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Pretty cool, although it's polluting so hopefully it wouldn't become too popular (probably not).

"And because such diminutive payloads don’t pose a danger to aircraft" even though they are small and wouldn't make a plane crash, I can imagine they would cause some damage if they ever enter a jet engine, although that would be unlucky as they would mostly fly higher than aircraft. I also wouldn't like it to fall on my head, but with the solar panels as depicted and the small weight I suppose it could somewhat glide.

It also reminds me of the recent incident where an object (potentially a weather balloon) struck a plane windscreen and caused significant damage to it, as well as injuring one of the flight crew. I don't know if it would cause the same amount of damage given it's size, but hitting any solid object at cruising speed is sure to leave a mark

shouldnt be cruising in the balloon lane then

Balloon doesn't teleport to the balloon lane though

That was a much larger balloon that had sand ballast. The sand was what did the damage

There are thousands of weather balloon starts every day without any damages to airplanes.

It's not factor as long they are not crossing a specific size/weight - jet engines and windows from airplanes are tested to withstand a direct impact.

Yeah, and pico baloons are extremely tiny, often at 10 grams or less, comprising some very thin plastic, some thin wire and tiny PCBs - this is also how they can fly so high for so long.

Lost of types of hail will be much heavier and harder on impact for example.

It is super cool - we managed to launch one on a pair of Aliexpress wedding baloons filled with helium and it tracked all the way from Europe to South Korea, for about a week.

It even breached the arctic circle and entered the jet stream for a bit (140+ km/h ground speed) :-)

Isn't H2 better because better lift and being a molecule of two hydrogen atoms it is not quite as slippery as helium and quite easy to make?

From wikipedia "lifting gas"

"Helium is the second lightest gas (0.1786 g/L, 14% the density of air, at STP). For that reason, it is an attractive gas for lifting as well.

A major advantage is that this gas is noncombustible. But the use of helium has some disadvantages, too:

    The diffusion issue shared with hydrogen (though, as helium's molecular radius, 138 pm, is smaller, it diffuses through more materials than hydrogen[4])."

and at this scale it seems like the hazards of h2 would be pretty minor. You're not exactly going to have a Hindenburg situation with only a couple dozen liters of H2.

No but you might get serverely hearing impaired..

It really seems like there is no downside to this, other than the minuscule risk of a low-altitude puncture + spark causing a fire, and even there the exposure is small because the amount of hydrogen gas is so much small.

Not to mention that hydrogen is free for anyone who has water and a power source.

The diffusion is the main advantage of using helium, it takes ~3x longer to leak out, which directly affects flight time.

Hydrogen is actually harder to buy in my experience, helium is sold everywhere for cheap in small canisters for parties, whereas the second requires like, industrial welding suppliers that will want to sell you a large tank for a few thousand or making your own electrolyser and compressor. There's no common use case for it you could piggyback on.

'Balloon Gas' for inflating party balloons is a mixture of Helium and Oxygen, at least in the UK, to stop Tweety Pie asphyxiating him/herself breathing the gas. So although it still is lighter than air, it's not as good as pure He.

I'm currently thinkering of building a balloon with a 2.4GHz LoRa transmitter (SX128x) and a low-power STM32U microcontroller.

Why?

- You can repurpose 2.4GHz Wifi gear opening many doors

- You can easily include volunteers dumping data from HF into a IP sink for telemetry. TTGO offers boards with 2.4GHz LoRa.

- Theoretically you still can add a "low rate" 868MHz/433MHz and a "high rate" 2.4GHz for transmitting pictures and other stuff more quickly.

- BOM friendly. As the balloon might get lost you have to plan a bit for costs.

Why not use the STMs that have the LoRa built in?

Not for 2400MHz LoRa.

For 433/868/915 they are great.

lol. WPRS works like 10.000km per WATT on HF. You can't do it with 2.4ghz.

Ham radio basics

Why do they do WSPR on HF and not 2.4GHz?

What's the important part that defines what kind of range you can get?

WSPR on HF makes sense down here on the surface of the planet because certain ranges of frequencies (not the same range always, but generally always within HF) can bounce off of upper atmosphere layers and pinball back and forth to get signals to someone or from someone who couldn't be seen line-of-sight because of the curvature of the Earth. For line of sight work, the 2.4GHz in theory would work as well as anything, but another trick WSPR has is that it doesn't allow for arbitrary data to be sent. Sender and receiver encode the limited information in an agreed-upon way and then it takes a long time, like minutes, to send that little bit of data. Very high redundancy.

Yeah, our baloon was recorded by WSPR eeceivers thousands of kilometers away when it crossed the arctic circle for a day - we wpuld have no data if it were dependent on line of sight or even just flying over inhabited territory.

