https://docs.google.com/presentation/d/1r6CPFJ1AX1ZULacguTf6...
https://news.ycombinator.com/item?id=8760732
https://en.wikipedia.org/wiki/High_Altitude_Venus_Operationa...
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.
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
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?
Basically balloon launches would only benefit small sub-orbital sounding type rockets.
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.
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.
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.
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.
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.
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.
So you're saying Jeff Bezos should look into this for Blue Origin since you essentially described his capabilities? ;-)
It's expensive to stay in space because you have to go sideways, really, really fast. 8 km/s fast, in fact.
Nature is enough of a gatekeeper to space, she doesn't need mortal deputies.
Edit:my terrible wording created answers to a different question.
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.
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.
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.
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.
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!
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.
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.
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).
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.
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.
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.
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.
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!)
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
This is actually smaller than i was imagining.
Container ships rarely if ever go that fast. Usually it’s in the 15-18 knots range (aka <20mph) from what I’ve seen.
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.
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.
-
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.
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.
They are more comparable to ships, trains or cars. And here their inefficiency is very bad.
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.
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.
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.
Propellers far away from passengers to minimize any noise.
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
> 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