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It would be cool if this entire planet could use zeppelin roadways instead of tarmac roads. Especially for countryside transport away from cities. A zeppelin for one person is about the size of a lorry, and with future materials, we can have fold-up, safe zepellins, with safety sensors, weather prediction, solar conversion. Negative buoyancy air transport will always use noisy big engines and fall down too fast, too noisy to replace cars and would disturb the forests.

Can zeppelins replace cars one day?

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  • $\begingroup$ I like this. The sail could be built vertically to take up less space, like an inflated sail, and hydrogen is actually way less dangerous than people think. I might make an answer if something else comes to my mind $\endgroup$ – SilverCookies May 21 '18 at 8:08
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    $\begingroup$ We can already build both and have been able to for a long time. Why do think that cars won not by a little bit but by so much that virtually nobody uses blimps to get someplace? Asking this question us kind if like asking if heavy cavalry could make a comeback if there was futuristic armor for horse and rider available. $\endgroup$ – Raditz_35 May 21 '18 at 9:30
  • $\begingroup$ Because the technology wasn't available, and it still isn't, for EV zeppelins... they needed 5x power density of today, and they only had lawnmower-engine blimps. A long time? i.e. cars took over from horses in the 1920s. Today we are seeing the first flying cars. times change. $\endgroup$ – com.prehensible May 21 '18 at 11:31
  • $\begingroup$ I don't think this is worthy of an answer, but I wanted to give you an idea for making this more viable. If the tech has been developed before this world is colonized, they can avoid ever building roads by adopting it. That saves a TON of money and space, and is a BIG plus one for flying vehicles. It's much harder to justify flight when the infrastructure for cars is already built and needing to be maintained. $\endgroup$ – Josh May 21 '18 at 13:17
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    $\begingroup$ "Zeppelins and blimps": isn't a blimp a zeppelin? Is there a subtle difference that I am unaware of? $\endgroup$ – ANeves May 21 '18 at 13:17
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Whilst the sci-fi "sky full of zeppelins" is awesome, I highly doubt lighter-than-air (LTA) craft are going to replace the automobile on a day-to-day transport level. They have several key disadvantages:

  • Helium is really expensive - and only likely to get more so. You could switch to hydrogen, but then everyone is driving around highly explosive pockets of gas. Fun, but no.
  • They are much more vulnerable to weather - even a stiff breeze can severely impact their performance and they have extreme issues in storms.
  • Even though they are fair simpler than normal aircraft, they still take quite a bit of skill to fly reliably, predictably and safely, so you're not going to want Joe Average careening around a city in a Mini-Hindenburg.
  • Things can still go wrong with the balloon, and then you're back to plummeting out of the sky.
  • While a one person blimp may be the size of a lorry, that's still pretty big, and it's not going to have room for cargo or haulage. I can fill my car to the gunnels, then attach a trailer and quite comfortably haul over a ton and a half of stuff, if I don't mind chewing though gas.

That's not to say that LTA craft won't have their roles in futuristic travel.

  • High altitude reconnaissance and experimentation
  • Advertising; the Goodyear blimp is an incredibly successful advert
  • Luxury travel through the skies
  • Weather monitoring - they are still the best at stationary hovering at high altitudes. Can quite happily stay up there for days.

There may also be a role for fast overland bulk transport that could be filled by super-blimps carrying cargo.

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    $\begingroup$ About the first bullet, also car drivers are driving around highly explosive pockets of gas....oline $\endgroup$ – L.Dutch May 21 '18 at 6:44
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    $\begingroup$ Fair enough - but that is in a small, shielded metal compartment underneath the car, not in a giant balloon above their heads. With the possible exception of petrol tankers $\endgroup$ – Chromane May 21 '18 at 6:50
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    $\begingroup$ Explosions are highly controllable, airbags use them in cars with microsecond accuracy. Hydrogen is safe without sparks, ignition temperature is about 500'C? Sparks are easy to contain today. If fusion of hydrogen is attained, it will supply very much He. I was thinking about rural travel, over forests and mountains, where roads are expensive and disruptive. There are already hydrogen tanks in cars. falling from the sky is fine with a graphene-spidersilk parachute and impact airbags. The hydrogen "pocket" can have 2-3 spidersilk strength walls and can be "cellular" and sealed. $\endgroup$ – com.prehensible May 21 '18 at 8:09
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    $\begingroup$ I think people are getting confused as to the differences between Petrol/Gasoline for cars, and hydrogen gas for airships... Petrol/Gas has a chemical potential energy of 45.8 MJ/KG and requires more than just a simple spark to ignite, does not burn well as a liquid and needs to vaporize before it becomes really really flammable. that's for cars... Airships will need this as well to power the engines, but will also need hydrogen gas has energy density between 120 and 143 MJ/KG dependent on compression, airships have a much higher potential to explode then a car $\endgroup$ – Blade Wraith May 21 '18 at 9:49
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    $\begingroup$ If its going to be luxury of tomorrow, it will be norm of the day after tomorrow. $\endgroup$ – Communisty May 21 '18 at 12:27
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We have more than 100 years of zeppelins under humanity belt. We made quite a technology leap with materials. Yet there are no smallish ones filled with hydrogen. And hydrogen is so easy to get that we have car engines producing it in cars that use hydrogen.

