Flying Around the World in under 80 Days • Hacker News Board

Re: Flying Around the World in under 80 Days

#21

Post by Trufa » Wed, Feb 04, 2026, 2:43 PM UTC

simonebrunozzi wrote: post #12

Trufa wrote: post #10

Can someone give me some notes on the legality of this?

Perhaps next time read the whole article? > Finally, can it be flown legally? Most of the trajectory can pass over the oceans, but skipping land completely would take too much of a detour, and likely be incompatible with prevailing winds. Although the political climate may be hostile, it is still legal to fly civil craft over other countries.

Perhaps next time be nicer.

I mean, I imagine this being a mess, each country having it's own rules

- maybe it's legal but regulated

- does size matter?

- does it matter when you cross a border?

- do you have to announce?

- does it matter how high you fly it?

- are the International norms?

- are there regulatory bodies?

Re: Flying Around the World in under 80 Days

#22

Post by poulpy123 » Wed, Feb 04, 2026, 2:53 PM UTC

simonebrunozzi wrote: post #12

Trufa wrote: post #10

Can someone give me some notes on the legality of this?

Perhaps next time read the whole article? > Finally, can it be flown legally? Most of the trajectory can pass over the oceans, but skipping land completely would take too much of a detour, and likely be incompatible with prevailing winds. Although the political climate may be hostile, it is still legal to fly civil craft over other countries.

It's legal to fly a civil craft over other countries but it doesn't mean there are no rules. The article touches the subject a bit at the end but doesn't go very much into details so I guess it's either a thought experiment or a planned in a future far enough that it is not relevant yet

Re: Flying Around the World in under 80 Days

#23

Post by cyberax » Wed, Feb 04, 2026, 10:32 PM UTC

cyberax wrote: post #14

Hydrogen containment: you might want to look at topping up hydrogen along the way. Have a small compartment inside the gas bag with lithium shavings and a small servo that can release water into this compartment. You'll get about 1/15-th of the lithium+water mass as hydrogen. So if you want to replenish 1 m^3 of hydrogen at STP (or around 1/8-th of the gas bag volume), you'll need around 600 grams of reagents.

It actually doesn't even have to be a servo. Just have a water container that slowly releases water through a capillary tube/wick into the gas bag, "moisturizing" the gas inside.

Lithium will then scavenge all the moisture from the gas inside the bag, releasing hydrogen in the process.

Re: Flying Around the World in under 80 Days

#24

Post by alexfernandez » Fri, Feb 06, 2026, 9:51 AM UTC

rgmerk wrote: post #20

Hmmm. If, rather than flying close to sea level, you flew at high altitude (above commercial airliners), and kept it relatively small, I suspect that you could do this and no one would notice unless you told them. Though at high altitudes the winds are such that it would be less of an airship and more of a steerable balloon.

At really high altitudes air density goes down quickly; this is good for planes but bad for airships because payloads are reduced. Plus, as you say, winds are really really strong: over 200 km/h. https://earth.nullschool.net/#current/wind/isobaric/250hPa/o...

I have seen many high altitude airship studies trying to hover around, but none have been viable in the end. To go around the world it seems better to just float, as in the comment above: https://news.ycombinator.com/item?id=46881679.