Flying around the world in the jet stream for ninety cents of hydrogen gas.. - Page 1
Forum section: electronics / general

author: DaveBev
author_rank: Contributor
timestamp: March 18, 2020, 01:46:52 pm
content: The radio has already flown around the world once and now is flying near Italy. The electronics are challenging but fun. The radio is carried by two party balloons filled with about 90 cents of hydrogen gas. The radio is quite light and transmits a WSPR signal which is received by Ham radio people and decoded. Electronics must work down to -40c. If you want to know more about this hobby, it is explained herehttp://qrp-labs.com/flights/u4b2.htmlDave VE3KCL

author: janoc
author_rank: Super Contributor
timestamp: March 18, 2020, 02:40:03 pm
content: That's a pretty impressive feat, congrats!BTW, you may want to fix the link - the final dot should be removed.I also suggest switching to e.g. OSM for the maps because Google doesn't like people publishing stuff with their development keys - once the map starts to get a lot of hits, you will have problems.

author: DaveBev
author_rank: Contributor
timestamp: March 18, 2020, 03:08:49 pm
content: Thanks JanocThe balloon is forecast to fly around Corsica and then head east over Russia

author: SparkFly
author_rank: Regular Contributor
timestamp: March 18, 2020, 08:21:43 pm
content: Very cool, I am always impressed with these superpressure flights. Can you share any more information on the balloon envelopes? I've been toying with the idea of doing my own flights, but haven't committed yet. Did you do any prestretching of the balloons? I've heard Leo Bodnar experimented with custom envelopes, but I can't seem to find any sheets of the right material/dimensions. Would love to find a supplier of that....Hats off to you.

author: DaveBev
author_rank: Contributor
timestamp: March 18, 2020, 11:40:49 pm
content: Sparkfly on the balloons they are clear party balloons available on aliexpress. I stretch them with .6psi of dry air. If you explore the website and look for previous flights all the details are there on how to build and fly them along with tons of mistakes made on the way.Dave

author: james_s
author_rank: Super Contributor
timestamp: March 18, 2020, 11:48:25 pm
content: I've been advocating hydrogen gas for this sort of unmanned stuff for a long time but few seem to care. IMHO it is a terrible waste of precious helium to lift balloons outdoors. Hydrogen is cheaper, readily available, 100% renewable and offers greater lifting capacity. The fact that it is extremely flammable is only a concern when it is used in close proximity to people or used to lift a manned craft.

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 19, 2020, 04:03:58 am
content: For applications where pure hydrogen is considered too dangerous to use, what about a hydrogen/helium mixture that's cheaper than pure helium but not flammable?

author: janoc
author_rank: Super Contributor
timestamp: March 19, 2020, 08:58:45 am
content: Quote from: james_s on March 18, 2020, 11:48:25 pmWell, that depends a lot on the mission too. There is a big difference whether your HAM radio tracker falls out of the sky because the gas has exploded (e.g. due to a static electricity buildup somewhere) or a large cargo craft costing millions blows up and possibly kills someone on the ground or starts a major fire where the burning bits rain down.Most of these helium applications fall exactly into those two categories "close to the people" (party balloons or weather probes while being filled, for ex) or too big/expensive to crash land should anything go wrong.It really isn't about manned craft - which are, in fact, very rare nowadays, only a handful of Zeppelin NTs are flying, because these things are useless as transports (only used for very expensive tourist sightseeing flights) and their use for photography/surveillance has been replaced by much cheaper drones. If hydrogen was safe for such use, it would have been used already, given the difference in price (hydrogen is about 2.5x-3x cheaper than helium).

author: richard.cs
author_rank: Super Contributor
timestamp: March 19, 2020, 04:25:51 pm
content: Hydrogen being diatomic should also leak lessI did read somewhere that some "balloon gas" is hydrogen with some buffer gas like nitrogen to make it less explody. Not sure where I came across it or how true it is. In the UK balloon gas seems to be helium padded out with as much nitrogen as they can get away with and still float for a couple of hours. You can even see it as they leak down - they asymptotically approach a fixed volume.Until the 1960's we piped a mixture of hydrogen and carbon monoxide into people's homes. People even filled party balloons with it

author: Zero999
author_rank: Super Contributor
timestamp: March 19, 2020, 08:29:59 pm
content: Quote from: richard.cs on March 19, 2020, 04:25:51 pmWhat about replacing some of the helium with hydrogen, just not enough to make it dangerous?

author: MadTux
author_rank: Frequent Contributor
timestamp: March 19, 2020, 10:34:30 pm
content: Pure hydrogen is non flamable and burns quite unimpressively in air.Only gets dangerous when mixed with oxygen.But that won't happen in party ballons, because hydrogen leaks out far more quickly than the oxygen leaks into it, due to size of molecules and difference in pressure.Using helium for balloons is a waste of helium, as stated above. But still only a very small % of the total amount of helium wasted into the atmosphere. Deep divers, rocket pressurization, venting cryogenic coolers without recovery, fancy TIG welding.... wastes a huge lot more of it. Until the helium from natural gas is depleted, than weight by weight, helium might become as expensivve as as gold

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 19, 2020, 10:54:34 pm
content: Quote from: MadTux on March 19, 2020, 10:34:30 pmVideo demonstration:Reminds me of the time in high school chemistry class when one of the class assignments was to build a small rocket fueled by hydrogen and oxygen, find the optimum mix of the two, then launch it.

author: james_s
author_rank: Super Contributor
timestamp: March 20, 2020, 01:05:52 am
content: Quote from: MadTux on March 19, 2020, 10:34:30 pmThe problem is mixing with air is precisely what it does as soon as the balloon pops due to proximity to an ignition source. I have filled balloons with hydrogen and ignited them many times, it's not nearly as impressive as filling them with hydrogen and pure oxygen but it creates quite a fireball none the less. This is why I say use them outdoors.

author: vk6zgo
author_rank: Super Contributor
timestamp: March 20, 2020, 01:26:53 am
content: Quote from: MadTux on March 19, 2020, 10:34:30 pmSeeing how great the mass of only a small bar of gold is, (Hollywood notwithstanding), that is a lot of helium on a weight for weignt basis.

author: ANTALIFE
author_rank: Frequent Contributor
timestamp: March 20, 2020, 07:44:14 am
content: Far out that is some cool stuff

author: DaveBev
author_rank: Contributor
timestamp: March 20, 2020, 05:17:57 pm
content: The balloon has been limping along for the last few days, but at times it has been recorded at over 164 knots , 193 mph , 311 kphDave