EDIT - why use Hydrogen and not helium. Helium is produced from natural gas. So in a plant that need to bottle it up and ship. Kind like fuel but you can drive on one gallon of fuel while you cannot fly with only one gallon of helium. You need to fill blimp to the brim. So no folding-up, either it need to stay blowed or you need to park next to station. Hydrogen can be made from glass of water. You know, the stuff that fall from sky. Taken that whole world helium production would suffice for 6 millions "uses" of lorry size blimp, ignoring other needs for helium, It's quite small compared to other means of transportation. Also helium have around 8% smaller buoyant lift.

Now for the math:
Cubic size of lorry - 30,10 m^3 (Vauxhall/Opel Monavo).
Gross buoyant lift of hydrogen 1,1399 kg/m^3

That give you 34 kilograms of lift. Even when you neglect the weight of blimp itself (assume the material and engine as 0) all you could carry is small child.

Great for late term abortion, not so good for traveling.

Also the size of the lorry is the size of the lorry. That equal 3 regular city cars. Equip those three cars with same hydrogen plants and you have very cheap means of travel that don't go sideways when wind blows.

I just had a vision of tragic yet hilarious balloons that go up in the air and bop each other in the air. Like a slow motion pinball.

Also for hot air balloon requirement for the balloon to take of are

In brief, the perfect weather conditions our hot air balloons need to fly are: ◾Dry ◾Good visibility ◾Light winds of less than 10-12 miles per hour.

Now TA in radio are "the roads are slippery, be careful". With blimps, it would be "the wind is 15 mph so stay home and don't travel"

Extra science. From this paper about fuel economy hydrogen engines take around 70 miles per gallon. From this conversion table one m^3 of hydrogen is 2,9 gallons. So what would you take 30 m^3 just to have the blimp would equal 2100 miles/3380 kilometres on the road. So a trip from New York to Chicago through Columbus and Indianapolis and back.
Or Chicago - Denver twice if you want that countryside transport.

So to quote some old guy from 1880 about flying balloons shaped like cigars:

It will never stick. Carriages without horses are the future.

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    $\begingroup$ Why are you talking about hydrogen engines? $\endgroup$ – Communisty May 21 '18 at 12:23
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    $\begingroup$ Lift-per-passenger is a key problem, and I'm glad you brought it up. A family blimp's lift must be very different on the trip to the grocery store if, say, one of the kids decides to go along (and different again for the weight of the groceries!). And it must vary quickly if an errand involves adding/dropping a family member or cargo. $\endgroup$ – user535733 May 21 '18 at 12:24
  • $\begingroup$ @communisty because you need fuel to turn the fans to navigate a zeppelin, and for that you need a lighter-than-air fuel (otherwise you’re making the problem of carrying capacity worse). $\endgroup$ – SRM May 21 '18 at 12:59
  • $\begingroup$ @Communisty Because hydrogen lift more than helium. And hydrogen cells can produce this element on demand, so along OP idea of using blimp, folding it and then filling again with gas when needed. $\endgroup$ – SZCZERZO KŁY May 21 '18 at 13:01
  • $\begingroup$ This was almost point for point the response I was going to give. Heck, even the snark was pretty close to what I was thinking. $\endgroup$ – ShadoCat May 21 '18 at 18:11
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It would be cool if this entire planet could use zeppelin roadways instead of tarmac roads.

