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Balloon Experiments with Amateur Radio (wikipedia.org)
65 points by peter_d_sherman on Jan 27, 2020 | hide | past | favorite | 25 comments

We launch about 8-12 HABs a year with K-12 schools across the US. We follow FAA guidelines, and file a Notice to Airmen (NOTAM) as well as contact local officials in the estimated landing zone. https://www.law.cornell.edu/cfr/text/14/part-101/subpart-D

Most of our payloads are under 2.5kg so we can fly on smaller 1000g balloons. There is a shortage of helium currently, but we prefer it over hydrogen because it is an inert gas.

If you like to volunteer your time, the US Dept of Education will be making an announcement in the next few weeks for a CubeSat Challenge. First stage is building prototypes - which of course could be launched in a HAB or High Power Rocket.

You can track a number of our flights on https://aprs.fi KK6UUQ. Here is a launch from Saturday that we did with USC and LA Unified School District: https://aprs.fi/#!mt=roadmap&z=11&call=a%2FKK6UUQ-11&timeran...

If you are into this, check out https://magnitude.io

>There is a shortage of helium currently, but we prefer it over hydrogen because it is an inert gas.

When we did our launch, we originally planned on a Hydrogen launch because we were informed of the Helium shortage. We bought all of our equipment based on Hydrogen being the gas. This is important for those that do not know as Hydrogen equipment has specific fittings so that it will not work with any other gas equipment. This is to prevent accidental/unexpected use of Hydrogen due to it being so volatile.

When we showed up to pick up the tank of Hydrogen, the employee really hesitated selling us the tank of gas. He explained that the flames from Hydrogen gas is colorless, so we could be on fire before we even saw the flames. The flames only display color when the flames catch other material begins to burn. He ultimately exchanged all of our Hydrogen equipment for Helium, and sold us the tank of Helium.

Father in law (rest in peace) worked for a while at a hydrogen reduced iron plant. Basically they were baking iron in ovens filled with H2. They had UV detectors hooked up to alarms for this reason.

Can I get in touch with you? I am located in southern California. My sons school would love this

How long do the balloons remain aloft? I wonder how practical a balloon-based emergency communications relay could work after a natural disaster. While high-altitude, long-endurance (HALE) drones carrying communications relays make more sense in some cases, a balloon-based system in a box with it's own helium bottle could be deployed by easily and quickly when needed... but if it's only good for 20 minutes then maybe it's not such a good idea.

You'd probably want to tether the balloon somehow. A balloon I worked on stayed aloft for about two hours, but in that time it traveled about 100 miles. Even then, when it was above the horizon we could hear it with our equipment on the ground.

I should note that the balloon only came down because it was designed to burst at a certain altitude and return under a parachute. Other designs that are meant for long or indefinite missions can last for weeks. As I understand it, other than lifting gas leakage the main limiting factors are energy (solved with solar panels, batteries, and smart usage) and balloon integrity under bright sunlight.

As for quick deployment, perhaps there are ways to do it, but it took our (admittedly inexperienced) team of 15 or so about an hour to string up our payloads, fill the balloon to the right volume, and release it. Lots of fun, though.

It totally depends on what type of balloon launch you want. There are balloons that are designed to burst when the external atmospheric pressure reduces to the point the gas in the balloon expands past the bursting point. That's somewhere in the ~90,000 foot altitude. That's when the parachute you (hopefully) attached allows the payload to float back down safely.

Lifting a helium tank would require a very large balloon. Larger than the single helium tank could fill on its own. These tanks are very heavy.

The idea isn't that the balloon would hoist a tank but that a ready-made kit has the balloon, gear, and helium tank to inflate and launch the gear. The tank would stay behind for recycling/reuse.

Ahh, I mis-read the meaning. However, the size of the tank of Helium would make this kit very expensive (if even possible) to ship. The more practical solution would be to have a working relationship with a company like AirGas or similar company so that the kit would include the payment for the tank of helium that could be picked up at a location near/local to them.

This would still make it a very practical kit and a good idea. It took several hours of looking online for local locations to purchase our gas, so including the pre-paid coupon would be a big plus. Especially for groups that might do this one time only.

Ours stayed aloft for about 2-3 hours when I did a launch with my college ham radio club! I can't remember exactly. It got up to ~60,000ft and then the balloon burst, quickly falling back down. We didn't have much of a parachute, so a larger parachute could've slowed the descent greatly. I'm not sure what the laws are about size of parachute/any required descent rates though.

Does it make sense to have dual balloons: one smaller one designed to burst at a target altitude (eg: 100,000 feet) and the other, more durable balloon, meant to provide a very slow descent, much slower a parachute? That could extend endurance aloft to several hours.

That sounds reasonable to me. Again, not sure as to the regulations around that, if you're allowed to use a balloon that doesn't burst at any point or anything.

Also, realistic bursting altitude is closer to ~60,000ft for most balloons, just FYI.

So did your chute slow the payload down enough to keep it from being damaged? Do you need insurance against it coming down on someone or their property?

1. Yes, but we also made sure that our payload was properly protected. Basically, it was a paint can with foam inside and the payload stuffed into the foam. It definitely didn't slow it down TOO much and without proper protection, the payload would have likely been destroyed. Also, the foam was necessary for thermal reasons too, the electronics needed to stay warm enough to operate when ambient temperature is -100F.