And indeed, the relions take minures to send a couple dozen bits of data. But the modulation is done in such a clever way, that it does not really matter - you know ehere the probe with your callsign was, how high, ground speed, temperature and panel volatage. There is quite agressive heuristics applied (eg. different precision for different altitudes as you don't really expect it to stay low for any ammount of time and survive, position via grid squares with course position still available even if you have incomplete data from a relation) so the few dozen bits are enough. :)

It is all super clever and hats off for those who developed this system. :)

You know that and I know that, it was a Socratic question aimed at OP ;-)

In the olden days we did QRSS, FSK Morse with a dot rate in the order of minutes.

lol. 10.000km with a few bits of fixed-structure payload you mean.

Encoding basics

If you're interested in high altitude ballooning, there's an active community around it.

https://arhab.org/

https://www.superlaunch.org/

This is way cooler than I expected. I had no idea you could do near-space stuff for the price of a dinner, or that ham radio networks like WSPR could track something globally without satellites. Feels like one of those “old tech + clever hacks” projects that shouldn’t work but somehow does. Also kind of wild that a party balloon can end up halfway around the world.

Very cool! Brings this to mind: https://www.theguardian.com/us-news/2023/feb/17/object-us-mi...

I wonder what your liability would be in the event your balloon were to be struck by a commercial aircraft and cause injury to the flight crew or passengers?

https://komonews.com/news/local/weather-balloon-launched-in-...

Jet engines are tested for this.

They basically can shoot (not only throwing!) entire frozen chicken cadavers into engines with zero damage.

The only way they managed break the entire engine was to place little explosives on the turbine wings. Even that didn't cause a fatal disintegration of the jet engine.

Somewhere on YT there's a super entertaining video from a test facility.

Well first, the linked article was regarding a weather balloon that impacted the windscreen, not the engine, and it did cause an injury to the flight crew. Here are pictures of the bloody, glass-shard filled flight deck. https://www.facebook.com/aviation247/posts/n17327-united-air... So the hazard is real.

Now back to your uninformed comment. I do certification testing of jet engines, and we most certainly DO NOT test jet engines against the ingestion of airborne electronics.

I have personally loaded and fired the five barrel bird gun at General Electric’s Peebles Test operation many times over the years. We use a range of birds and bird simulators, but none of them are ever chickens, and none of them are frozen.

There is not any requirement for zero engine damage. Little sparrows will do no damage. Ducks and geese cause extensive damage every single time. Extensive engine damage is permitted so long that the engine shuts down without causing catastrophic damage to the airframe. The specific damage that must be prevented, per 14 cfr 33.75, is below. Any other damage is acceptable.

(i) Non-containment of high-energy debris;

(ii) Concentration of toxic products in the engine bleed air intended for the cabin sufficient to incapacitate crew or passengers;

(iii) Significant thrust in the opposite direction to that commanded by the pilot;

(iv) Uncontrolled fire;

(v) Failure of the engine mount system leading to inadvertent engine separation;

(vi) Release of the propeller by the engine, if applicable; and

(vii) Complete inability to shut the engine down.

https://www.ecfr.gov/current/title-14/chapter-I/subchapter-C...

Thanks for the very informative post on airline engine testing. One of the quickest upvotes ever. Never knew the details on the range of birds fired and actual damage allowables.

Couple follow on questions. What are the test conditions like? Is the test basically a static air test with a fixed engine and a 500 mph duck / goose carcass striking an operating engine? Or do they put it in a wind tunnel to simulate high speed wind forces also?

Also, what's the method of actually firing and accelerating a duck / goose carcass up to airline speeds for impact. Did this a bit for NASA impact testing, and we tended to use peel away sabot rounds to throw bricks at objects.

Also, borders a bit on a Monty Python joke, yet is there a regulation duck / goose? They can vary pretty wildly in size / weight. 5lb, 10lb, 20lb? Are they firing all the way up airline cruise speeds (500-600 mph? or just take off / landing runway issues?

Finally, being in the industry, any idea on what's been going on with the engines peeling off airplane wings, like that Louisville, Kentucky cargo plane? That seems like a rather drastic failure mode, since apparently there were cracks in the mounting and people just weren't checking?

FAA explicitly requires birds used in strike tests NOT be frozen, because frozen birds do not realistically simulate real bird strikes.

https://en.wikipedia.org/wiki/Chicken_gun

That balloon was several orders is magnitude heavier, pico balloons pose no risk.

Note that there are operators running balloons several orders bigger still, like Aerostar. They're essentially flying mid size satellites

QRPLabs sell even lighter trackers https://www.qrp-labs.com/u4b.html

and AFAIK are the goto supplier for HAB (High Altitude Ballooning) enthusiasts.

I always like their illustrations that "minimalist?" two-three color orange

Thank you, I'm glad you agree they are nice! The artist is James Provost, he's done most of the illustrations for Hands On since we switched over from photography a few years ago (I'm the IEEE Spectrum editor responsible for the column).

I like your Video Fridays, good to see latest in robotics

This sounds so cool!

> I’m a little puzzled about the balloons’ telemetry messages received on the WSPR network, as they have been few and far between.

