500 of those to replace one big container ship.
Seems not a realistic option to replace container ships, but might be realistic for specific use cases.
Seems not a realistic option to replace container ships, but might be realistic for specific use cases.
So like to move a shipping container weighing 40 tons requires what 32x32x32 cubic meter space to be supported that's pretty tiny considering the other advantages. They could travel fast and in basically all weather. Lightening is a worry but if you isolate your hydrogen well it shouldn't be a problem. Not to mention they would be much more fuel efficient. Heck you could probably slap solar on them and get net zero energy discharge for low container ship speeds. The only issue being is I don't know if they would alleviate unloading issues if there was high winds. I don't really know the method for securing an airship but if they just let down a big rope and tie themselves done you can do that anywhere.
You can’t use an airship in anything much stronger than a stiff breeze - and major air currents and the like are a problem on any trip of significant length. There is a reason the zeppelins fell out of favor, and it was because their safe operational envelope was pretty small - once you looked at real long term safety record.
The US Navy ran many of them for awhile and they stopped because they crashed so often.
Theoretically they are safe. In reality, they aren’t outside of very controlled circumstances
The US Navy ran many of them for awhile and they stopped because they crashed so often.
Theoretically they are safe. In reality, they aren’t outside of very controlled circumstances
The relevant question is not: “Could airships move full shipping containers?” but rather: “Could airships find
an economic niche and turn a profit in that niche?” Perhaps
they move cargo in lighter containers (fiberglass, aluminum, etc.), or in moving high-volume low-mass cargoes like prefabricated cylindrical tanks, or wind turbine blades. Perhaps they specialize by replacing “ice road” transport to tundra or arctic locations. Or to jungle locations - mining or drilling operations. Maybe they replace sky-crane helicopters rather than replacing barges, container ships, trains, or trucks. We have mostly replaced sailing ships,
canal narrow boats, stagecoaches, and the pony express.
Nothing is forever. We’ll know that H2 airships have really
arrived when they are mentioned in country music.
-Also, much slower and lower cargo capacity.
That being said, I can see them being used where roads are sparse, inland (so shipping is not an option) and far away from the nearest railroad.
We definitely need more green-tinged options; I root for airships!
That being said, I can see them being used where roads are sparse, inland (so shipping is not an option) and far away from the nearest railroad.
We definitely need more green-tinged options; I root for airships!
They could conceivably be very cheap if the gas pockets were mass produced. Everything else on board for propulsion and housing the pilot would be on the scale of a small prop aircraft. As long as the cargo can be easily managed, perhaps in a shipping container, then these would be easy to deploy en masse. They can land in any suitable field that has a crew on hand to guide them in with ropes. You might not even need pilots since these would be perfect targets for automation.
As for speed, you can optimize the shape of the aircraft and the position of the propeller for this. I've seen a number of videos that show surprisingly good performance for pointier fuselage with a pusher prop on the tail.
As for speed, you can optimize the shape of the aircraft and the position of the propeller for this. I've seen a number of videos that show surprisingly good performance for pointier fuselage with a pusher prop on the tail.
> Everything else on board for propulsion and housing the pilot would be on the scale of a small prop aircraft
It's likely that any cargo airship would fly for days/weeks at a time and would require at least 4 crew-members and everything they would need for the length of the voyage. So less a small prop and more something akin to facilities available on a yacht/Large RV.
> You might not even need pilots since these would be perfect targets for automation.
This would perhaps be the best solution
It's likely that any cargo airship would fly for days/weeks at a time and would require at least 4 crew-members and everything they would need for the length of the voyage. So less a small prop and more something akin to facilities available on a yacht/Large RV.
> You might not even need pilots since these would be perfect targets for automation.
This would perhaps be the best solution
Why would it need crew? What would they do?
A cargo airship drone remotely controlled would get rid of most of the non-cargo mass requirements.
A cargo airship drone remotely controlled would get rid of most of the non-cargo mass requirements.
Not necessarily slower than cargo ships, and possibly significantly faster. This paper claims that by using the jet streams a hydrogen blimp could circumnavigate the globe in about 14-16 days [1]. Google gives about 77 days to do the same on cargo ship. Of course there would be lots of details to consider on the exact route taken, but from first principles it seems plausible.
1: https://www.sciencedirect.com/science/article/pii/S259017451... 2: https://arimotravels.com/how-long-does-it-take-a-cargo-ship-...
1: https://www.sciencedirect.com/science/article/pii/S259017451... 2: https://arimotravels.com/how-long-does-it-take-a-cargo-ship-...
You're forgetting train (completely viable for China -> Europe), and the times where train isn't viable, a direct shipping express can be as efficient as allowing. What you quote with regards to 77 days is around the world but that isn't interesting for transport (that's interesting for leisure of just for the sheer competing; not transportation business).
What is interesting is the amount of time from large industrial ports such as say Singapore or New York to Rotterdam or Hamburg or Antwerp, the associated costs, and the risk of losing the transport (and its contents).
Either way, the last mile is the inefficiency with regards to carbon footprint. Ie. the transportation ship (and more so train) is relatively efficient; the last mile of the minivan delivering the one packet to you is the one which has the largest (relative) carbon footprint. To solve that, we need to invest in electric vehicles.
What is interesting is the amount of time from large industrial ports such as say Singapore or New York to Rotterdam or Hamburg or Antwerp, the associated costs, and the risk of losing the transport (and its contents).
Either way, the last mile is the inefficiency with regards to carbon footprint. Ie. the transportation ship (and more so train) is relatively efficient; the last mile of the minivan delivering the one packet to you is the one which has the largest (relative) carbon footprint. To solve that, we need to invest in electric vehicles.
Train needs a massive upfront infrastructure investment, and isn't flexible for route when passing through politically unstable areas. China -> Europe needs to cross through at some point. Similarly, Africa -> Europe by train needs to cross in a politically unstable area. Being able to choose your route is very valuable.
The infrastructure for trains is already there (China -> Europe), its just static and therefore inflexible. It isn't going through politically unstable areas, just Russia. As long as you don't bet on one horse you're going to be fine. I don't know anything about trains from Africa to Europe. I believe China exports more than Africa.
Since we don't talk about last mile, they're competing with ship and airplane. For last mile, there's only the minivan/truck solution, though I'm not sure how widely adopted or sustainable drone delivery is as of now. A low carbon footprint of drone delivery would be a plus for adopting it long term.
Since we don't talk about last mile, they're competing with ship and airplane. For last mile, there's only the minivan/truck solution, though I'm not sure how widely adopted or sustainable drone delivery is as of now. A low carbon footprint of drone delivery would be a plus for adopting it long term.
A blimp still needs to cross those areas, and could be shot down
I haven’t clicked the links to see if it’s mentioned because mobile, but it should be more than plausible - it was done 80 years ago; the Graf Zeppelin hydrogen lift airship did a round the world flight in five stages in about 15 days total flight time in 1929:
https://www.airships.net/blog/graf-zeppelin-round-the-world-...
(And it was the first air vehicle to pass 1,000,000 miles travelled, with no accidents, the first to reach the North Pole, the first regular transatlantic commercial flights, etc. all with 1920s technology and tens of thousands of hand-glued animal intestines for the lift bags)
https://www.airships.net/blog/graf-zeppelin-round-the-world-...
(And it was the first air vehicle to pass 1,000,000 miles travelled, with no accidents, the first to reach the North Pole, the first regular transatlantic commercial flights, etc. all with 1920s technology and tens of thousands of hand-glued animal intestines for the lift bags)
The OP article suggests airships would be on par with conventional shipping freight for time. But in terms of capacity it makes an excellent point:
> Cargo airships would need to be big—bigger than the Hindenburg. Airships are blessed and cursed with a square-cube law: the drag of the airship, which is proportional to its cross-sectional area, scales with length squared, but the volume of lifting gas, and thus the gross lift, scales with length to the third power. Therefore, the lift-to-drag ratio, a critical parameter in aircraft performance, gets better as the airship gets bigger.
> Cargo airships would need to be big—bigger than the Hindenburg. Airships are blessed and cursed with a square-cube law: the drag of the airship, which is proportional to its cross-sectional area, scales with length squared, but the volume of lifting gas, and thus the gross lift, scales with length to the third power. Therefore, the lift-to-drag ratio, a critical parameter in aircraft performance, gets better as the airship gets bigger.
Shouldn't it scale linearly with length?
It's basically a cylinder, who's volume is heightPiradius^2.
Unless you're also making it wider and taller, it's not a cubed growth
It's basically a cylinder, who's volume is heightPiradius^2.
