High-Altitude Adventure with a DIY Pico Balloon
spectrum.ieee.org
spectrum.ieee.org
"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'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.
Lost of types of hail will be much heavier and harder on impact for example.
It even breached the arctic circle and entered the jet stream for a bit (140+ km/h ground speed) :-)
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])."Not to mention that hydrogen is free for anyone who has water and a power source.
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.
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.
Ham radio basics
Encoding basics
What's the important part that defines what kind of range you can get?
In the olden days we did QRSS, FSK Morse with a dot rate in the order of minutes.
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. :)
For 433/868/915 they are great.
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.
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.
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.
and AFAIK are the goto supplier for HAB (High Altitude Ballooning) enthusiasts.
https://komonews.com/news/local/weather-balloon-launched-in-...
Note that there are operators running balloons several orders bigger still, like Aerostar. They're essentially flying mid size satellites
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.
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...
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?
> 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).
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 ;-)
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.
As if we needed more junk in the ocean.