I agree with the cool factor! However, the problem is with the where. It isn't likely to happen in our planet's future, because dirigibles have terrible density. If anything, our world's future will probably see more boxy city cars.

However, there is another way. Humans have demonstrated the ability to breathe gas mixes that are about 6 times denser than air at atmospheric pressure, and function continuously. More than 6x increases the work of breathing too much for our physiology. This has been demonstrated in technical and commercial diving and the Sealab experiments.

A planet with 6x the atmospheric density would make LTA craft about twice smaller in every dimension - the volume improvement is better than 6x due to improved structural efficiency. If you want to create a world where LTA transport is more feasible, try looking in that direction.

The abundance of room, the lack of legacy infrastructure (we still use some Roman roads), low population density, and possibly difficult terrain on a colonized planet would also work strongly in LTA crafts' favor. Colonization is likely to focus on the most favorable region, making flight distances short enough for LTA. Adding a lack of fossil fuels could be the tipping point - kerosene is very convenient for heavier-than-air craft, while dirigibles are easy and practical to electrify.

P.S. Keep in mind that real-life air traffic is anything but unregulated. The planes mostly fly alongside designated airways and air corridors, on predefined flight levels, maintaining a lot of separation. That's what it takes, with ATC assistance, to keep just the 23,600 commercial and ~400,000 other aircraft in the world right now from colliding. Think for a moment about how small that number is for a 7-billion planet.

Airway map example

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  • $\begingroup$ Your edit suggests that the air is so full of aircrafts that more will not fit. Do you have any sources that would back up this claim? $\endgroup$ – Communisty May 21 '18 at 14:20
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    $\begingroup$ That's not what I'm saying. More certainly will fit - just keep in mind that the airspace is quite congested over large cities as it is. A number as high as 1,000 times more would be... Difficult to imagine. One thing I know for sure is flying won't be the same anymore. It would have to get A LOT more regulated. And that's another thing I have trouble imagining. $\endgroup$ – Therac May 21 '18 at 15:04
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    $\begingroup$ @Therac There would have to be quite a few more "skyways" (pre-defined lines where everyone flying at a certain altitude would be going the same direction at basically the same speed to allow ATC to switch from being "cops at intersections directing traffic" to more monitoring for exceptions from the rules and getting those corrected ASAP. Having flights 100% pre-planned (with allowances for developing weather conditions forcing changes en route) so that an autopilot could keep you locked to that precise route and timing would be an absolute necessity. $\endgroup$ – Monty Harder May 21 '18 at 17:55
  • $\begingroup$ That's along the lines of how I imagine it. Way less freedom than we enjoy now in class E airspace. Actually likely to resemble traffic along a complex system of highway interchanges, but with the patterns stretching dynamically in one direction or the other to account for wind conditions. $\endgroup$ – Therac May 21 '18 at 18:11
  • $\begingroup$ @Therac, one way to deal with the regulation is to ban heavier than air craft. That way, when the wind blows and all the blimps go careening East like a flock of birds, there won't be any aircraft to get in their way; just blimps that can bounce off of each other. $\endgroup$ – ShadoCat May 21 '18 at 18:15
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IMHO Zeppelins and blimps are too large and not good replacements for single family cars but could possibly be good replacements for railroads, intercity buses, airplanes, ocean liners, container ships, trucks, etc. under the right circumstances.

Possibly hybrid vehicles combining zeppelin and airplane characteristics, or zeppelin and helicopter characteristics, or zeppelin and ground effect vehicle characteristics, may be the way to go.

If fusion power becomes practical in small, lightweight generators, then plain air or common gases from the atmosphere could be heated up to become as light as hydrogen or helium, making hot air Zeppelins practical.

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You couldn't replace cars with blimps and leave everything else the same.

I'm assuming in here we have an infinite source of some light, safe material, and a sufficient source of energy to power them.

They are too slow for country travel. They take time to get ready for takeoff, get to altitude and get to maximum speed. So a car would be a long way ahead when the blimp gets to max speed. And the car would continue to get further ahead - a non rigid airship has a maximum speed of around 95 km/h. I doubt we can actually get much faster than that without going to rigid airships, which then introduce problems of parking and storage. Plus then time to land and park the blimp at the end. Perhaps in very poor terrain a blimp could be justified, but on a relatively flat, straight road, the car would be vastly superior.