But wouldn't there be a way to send messages to Starlink satellites instead of WSPR? Is it a problem of power consumption? (It would be great to be able to transmit images, not just GPS pings).

If you are wanting to send images, there are already some cool ways to do that: either SSTV (https://en.wikipedia.org/wiki/Slow-scan_television) or Wenet, which sends them at a much higher speed: https://github.com/projecthorus/wenet.

I wrote some code to send SSTV because everything was either proprietary and didn't work, shareware and didn't work (and often with the original author gone Silent Key so no way to get the real version), or under some vaguely-specified licence and written with Tk widgets in Fortran or some damn thing.

I wrote it about 25 years ago and can't currently find it but it's one one of these hard disks in these here blue moving crates somewhere. It'd take less time to recreate than find, I suspect, especially if I also wanted to make it build nicely in gcc from this decade.

It just grabbed from a V4L2 source, and emitted a burst of Robot36 over the soundcard. In conjunction with a heavy-duty Tait T2000-family transceiver I used it to livestream a drive across Glasgow, slowly and noisily, sending one picture per minute which gave the poor PA transistor time to cool a bit ;-)

Starlink is totally oit of picobaloon range by orders of magnitude - we are talking hundreds of mW at most.

At the same time it is true the board (rpi pico usually) could totally support a camera or other high bandwidth instruments - it just does not have the bandwidth to send the data over wspr, possibly with the exception of some flags based on local processing.

AFAIK some poeple have built dual APRS & WSPR pico baloons, but you will still get pictures back only over populated areas due to APRS having in general much shorter range than WSPR.

Tracking site: https://amateur.sondehub.org

> "My first pico balloon made it only halfway across the Atlantic before going silent."

As if we needed more junk in the ocean.

I’ve been working on a hobby project to send a Raspberry Pi into the stratosphere (nothing really novel) but with all custom software. The entire process, hardware, and stack is documented on the GitHub [1]. Essentially all the software and major components are purchased. I’m just waiting for the spring and then start some tests with balloons, helium mixtures, and iron out any regulatory issues. If this interest you or you have any experience would love help or contributions. The launch will happen in Tennessee.

[1] https://github.com/stratopi-org/stratopi

Very cool project!

I saw you were looking for help sourcing things like balloons and gas. https://groups.io/g/GPSL/ worried be a great place to go and ask for help with that, if you haven't already.

I wish the regulations around HAB were not so lighter-than-air gas centric. Hot air balloons are much more accessible, especially solar heated hot air balllons. But they have much less lift per volume and so the FAA FAR 101 rules basically say they all have to be treated as the type where you inform the FAA beforehand and then every hour about their position among other things.

https://www.ecfr.gov/current/title-14/chapter-I/subchapter-F...

>any balloon that is moored to the surface of the earth or an object thereon and that has a diameter of more than 6 feet or a gas capacity of more than 115 cubic feet.

And the regulations on tethered balloons end up being even stricter than letting them go.

FAA wants you to use hydrogen. >roll safe<

Okay, though, for very small hobbyist payloads, though, wouldn't hydrogen balloons be feasible?

Some quick math tells me that you can lift approximately a kilogram of mass per cubic meter (at sea level, anyway). If your balloon's full weight is a half of a kilogram, you'd only need about a large beach ball filled with hydrogen to lift it. That seems like something that would be attainable for an outdoor DIY electrolysis setup.

Oh for sure - in fact I believe weather balloons usually use hydrogen (not for demos, but for large scale/daily actual weather purposes). It's just amusing that the regulations effectively encourage use of the more... energetic lifting gas.

As well they should be. The tether represents far more of a risk to aviation than the actual baloon. Not only it is much larger a collision risk, it cuts through GA airspace where all the delicate stuff flies.

In the summer you could theoretically station-keep a few of these over a city for a few hours at least with proper wind and lift gas planning. Could be enough to fly a stripped town T1000e or similar meshtastic relay during a natural disaster

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Yep, cost effectiveness of project is amazing & really nice application for WSPR. WSPRnet for checking readings seems to be still online https://www.wsprnet.org/drupal/wsprnet/map .

If you keep the payload under 4 pounds I believe it's theoretically unregulated in the US except section 101.7 - don't create a hazard. I would still try to be approximately in compliance with part 101 though. Not a laywer.

Four pounds of hardware ingested by a jet engine is going to do a shitload of damage.

Exactly. Given that most birds weigh less than 4 pounds and bird strikes can take an engine out completely.

Plus, if @jacquesm says it, it must be true. ;-)

I agree, but apparently that's the rule.

These pico balloons weigh grams.

Yeah, I think ours was less than 10 grams.

As rules go, IIRC at least here in the Czech Republic anything below 100 g is unregulated, you just need to have a licensed amateur radio operator, so that the probe can broadcast in the 20 meter WSPR band under his callsign.

Parent to mine mentioned 4 pounds.