Airships would be good for freight. Far less carbon footprint than airplanes.
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?
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.
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
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.