In June of 2025, I worked pinch New England Sci-Tech arsenic a portion of Apex to motorboat StratoSpore: my first ballooning project. I utilized this opportunity to usage algae arsenic a biosensor for altitude, and I learned a batch successful the process. Wanting to research successful the stratosphere again, I worked pinch Sam Flynn to make a reliable and flight-ready payload.
I had a fewer goals pinch this payload from what I learned from past year:
- Have redundancy for search systems
- Send images to the crushed pinch existent details
- Last payload sent pictures 18x10 pixels
- Use a much reliable GPS module
- Implement much elaborate power functionality
- Use my amateur power license?
- Use much businesslike information packing techniques for telemetry
My scheme for this station is to screen really I implemented these changes, on with documenting my learning process successful hopes to pass my early launches.
The Experiment(s)
StratoSpore past twelvemonth had 2 goals: analyse really altitude/UV vulnerability affects algae fluorescence, and nonstop images to the crushed complete a power link.
UpLink, our payload this year, follows a akin style and did 2 things:
- Test really 3D printing filaments (foaming PLA vs. non-foaming) affects payload insulation
- Send high-resolution images complete a power link
Testing Payload Insulation
Historically, astir high-altitude investigation teams usage styrofoam boxes for payload enclosures. There is simply a logic astir teams debar experimenting pinch other types of enclosures: styrofoam provides fantabulous thermal insulation and is easy to manipulate.
Despite their popularity, they person a fewer disadvantages:
- They travel successful predefined sizes which instruction a definite weight allowance
- They cannot beryllium elastic for your circumstantial payload, making it difficult to be efficient pinch payload layout
- They are costly compared to much civilization solutions
The full payload (parachute, formation line, electronics, enclosures) we sent up weighed 491 grams. A accepted foam enclosure would already measurement ~200 grams. Ultralight payloads are much charismatic the lighter your balloon is. Ours was a 350 gram balloon from Kaymont. As a wide rule, the bigger the balloon, the much helium you will need. Costs of it adhd up quickly!
Sam designed our enclosure successful Fusion360 complete a fewer weeks, creating thing that fit our payload perfectly, had predefined standoffs, standardized mounting hardware, and pockets for fitting cameras, somesthesia sensors, and different electronics.
For measuring really the different filaments insulate the somesthesia sensors, small capsules were attached to the payload’s lid. Internally, the sensors were sealed pinch basking glue to isolate them from ambient aerial that would effect similarity between the pods.
The enclosure was printed successful Sunlu’s LW-PLA filament. It is dissimilar normal filament, and contains microscopic aerial bubbles which actively foam during the printing process. At the advantage of being 30-50% lighter than PLA, it is simply a nightmare to people with. I created a typical people profile to make it somewhat bearable:
- It must beryllium printed ~7x slower
- Cooling must beryllium disabled/limited arsenic it impacts foam description
- Bed somesthesia must beryllium accrued arsenic adhesion is not great
- Acceleration must beryllium abnormal aliases other infill and walls will person varying strengths
With each these changes, it tin still beryllium very brittle and difficult to people if not decently dried. If you are willing successful experimenting pinch this filament, you tin download my print profile for Orca Slicer. I americium unfastened to recommendations!
The results
The presumption pinch the foaming PLA filament is that the microscopic aerial bubbles would supply a noticeable quality successful insulation capacity complete emblematic PLA.
The information told a different story:
As you tin see, location are nary conclusive results regarding how foaming PLA performs versus bare PLA. There are times wherever foaming performs better, but the other tin besides beryllium observed.
My suspicion is that the microscopic aerial bubbles successful reality did thing for actual insulation, and that for due payload enclosures, infill and wall count matters much much than filament composition. Another point to effort whitethorn beryllium multiline infill: insulation useful connected the spot of aerial pockets slowing down power transfer. Perhaps thicker walls betwixt soul aerial pockets would help?
Even pinch the deficiency of results regarding insulation properties, it is clear that printing a civilization payload enclosure is beneficial, arsenic insulated sensors were ~7°C warmer than the ambient air. Better sealing would apt amended this substantially, and we besides observed done simulations that radiation from the sun heated the payload respective degrees if painted achromatic alternatively of white.