Unless you're also making it wider and taller, it's not a cubed growth
The way I read it, is that drag increases ^2 for length, but because volume increases lift for airships (as opposed to other aircraft) you get this ^3 increase in lift by increasing length. So airship economy increases with size, as opposed to an airplane.
For the square-cube law, a cursory wiki search yields:
> The square–cube law can be stated as follows:
> When an object undergoes a proportional increase in size, its new surface area is proportional to the square of the multiplier and its new volume is proportional to the cube of the multiplier.
https://en.wikipedia.org/wiki/Square%E2%80%93cube_law
For the square-cube law, a cursory wiki search yields:
> The square–cube law can be stated as follows:
> When an object undergoes a proportional increase in size, its new surface area is proportional to the square of the multiplier and its new volume is proportional to the cube of the multiplier.
https://en.wikipedia.org/wiki/Square%E2%80%93cube_law
> -Also, much slower and lower cargo capacity.
I've always found airships and lifting gasses fascinating, but I'm not fully educated on this point. I thought that airships could potentially have very large cargo capacity, especially because larger airships increase aerial stability. Speeds would be slow, but I thought it was feasible to ship huge payloads, no?
I've always found airships and lifting gasses fascinating, but I'm not fully educated on this point. I thought that airships could potentially have very large cargo capacity, especially because larger airships increase aerial stability. Speeds would be slow, but I thought it was feasible to ship huge payloads, no?
-I know next to nothing of airships, but I believe your problem would be controlled flight; a huge airship has huge drag and once winds pick up, you'll soon run out of engine power to counter that drag - and all of a sudden you find yourself going the way the wind blows, which may or may not be where you intended to go...
(Presumably that same drag will cause problems for the structural integrity of the airship, too.)
(Presumably that same drag will cause problems for the structural integrity of the airship, too.)
I suppose winds will be the major problem for very big airships, but I believe there are lots of ways to deal with it. Using the wind in sailing is a known art. There could be technics to counter that? Or cruise along the wind and take a slightly different route. Or in general, probably you will have to take the winds into account a lot more, when planning blimps routes. And the winds are also different at different altitude.
And above a certain height, >10000 m, it is usually much calmer, but I think ordinary blimps cannot go that high. Different outside pressure etc. Possible to mitigate with adjusting the amount of hydrogen by compressing/releasing?
And above a certain height, >10000 m, it is usually much calmer, but I think ordinary blimps cannot go that high. Different outside pressure etc. Possible to mitigate with adjusting the amount of hydrogen by compressing/releasing?
Especially for oversize or awkwardly shaped items.
Source needed! Airships are quite inefficient, have high air drag and are slow.
They are more comparable to ships, trains or cars. And here their inefficiency is very bad.
They are more comparable to ships, trains or cars. And here their inefficiency is very bad.
With a huge balloon and flexible solar panels + fuel cell (they've already got to carry H2) they could be nearly zero.
Except they don’t compete with planes, but with water ships.
Except not really, as it's quite difficult to float a barge across a continent.
In that case, they're competing with trains.
Trains need tracks, barges need rivers, trucks need roads.
A cargo airship needs a clear field, and probably some really good tie-downs -- dropping off one or five thousand kilograms of cargo will produce a major lift imbalance.
A cargo airship needs a clear field, and probably some really good tie-downs -- dropping off one or five thousand kilograms of cargo will produce a major lift imbalance.
Curiously enough, virtually everywhere with any significant human activity exists ... near ports, roads, rivers, or rail.
Roads or tracks can be quickly laid through wilderness if necessary (provided the natives are friendly).
If you're dealing with frozen terrain, ice roads can be used.
There are some exceptions to this. They are extreme outliers, both figuratively and geographically.
Roads or tracks can be quickly laid through wilderness if necessary (provided the natives are friendly).
If you're dealing with frozen terrain, ice roads can be used.
There are some exceptions to this. They are extreme outliers, both figuratively and geographically.
Yeah, ballasting is often forgotten when people talks about huge cargo airships.
Yes, it can drop a huge generator into the middle of nowhere for your construction project, but unless you do something it will then shoot up to the stratosphere due to all the extra lift.
Still, its solvable with either some rudimentary infrastructure (pump water aboard as you unload cargo) or by removing some of the lifting gas (much less of an issue with hydrogen).
Yes, it can drop a huge generator into the middle of nowhere for your construction project, but unless you do something it will then shoot up to the stratosphere due to all the extra lift.
Still, its solvable with either some rudimentary infrastructure (pump water aboard as you unload cargo) or by removing some of the lifting gas (much less of an issue with hydrogen).
Don't you just need to compress some of your lifting gas? Just pump/compress it into a tank, reverse it when you need the lift?
There is (was?) an effort to restart Airships for cargo traffic. They solved the ballast issue with onboard compressors. If understood it correctly that solved this problem complete with [effectively?] no loss of lift gas.
Interesting! Setting the weight of the compressors and the energy requirements (I guess you could supply that ground side if possible) it really does solve the issue of loosing helium. :)
For hydrogen you I guess you could either let it go or also use the compressors in case there is no way to replenish the lifting gas & you might need the extra lift before returning to your primary maintenance base.
For hydrogen you I guess you could either let it go or also use the compressors in case there is no way to replenish the lifting gas & you might need the extra lift before returning to your primary maintenance base.
Right but now you're consuming energy to run those compressors, making the energy-savings moot. If you look at the history of airship development (which admittedly is ancient by modern technological standards), there were several incidents of airships floating away from their mooring. Mooring an airship is actually a fairly difficult problem.
Energy usage for compression is tiny compared to actually transiting, and you can get some of the energy back. Or if it was hydrogen fueled, just run your engines for a short time.
Or, just have the compressor ready at the dock, and wait with the unloading until the hydrogen has been compressed.
But yeah, simply running a compressor powered by hydrogen should suffice. I assume the airships would require some surplus hydrogen anyway, in case there's a mid-flight leak or something.
But yeah, simply running a compressor powered by hydrogen should suffice. I assume the airships would require some surplus hydrogen anyway, in case there's a mid-flight leak or something.
Fair enough you're probably right. And if you have a battery onboard and charge it using solar cells on the ship, you should have enough energy generated to at least run the compressor and dock the ship.
This might be slow, but what about using the lift gas in a fuel cell with atmospheric O2 for extra efficiency? You reduce the lift gas in the bags, and if you store the water aboard then you get extra ballast. You could even “unload” the extra electricity for use groundside.
The corollary pipe dream here is to line the entire interior of the envelope as a fuel cell membrane and use the airship as a portable battery.
The corollary pipe dream here is to line the entire interior of the envelope as a fuel cell membrane and use the airship as a portable battery.
Cover the whole outside of the blimp in solar panel foil? I do not see energy as the problem.
This is only really an issue with Helium. When Hydrogen is your lifting gas, you can use it with fuel cells to power the cranes, producing water as a further ballast.
In the hypothetical hydrogen powered future, cargo Zeppelins could pull double-duty as a hydrogen tanker.
In the case of hauling gensets around, that would basically make it a fully self-contained power plant.
In the case of hauling gensets around, that would basically make it a fully self-contained power plant.
The NIMBYs would never allow a hydrogen fuelled airship anywhere near anywhere.
Also confidence of calm weather until it reaches the next field, no? I'm not sure how strict a constraint that'll be.
They make a lot of sense in the north (northern Canada and Siberia) where roads and railway are not economical or not possible because of permafrost.
Western Europe uses its rivers and hundreds of thousands of km of canals to ship between a quarter and a half of its freight this way. It's the most economical and environmentally friendly form of transport. Youre right that this sort of infrastructure does not come cheap, which is why hydrogen dirigibles are very interesting.
That's nice in Europe, great that it has that system. But that doesn't work in North America (east to west navigation across continent impossible by barge), Asia, Africa or South America.
May I introduce you to the emergent advanced experimental technologies of the shipping canal and river barge?
> Too slow for transportation, maybe. But leisure travel? Imagine a one week air safari over the Serengeti, Ngoro Ngoro crater, and Kruger Park. It could be awesome.
Well, if we're talking about weird Sci-Fi ideas (that might be possible), lets just go all in on it.
Rocket launches are extremely expensive, and most of it is in the lifting costs. Would it be cheaper to "lift" a rocket with hydrogen slowly?
Yeah, we also need to get enough kinetic energy to enter orbit. But surely getting rid of a huge chunk of "Gravity" costs could lead to substantial rocket-fuel savings?
Well, if we're talking about weird Sci-Fi ideas (that might be possible), lets just go all in on it.
