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.
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:
(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.
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.
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.
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.
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.
> 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.
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.)
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?
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.
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).
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.
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.
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.
IIRC some military airships condensed water from their their engine exhaust to keep better control over their balance (the ship otherwise gets lighter as you burn fuel and you might have to release some of the irreplaceable lifting gas instead).
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.
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.
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.
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.
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.
-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!)
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.
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
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.
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.
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.
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?
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.
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.
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.
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.
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.
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?
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.
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?
- 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.
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.
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.
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).
> 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.
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.
>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.
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.
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.
