The Guardian: Thousands march in Cuba in rare mass protests amid economic crisis

[jim bell]

 On Sunday, July 25, 2021, 01:17:03 AM PDT, grarpamp <grarpamp at gmail.com> wrote:
 
 On 7/24/21, jim bell <jdb10987 at yahoo.com> wrote:
>> The balloon could use hydrogen. [1]
>> day electrolyzing

>That's two fun energy sources (H + solar), plus buoyancy.

>If tethered then you're not spending much if any energy
on stationkeeping, only on keeping the RF gimbal
aimed at a target, or none if using omnidirectional-RF.
If not tethered then you have a lot of energy expense
just to keep in range of target.

I see no need at all to do station-keeping.  The balloon could simply detect its GPS location, and using that re-calculate what its optimum aim for the antenna(s).  The people 'watching' the microwave signal would see only a slight change in azimuth., presumably not enough to require them to re-aim.   

>Are liquid hydrogen tanks light enough to replace
their weight with gas volume then jettison?
No, that's totally impractical.  That's why I suggest creating new hydrogen,  in gas form, storing it into the huge balloon, and using a bit of it, at night, to generate electricity in the fuel cells.  I've never worked with fuel cells, but I believe it's fairly simple, because the components already exist.  

>Not much altitude is needed to reach out 12NM
with any system, so your tether might also carry
whatever you need.

> The water could be obtained by dessicating it out of the
> atmosphere with a deliquiescent dessicant, perhaps concentrated sulfuric

>Reagents and catalysts would need refilled too.
I don't think so.  The article says that the lifetime of the balloon would be relatively short, was it 7 months?  The dessicant (I proposed concentrated sulfuric acid) wouldn't evaporate, so it would never run out.  The catalysts in the fuel cell would be essentially permanent for the life ot the balloon's million.  

>See about making water from atmosphere via
free sun/shade/dewpoint condensation methods.
I assume the altitude will be about 40-50,000 feet.  

>Solar-day battery-night powered planes already exist,
but they cost a lot more than simple balloons.
solar powered 24hr plane at DuckDuckGo
That's one reason to use a hydrogen-filled balloon, doubling for life and fuel-cell fuel storage.  


>If you're already hanging out at 12NM with a tether
or base station, surely you can also just run whatever RF
system you want from the boat deck that will cover that
distance, no balloons or planes needed, assuming your
target has matching RF gear.
I don't see an obvious need for a boat.  just an anchor.  One big reason is that any boat would stick out by radar, directing the enemy  Cuban military  to try to cut the tether.     I think that there could actually be multiple tethers, maybe even 5, tied together at perhaps 5,000 altitude, and each anchored at perhaps a mile apart, so that if one gets cut by a passing plane, the rest will take over the function.  



  
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