Rocket launches are extremely expensive, and most of it is in the lifting costs. Would it be cheaper to "lift" a rocket with hydrogen slowly?
Yeah, we also need to get enough kinetic energy to enter orbit. But surely getting rid of a huge chunk of "Gravity" costs could lead to substantial rocket-fuel savings?
I can't find it now, but there was previous discussion on HN, about the amount of atmospheric drag a balloon-launched rocket would save as not being worthwhile. Most of the orbital velocity is spent going horizontally, the vertical part is <20% of even the most aggressive orbital trajectory, and the drag is virtually nil past 150K feet. And the delta-v needed to reach orbit is some very high percent of the total fuel and thrust.
Basically balloon launches would only benefit small sub-orbital sounding type rockets.
Basically balloon launches would only benefit small sub-orbital sounding type rockets.
I researched this pretty comprehensively, at least as a curious person in an armchair, and this is 100% correct.
There's one possible way it may pencil out, which is you gain some flexibility in terms of launch site. There's one company pursuing airplane based launches for this reason, but I'm still skeptical. Elon et all haven't had much trouble securing land for launch facilities.
There's one possible way it may pencil out, which is you gain some flexibility in terms of launch site. There's one company pursuing airplane based launches for this reason, but I'm still skeptical. Elon et all haven't had much trouble securing land for launch facilities.
There's an XKCD blog (?) that explains space launches in an intuitive way, with pictures:
https://what-if.xkcd.com/58/
Getting space isn't about getting "really high" (although of course you need to do that too). It's more about going "really fast" (relative to the ground). Like wantoncl mentioned, most of the fuel getting into orbit is spent on building that speed along the ground, not the height into the sky.
Think of it this way: space is only 100km away. ("If you're in Sacramento, Seattle, Canberra, Kolkata, Hyderabad, Phnom Penh, Cairo, Beijing, central Japan, central Sri Lanka, or Portland, space is closer than the sea.") You can drive that distance in a car in a moderately short time. The challenge is getting to the speed to stay in space and not fall back to earth.
Leaving Earth orbit for other astronomical bodies is another very interesting problem entirely. If you'd like to learn more about this, I'd encourage you to explore the video game Kerbal Space Program which has very accurate orbital mechanics.
https://what-if.xkcd.com/58/
Getting space isn't about getting "really high" (although of course you need to do that too). It's more about going "really fast" (relative to the ground). Like wantoncl mentioned, most of the fuel getting into orbit is spent on building that speed along the ground, not the height into the sky.
Think of it this way: space is only 100km away. ("If you're in Sacramento, Seattle, Canberra, Kolkata, Hyderabad, Phnom Penh, Cairo, Beijing, central Japan, central Sri Lanka, or Portland, space is closer than the sea.") You can drive that distance in a car in a moderately short time. The challenge is getting to the speed to stay in space and not fall back to earth.
Leaving Earth orbit for other astronomical bodies is another very interesting problem entirely. If you'd like to learn more about this, I'd encourage you to explore the video game Kerbal Space Program which has very accurate orbital mechanics.
somewhat unrelated but wouldn't this also defeat the purpose of a space elevator? It seems that also would only save on the vertical part. I realize I'm almost certainly wrong but I'm curious why.
The idea of a space elevator usually requires an orbital anchor point, in which case lifting yourself up the tether would pull you fully out of the gravitational well.
I've not done the mechanics in a long time (not since college), but I believe the tether itself would be providing all horizontal propulsion. Essentially by riding the tether up, it starts pushing you faster and faster. Since the payload's mass would be small compared to the anchor, the drag on the anchor would be negligible.
There's likely some need for thrust compensation on the anchor over time to counteract the delta V lost to the lifting of payloads, but that would all be part of station-keeping and would be there for tether drag as well.
I've not done the mechanics in a long time (not since college), but I believe the tether itself would be providing all horizontal propulsion. Essentially by riding the tether up, it starts pushing you faster and faster. Since the payload's mass would be small compared to the anchor, the drag on the anchor would be negligible.
There's likely some need for thrust compensation on the anchor over time to counteract the delta V lost to the lifting of payloads, but that would all be part of station-keeping and would be there for tether drag as well.
The anchor is past geosynchronous orbit so it’s applying a constant upwards force. The energy for horizontal motion comes from the rotation of the earth, much like how a rotating ice skater slows down when they spread their arms.
Station keeping may be used to dampen oscillations, but managing climbing rates works just as well.
Station keeping may be used to dampen oscillations, but managing climbing rates works just as well.
So the constant upwards force is providing enough tension to keep the cable in the realm of a rigid body approximation? I would have assumed the force applied to accelerate the payload would also deflect the tether and anchor backwards (in a miniscule amount) and would have built up over successive payloads.
Not arguing, just curious. It's been at least a decade since I've messed with orbital mechanics.
Not arguing, just curious. It's been at least a decade since I've messed with orbital mechanics.
It does defect the anchor from pure vertical, but like a ball on a pendulum the vertical force from the anchor translates into a horizontal force.
EX: https://www.researchgate.net/publication/312934526/figure/do...
Of course if you really dig into things it’s more complicated, but the basic principle is very similar.
EX: https://www.researchgate.net/publication/312934526/figure/do...
Of course if you really dig into things it’s more complicated, but the basic principle is very similar.
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Space elevators get you all the way out to geosync orbit (and beyond) - as you climb you accelerate as you move away from the surface of the earth, and so by the time you reach geosync height you are traveling at orbital velocity.
To be effective, a space elevator would have to deliver the payload all the way out to geostationary orbit altitude. At that hight, the payload would already be in orbit without adding any additional horizontal velocity. But almost all of the height is higher than you can float a lighter than air craft (42164km vs ~40km for lighter than air craft).
My guess would be: top of the space elevator needs to stay in orbit so it already needs to have appropriate "horizontal" part.
With the space elevator, you can get to space easily, but getting to orbit is much harder. Basically, you only achieve orbital speed once you have crawled to the geostationary orbit, e.g. 35,786 km above the Earth. Crawling that far from the Earth costs a lot of energy.
If you crawl only to the LEO altitude (e.g. 300 km) on the space elevator, you will be in space, but not in orbit. If you let go of the elevator there, you will immediately start falling to a gruesome death.
If you crawl only to the LEO altitude (e.g. 300 km) on the space elevator, you will be in space, but not in orbit. If you let go of the elevator there, you will immediately start falling to a gruesome death.
It could become a thing.
https://en.wikipedia.org/wiki/Space_diving
https://en.wikipedia.org/wiki/Space_diving
If it’s any comfort, you’d asphyxiate before the fall killed you.
Assuming one didn't asphyxiate or freeze to death on the way up, unfortunately, if during the day, you'd likely suffer immolation (due to high temperatures in the thermosphere) before losing consciousness from asphyxiation. Also, even if not either, the fall doesn't kill you; it's the impact.
Huh? Isn't the air too thin up there for that? One high temperature particle isn't going to set you on fire
Because a real space elevator would go all the way to geostationary orbit where the orbital speed is the same as the rotation of the planet. Remember that the further up you go, the slower the orbital velocity, i.e. the "horizontal part" shrinks until the "vertical part" becomes the whole thing.
In fact, the way to build a space elevator is not to build a "tower to space", but to put an anchor rock into geostationary orbit and then hang a cable down to earth from it. You can then connect the cable to terra firma so that it doesn't sway, but in terms of the main forces involved it's hanging down, not standing up.
In fact, the way to build a space elevator is not to build a "tower to space", but to put an anchor rock into geostationary orbit and then hang a cable down to earth from it. You can then connect the cable to terra firma so that it doesn't sway, but in terms of the main forces involved it's hanging down, not standing up.
The tether needs to go past geosynchronous orbit to act as a counterbalance
A space elevator not only raises payloads, but also accelerates them to geostationary orbital velocities (~3000 m/s). Luckily these velocities are much much lower than LEO orbits (7600 m/s).
Ideally the energy to perform this acceleration comes from the rotation of the planet below, transmitted via the tether. The anchor station would have to be stabilized to prevent oscillation and rotation. However that technical challenge is minor compared to the tether material itself.
Another advantage of a space elevator is that we can use electrical power from a base station instead of onboard power on the vehicle alone. Also the power can be much lower than a comparable rocket. To ascend on the rail/tether you can accelerate much slower. It doesn't need to lift fast or fall. It can just slowly accumulate altitude and velocity.
Ideally the energy to perform this acceleration comes from the rotation of the planet below, transmitted via the tether. The anchor station would have to be stabilized to prevent oscillation and rotation. However that technical challenge is minor compared to the tether material itself.