Congestion would be crazy for city travel. Sure, being able to have vertical lanes would cut down on congestion during the commute, but parking will be hell. A CBD (downtown) area might have a million workers coming in from the suburbs. Lets say that it takes 10 minutes to land, fold your blimp and clear the landing area (for context, I can't even take down and pack away a 2 person tent in 10 minutes). In order to get everyone landed within 3 hours, you need 1,000,000/180*10 landing pads suitable for a zeppelin. That's just over 55,000 landing pads in the center of the city. Assuming each landing pad is 10 meters by 10 meters (100m^2), then this would be 5.5 km^2, or 80% of the area of Melbourne (Australia) CBD as landing pads.

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As the other answers suggest there are many downsides to be conquered in one person zeppelin travel and other means of transportation that will be more reliable and easy. But there is a niche for it if some problems are solved. First the ideas that you present: fold up and solar conversion are crucial as they solve a few problems.

A fold up system would eliminate the need of large hangars or garages where to store the zeppelin when not in use: you could simply unfold it in your backyard and your destination backyard when not in use in case a storm comes and tries to steal your blimp. The lifting gas should be helium, since hydrogen is flammable (for safety), and could be pumped in a pressurized gas container when folded. The folding would be achieved by building the hull from hydraulic components.

The power source would be solar and lightweight solar film would cover most of the surface area. The energy would be stored in a battery while electric engines would provide the thrust to move. This would allow for electric charging when the zeppelin is not in use/folded.

The downsides would be unability to carry heavy cargo, slow movement speed and vulnerability to weather. The upsides would be zero emissions, nice view and no traffic (traffic in highways might be the driving forces to develop personal flying transportation). A competitor would be a drone type helicopter capable of carrying a person. That would be faster than a zeppelin, but limited to shorter distances since it can't use solar on the go and uses energy also to keep the vehicle up.

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  • $\begingroup$ Cool, I agree, I'd say that helium is a limited supply element, many scientists worry that using it for leisure bay deplete the world reserves of it. I know the USA has a bunker of thousands of barrels of it for safekeeping. $\endgroup$ – com.prehensible May 21 '18 at 13:13
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    $\begingroup$ I gave folding a thought, but it takes a lot of energy and hardware to compress the gas for storage every time. The size of zeppelins would also lead to quite a bit of traffic along the air corridors (necessary to manage the flow). $\endgroup$ – Therac May 21 '18 at 13:14
  • $\begingroup$ @Therac there could be an autopilot in every zeppelin that talk to each other to avoid collisions. There would definitely be orders of magnitude more space than in roads. You could travel straight towards your destination always and even use multiple flying levels. $\endgroup$ – Communisty May 21 '18 at 13:23
  • $\begingroup$ There's more space, but you also need far more separation in the sky than on a road. Real-life commercial aircraft follow predefined airways and FL under ATC control so as not to collide (except every now and then). Zeppelins aren't as fast as fixed-wing, but the consequences of a "fender bender" are much more severe for them than for cars. $\endgroup$ – Therac May 21 '18 at 13:52
  • $\begingroup$ I agree that there should be more safety distance between in air. Therefore the actual size of the zeppelins isn't the main limiting factor. $\endgroup$ – Communisty May 21 '18 at 14:09
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Since we're talking future tech here with a foldable zeppelin... If the structure were strong enough to withstand atmospheric pressure your lifting gas could be a displacement bubble full of nothing.

You unfold your zeppelin, you have a big hard shelled 'balloon' full of atmosphere. You pump the atmosphere out, leaving less and less air volume until you have the buoyancy you want, and off you go.

Vacuum is light, safe, non flammable, and infinitely renewable with nothing more than a pump. All you have to do is make a very light, very strong structure that can push back against 14psi of atmospheric pressure.

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For terrestrial applications, light-than-air craft are not practical for routine short-range travel. On other planets with the right kind of atmosphere, however, they might work much better. In atmosphere of sulfur hexafluoride at terrestrial standard temperature and pressure, for example, the volume of gas required to achieve a given amount of lift would be about 80% less than on Earth, and if atmospheric pressure were e.g. twenty times that of earth, that would offer another 95% reduction. If the atmosphere contained the right percentage of oxygen, humans could probably become acclimated to breathing such it directly, and shrinking lighter-than-air craft by 99% would bring them near the point of practicality. Even at that reduced size they might not be 100% practical, but the amount of handwavium necessary to fix that would be less than with terrestrial vehicles.

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