51–60 of 61 posts
I always like their illustrations that "minimalist?" two-three color orange
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 pictu…
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).
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: Th…
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.
Earlier quoted context omitted.
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 tes…
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’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…
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.
Earlier quoted context omitted.
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 electroly…
Earlier quoted context omitted.
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.
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 pictu…
Why not use the STMs that have the LoRa built in?
For 433/868/915 they are great.
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: Th…
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…