Another advantage of a space elevator is that we can use electrical power from a base station instead of onboard power on the vehicle alone. Also the power can be much lower than a comparable rocket. To ascend on the rail/tether you can accelerate much slower. It doesn't need to lift fast or fall. It can just slowly accumulate altitude and velocity.
A space elavator would also lend alot of centrifugal force past the atmosphere due to the tethered rotation that you wouldn't get with a balloon, if it's high enough it will be able to escape just by virtue of that when released
JP Aerospace has an interesting concept where the entire balloon would get slowly accelerated to orbital velocity using electric/chemical hybrid propulsion: http://www.jpaerospace.com/atohandout.pdf
That could potentially be viable, as it'd save fuel over more traditional rockets by allowing for the use of high efficiency, low thrust engines which would otherwise be infeasible for an orbital rocket due to gravity losses.
Not sure though, I haven't done the math. It might be that the losses due to drag exceed what a more traditional rocket would lose to gravity.
That could potentially be viable, as it'd save fuel over more traditional rockets by allowing for the use of high efficiency, low thrust engines which would otherwise be infeasible for an orbital rocket due to gravity losses.
Not sure though, I haven't done the math. It might be that the losses due to drag exceed what a more traditional rocket would lose to gravity.
Pretty cool that they’ve built some prototypes
>Basically balloon launches would only benefit small sub-orbital sounding type rockets.
So you're saying Jeff Bezos should look into this for Blue Origin since you essentially described his capabilities? ;-)
So you're saying Jeff Bezos should look into this for Blue Origin since you essentially described his capabilities? ;-)
There is a big benefit... Rocket nozzles that are most efficient in a vacuum don't work at sea level (oscillations cause the whole thing to shake apart). Therefore launching from high up means you can skip the less efficient rockets and just have a single type of more efficient rocket engine.
This is a very interesting point. Is there a counterargument to this?
Vacuum optimised rockets require a vacuum. Balloons require atmosphere… so there is a gap where the balloon can’t go higher and the engine isn’t in vacuum yet
Combine balloons with skyhooks. https://www.youtube.com/watch?v=dqwpQarrDwk
Edit:
According to proprietary imtringued numbers the hydrogen for a balloon capable of lifting 1kg to 50km would be $800 if you do not reuse the hydrogen. The skyhook would accept vehicles at an altitude of 100km so no, keep balloons out of the space launch industry.
Edit:
According to proprietary imtringued numbers the hydrogen for a balloon capable of lifting 1kg to 50km would be $800 if you do not reuse the hydrogen. The skyhook would accept vehicles at an altitude of 100km so no, keep balloons out of the space launch industry.
Thin-atmosphere-optimized is a thing, and lets you get most of the benefits.
Rockets use stages partially to solve this problem, also to deal with rocket equation issues.
So already a solved problem
So already a solved problem
1. Stages
2. Adaptive rocket nozzles are a thing.
2. Adaptive rocket nozzles are a thing.
Nope. I don’t have numbers but according to Elon Musk (who we probably at least agree on has a grasp of the basic principles) “space is easy, orbit is hard”.
> Rocket launches are extremely expensive, and most of it is in the lifting costs. Would it be cheaper to "lift" a rocket with hydrogen slowly?
No: https://what-if.xkcd.com/58/
No: https://what-if.xkcd.com/58/
The idea is that this gets you above the densest atmosphere and that could save you fuel. I used to think this, but if you run the numbers it doesn't work out.
>Getting to space[1] is easy. It's not, like, something you could do in your car, but it's not a huge challenge. You could get a person to space with a small sounding rocket the size of a telephone pole. The X-15 aircraft reached space[2] just by going fast and then steering up.[3]
Loved that line. Puts the Branson/Bezos thing into perspective.
Loved that line. Puts the Branson/Bezos thing into perspective.
These days there are even amateur rocket clubs that have managed (unmanned) suborbital space launches [1].
[1] http://www.uscrpl.com/traveler-iv
[1] http://www.uscrpl.com/traveler-iv
https://en.wikipedia.org/wiki/Rockoon
https://en.wikipedia.org/wiki/Northrop_Grumman_Pegasus
https://en.wikipedia.org/wiki/Scaled_Composites_Stratolaunch
https://en.wikipedia.org/wiki/Northrop_Grumman_Pegasus
https://en.wikipedia.org/wiki/Scaled_Composites_Stratolaunch
It's not impossible, sure. It's just usually not worth it.
You would save around 5% fuel and multiply costs by 10. People have tried and tested, much better to just make the rocket reusable.
From linked xkcd what if: Gravity in low Earth orbit is almost as strong as gravity on the surface. The Space Station hasn't escaped Earth's gravity at all; it's experiencing about 90% the pull that we feel on the surface.
Parent isn't talking about gravity, he's talking about alleviating the rocket equation by not having to lift your fuel with fuel.
Yes, but...
The majority of energy expended in getting to orbit is spent in getting to orbital velocity (going sideways), rather than getting to orbital altitude (going up). Balloons only help in going up, and only to where the density of the atmosphere is so low that the balloon is no longer lifting, they are still far short of the altitude necessary for orbit. Balloons top out at around 20-30 miles while LEO is ~100 miles.
So launching using a balloon only really gives you a very small fuel savings
The majority of energy expended in getting to orbit is spent in getting to orbital velocity (going sideways), rather than getting to orbital altitude (going up). Balloons only help in going up, and only to where the density of the atmosphere is so low that the balloon is no longer lifting, they are still far short of the altitude necessary for orbit. Balloons top out at around 20-30 miles while LEO is ~100 miles.
So launching using a balloon only really gives you a very small fuel savings
That's the issue though. The hard part about achieving orbit isn't the height, it's the speed. In both a ground launch and a balloon launch you are starting at 0.
This article does a better job explaining it than just about anything else on the web: https://what-if.xkcd.com/58/
So complex schemes to lift the rocket to the edge of space don't end up buying you very much.
This article does a better job explaining it than just about anything else on the web: https://what-if.xkcd.com/58/
So complex schemes to lift the rocket to the edge of space don't end up buying you very much.
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It's not expensive to go to space because you have to go up. Going up into space is 'easy'.
It's expensive to stay in space because you have to go sideways, really, really fast. 8 km/s fast, in fact.
It's expensive to stay in space because you have to go sideways, really, really fast. 8 km/s fast, in fact.
This is fun to think about. You only need that horizontal velocity to stay in orbit, right? But what about getting to the moon? Turns out it only goes about 1km/s. Still bloody fast, but it's a bit less scary. Daydreams of capturing that energy on descent to power a moonbase... but then the moon is quite a long way away, and you need to escape over 99% of the earth's gravity, opposed to the 10% needed to reach space. Phooey, lunch is never free.
That would also let us do the rocket launch from the middle of the ocean rather than near inhabited areas.
I asked this question once and got laughed at. My embarrassment burned it into me: Going fast is the challenge with orbiting, not going up.
Well, if you could go high enough, you could be in a geosynchronous orbit without moving horizontally at all. I think that's how space elevators would work. But then to move to a lower orbit you would actually need to speed up.
If you "fell" from geosync, wouldn't you speed up? Angular momentum needs to be conserved, right?
Edit:my terrible wording created answers to a different question.
Edit:my terrible wording created answers to a different question.
If you ’fall’ from geosync orbit, you fall in a circle and wind up where you started. Orbiting is falling.
That's my understanding, geosync is the point at which you continually fall toward the Earth and miss, closer and you'd eventually hit, farther and you would move away.
That’s not really correct.
Geosync is the altitude at which a circular orbit takes 24 hours - meaning it takes as long to complete one orbit as it takes the earth to complete one revolution.
But there’s an orbital velocity at EVERY altitude, and therefore there’s an orbital period at every altitude too.
If you are at a particular altitude and you are going at a different speed than the one needed for a circular orbit, you are either going too fast (in which case you are in an elliptical orbit and you will gradually increase altitude and lose speed until you reach the top of that ellipse) or you are going too slow to stay in a circular orbit (in which case you will follow an ellipse down to a lower altitude and gain speed).
In that ‘too slow’ case, if it’s much too slow then the ellipse you follow will take you low enough to hit the surface or atmosphere of whatever you’re orbiting (ie you will crash into it)
Geosync is the altitude at which a circular orbit takes 24 hours - meaning it takes as long to complete one orbit as it takes the earth to complete one revolution.
But there’s an orbital velocity at EVERY altitude, and therefore there’s an orbital period at every altitude too.