2. We didn't purchase any specifically, but given we were an official campus organization, we would have likely gone through them had something like that happened. Given the rural area we were launching from, and where we knew it would travel, the likelihood of this happening is close enough to 0 that we didn't have to worry.

I did one of these last year with my college ham club! Had a blast. We made a custom PCB with some sensors on it that was supposed to transmit data via APRS but it didn't end up working. We think it was because the AVR onboard didn't have enough processing power to reliably generate the audio without missing bits or somehow garbling it slightly (there's no error correction in the AX.25 protocol used by APRS). Thankfully we had a redundant transmitter that did keep it at least sending GPS data, and we had a 360 degree camera on it that got some REALLY cool footage.

AMA about it!

I’d love to start on this hobby this summer he’ll be 13). I’m not much of a HW or ham guy. What resources would you recommend to get started on our first balloon?

You'll want to find out the laws in your area about launching them. In the US, you can launch them freely without necessarily notifying anyone as long as they're below a certain weight and meet other requirements (maximum breaking strength of the line used to attach the balloon to payload, using a radar reflector, etc.) However, it's still HIGHLY RECOMMENDED that you call and let any airports know if you're launching close to one.

Look into APRS and how to build (or you can purchase one) an APRS GPS transmitter, that'll be the most important bit as if that isn't working, you'll very likely never find your balloon. Once that's working, you can use a site like aprs.fi to track the balloon in realtime from a laptop/mobile device and follow it as it flies. Keep in mind it could VERY well travel over a hundred miles. We launched ours from Decorah, Iowa and we had legitimate concerns about wind patterns causing it to fly as far as Chicago.

I'd also recommend looking into how to build a "Fox" and how to foxhunt. That's a big part of these balloon launches too! Once you've gotten as close as you can with GPS (once the balloon falls below a certain altitude, relays will stop picking it up on APRS so you'll have only a general idea of where it fell), you'll want to use a directional (for instance, a Yagi-Uda) antenna and a handheld radio to try to directionally locate the fallen payload. Funnily enough for us, we didn't have to foxhunt since it landed in the middle of a guy's field, when we parked across from his house, he asked what we were up to - he was friendly and just curious - and we told him, he said he thought he saw something shiny in his field and assumed it was garbage blown over from the road or something and let us come over to look at it. Turns out it was our balloon! The shiny thing was the radar reflector.

Then, put whatever you want in your payload really! We used a paint can stuffed with foam (it gets REAL cold up there, like -100F, keep that in mind!) and shoved sensors into it and attached a 360 gopro to the side. You can find stuff about how to build temperature/humidity/etc data logging setups that log to an SD card. I'd also recommend that after you retreive your balloon, go to some place like aprs.fi and download the GPS track data from the launch! Those sites don't keep it around forever, you'll definitely want a copy for yourself.

You can get the balloons themselves quite easily, and welding gas suppliers should be able to get you a cylinder of helium.

Good luck!

For anyone interested in high-altitude ballooning, one of my close friends sells high-altitude balloon gear here: https://www.highaltitudescience.com/.

I'm beginning to think that a majority of high-altitude balloon experiments are facilitated by amateur radio APRS transmitters. Balloon launches are also huge PR events and great for students to get involved into science (and ham radio!).

You can see almost every balloons with a ham radio payload currently in the air, in real time at https://tracker.habhub.org/

This is one of those projects that I keep telling myself I’m going to do ‘next summer’. There’s just enough detail for a successful flight that you really have to start working on it months in advance, which is why I never seem to be able to get my balloon off the ground.

One thing I really would like to do is get a stabilized camera and experiment with some rigging that reduces payload rocking. A steerable parafoil recovery is also rolling around in the head. All of these ideas exacerbate the procrastination situation lol.

I've done one of these smaller launches with GoPros up to ~90k. It was a very fun project including the research on what equipment to use on our budget, the flight predictions to find a good launch point, to the actual launch and recovery. I would highly recommend doing it to anyone thinking about it. We were a group of adults, but it is definitely kid friendly.

I still want to do another launch with improvements learned from the first launch. All of the improvements definitely require a much larger balloon (meaning more expensive). I now have friends with HAM license so we can use a radio for real-time data transmission. I have my Arduino flight computer with all of the sensors completed. The camera stabilization was the biggest thing I wanted to solve. Many ideas rolling around in my head as well. Might need a 3rd or 4th flight to finesse, you know, for science!

I did a bunch of research into this last year. High altitude balloons combine a bunch of super fun science stuff. You've got radio, photography, space/weather research. Plus when it's all done you go on a treasure hunt in the wilderness to recover it! Now if only I had bandwidth outside of work/family.


And here's the link that started me down the rabbit hole: http://leobodnar.com/balloons/

https://ukhas.org.uk/ has some really good information for people launching balloons in the UK (such as how to track them, along with the power etc. you can use).

I've only tracked one once, using an old scanner and antenna, but I'd like to get a decent collinear antenna to use with an SDR.

You can learn a lot about the hardware used over at


Of course he sells stuff to do it, but there are many balloon flights documented on that site too. Some of them have circumnavigated the Earth more than once!

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