This is simply a simulation Sam ran to verify that the 3D printed payload would be able to insulate the electronics from the acold ambient air:
Painting the foaming PLA enclosure pinch achromatic acrylic paint
Foaming PLA filament still bears the crown successful position of the weight to spot ratio, so I americium assured utilizing it for early launches.
Image Transmission
Most amateur ballooning payloads person cameras. The position astatine 30 km up is incredible, and knowing those pictures came from a civilization designed payload makes them even more special.
Last year, I transmitted images that were 18x10 pixels, which had nary discernible details visible:
The logic I sent down specified mini images was owed to limitations successful the power link: transmissions are slow and constricted (by protocol) to 255 bytes. To combat the challenge, I designed an excessive and overly analyzable image compression algorithm, which successful move made transmitted images unusable.
While studying for my amateur power licence past year, I learned about SSTV (Slow Scan Television), a method of transmitting pictures complete an analog video link. SSTV requires a precocious powerfulness fund (at slightest 5-20 watts) and produces images that are not up to my standard.
I did immoderate much investigation and recovered SSDV (Slow Scan Digital Video), a packetized integer type of SSTV. Even if the ground station misses packets, the image tin beryllium reconstructed.
I modified Philip Heron’s C implementation of SSDV for my circumstantial needs: I reduced the packet size, removed telephone motion transmission, and abnormal the Reed-Solomon correction correction arsenic the power nexus already does this. You tin find my changes on GitHub.
The camera takes an image, saves a afloat solution transcript to the SD card, and encodes the 320x240 type earlier transmitting ~15 packets per image.
The crushed position received 328 images passim the flight, which you tin view at the gallery.
Here is immoderate image subject connected really images were captured astatine different altitudes, and really ray was scattered otherwise starring to the entity turning black.
On the descent, the payload was swinging heavily. Here is simply a image it captured of the sun:
The Sun Is A Deadly Lazer
This chart shows really images tended to look arsenic altitude increased, pinch later images being capable to spot the achromatic of space.
This shows a representation of images taken passim the flight.
I americium very happy pinch really the images turned retired this year!
Electronics
Prior to everything I person made since, past year’s payload circuit boards were the astir analyzable creation I had made. Since then, I person learned KiCad, a free and unfastened root EDA program. With my changes successful tooling, my accomplishment has grown significantly.
The civilization electronics had 4 main sections:
- Power Electronics (voltage regulator, load switch)
- Microcontroller (ESP32-S3, camera, SD card)
- GPS & Tracking (module, antenna, redundancy)
- Radio Link (SX1262)
- Sensor Integration (external SPI ADC, somesthesia sensors)
As usual, I had the boards manufactured by OSH Park, and they turned retired perfect. Additionally, I sewage the boards open-source certified.
Power Electronics
With a debased expected weight budget, my powerfulness fund was moreover little than I thought. The usage of 4x Energizer Ultimate Lithium double-A batteries worked good past launch due to ample weight, but I had to make tradeoffs and usage 3x triple-A from Energizer’s same series. With a precocious powerfulness fund previously, I ran a Raspberry Pi Zero 2 W, an RP2040, and various sensors. The situation pinch debased powerfulness is uncovering solutions that work well, but efficiently and really you would like.
This payload utilized a buck-boost converter for power: meaning it stabilizes a solid 3.3V proviso to the electronics whether aliases not the batteries are really supra this voltage. This is simply a important upgrade, wherever I antecedently utilized highly inefficient low-dropout regulators, which purely driblet voltage.
Mistakes Made
I primitively had planned connected utilizing a load move to power if the payload was turned on aliases off. This later proved to not really activity the measurement I implemented it, and provided powerfulness moreover if not intended to. In hindsight, the amended solution would be utilizing the mechanical move arsenic an ENABLE awesome for the voltage regulator.
Later connected successful the project, I besides accidentally shorted retired the committee erstwhile working on the artillery holders and powerfulness supply. I was past incapable to usage the committee with a functioning powerfulness supply, and alternatively relied connected the microcontroller’s built-in buck regulator.
Battery voltage wasn’t correctly reported during formation owed to the truth I possibly killed the voltage dividers meant to study artillery health.
Microcontroller
I chose to usage an ESP32-S3 microcontroller for information postulation and transmission. Seeed Studio makes a assortment of mini microcontroller boards, including ones pinch cameras, SD cards, microphones, and WiFi. Using their XIAO ESP32-S3 Sense, I was capable to fresh the intent of the Pi past twelvemonth successful a much smaller and much powerfulness businesslike shape factor.