If you are at a particular altitude and you are going at a different speed than the one needed for a circular orbit, you are either going too fast (in which case you are in an elliptical orbit and you will gradually increase altitude and lose speed until you reach the top of that ellipse) or you are going too slow to stay in a circular orbit (in which case you will follow an ellipse down to a lower altitude and gain speed).
In that ‘too slow’ case, if it’s much too slow then the ellipse you follow will take you low enough to hit the surface or atmosphere of whatever you’re orbiting (ie you will crash into it)
I think you knew this but it wasn't obvious from how you wrote it. Your orbit is not required to be a circle. The diagrams we draw for children are nice circles, but most things that we know are orbiting something do not travel in a circle, e.g. the Earth -- if the orbit was circular our seasons would be slightly different† and the insight that the orbits can be non-circular ellipses was critical to the reasoning that eventually got us a heliocentric model of our solar system.
Geostationary communications satellites do have a basically circular orbit, as you said, but many other birds do not.
Russia has a bunch of stuff in orbits that "linger" very high over Russian territory for much of their orbital period then shoot right around close to the back side of the planet quickly and linger again, these are called Molniya orbits.
The US has a bunch of secret (presumably spy) satellites that fly less obvious orbits like this too, for presumably similar reasons.
† Edited: This post originally said "very" different, but in fact the difference would be modest since our orbit just isn't that elliptical. I wasn't able to find out how modest, but certainly if you think summer in New Zealand (in December) is pretty similar to summer in England (in June) then it's reasonable to say at least that similar.
Geostationary communications satellites do have a basically circular orbit, as you said, but many other birds do not.
Russia has a bunch of stuff in orbits that "linger" very high over Russian territory for much of their orbital period then shoot right around close to the back side of the planet quickly and linger again, these are called Molniya orbits.
The US has a bunch of secret (presumably spy) satellites that fly less obvious orbits like this too, for presumably similar reasons.
† Edited: This post originally said "very" different, but in fact the difference would be modest since our orbit just isn't that elliptical. I wasn't able to find out how modest, but certainly if you think summer in New Zealand (in December) is pretty similar to summer in England (in June) then it's reasonable to say at least that similar.
I think GP means that if you are stationary relative to the ground (such as on a space elevator or a rocket going straight up), 35786 km up is the only height which is a stable orbit. If you let go of the elevator too early, you'll fall to the ground; too high and you'll fly off into space.
[deleted]
Theoretical geosync means zero velocity in any direction relative to ground. Zero up, down, forward, back, left, or right. You're stuck above a single point of dirt/water, over the equator, at a fixed altitude.
The only way to "fall" (lower your altitude) from here would be via some sort of acceleration force towards ground (like a burn). So yes, your speed would have to increase.
The only way to "fall" (lower your altitude) from here would be via some sort of acceleration force towards ground (like a burn). So yes, your speed would have to increase.
Well fine. I meant that orbital speed (the "along track part") would increase if you lowered the altitude of a geosync object with rockets, string, or any other force, I think.
It doesn’t. If you pulled ‘down’, it would just make the orbit eccentric.
Nobody should have laughed—your misconception was one 99% of the population shares!
Nature is enough of a gatekeeper to space, she doesn't need mortal deputies.
Nature is enough of a gatekeeper to space, she doesn't need mortal deputies.
The learning journey has been more good than bad. My favorite was that orbit seems far away, until you look out from an aircraft and realize you're 30% of the way there. Usually, from where you live, the next major town is further than LEO.
This is a brilliant turn of phrase and I’m definitely going to steal it
Certainly no need to feel bad. Orbital mechanics are counterintuitive to us ground dwellers- even astronauts sometimes need a refresher course!
You're describing rockoons [1], which were used for launching (non-orbital) sounding rockets back in the 1950s.
I think they fell out of use as high altitude jet aircraft became more common and economical as a launch platform.
[1] https://en.wikipedia.org/wiki/Rockoon
I think they fell out of use as high altitude jet aircraft became more common and economical as a launch platform.
[1] https://en.wikipedia.org/wiki/Rockoon
Never mind how crazy is your idea, there is always somebody that it's already trying it:
https://www.zero2infinity.space/bloostar/
Of course, you still have to accelerate to orbit, but you don't have to deal with the atmosphere.
https://www.zero2infinity.space/bloostar/
Of course, you still have to accelerate to orbit, but you don't have to deal with the atmosphere.
What about doing the 2-stage system similar to Virgin Galactic? Use the "balloon" to lift the system to upper altitudes, and then fire off the rocket to do orbital insertion type stuff.
Imagine an open deck on an airship. Or at least being able to open your window.
Propellers far away from passengers to minimize any noise.
Propellers far away from passengers to minimize any noise.
I completely agree with the leisure air travel scenario for airships. It would be incredible anywhere. Massive windows, tons of interior space, and quiet. Here is a deck I prepared luxury airships and opportunities for hydrogen airships:
https://docs.google.com/presentation/d/1r6CPFJ1AX1ZULacguTf6...
https://docs.google.com/presentation/d/1r6CPFJ1AX1ZULacguTf6...
The title image has a solid-fuel missile in it (attached to left-blimp). That render has very interesting backstory:
https://news.ycombinator.com/item?id=8760732
https://en.wikipedia.org/wiki/High_Altitude_Venus_Operationa...
https://news.ycombinator.com/item?id=8760732
https://en.wikipedia.org/wiki/High_Altitude_Venus_Operationa...
Airships would make a fantastic, greener alternative to a cruise ship. I suspect winds to be its biggest sticking point.
The problem is scale.
The Hindenberg design, despite being 800ft long, only accommodated 50 passengers, in TINY cabins (6.5' x 5').
The entire cabin was 6000 sqft.
Even the "cheap" cabins on a modern cruise ship are ~150sqft each, and all have private bathrooms.
The Hindenberg design, despite being 800ft long, only accommodated 50 passengers, in TINY cabins (6.5' x 5').
The entire cabin was 6000 sqft.
Even the "cheap" cabins on a modern cruise ship are ~150sqft each, and all have private bathrooms.
But we do have lighter materials to build with, avaiable today?
So a same size blimp could give more room. And why not just build bigger blimps.
So a same size blimp could give more room. And why not just build bigger blimps.
Yes, we could make a larger cabin with the same weight constraints using modern composite materials.
But even with lighter materials, you would still not be able to accommodate more passengers comfortably. The majority of weight-per-passenger will come from water (which every passenger needs for showering, toilets, food preparation). You would need to land regularly just for passenger hygene reasons. So I still don't expect blimps will be a 'comfortable' alternative to cruise ships.
Random fun fact: The Hindenburg had a grand piano made from aluminium, as a regular piano would have been too heavy.
But even with lighter materials, you would still not be able to accommodate more passengers comfortably. The majority of weight-per-passenger will come from water (which every passenger needs for showering, toilets, food preparation). You would need to land regularly just for passenger hygene reasons. So I still don't expect blimps will be a 'comfortable' alternative to cruise ships.
Random fun fact: The Hindenburg had a grand piano made from aluminium, as a regular piano would have been too heavy.
Random fun fact 2: They even removed that piano because it was to heavy.
> Random fun fact: The Hindenburg had a grand piano made from aluminium, as a regular piano would have been too heavy.
This is truly fascinating. I didn't know that.
This is truly fascinating. I didn't know that.
Random fun fact-- the only lady on the first round the world zeppelin trip secretly brought on a phonograph!
Cruise ships are absolutely massive. They're floating cities, housing and feeding thousands of people. The new materials would have to be very light indeed to scale from 50 to 5000 passengers.
I would be fine with 50-150 people per module. And then you can maybe meet in air. Combine them or seperate them. Land or go up very high. Drift where the wind blows. The sky is big.
I have gone on a of number cruises, especially on the Alaskan cruise and Panama cruise the one thing I never heard from anyone was "I wish they traveled faster.".
There is a number of trips that a slow and quiet trip would make for great fun.
There is a number of trips that a slow and quiet trip would make for great fun.
During the uncertainty of when/if ports would reopen across Europe, some UK cruise companies went so far as to simply offer "cruises to nowhere".
I.e. they would set off the usual ports, but not head for continental Europe, just sail out to a calm spot with agreeable climate and hang out there for a while.
I.e. they would set off the usual ports, but not head for continental Europe, just sail out to a calm spot with agreeable climate and hang out there for a while.
Why did they leave the port at all?
Because I can't imagine people are happy to pay to sit for a week in an industrial dock in Portsmouth. Also sailing to warmer waters means you can sit on the outside deck/balcony and enjoy the sun. Again, not exactly the things UK ports are well known for.
