Someone should post the ballooning guys blog. He used metal balloons that stayed afloat for days and went around the world.
The US military is testing stratospheric balloons that never have to come down
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Re: The US military is testing stratospheric balloons that never have to come down
#12How do these balloons change their altitude? Is there a pump that can move gas between the balloon and a pressurized container?
At least at loon, the balloon has a ballonet that takes on atmosphere as ballast for descending.
Re: The US military is testing stratospheric balloons that never have to come down
#13Don't balloons expand in the day and contact at night a bit due the sun heating the gas inside? Couldn't this stretch/release weaken the material a little and result in potential gas leaks? To counteract this, I recall reading about people trying to send balloons across the Atlantic and needing to use ballast to stabilize the altitude and handle the gas losses. I wonder how DARPA can go without this requirement, as H…
Maybe the balloon could condense water in its environment and electrolyze it to refill itself with the produced hydrogen. (Though I'm pretty sure you also need salt.)
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Re: The US military is testing stratospheric balloons that never have to come down
#14From reading the actual article, the headline sounds dramatically overblown. It largely talks about a system to measure non local wind speeds so the balloon can adjust altitude to use the wind for navigation (including standing still). It seems to largely leave out any questions I'd have around confining helium or whether power equilibrium can be achieved.
> "overblown"
Ha!
Re: The US military is testing stratospheric balloons that never have to come down
#15The article fails to mention these are called "superpressure" balloons in case you're interested in reading more about them: https://en.m.wikipedia.org/wiki/Superpressure_balloon There are some fantastic amateur projects doing similar things, such as this 11 gram payload (!) that circumnavigated the earth 6 times: http://leobodnar.com/balloons/B-64/index.html
So the "never have to come down" is ~100 days record which is held by project Loon?
Re: The US military is testing stratospheric balloons that never have to come down
#16The article fails to mention these are called "superpressure" balloons in case you're interested in reading more about them: https://en.m.wikipedia.org/wiki/Superpressure_balloon There are some fantastic amateur projects doing similar things, such as this 11 gram payload (!) that circumnavigated the earth 6 times: http://leobodnar.com/balloons/B-64/index.html
So the "never have to come down" is ~100 days record which is held by project Loon?
~6 months is the current best, actually. [1] This is a development project; there's no reason to assume that the current record is a hard limit.
Re: The US military is testing stratospheric balloons that never have to come down
#17Amateur ballooning blog http://www.leobodnar.com/balloons/
Re: The US military is testing stratospheric balloons that never have to come down
#18To my knowledge, there has been one successful SPB scientific payload that made it across the Pacific. SPB-EUSO was less successful...
Re: The US military is testing stratospheric balloons that never have to come down
#19The article fails to mention these are called "superpressure" balloons in case you're interested in reading more about them: https://en.m.wikipedia.org/wiki/Superpressure_balloon There are some fantastic amateur projects doing similar things, such as this 11 gram payload (!) that circumnavigated the earth 6 times: http://leobodnar.com/balloons/B-64/index.html
my interest was piqued, but the wikipedia page is actually quite substandard compared to other articles on wikipedia: while it does explain the problem of non SPB and the requirement to have a SPB, it does not state how this is arranged for: are they literally using a much higher pressure? apart from weight issues of stronger sking, so assuming the same weight for a stronger skin, doesn't this cause the balloon to be heavier (since more gas in the same volume) such that it has a lower ceiling? or is that the design tradeoff?
Re: The US military is testing stratospheric balloons that never have to come down
#20I read a lot of books about the US involvement in the middle east, specifically Iraq, Afghanistan and Pakistan.
These persistent, balloon based "eyes on the sky" are/were a huge difference maker in the security in Iraq, and were then transferred to Afghanistan to provide US military base security.
I don't have a link handy (I'll try to find), but I remember as attention was re-focused on Afghanistan (after Iraq) those in charge were eager to bring this successful tech to the battlefield as it offered them a 360 degree, real time tracking ability for immediate base security.
Edit: I found a link, not my source but it gives some background: https://www.nytimes.com/2012/05/13/world/asia/in-afghanistan...