The XIAO boards person fewer GPIO pins, and the camera and SD paper declare astir of them. To publication analog sensors, I added an outer SPI ADC (MCP3204), which the analog temperature sensors (MCP9700A) and the artillery voltage divider some connect through. The divider is the 1 that stopped reporting mid-project.
Firmware was written successful Arduino, alternatively than CircuitPython arsenic I did past year. I person been wanting to constitute little level codification for a agelong time, and doing truthful this launch was a immense measurement for me. There are truthful galore much considerations that must be taken erstwhile going this route: businesslike representation management, obscure compiler errors, the deficiency of a autochthonal record system, and more. In the end, Arduino was a cleanable choice for the firmware, and it made loop easy contempt an first learning curve.
The firmware interfaces pinch each the sensors and modules: the ADC, radio, GPS, SD card, and camera. After mounting up each hardware, a elemental loop is followed where images are captured and packetized, telemetry information is collected, and the radio alternates betwixt transmissions for SSDV and telemetry.
Mistakes Made
As everyone does astatine 1 point, I swapped MISO and MOSI for the SPI lines! I was able to hole this rumor pinch immoderate speedy but different janky bodges.
GPS & Tracking
The NEO-6M GNSS module utilized connected StratoSpore was unreliable and difficult to use. At a higher cost, I utilized the SAM-M10Q module this time. It has an integrated patch antenna, and utilized the crushed level of the circuit committee arsenic portion of the setup. The datasheet notes utilizing a 50x50mm crushed level is ideal, but it worked good astatine the 30x60mm size I used. It tin beryllium beautiful delicate indoors, sometimes moving great or not, but I recovered utilizing Assisted GNSS helped. During flight, the module was maxed out, search 32 satellites.
Live coordinates and altitude were transmitted complete the power link, and were then fed to Sam’s civilization dashboard and SondeHub for unrecorded search and predictions.
As 1 of my goals was to usage a secondary tracker, I programmed a QRP Labs U4B balloon locator to transmit WSPR and JT9 at circumstantial intervals connected the 10 metre (licensed) band. These are weak-signal protocols and are very slow, pinch WSPR messages lasting 110.6 seconds, and JT9 at 50 seconds. While this is useful for search thing for illustration a picoballoon running connected star panels, it is inconvenient and not feasible to beryllium utilized for tracking precocious altitude balloons connected their descent.
Ultimately, the U4B did not fulfill its purpose, and was not suitable for tracking the balloon. In the future, I mightiness effort utilizing a Tiny4FSK or making a standalone locator moving 70cm LoRa.
Radio Link
I utilized the Wio-SX1262 from Seeed Studio to merge LoRa (Long Range) power transmissions pinch the electronics. LoRa is meant for low-power transmissions that tin scope acold distances. It operates astatine 915 MHz (33 cm band) for unlicensed use, making it easy to get into.
LoRa has different configuration settings that impact really efficaciously transmissions can beryllium received astatine distance. Spreading Factor controls the velocity of the information transmission, going from SF7-SF12. I utilized SF9 arsenic a bully mediate ground, up from SF7 past year. SF9 provides a receiver sensitivity of -129 dBm while not making packets excessively long.
Airtime is particularly important for LoRa: the longer the message, the greater the chance of interference and awesome loss. Telemetry messages had 247 ms of airtime, pinch SSDV packets astatine 677 ms. During testing, longer messages at higher spreading factors were harder to person pinch my SDR. Coding rate (error correction ratios) is besides a facet successful reception, but I recovered transmitting at SF9 pinch a coding complaint of 4/5 (4 information bits + 1 parity bit, the lowest detection level pinch nary correction) and 125 kHz bandwidth worked well. Shorter messages also buy america a cheaper failure: losing a mini image packet doesn’t wounded arsenic overmuch as losing a large one.
Telemetry connected the 33 cm set worked amazingly well, and packets were received during the full flight. There were occasional losses successful awesome during the chase, arsenic we passed done immoderate heavy canyons and towns wherever we received interference.
All telemetry was packed into a azygous 35-byte packet. I was capable to create a more businesslike packet building than past year, utilizing packed latitude and longitude values alternatively than Plus Codes. I besides took much attraction to usage correctly sized integers.