I'm going to guess that there are laws that make that pretty undesirable. For example: There were (and maybe still are) gambling ships on the Ohio river and on Lake Michigan - all of which docked in Indiana. Unfortunately, such gambling was illegal in Indiana. The ships had to leave dock and go out a little on the water. Suddenly, the gambling was legal.
There are probably dozens of these laws that encourage leaving the dock, especially if you are going into international waters instead of simply between states.
There are probably dozens of these laws that encourage leaving the dock, especially if you are going into international waters instead of simply between states.
Yes, the LA to Las Vegas gambling air cruiser would be a profitable route. Sunsets would be fantastic!
Then any sufficiently interesting city in the world will be able to experience the joys of regularly being invaded by cruise tourists - yay for that! Fortunately airships won't be able to hold quite as many passengers as a cruise ship...
The hyperloop calculations are way off. the longer the tube, the thicker it has to be to support itself.
Instead, "aerial airstrip" on slide 21 would make a ton of sense. Move airports from the ground to above the clouds (3km up in the air?). Advantages:
1) 10-15% less fuel consumption (after take-offs you are already at 3km altitude)
2) much less noise for the surroundings
3) less subject to bad weather conditions.
etc.
Instead, "aerial airstrip" on slide 21 would make a ton of sense. Move airports from the ground to above the clouds (3km up in the air?). Advantages:
1) 10-15% less fuel consumption (after take-offs you are already at 3km altitude)
2) much less noise for the surroundings
3) less subject to bad weather conditions.
etc.
The Hyperloop to the sky calculations are admittedly very back-of-the-napkin. Contributions welcome!
Glad you like the aerial airstrip
Glad you like the aerial airstrip
Y'all need to read Kenneth Oppel's Matt Cruse series (Airborn, Skybreaker and Starclimber, but mainly Airborn)
That and a Starlink not bound to a location - would be awesome. Would it be possible to live on such a ship?
People live in RVs. The real question is: is it practical to have an airship with the top covered in photovoltaic cells sufficient to run all your normal electrical needs?
A residential-class airship would probably be limited to visual flight rules conditions and have to land or at least be docked every night. You'll want to do that for a variety of comfort reasons, too -- water is heavy, so finding a campground with electrical and water hookups would be preferred.
A residential-class airship would probably be limited to visual flight rules conditions and have to land or at least be docked every night. You'll want to do that for a variety of comfort reasons, too -- water is heavy, so finding a campground with electrical and water hookups would be preferred.
Storms could be an issue - storm won't usually sink a houseboat or destroy a RV trailer.
But it might very well smash a residential airship into the ground even if securely moored just due to the sheer size of its gas envelope being effectively a giant sail.
But it might very well smash a residential airship into the ground even if securely moored just due to the sheer size of its gas envelope being effectively a giant sail.
> Would it be possible to live on such a ship?
People live on house boats smaller than early Zeppelins. The challenge will be supplies and human excretions - if you live on such a thing and it's anchored over land you can't just drop your feces on a whim.
People live on house boats smaller than early Zeppelins. The challenge will be supplies and human excretions - if you live on such a thing and it's anchored over land you can't just drop your feces on a whim.
Imagine: Trash airships that can deposit loads at flying solar furnace platforms (equipped with co2 capture technology) to burn everything. Use various stages of processing to chemically or physically extract commercially valuable material, like phosphorous, then turn the rest into slag - not perfect, but one helluva lot better than burying and wasting the raw trash. Use the captured co2 and solar power alongside the artificial leaf tech to produce synthgas and other fuel.
Solar and wind platforms could anchored to cables on the ground, with municipal battery storage on the ground, then use airships to swap charged battery packs from centralized power stations.
A cellular/modular approach to ship design could prevent hindenburg disasters. Individual carbon fiber balloons could be made to link together, and they'd be during enough that even if you detonate a cell, its neighbors remain intact. Cells as small as a cubic meter would still provide lift while limiting the explosive potential - make the cells "smart" and you could design resilient airships that failed gracefully, even under fire, for military and security sensitive applications.
Platforms could be made huge, big enough to build houses, factories, hospitals, or resorts.
Airships don't have to be blimps. It's more practical than seasteading and probably multiple orders of magnitude cheaper in combined maintenance and development.
Solar and wind platforms could anchored to cables on the ground, with municipal battery storage on the ground, then use airships to swap charged battery packs from centralized power stations.
A cellular/modular approach to ship design could prevent hindenburg disasters. Individual carbon fiber balloons could be made to link together, and they'd be during enough that even if you detonate a cell, its neighbors remain intact. Cells as small as a cubic meter would still provide lift while limiting the explosive potential - make the cells "smart" and you could design resilient airships that failed gracefully, even under fire, for military and security sensitive applications.
Platforms could be made huge, big enough to build houses, factories, hospitals, or resorts.
Airships don't have to be blimps. It's more practical than seasteading and probably multiple orders of magnitude cheaper in combined maintenance and development.
You know hol little CO2 you capture with solar power right? And whats the incentive to buils these fantastical structures?
It can be solar concentrator style generation and furnaces if you think big enough. Mobility and new frontiers could be enough incentive, but cargo transport, power infrastructure, hydrogen generation, and waste recovery would be advantageous. Large fixed platforms could solve a big part of the offloading problems. If the cells use standardized fittings, then cargo stations could swap hydrogen for co2 as ballast during offloading.
Aerial platforms would be great for telescopes and helicopters, too.
Aerial platforms would be great for telescopes and helicopters, too.
What possible advantage is there to lofting furnaces and trash transport rather than accomplishing both on the ground?
Yes, we could build floating cities above the clouds with always sun for energy and little wind.
(people would have to be indoors, though above a certain height)
Air nomads.
(people would have to be indoors, though above a certain height)
Air nomads.
Would cubic meter cells work? You'd have a lot of material for small cells, compared to one large cell blimp.
If I recall correctly, you can do some leisure travel around the Bodensee (Lake Constance) on one that is moored out of the historical harbor in Friedrichshafen. A friend who’s a pilot even logged training hours on one of them — just to check that off the bucket list. They can be seen circling the lake nearly every day in summer.
https://zeppelin-nt.de/de/zeppelin-fluege/uebersicht.html
https://zeppelin-nt.de/de/zeppelin-fluege/uebersicht.html
> Edit to add:
> (Leisure air travel/Safari is my own pipe dream. The article suggests cargo)
Please, people who write tl;drs, read the whole article so you don't miss the punch line. The last 6 paragraphs (25%) of the article is devoted to cargo being the best value proposition
Please, people who write tl;drs, read the whole article so you don't miss the punch line. The last 6 paragraphs (25%) of the article is devoted to cargo being the best value proposition
An entertaining read https://twitter.com/RealhumanSchwab/status/14219494217810616...
Very related. I won’t spoil it for you but it’s entertaining.
Edit: Responders, please! You’re spoiling the fun! If https://twitter.com/RealhumanSchwab/status/14219496075426160... doesn’t give it away I don’t know what will.
Very related. I won’t spoil it for you but it’s entertaining.
Edit: Responders, please! You’re spoiling the fun! If https://twitter.com/RealhumanSchwab/status/14219496075426160... doesn’t give it away I don’t know what will.
That thread went down the insane conspiracy rabbit hole in a hurry.
Disappointing. The first 2/3 of the thread was pretty good, nice narrative with pictures. The twitter format sucks though.
Echoing a sibling comment, that thread goes down the conspiracy rabbit hole very quickly. A few inaccuracies I noticed before giving up:
* "Remember, only 13 deaths out of the 36 passengers on the airship died." This skips the crew deaths (who also died at about the same rate).
* There were a bunch of photographers present at Lakehurst as it was the first crossing of 1937. The audio recording was not scripted, the original disc records a pressure wave which is followed by Morrison exclaiming that the Hindenburg is on fire.
* "Mary Jane" can be a real person's name.
* "Hugo Eckener, former head of the Zeppelin Company, Charles Rosendahl, commander of the Naval Air Station at Lakehurst, Max Pruss, captain of the Hindenburg and most of the surviving crew believed the airship had been sabotaged.". Eckener stated that it could be sabotage when he was first told the Hindenburg had gone down. He later backed the static spark theory.
* "Remember, only 13 deaths out of the 36 passengers on the airship died." This skips the crew deaths (who also died at about the same rate).
* There were a bunch of photographers present at Lakehurst as it was the first crossing of 1937. The audio recording was not scripted, the original disc records a pressure wave which is followed by Morrison exclaiming that the Hindenburg is on fire.
* "Mary Jane" can be a real person's name.
