xkcd #3298: Aerospace Flowchart

Title text:

Someday, we will find the problem that goes with this solution.

Transcript:

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Source: https://xkcd.com/3298/

explainxkcd for #3298

Someday, we will find the problem that goes with this solution.

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[–] 32 points 1 month ago (1 child)

I feel like you're ignoring how cool massive airships are

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  • [+] 25 points 1 month ago* (last edited 2 weeks ago)
    [–] 14 points 1 month ago

    But how do we convince investors to fund huge airship hangars in low density regions? They need adventure pools too, you know?

    Tropical island adventure pool

    Wiki link

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  • [–] 14 points 1 month ago (15 children)

    But what if the problem is that you want to be able to hover in one place and lift stuff without having to continuously spend energy on enough thrust to push that weight upwards?

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  • [–] 6 points 1 month ago (12 children)

    Lifting stuff with an airship is surprisingly terrible.

    Why?

    Our old arch nemesis, physics....

    The problem is not that you can't build an airship that can lift say ten tons of cargo.

    The problem is what you do when you remove the cargo from the airship.

    Without the cargo, the airship will be ten tons light, you would need to make sure you could hold it down against a lifting power of ten tons.

    Ok, so let's just fill it with water on the return journey, easy!

    How would you do that in sync with removing cargo, the cargo which probably is a cargo container, and is just disconnected, you can't just suddenly move ten tonnes of water onboard the airship, it takes time to fill up.

    Ok so you get another container with a dummy load to enable a simple connect disconnect at the loading dock, fine that would work, apart from what you would do when the next load arrives, do you just manufacture dummy loads and take them back to the start, how do these get back to the other side where they are needed, and why don't we use the same method to move the initial cargo?

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  • [–] 2 points 1 month ago (3 children)

    Vacuum the lifting gas out of the giant balloon into some storage tanks to compress it and use some smaller balloons as a tiny giant airship to transport the apparatus back?

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  • [–] 1 point 1 month ago (2 children)

    You need the lifting gas to fill out the envelope and maintain structural integrity, a floppy envelope isn't amazing at control

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  • [–] 2 points 1 month ago (1 child)

    Maybe some balloon animal structures inside the balloon to give it a shape?

    I started off being a bit silly, but this question is serious. If you had a magic material that was rigid and could maintain that inflated shape for the same weight as the current material they use, could you selectively change its buoyancy by vacuum? Don't submarines and fish with their swim bladders do the same thing? That would make it a materials problem correct?

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  • [–] 3 points 1 month ago

    Ok, say you have an extremely lightweight yet strong material that you could make a large vacuum chamber out of. It would be quite effective as a lifting device.

    And as you note, regulating the pressure inside with bladders would enable you to adjust the buoyancy, this is actually a system that the modern Zeppelin NT uses, though not for adjusting lift in response to loading/unloading, more as a general setting for the area and air pressure.

    The NT is usually calibrated to weigh about 300kg and uses movable propellers to move up/down and relies on the airfoil shape of the inflated envelope to generate the tiny amount of lift to stay up while moving forward.

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  • [–] 2 points 1 month ago (3 children)

    Ok so you get another container with a dummy load to enable a simple connect disconnect at the loading dock, fine that would work, apart from what you would do when the next load arrives, do you just manufacture dummy loads and take them back to the start, how do these get back to the other side where they are needed, and why don’t we use the same method to move the initial cargo?

    If you just have a tank for the water, you could just fill it before unloading.

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  • A few solutions I could think of right off the bat:

    • A logistical network so that not every A-B path has to be a net-zero-mass trip, only the nodes - reduces dummy load requirement
    • Mass congestion pricing to help balance out the nodes
    • Large water bags, send them back empty
    • One-way airship travel tourism, brings extra revenue and publicity as a plus
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  • [–] 2 points 1 month ago*

    How would you do that in sync with removing cargo, the cargo which probably is a cargo container, and is just disconnected, you can't just suddenly move ten tonnes of water onboard the airship, it takes time to fill up.

