New aircraft rises 'like a balloon' • Hacker News Board

Re: New aircraft rises 'like a balloon'

#71

Post by 0db532a0 » Thu, Apr 25, 2019, 8:39 AM UTC

TimTheTinker wrote: post #63

0db532a0 wrote: post #39

Earlier quoted context omitted.

That is an interesting idea, and I don’t know why this has been downvoted.

Sounds kind of ludicrous to propose switching from helium to hydrogen in flight to save on the cost of helium. You’d still have to buy the helium (how else does it get off the ground?). Probably more if you intend to safely bring it back down.

The idea I got was that for long-term flights, the helium would be used for launch, and lost helium would be replaced with hydrolysed hydrogen. Doesn’t sound too unrealistic.

Re: New aircraft rises 'like a balloon'

#72

Post by lawlessone » Thu, Apr 25, 2019, 9:05 AM UTC

astazangasta wrote: post #21

lawlessone wrote: post #16

Earlier quoted context omitted.

To add to your Idea, could a "null ship" be carried to a greater height and then where the air is thinner have it's gas removed to take everything a little higher? Like rocket stages but for airships.

At a greater height you need a larger airship to provide the same lift. As you move towards the vacuum of space and the differential becomes less the lift per unit volume is less.

aww :(

Re: New aircraft rises 'like a balloon'

#73

Post by salawat » Thu, Apr 25, 2019, 1:55 PM UTC

gnode wrote: post #30

Rerarom wrote: post #25

Earlier quoted context omitted.

What about helium?

Helium is expensive and practically non-renewable on Earth. It forms slowly by beta decay, with most of it escaping into space (because it's molecular mass is so low, its velocity commonly exceeds Earth's escape velocity). A small amount gets trapped in deposits which we can extract.

Hydrogen will have issues supply-wise if we kick into industrial scale processes with high loss rates without some way to ensure the gas recombines with Oxygen to precipitate as water again. Which at the operating heights being suggested, would be problematic. Furthermore, what about all that waste Oxygen from Hydrolysis?

We already run into issues with water without cracking water vapor and venting hydrogen into the atmosphere at scale. I shudder at the thought of unconstrained industry being cut loose with the idea that we have an essentially limitless supply without sitting down to really figure out the numbers.

Never mind the maintenance issues. High levels of electrical generation/storage +volatile gas generator? What could possibly go wrong? Hydrogen embrittlement, high level of oxidative stress, increased radiation exposure...

Mean-time-to-failure is not giving the magic 8 ball warm fuzzies. Could be super neat for meteorological/astronomical purposes/reconnaissance purposes though.

I can see the international incidents rolling in now.

"North Korea protests American Weather Baloons"

"Russia introduces new anti-balloon laser"

"China threatens Taiwan over balloon based infrastructure"

Unfortunately, I wouldn't put it passed ad companies to utilize this "exciting new breakthrough in audience outreach" as well.

I'd really like to look at this kind of stuff how I used to as a kid again. Too much time in the tech industry has absolutely ruined my outlook however.

Re: New aircraft rises 'like a balloon'

#74

Post by TimTheTinker » Thu, Apr 25, 2019, 3:32 PM UTC

0db532a0 wrote: post #71

TimTheTinker wrote: post #63

Earlier quoted context omitted.

Sounds kind of ludicrous to propose switching from helium to hydrogen in flight to save on the cost of helium. You’d still have to buy the helium (how else does it get off the ground?). Probably more if you intend to safely bring it back down.

The idea I got was that for long-term flights, the helium would be used for launch, and lost helium would be replaced with hydrolysed hydrogen. Doesn’t sound too unrealistic.

That makes sense, thanks. I apologize for my acerbic ignorance in the above comment.

Re: New aircraft rises 'like a balloon'

#75

Post by gnode » Fri, Apr 26, 2019, 2:17 PM UTC

salawat wrote: post #73

gnode wrote: post #30

Earlier quoted context omitted.

Helium is expensive and practically non-renewable on Earth. It forms slowly by beta decay, with most of it escaping into space (because it's molecular mass is so low, its velocity commonly exceeds Earth's escape velocity). A small amount gets trapped in deposits which we can extract.

Hydrogen will have issues supply-wise if we kick into industrial scale processes with high loss rates without some way to ensure the gas recombines with Oxygen to precipitate as water again. Which at the operating heights being suggested, would be problematic. Furthermore, what about all that waste Oxygen from Hydrolysis? We already run into issues with water without cracking water vapor and venting hydrogen into the…

I'm not exactly sure what it is you're decrying. That we'll lose a significant quantity of Earth's hydrogen to space, leaving the atmosphere with too much oxygen? That we'll suffer a water shortage because we're using too much of it to make hydrogen? That nations will increasingly ignore other nations' aerospace sovereignty because balloons are filled with hydrogen instead of helium?

Hydrogen is still expensive to split from water, and the quantities required for deleterious effects to present are so high, that these are really distantly hypothetical "what ifs".