* "Hugo Eckener, former head of the Zeppelin Company, Charles Rosendahl, commander of the Naval Air Station at Lakehurst, Max Pruss, captain of the Hindenburg and most of the surviving crew believed the airship had been sabotaged.". Eckener stated that it could be sabotage when he was first told the Hindenburg had gone down. He later backed the static spark theory.
Fossil fuel companies getting PR to spin everything they can into trying to improve hydrogen's image.
What's wrong with hydrogen? You can produce it with renewables, it basically works with existing IC technology and the exhaust is just water. The only hangup is the energy/volume ratio, which is an area of ongoing research.
Hydrogen burns and produces greenhouse gas!
uh, no?
Yes
》Water vapor is known to be Earth’s most abundant greenhouse gas
https://www.nasa.gov/topics/earth/features/vapor_warming.htm...
》Water vapor is known to be Earth’s most abundant greenhouse gas
https://www.nasa.gov/topics/earth/features/vapor_warming.htm...
Run it through a condenser, feed it into a holding tank and dispose of the water at each filling station?
No need, the atmosphere is a sufficient condenser. Unless you heat the atmosphere with a lot more energy than the little bit you get from combusting the hydrogen in question... but then you'll have bigger problems as your oceans begin to evaporate.
Well technically yes
Although water vapor is technically a "greenhouse gas", it is not responsible for forcing any global warming. That's because at the temperatures we're interested in water is a liquid, not a gas, and what small amount of water remains gaseous is entirely determined by the air's temperature. So water vapor can't force any warming, it can only amplify other forcings.
Large-scale hydrogen production is commonly based on fossil fuels right now, and that's what many fossil fuel companies push when they talk hydrogen. End-to-end efficiency is also not that great. That doesn't necessarily disqualify hydrogen, but it's not as obvious as often presented.
It seems like a good hydrogen chain could look like: solar panels floating in the ocean split the water and store it, a tanker picks it up and takes it to port. Burn hydrogen at a power plant for the grid, condense the vapor and use it for drinking or farming.
It seems like a great fit for...a lot of use cases. (if we can get over some of the storage hurdles)
It seems like a great fit for...a lot of use cases. (if we can get over some of the storage hurdles)
Even then it's comparatively trivial to capture the carbon dioxide from steam reforming, as opposed to gasoline in a car.
Hard to imagine a solution to climate change that doesn't involve the fossil fuel companies given their enormous political importance.
I've found it interesting that power plant generators are sealed and cooled with hydrogen gas. A hundred tons of steel and copper generating thousands of volts of electricity is cooled with hydrogen.
Sounds like a recipe for an explosion movie style, yet there aren't any.
Sounds like a recipe for an explosion movie style, yet there aren't any.
There aren't any because hydrogen cooled turbomachinery is complex and high-touch. There are systems that circulate the gas out of the generator and into separators that remove the inevitable air contaminants and dryers to remove the water. They aren't really seal-and-forget systems like a helium-filled hard disk drive might be.
Is this a reprint from April 1st?
One nice feature of hydrogen is that you can use it for lift and also for fuel (and it has good energy density).
I've been wondering for a while if hydrogen airships couldn't make flying cars a reality. It seems like a hybrid jet/zeppelin could find a sweet spot in terms of performance and sustainability.
I've been wondering for a while if hydrogen airships couldn't make flying cars a reality. It seems like a hybrid jet/zeppelin could find a sweet spot in terms of performance and sustainability.
The necessary bulk of the airship for human transportation is a serious crimp in the practicality of such a solution. Technology can't make the bag small enough because it is limited by physics.
Even if we could build ultra-rigid and outrageously light bags that could have all of the air pumped out for a vacuum you still need a fairly large balloon to carry people. One person would displace 70 meter^3 of air, not counting anything else. That's not going to fit in your driveway.
Even if we could build ultra-rigid and outrageously light bags that could have all of the air pumped out for a vacuum you still need a fairly large balloon to carry people. One person would displace 70 meter^3 of air, not counting anything else. That's not going to fit in your driveway.
this article reads like the "a world without zinc!" school documentary spoof subplot on the Simpson's https://www.youtube.com/watch?v=U1iCZpFMYd0
and the spat He... no, that's helium... She has with helium and in favor of hydrogen overshadows the more interesting suggestion at the end, that airships might make a lot of sense for cargo transportation. I wish the article made that case better!
and the spat He... no, that's helium... She has with helium and in favor of hydrogen overshadows the more interesting suggestion at the end, that airships might make a lot of sense for cargo transportation. I wish the article made that case better!
Interesting piece! I think the article makes some good points, but I don't think that helium is the reason that airships have failed to find use cases. The benefits of hydrogen do not change the fundamentals of the business case. Hydrogen's cheaper, but even using helium the lifting gas is <20% of the operating cost of the airship. The hangar, cost of the vehicle, and maintenance are all more impactful than the cost of the lifting gas.
The bigger hurdle that airship startups have faced is the upfront cost of developing a new vehicle with a many ton payload. Projects trying to build very large airships have so far to get a vehicle to market, because of the amount of capital it requires and the lack of a strong, specific commercial case (Hybrid Air Vehicles, Cargolifter, Lockheed's Hybrid Airships). Changing the lifting gas to hydrogen does not address those challenges. But airships are certainly underutilized - I'm optimistic for their future!
The bigger hurdle that airship startups have faced is the upfront cost of developing a new vehicle with a many ton payload. Projects trying to build very large airships have so far to get a vehicle to market, because of the amount of capital it requires and the lack of a strong, specific commercial case (Hybrid Air Vehicles, Cargolifter, Lockheed's Hybrid Airships). Changing the lifting gas to hydrogen does not address those challenges. But airships are certainly underutilized - I'm optimistic for their future!
I thought the bigger safety problem with lighter than air travel was weather? As in, anything less than perfect surface conditions may result in disaster when you go to moor the aircraft.
A clear example how money in the military-industrial complex (or DARPA) directs innovation paths. The military does not approve of hydrogen blimps, and so neither can the civilian sector use them.
The military haven't used airships since the 1930's because transatlantic aeroplanes rendered them obsolete. Not because of some military-industrial complex conspiracy.
Every couple of decades the DoD decides that blimps are back in fashion and throws millions of dollars into blimp projects. Inevitably they cancel the project and decide they don't want them. Admittedly they've all been helium, but the reasons for cancelation are usually related to capability and the intrinsic qualities of lighter-than-air flight, and not cost.
The past 20 years, they tried Integrated Sensor is Structure (USAF) [1]; Long-endurance, Multi-intelligence Vehicle (Army) [2], Blue Devil (USAF) [3], Walrus advanced technology demonstration (DARPA) [4], and a handful of other boondoggles [5].
If anything, the concept of viable airships in the 21st century is just a defence contractor gravy train.
[1] https://en.wikipedia.org/wiki/Integrated_Sensor_is_Structure
[2] https://www.ainonline.com/aviation-news/defense/2013-02-22/u...
[3] https://defense-update.com/20120529_blue-devil-2-airship-def...
[4] https://www.flightglobal.com/darpa-details-plans-for-ultra-l...
[5] Congressional Budget Office, "Recent Development Efforts for Military Airships" (2011) https://fas.org/irp/program/collect/cbo-airship.pdf
Every couple of decades the DoD decides that blimps are back in fashion and throws millions of dollars into blimp projects. Inevitably they cancel the project and decide they don't want them. Admittedly they've all been helium, but the reasons for cancelation are usually related to capability and the intrinsic qualities of lighter-than-air flight, and not cost.
The past 20 years, they tried Integrated Sensor is Structure (USAF) [1]; Long-endurance, Multi-intelligence Vehicle (Army) [2], Blue Devil (USAF) [3], Walrus advanced technology demonstration (DARPA) [4], and a handful of other boondoggles [5].
If anything, the concept of viable airships in the 21st century is just a defence contractor gravy train.
[1] https://en.wikipedia.org/wiki/Integrated_Sensor_is_Structure
[2] https://www.ainonline.com/aviation-news/defense/2013-02-22/u...
[3] https://defense-update.com/20120529_blue-devil-2-airship-def...
[4] https://www.flightglobal.com/darpa-details-plans-for-ultra-l...
[5] Congressional Budget Office, "Recent Development Efforts for Military Airships" (2011) https://fas.org/irp/program/collect/cbo-airship.pdf
None of the other countries are doing it either, so it isn't just DARPA. I think it just doesn't have an obvious use case.
Everyone says cargo, but what is it better at at than rail, truck, ship, or air (cargo jet)? If you want cheap you go with rail or ship. If you want fast you go with jet and then truck for the last mile. Airship would be cheaper than air, but noticeably slower, so it basically has to compete with truck on price. Can it do that? Maybe, I have no idea.
