Fun writeup! I was surprised by the part about styrofoam boxes though:
Despite their popularity, they have a few disadvantages:
They come in predefined sizes which mandate a certain weight allowance
They cannot be flexible for your specific payload, making it hard to be efficient with payload layout
They are expensive compared to more custom solutions
This shocks me, as styrofoam is one of the easiest materials in the world to cut, shape, fasten, and customize to your heart's content. I'm all for 3d printing stuff, but in the theater world we build a ton of very detailed (and shockingly durable) stuff out of foam all the time....
Buying a styrofoam box and just accepting that it's gotta be that shape and size feels like a huge waste.
rtkwe 23 hours ago [-]
Seems like the simple solution is a Styrofoam sheet, a $10 hot knife and some glue solves the customization problem almost trivially.
radeeyate 22 hours ago [-]
I think another point I hadn't included was the flexibility I had with prototyping different boxes. The hardware was changing all the time, and being able to just 3d print another revision was very convenient.
If I did something like that with styrofoam, it probably would have gotten pretty expensive. The precision you get from printing was also a plus, as there needed to be slots for cameras, antennas, and circuit board mounting holes.
happyopossum 18 hours ago [-]
There’s something to be said for using the tools your comfortable with. I’m a woodworker by passion, and a technologist by trade so I dabble in everything from cnc to 3d printing to hand tools.
If I happened to be super comfortable with fusion360 and 3D printers and not my overstuffed workshop full of other tools, I’d probably make the same choice.
wlesieutre 21 hours ago [-]
You can get a 4' x 8' sheet of 1" EPS insulation from Home Depot for under $20 (thicker available if you need it, costs more) along with compatible construction adhesives.
You do have to be careful with glue selection because a lot of solvents will dissolve it, but there's plenty that will work.
TylerE 21 hours ago [-]
What's expensive? You can buy a medium sized cooler for $5 at Walmart. That's a fair bit of foam.
nkrisc 23 hours ago [-]
In my intro Industrial Design class long ago we fashioned styrofoam and many other kinds of foam into every shape imaginable with a hot wire, some utility knives, and contact adhesive. A wood rasp worked well for organic and rounded forms (wear a mask), though that’s probably not needed in this application.
Felger 20 hours ago [-]
"which would have otherwise been expensive for the budget of two high school students"
High school students !? You are more capable than most of adults from my country, even "of the trade" if I might say.
macintux 24 hours ago [-]
Impressive level of detail, impressive work for anyone, much less high school students.
colingauvin 21 hours ago [-]
I live in Montana and routinely hunt the Musselshell river valley/Meagher county area. It's maybe my favorite place in the world. So few folks have been there, but spend some time there and you might just find yourself feeling depressed when you leave and not knowing why.
Glad to see other folks go through the area. The wind in Judith Gap is insane, so I'm surprised that you never found it. I'll keep an eye out when I'm out there in Sept/Oct.
jmpman 13 hours ago [-]
I'd assume hydrogen is a significantly cheaper fill gas than helium. Other than the danger during filling, any other concerns?
radeeyate 13 hours ago [-]
That was really our main concern. Being our first launch, we didn't want to risk it and wanted to wait until we were more comfortable with the process until taking that step.
verelo 24 hours ago [-]
Wait, so at 28k/km the temp goes up to 15C?
This is all very cool but this temperature reading caught my eye as unexpected.
radeeyate 23 hours ago [-]
I found that surprising too! This probably isn't a completely accurate number, as the sensor is black and likely experienced some heating from the sun. Something also worth noting is that different layers of the atmosphere experience different temperatures www.noaa.gov/jetstream/atmosphere/layers-of-atmosphere
verelo 23 hours ago [-]
Amazing. I love that i didn't know this. When i was studying weather as part of my pilots license i noted the basic mental math that i'd lose ~2 degrees celsius per 1000ft, but never did i take a second to ask, what happens when i go up 28,000 km.
newtwentysix 23 hours ago [-]
the article says 28.42 km. where are you seeing 28000 km ?
verelo 22 hours ago [-]
yeah i have no idea why my brain decided to type that (twice...), its clearly 28km
ErroneousBosh 24 hours ago [-]
The images seem a bit scrambled, presumably due to missing data blocks. At that low a resolution, have you considered maybe Robot36 SSTV?
radeeyate 23 hours ago [-]
Images are all in order, but some have missing packets.
The problem with SSTV is the power required. From some looking it seems that transmitting would need at least 5 watts. This wouldn't be feasible running on the balloon, as it was powered by Energizer Ultimate Lithium batteries.
ErroneousBosh 22 hours ago [-]
Oh, yeah FM transmitters can require a fair bit of power.
What is it using then, LoRA type stuff?
radeeyate 22 hours ago [-]
Yep, the radio link runs LoRa on the 33 cm band (915 MHz)
iberator 18 hours ago [-]
you should read about ham radio mate... there are some amazing protocols and modulations to save power.
And of course: 7mhz 0.5W transmitter could be heard worldwide... no jokes.
radeeyate 17 hours ago [-]
I have my license, and I noted about this in the post. I experimented with the U4B for tracking and found it not to be reliable enough. For the future, I'm planning on using the 70 cm ham band for LoRa.
ErroneousBosh 9 hours ago [-]
It's on a balloon, right?
No point pissing about. Go to 4 metres, dangle a J-pole from the bottom.
There, now you've just about got Over The Horizon capability.
karim79 21 hours ago [-]
Must have been a UAP.
Rendered at 17:33:59 GMT+0000 (Coordinated Universal Time) with Vercel.
Buying a styrofoam box and just accepting that it's gotta be that shape and size feels like a huge waste.
If I did something like that with styrofoam, it probably would have gotten pretty expensive. The precision you get from printing was also a plus, as there needed to be slots for cameras, antennas, and circuit board mounting holes.
If I happened to be super comfortable with fusion360 and 3D printers and not my overstuffed workshop full of other tools, I’d probably make the same choice.
You do have to be careful with glue selection because a lot of solvents will dissolve it, but there's plenty that will work.
High school students !? You are more capable than most of adults from my country, even "of the trade" if I might say.
Glad to see other folks go through the area. The wind in Judith Gap is insane, so I'm surprised that you never found it. I'll keep an eye out when I'm out there in Sept/Oct.
This is all very cool but this temperature reading caught my eye as unexpected.
The problem with SSTV is the power required. From some looking it seems that transmitting would need at least 5 watts. This wouldn't be feasible running on the balloon, as it was powered by Energizer Ultimate Lithium batteries.
What is it using then, LoRA type stuff?
And of course: 7mhz 0.5W transmitter could be heard worldwide... no jokes.
No point pissing about. Go to 4 metres, dangle a J-pole from the bottom.
There, now you've just about got Over The Horizon capability.