Bring back hydrogen lifting gas
thecgo.org
thecgo.org
> 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
You wouldn't be able to put many of those under an airship, hence you'd need a lot of rather space-hogging airships.
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.
Container ships rarely if ever go that fast. Usually it’s in the 15-18 knots range (aka <20mph) from what I’ve seen.
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 is actually smaller than i was imagining.
Seems not a realistic option to replace container ships, but might be realistic for specific use cases.
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
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!
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.
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
A cargo airship drone remotely controlled would get rid of most of the non-cargo mass requirements.
1: https://www.sciencedirect.com/science/article/pii/S259017451... 2: https://arimotravels.com/how-long-does-it-take-a-cargo-ship-...
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)
> 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.
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
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.
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.
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.
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?
(Presumably that same drag will cause problems for the structural integrity of the airship, too.)
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?
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.
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.
So what conditions other than unestablished areas make airships better than sea ships?
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.
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.
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.
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?
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.
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...
- 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.
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.
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.
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.
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).
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.
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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.
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.
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.
Storms are no danger for airships.
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.
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?
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
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.
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.
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.
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.
They are more comparable to ships, trains or cars. And here their inefficiency is very bad.
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.
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).
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.
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.
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.
In the case of hauling gensets around, that would basically make it a fully self-contained power plant.
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.
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.
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?
Loved that line. Puts the Branson/Bezos thing into perspective.
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
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.
It's expensive to stay in space because you have to go sideways, really, really fast. 8 km/s fast, in fact.
Basically balloon launches would only benefit small sub-orbital sounding type rockets.
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.
Station keeping may be used to dampen oscillations, but managing climbing rates works just as well.
Not arguing, just curious. It's been at least a decade since I've messed with orbital mechanics.
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.
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.
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.
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.
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.
So you're saying Jeff Bezos should look into this for Blue Origin since you essentially described his capabilities? ;-)
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.
So already a solved problem
2. Adaptive rocket nozzles are a thing.
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.
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.
Edit:my terrible wording created answers to a different question.
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)
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.
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.
Nature is enough of a gatekeeper to space, she doesn't need mortal deputies.
I think they fell out of use as high altitude jet aircraft became more common and economical as a launch platform.
https://www.zero2infinity.space/bloostar/
Of course, you still have to accelerate to orbit, but you don't have to deal with the atmosphere.
Propellers far away from passengers to minimize any noise.
https://docs.google.com/presentation/d/1r6CPFJ1AX1ZULacguTf6...
There is a number of trips that a slow and quiet trip would make for great fun.
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.
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.
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.
So a same size blimp could give more room. And why not just build bigger blimps.
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.
This is truly fascinating. I didn't know that.
https://news.ycombinator.com/item?id=8760732
https://en.wikipedia.org/wiki/High_Altitude_Venus_Operationa...
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.
Glad you like the aerial airstrip
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.
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.
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.
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.
Aerial platforms would be great for telescopes and helicopters, too.
(people would have to be indoors, though above a certain height)
Air nomads.
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
> Fun fact: pure hydrogen doesn’t burn. It needs an oxidizer—like the oxygen in air.
Airships literally float in that oxidizier!
Although I am enjoying the side discussion about monopropellants.
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.
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...
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.
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).
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:
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.
> 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.
And then when scientists do invent new words so they don’t “redefine words out under people” they’re called snobs. Its why burning usually is talked about specifically as combustion if there’s any chance of confusion. For scientists it’s a damned if you do and damned if you don’t situation.
I just think theres room to be precise and I do think it has value. Trying to understand one another can be hard… miscommunication sometimes result in horrible results. And science education and communication to the lay person has been an unsolved problem since antiquity when then Library of Alexandria got burned down by an angry mob.
I still think we can all benefit from talking things over, trying to be open minded and having civil discussions like we’re doing right here. Communicating clearly never seems like a bad thing to me.
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.
I agree I wouldn't call this example combustion (which is typically required to be highly exothermic and therefore not easily reversible), but I believe it is a redox reaction. It's the transfer of electrons from one ion to another, which meets the definition I was taught.
Wikipedia seems to agree, both with my definition of redox reaction [1], and that this is one [2].
[1] https://en.wikipedia.org/wiki/Redox
[2] (See Introduction and History): https://en.wikipedia.org/wiki/Disproportionation
So they (two chemistry PhD students) both agree that it should be possible, but don't have any great examples. They point at disproponation as the right class of reactions (where I got Sn2+ from). They agree that the different ends of a hydrocarbon can react in a redox reaction, but at least for common chemicals it's usually a slow reaction.
For more combustion like examples what I got was "maybe look at peroxides" and "maybe caro's acid" (H2SO5).
I can't find anyone who actually managed to get Caro's acid outside of aqueous solution to explode it (in a reaction not involving water)... so I can't find anyone who is stating authoritatively what would happen if you managed to do so.
I can find plenty of explosive peroxides in literature, but haven't found any that are a simple redox reaction...
Anyways, I'm reasonably satisfied that it should in some sense be possible, even if not practical.
https://news.ycombinator.com/newsguidelines.html
>Eschew flamebait. Avoid unrelated controversies and generic tangents.
But who am I to throw water on your fire?
;)
Monopropellants, that aren't mixtures, exist and "burn" too, high concentration H2O2 for instance.
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.
Sulfur is commonly used as an oxidizer for metal fuels. In the case of gunpowder, that would be the potassium in potassium nitrate.
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 N2Sulfur 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.
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.
Gave a fairly full reply to this over here
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.
> 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".
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
The stochiometric mixture explodes more violently, true. But again, both explode.
Periodic Videos, feat. Destin Sandlin: https://youtube.com/watch?v=qOTgeeTB_kA
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.
Have you thought through this at all?
I could understand if hydrogen balloons were never tried before tech, but you're just gaslighting now.
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 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.
The British anti-zeppelin forces researched this problem and were unable to come up with a method of reliably igniting the hydrogen gas.
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.
He also wrote a book.
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’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”
(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.
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.
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.
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.
It is renewed, by radioactive decay within the Earth, but very, very slowly.
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.
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.
"Rigid airship" is the generic term.
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?
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...
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#...
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 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?
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.
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'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.
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.
Sounds like a recipe for an explosion movie style, yet there aren't any.
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!
》Water vapor is known to be Earth’s most abundant greenhouse gas
https://www.nasa.gov/topics/earth/features/vapor_warming.htm...
It seems like a great fit for...a lot of use cases. (if we can get over some of the storage hurdles)
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...
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.
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
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.
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.
* "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.