Everyone says cargo, but what is it better at at than rail, truck, ship, or air (cargo jet)? If you want cheap you go with rail or ship. If you want fast you go with jet and then truck for the last mile. Airship would be cheaper than air, but noticeably slower, so it basically has to compete with truck on price. Can it do that? Maybe, I have no idea.
Hydrogen gas leaks through everything, and embrittles most metals. It is not an easy substance to work with. Combine that with having one of the widest ignition ranges of any flammable material, and I'll just stay on the dubious side of it ever getting used as a large-scale lifting gas again.
It doesn't embrittle aluminum at normal temperatures and stainless steel is significantly less affected. I agree it is hard to work with, but think the reason it isn't used in this sort of application is more due to economics than inherent properties of hydrogen.
So like I think the claim about the thermite coating could be wrong. That is my only concern you can't have the ship burst into flames in a minute. I don't know the truth of the hindenburg but it does seem like you could mitigate the flammability risk under good conditions but like security also comes to mind what if these things get hijacked. Like they do move slow but are basically a moving ball of death if they light on fire.
https://www.airships.net/hindenburg/disaster/myths/
https://www.airships.net/hindenburg/disaster/myths/
Aeroplanes are also all of these things. And things go south a lot quicker when they get hijacked.
[deleted]
Out of curiosity, would it be feasible to produce enough helium for commercial use through fusion (either power generating or not)?
Although there's a slight difference in meaning, I prefer the term zeppelin to blimp.
fyi: the difference is in the frame construction. A zeppelin has a rigid frame that keeps it's shape if the gas is lost, whereas a blimp has a semi-rigid frame that will deflate if the gas isn't present.
fyi: the difference is in the frame construction. A zeppelin has a rigid frame that keeps it's shape if the gas is lost, whereas a blimp has a semi-rigid frame that will deflate if the gas isn't present.
"Zeppelin" is a manufacturer designation or brand name, akin to "Kleenex", though it's become somewhat genericised.
"Rigid airship" is the generic term.
"Rigid airship" is the generic term.
I think "rigid airship" is an often used term as well
This article is interesting. “Hydrogen doesn’t explode without being mixed with air first then ignited” is a kind of funny statement. I read that as “hydrogen doesn’t explode outside of when it does”
I’d ask “was this written by a hydrogen sales team?” but it’d be mind boggling if it weren’t. The blaming of special interest groups right off the bat, and the blaming the lower-performing helium as the cause for a crash (that iirc, involved a leak so I’m not sure how that 8% difference could’ve saved everyone) are naked examples of sales speech.
“Maybe you’ll blow up! Who cares? You get 8% more lift and stick it to the uh, Bureau Of Mines”
I’d ask “was this written by a hydrogen sales team?” but it’d be mind boggling if it weren’t. The blaming of special interest groups right off the bat, and the blaming the lower-performing helium as the cause for a crash (that iirc, involved a leak so I’m not sure how that 8% difference could’ve saved everyone) are naked examples of sales speech.
“Maybe you’ll blow up! Who cares? You get 8% more lift and stick it to the uh, Bureau Of Mines”
The article does have a point. On airplanes we have highly flammable fuel. It's safe because it is contained. The same could be done with the hydrogen in an airship.
Jet fuel doesn't inherently mix with air, on its own.
(It does mix with air in high-speed impacts, which results in flame but not *explosions.)
Jet fuel, kerosene (intermediate in weight, viscosity, and volatility between petrol and diesel fuels) is remarkably inert for something that burns. You can extinquish a match in it.
(It does mix with air in high-speed impacts, which results in flame but not *explosions.)
Jet fuel, kerosene (intermediate in weight, viscosity, and volatility between petrol and diesel fuels) is remarkably inert for something that burns. You can extinquish a match in it.
I'm always hopeful that airships will make a comeback. I would love to be able to travel from the United States to Europe on an airship, just like they did at the in the early 20th century. I can see a lot of advantage from a comfort perspective, even if it does take more time than a plane.
If you are interested in the history of airship travel, and its rise and fall, I highly recommend The Deltoid Pumpkin Seed by John McPhee. It's a short book about an unlikely union of ex Navy airshipmen and evangelical Christians chasing the impossible dream of brining airship travel back in an era where the world had moved on from airship travel.
If you are interested in the history of airship travel, and its rise and fall, I highly recommend The Deltoid Pumpkin Seed by John McPhee. It's a short book about an unlikely union of ex Navy airshipmen and evangelical Christians chasing the impossible dream of brining airship travel back in an era where the world had moved on from airship travel.
Is it possible to make a road ready hovercraft that uses lifting gas like hydrogen? Getting tired of particulate matter from tires, brakes, road wear, etc.
This article is very USA centric — it centers around it being banned for lift in the states — but that wouldn’t stop just about everywhere else on the planet from building hydrogen air ships, if they are viable.
How often are the blimps fully deflated of their helium and then refilled, and is all that helium just basically let up into the atmosphere and wasted? Given some of our recent helium shortages, it seems really wasteful, even if it may be (currently) not costly.
A couple other options beside hydrogen/helium: vacuum chambers, hot air.
I don't know if we have the technology to build a compressive structure that can withstand atmospheric pressure and yet be lighter than the air it displaces. That sounds like an interesting problem to work on. I imagine getting it to work out would be easier the larger the structure is, within reason.
I assume that hot air isn't competitive with either hydrogen or helium in terms of lift, and it takes additional energy to keep it hot. On the other hand, air is free and it's not inherently flammable by itself. Maybe a well-insulated airship that acts as a solar greenhouse could get quite warm and stay that way?
I don't know if we have the technology to build a compressive structure that can withstand atmospheric pressure and yet be lighter than the air it displaces. That sounds like an interesting problem to work on. I imagine getting it to work out would be easier the larger the structure is, within reason.
I assume that hot air isn't competitive with either hydrogen or helium in terms of lift, and it takes additional energy to keep it hot. On the other hand, air is free and it's not inherently flammable by itself. Maybe a well-insulated airship that acts as a solar greenhouse could get quite warm and stay that way?
> I don't know if we have the technology to build a compressive structure that can withstand atmospheric pressure and yet be lighter than the air it displaces. That sounds like an interesting problem to work on. I imagine getting it to work out would be easier the larger the structure is, within reason.
It doesn´t exist so far. There are very strong forces involved. I`d say it´s more likely there would be connected small enclosures that could make that work. Perhaps some sort of solid foam blocks with vacuum inside - but it may provide much less lift than a true vacuum.
It doesn´t exist so far. There are very strong forces involved. I`d say it´s more likely there would be connected small enclosures that could make that work. Perhaps some sort of solid foam blocks with vacuum inside - but it may provide much less lift than a true vacuum.
To follow up my own comment: I suppose these aren't mutually exclusive. For instance, you could have an airship filled with hydrogen or helium at 1/2 atmospheric pressure and kept hot by solar heating.
For helium especially it might be an effective way to keep costs down (since helium is so expensive) and maybe keep it from leaking out quite so much.
Similarly, using hydrogen at partial vacuum would mean having less of it on board, which is sort of good from a flammability point of view. Though on the other hand, it means that if the skin is ever broken you'd have outside air mixing very quickly with the hydrogen inside due to the pressure difference. That's probably a bad thing.
For helium especially it might be an effective way to keep costs down (since helium is so expensive) and maybe keep it from leaking out quite so much.
Similarly, using hydrogen at partial vacuum would mean having less of it on board, which is sort of good from a flammability point of view. Though on the other hand, it means that if the skin is ever broken you'd have outside air mixing very quickly with the hydrogen inside due to the pressure difference. That's probably a bad thing.
I haven't seen anyone mentioning cargolifter [1] which was a company in Germany which tried to commercialise the development of a cargo airship (incidentally using helium). They had a lot of press coverage at the time and many shareholders were private investors. They did got bankrupt in 2002, largely because development of an aircraft is expensive and long. Maybe someone needs to excite Elon about it to get sufficient funding.
[1] https://en.m.wikipedia.org/wiki/CargoLifter
[1] https://en.m.wikipedia.org/wiki/CargoLifter
Hydrogen airships are terrible against any kind of attack. They are so slow and flammable that one can bring them down with just a flying toy. I'm not even talking about incendiary ammunition. You would not put people or expensive cargo on a low and slow flying bomb in 21 century.
> Fun fact: pure hydrogen doesn’t burn. It needs an oxidizer—like the oxygen in air.
Airships literally float in that oxidizier!