    A cargo container of water? You're literally throwing your hands up at the smallest issues and pretending you hit mount everest.

    Not to mention there's no requirement the weight has to stay the same. Inflating and deflating the balloon controls the buoyancy.

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  • [–] 1 point 1 month ago

    As I always say: Physics knows no favours and no bosses.

    Boss wants me to do something that physic doesn't allow? I laugh at him for his hybris. No, won't work, because... See first line of this comment.

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  • [–] 13 points 1 month ago

    We should do it anyway, just to be sure.

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  • [–] 12 points 1 month ago (6 children)

    Last month I went on a Zeppelin ride, there are some tasks that airships do well. Tourism tours, long term temporary monitoring, some specific geo surveys and advertising.

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  • [–] 6 points 1 month ago

    High altitude airostat balloons have also been considered as a superior alternative to satellites for some applications due to lower ping and greater resistance to solar activity. Unfortunately it turns out its also harder to make a long lasting high altitude balloon with consistent positioning than it is to launch something into space.

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  • [–] 9 points 1 month ago (3 children)

    I find it hard to believe that there are problems you can't solve with giant airships.

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    [–] 7 points 1 month ago (3 children)

    Could we put an airship in Venus's atmosphere? It seems like it'd be more useful than sending something to the surface, but I know nothing about the engineering involved.

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  • [–] 4 points 1 month ago (2 children)

    For a short time, maybe. Until it is shred to pieces or dissolved by the atmosphere I would guess. But I'm not an aerospace engineer. :)

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  • [–] 4 points 1 month ago (1 child)

    No, it's actually kind of an idea that people have thought about. The upper atmosphere on Venus is a kind of OK environment and because of the thick atmosphere, it's even easier to float there than on earth. The trouble really starts when the acid clouds begin.

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  • [–] 7 points 1 month ago

    I studied aerospace engineering. Can confirm

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  • [–] 6 points 1 month ago

    What about huge underwater submersibles ?Won't someone think of the captains obsessed with the cleanliness of sheets?

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  • [–] 5 points 1 month ago

    I noticed the lack of a 'Yes' flow.

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  • [–] 5 points 1 month ago (10 children)

    I find it odd that the answer is ALWAYS no. Surely at least one problem has been solved by building giant airships.

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  • [–] 2 points 1 month ago (8 children)

    Airships are the most expensive, worst and most dangerous solution to any problem.

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  • [–] 4 points 1 month ago* (7 children)

    i disagree. you could build catamaran-style airships.

    that sounds far more expensive and more dangerous.

    not worse though, that sounds way cooler.

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  • [–] 2 points 1 month ago (6 children)

    Building a worse airship is still building an airship.

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  • [–] 1 point 1 month ago (5 children)
  • [–] 2 points 1 month ago (4 children)

    And name them Akron and Macon.

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  • [–] 1 point 1 month ago (3 children)

    i was going to name them after match companies but i like your idea

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  • [–] 2 points 1 month ago (2 children)

    Oh you must be European, if you're concerned about fires aboard airships. American airships don't burn; we've never been stupid enough to use hydrogen as a lifting gas. USS Akron and USS Macon both crashed, much of the crew of one froze to death and the other proved surprisingly survivable. Compare that to the Hindenberg or R-101.

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  • [–] 1 point 1 month ago* (1 child)

    No we use good old fashioned methane yes sir patented blimp gas here

    I have spent the last year trying to find copies online of a musical some friends wrote while I was in college. It's called Hindenburg: Oh the Humanity!

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  • [–] 4 points 1 month ago*

    There is hope though:

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  • [–] 2 points 1 month ago

    sadly there is no yes line in first triangle of flowchart.

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  • [–] 2 points 1 month ago

    pretty please?

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  • [–] 1 point 1 month ago
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