15 ms·
At first I thought the kicker was going to be: the gas is helium, it just floats. And then I thought: why is that a joke? Could you save fuel keeping it aloft
by projectramo 9y ago
At first I thought the kicker was going to be: the gas is helium, it just floats.
And then I thought: why is that a joke? Could you save fuel keeping it aloft with a lighter than air gas and just use the fuel to move it around?
- okreallywtf 9y agoI thought of that the other day, wondering how well you could possibly control a hot air balloon (or helium) based drone. My guess is wind forces etc would be extremely difficult to deal with
- andygates 9y agoWith a (very) good weather model, it's possible to change altitude to pick up winds going roughly where you want to go. I don't know if anything does this autonomously - Google's Project Loon is the obvious candidate.
- PatentTroll 9y agoI think you just invented the dirigible?
- projectramo 9y agoHa, yes. I guess another way to phrase the question would be: why don't they use dirigibles to solve extended air time problems?
- mikeash 9y agoDirigibles require huge volumes, because the lifting power of gas is small. Those huge volumes make for a relatively weak, slow, and difficult-to-maneuver craft. A big reason why airships disappeared in favor of airplanes was that airships had a really tough time handling or avoiding bad weather because of these limitations.
- acchow 9y agoI assume huge volumes are also easily detectible?
- mikeash 9y agoSeems reasonable. All else being equal, your radar cross section is proportional to your actual cross section. Plus it's probably easy to spot a blimp with your eyes.
- jp555 9y agoI have a blurry recollection of seeing an aircraft design that was a combination of an airplane and a dirigible. It looked like a poofy manta ray, an inflated rigid lifting body or flying wing. It wasn't quite VTOL & needed a very short runway, but it also gained more maneuverability in flight. Maybe it was too much of a compromise though.
- theophrastus 9y agoPerhaps you're thinking of the infamous 'Deltoid Pumpkinseed'[1][2] ? [1] https://en.wikipedia.org/wiki/AEREON_26 https://en.wikipedia.org/wiki/AEREON_26 [2] https://www.amazon.com/Deltoid-Pumpkin-Seed-John-McPhee/dp/0374516359/ https://www.amazon.com/Deltoid-Pumpkin-Seed-John-McPhee/dp/0...
- cr0sh 9y agoYou mean this one? http://mashable.com/2017/05/24/airlander-butt-plane-successfully-flies/ http://mashable.com/2017/05/24/airlander-butt-plane-successf... There's actually been more than one of these types of aircraft (known as Lighter Than Air - or LTA Aircraft), either as an idea or prototype throughout history.
- astebbin 9y agoCould it be this one [0], or its predecessor [1]? [0] http://www.latimes.com/business/la-fi-lockheed-martin-aircraft-20160308-story.html http://www.latimes.com/business/la-fi-lockheed-martin-aircra... [1] https://en.wikipedia.org/wiki/Lockheed_Martin_P-791 https://en.wikipedia.org/wiki/Lockheed_Martin_P-791
- jianshen 9y agoI wondered why this wasn't applied to suitcases to make them lighter and then common sense kicked in regarding just how much actual helium would be required to lift even an empty suitcase...
- teraflop 9y agoIt's not even an issue of how much helium is needed; no amount of helium will make a typical suitcase buoyant. Filling it with helium at ambient pressure wouldn't produce nearly enough lift, and increasing the pressure would make it heavier, not lighter. What's needed is not mass, but volume.
- Sohcahtoa82 9y agoI feel like you're being deliberately obtuse. I think jianshen meant how big of a helium balloon you'd need, not how much helium you'd have to put inside the suit case.
- lostlogin 9y agoMaking them a vacuum would help better.
- tpeo 9y agoThey are used to solve extended air time. That's what a weather balloon is. If what's bugging you is why lighter-than-air vehicles aren't used for commercial transportation, that's an entirely different issue.
- zeropoint46 9y agoweather balloons are typically not up for that long, 90 or so minutes on average. So I don't think that's solving the extended air time. In fact they are pretty much designed to go up and pop and come back down. Lighter than air in general can be used to solve extended air time, and we're back to dirigibles, not weather balloons.
- NickSharp 9y agoProject Loon seems to be doing fine. They're using balloons to keep equipment aloft for months at a time.
- zeropoint46 9y agosure, but I wouldn't exactly call that a weather balloon.
- tpeo 9y agoWell, I'm disappointed that the majority of their flights are this short. I thought there were some of them which were permanent atmospheric weather stations. But short flight times don't really have to be the case, because it seems that they can fly for extended periods of time: one of NASA's balloons stayed up for 46 days [0]. The US air force also uses balloons as surveillance stations, though I don't know the actual flight time of these [1][2]. JLENS was supposed to stay up for 30 days at a time. [0]: https://www.nasa.gov/centers/wallops/news/supertiger-record.html https://www.nasa.gov/centers/wallops/news/supertiger-record.... [1]: https://en.wikipedia.org/wiki/Tethered_Aerostat_Radar_System https://en.wikipedia.org/wiki/Tethered_Aerostat_Radar_System [2]: https://en.wikipedia.org/wiki/JLENS https://en.wikipedia.org/wiki/JLENS
- exhilaration 9y agoThe U.S. military is way ahead of you, they've been used for extended surveillance in war zones since 2004: http://www.nytimes.com/2012/05/13/world/asia/in-afghanistan-spy-balloons-now-part-of-landscape.html http://www.nytimes.com/2012/05/13/world/asia/in-afghanistan-... and even domestically: https://theintercept.com/2017/04/24/nsa-blimp-spied-in-the-united-states/ https://theintercept.com/2017/04/24/nsa-blimp-spied-in-the-u... And before that, I believe surveillance blimps have been used in some form or another since the 19th century.
