The need to maintain relative station keeping without the need for tethers or propulsion was one of the hallmarks of Loon tech.
On Sun, Jul 25, 2021, 9:40 AM jim bell <[email protected]> wrote: > On Sunday, July 25, 2021, 01:17:03 AM PDT, grarpamp <[email protected]> > wrote: > > On 7/24/21, jim bell <[email protected]> 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 > <https://duckduckgo.com/?q=solar+powered+24hr+plane> > > 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. > > > >
