From 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.
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
Bursting is not a goal in itself - it is just a side-effect of using cheap and simple latex or rubber balloons.
You fill the balloon so it has slightly positive buoyancy. As it rises, it encounters lower outside air pressure, and expands to match it. Eventually it will rise to an altitude where the pressure is so low, that the latex is stretched beyond its limits and bursts. Typically at about 40km and about 100x expansion in volume.
To prevent bursting, you need a more complex material that will expand many times at first (to allow the balloon to rise to operating height), but will then stop expanding without breaking.
Or perhaps some sort of venting system that engages at a certain altitude or pressure preventing the ballon from over expanding. Like a hot water tank has a pressure release it the tank gets too hot will vent releasing pressure.
Venting does not work. For a given altitude, there is no amount of helium which will make your craft stable unless the volume of your craft is non-linear with pressure (usually done by having something that stretches to a limit, and then cannot stretch further)
> Loon balloons are helium, and helium gas is famously hard to contain
It's not like there are any better options? The only two practical lifting gases are hydrogen and helium. Hydrogen leaks even more than helium and is flammable, even though it is much cheaper and abundant.
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?
Don'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 Helium really likes to escape whatever it's trapped inside of.
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.)
If a balloon is relatively small, and designed never to come down, would it be such a bad idea to use hydrogen as the lifting gas? We're understandably a little gunshy about using hydrogen after the Hindenburg, but surely we could come up with some safer designs now.
I 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.
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[ 3.2 ms ] story [ 75.7 ms ] threadHa!
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
You fill the balloon so it has slightly positive buoyancy. As it rises, it encounters lower outside air pressure, and expands to match it. Eventually it will rise to an altitude where the pressure is so low, that the latex is stretched beyond its limits and bursts. Typically at about 40km and about 100x expansion in volume.
To prevent bursting, you need a more complex material that will expand many times at first (to allow the balloon to rise to operating height), but will then stop expanding without breaking.
https://sites.wff.nasa.gov/code820/spb_differences_between_z...
[1]https://en.m.wikipedia.org/wiki/Loon_(company)#Timeline
I don't see any way to make a balloon stay up forever unless you have a particle accelerator to manufacture new helium to make up for leakage...
It's not like there are any better options? The only two practical lifting gases are hydrogen and helium. Hydrogen leaks even more than helium and is flammable, even though it is much cheaper and abundant.
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 Helium really likes to escape whatever it's trapped inside of.
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...