- vilhelm_s 9y agoNot to mention outside Washington DC. :) https://www.washingtonpost.com/news/the-switch/wp/2015/10/28/the-army-lost-control-of-a-giant-unmanned-surveillance-blimp/ https://www.washingtonpost.com/news/the-switch/wp/2015/10/28...
- traviscj 9y agoJesus, they shaped it like a giant bomb. No wonder everyone is uncomfortable. :-/
- walrus01 9y agoHelium is rare and expensive and becoming even more so as time goes on. Hydrogen has this nasty habit of being extremely flammable. Rigid or semi-rigid airships when scaled up are really difficult to moor and arrange ground handling for, which is why some of the recent prototypes that have been flown integrate skirts and reverse-hovercraft like suction apparatus that can hold them down on a flat field. The empire state building was originally intended as a Zeppelin mooring location, but the plan was abandoned due to wind and inability to control a zeppelin to that level of precision.
- throw_away 9y agoNot sure what the flight-time is, but this is pretty cool (helium-filled RC craft that looks like an airliner and flies indoors): https://www.youtube.com/watch?v=2Kk5EGpYuck https://www.youtube.com/watch?v=2Kk5EGpYuck
- jandrese 9y agoThe article said that the lighter than air aircraft got blown around by the wind too much. They needed a drone that could loiter over a specific area for an extended period of time, presumably acting as a communication relay for disaster or war zones.
- novaleaf 9y agoprobably because the need is real, just not the "for natural disaster" reason they gave.
- samstave 9y agoI assume you're only asking what address to send the summons to, huh?
- enraged_camel 9y agoThink about how much weight a party balloon with helium can support. Not a lot. It could definitely not carry a camera, for example. Hot air balloons adjust altitude by heating the helium inside the balloon and letting it cool back down as appropriate. You would need a similar mechanism, but in much smaller format.
- snewk 9y agohot air balloons use hot air (which is less dense than cool air) not helium. they are open by design, unlike dirigibles. hot air balloons increase altitude by adding more hot air via a burner, and decrease altitude by letting the air diffuse out through holes in the top of the balloon.
- enraged_camel 9y agoWhoops, yeah you are right. I blame lack of caffeine!
- deleted 9y ago[deleted]
- faragon 9y agoThat was my thought, too. E.g. a zeppelin-like drone could fly forever.
- seanp2k2 9y agoHeat the air with direct solar to give it lift. Make it clear on the outside and have something black on the inside to absorb more heat. For bonus points, let it be deployable during flight...fly drone into position in plane mode, pop the blimp, inflating it with air from the forward travel inertia, heat it once with a small rocket motor or something, then let the sun keep it hot enough to float. When done, eject the balloon and fly back. I'm sure there are lots of details around why they don't do this.
- cr0sh 9y agoThere used to be (maybe still is?) a toy, sold by Edmund Scientific and others - that was basically a thin black and big dry cleaning bag. You'd basically take it outside on a sunny day, whip it around a bit to "fill" it with some air, tie it closed, and then let it heat up in the sun. Eventually, it would take shape, becoming buoyant, at which point you could let it go to float off (presumably tied down with a string if you wanted to keep it). I don't know if it is still available or not, or whether anyone ever added remote controls to it... Hmm - apparently it or something similar is still available - or you can try to build one yourself: http://www.instructables.com/id/Make-a-Solar-Heated-Balloon/ http://www.instructables.com/id/Make-a-Solar-Heated-Balloon/
- honestoHeminway 9y agoBonus points- make the Ballonhull in place from carbon harvested from the atmosphere..
- skybrian 9y agoBalloons work well if you're travelling with the wind. It's a lot of drag if you're fighting the wind. But suppose you change altitude to find favorable winds? That's what Project Loon is doing: https://x.company/loon/ https://x.company/loon/
- toast0 9y agoFill it with methane/natural gas, and you can use the fuel to keep it aloft, and to move it around.
- Someone 9y agoYour balloon would have to be about twice as large to compensate for the higher density of methane (.656, according to google) I also am not sure that would be much safer than using hydrogen. Methane ignites a bit harder and would initially burn a lot slower (hydrogen has a much higher upper explosive limit (https://en.wikipedia.org/wiki/Flammability_limit https://en.wikipedia.org/wiki/Flammability_limit), so it would need to disperse more for the gas at the center of the balloon to ignite), but _any_ fire near the surface of the balloon eventually would be catastrophic, and putting fire extinguishers everywhere isn't an option because of their weight, in combination with the huge area of your balloon)
- ableton 9y agoLol, look up google's project Loon. They are trying to give everybody internet with balooons that stay in the air a long time. They steer by going up or down into different wind currents at different altitudes