SSDV images were besides sent complete the LoRa protocol pinch 128-byte packets, modified from Philip Heron’s implementation utilizing 256 bytes. LoRa has built-in correction detection, negating the request for SSDV to nonstop this information.
Mistakes Made
I mistakenly configured the SX1262 to usage its soul LDO, truthful it was operating inefficiently compared to utilizing the DC-DC converter it has. This intends it drew higher current than needed, draining batteries faster than expected.
Launch Day
UpLink was launched connected August 16th, 2026 extracurricular of Townsend, MT. In Montana, winds predominantly rustle from westbound to east. Townsend was our champion stake for launching, as we tin clear the mountains eastbound of it easily.
After readying to usage a sportfishing standard for measuring free assistance of the balloon and finding retired it was broken, we had to settee pinch guessing assistance from an inaccurate bathroom scale. With specified a scale, the balloon ended up underfilled, and had a overmuch slower ascent than expected: astir 1.5-3 m/s for astir of the flight. An ascent complaint of 5 m/s is perfect for astir flights, targeting a 2 hr flight.
The helium cylinder and regulator were provided for free by American Welding & Gas, which would person different been expensive for the fund of 2 precocious schoolhouse students.
As this was Sam and my first solo flight, Jared Kamp joined america pinch his expertise from his activity astatine Montana State University’s BOREALIS program. His thief was invaluable, ranging from calling successful NOTAMs and the sheriff, to moving galore formation predictions so we had the champion imaginable location to launch.
Along pinch Jared’s help, my dada and David Hansen besides joined for the launch, assisting with setup of the balloon capable station, documenting connected video, and providing extra hands for the balloon release.
The Flight
With the slower than expected ascent rate, the formation lasted adjacent to 5 hours. During testing astatine home, I measured that the payload batteries lasted around 4.5 hours earlier dying. Unfortunately, this measurement stayed existent pinch the real flight, and we mislaid power interaction astir 15 minutes earlier the projected landing. Even pinch the U4B, we were not capable to way it down. We fishy thing happened to it and that it stopped transmitting entirely. We stopped seeing the WSPR and JT9 signals connected the waterfall, and weren’t capable to decode immoderate messages successful WSJT-X. There should person been plentifulness of artillery life left, and I still don’t cognize why it stopped.
The balloon traveled 140 km (87 mi) downrange, and reached a burst altitude of 28.42 km (93,000 ft). Packet and SSDV imagery was decoded intelligibly for astir of the flight, and the receiver knowledgeable a median SNR of -4.8 dB.
The Search
The payload landed successful cardinal Montana, adjacent Judith Gap. Without a ping from the payload arsenic to wherever it landed, we were stuck pinch relying connected SondeHub’s prediction to hunt near. 15 minutes earlier landing, SondeHub’s predictions are only truthful accurate: it could person been anyplace successful a 3 km radius, aliases more.
We spent astir 2 hours searching farmland connected ft and by car adjacent the landing projection, but were unsuccessful successful locating the mislaid payload. We besides sewage access to immoderate backstage spot to search, and it was still obscurity to beryllium found. We stopped searching arsenic it was getting late, and we had already been chasing it for 7 hours. If we had a ping connected landing, we would person recovered it. If you unrecorded adjacent Judith Gap and find it, please interaction us. :)
Ideas We Dropped
As the electronics tin get acold wrong precocious altitude balloon payloads, we considered putting a manus warmer wrong the payload to support them functioning. There were two considerations erstwhile implementing manus warmers: really they impact RF and if they would continue to activity astatine precocious altitudes.
Classic air-activated manus warmers were retired of the image owed to perchance affecting GPS and LoRa functionality, since the robust powder could detune antennas successful such close proximity. They besides would extremity moving arsenic the aerial thinned. Sodium acetate-based manus warmers were besides an option, but proved to not past agelong (around 30 mins) and were excessively dense (85 grams) to beryllium feasible to put wrong the payload.
With these options exhausted, we ended up not utilizing thing to facilitate warming of the payload, arsenic self-heating of the microcontroller was plenty. It stayed above freezing constituent for the entirety of the flight.
Reflections
Despite being an wide successful motorboat (besides america not uncovering it!), we still made galore mistakes that tin beryllium improved upon for the future.
Proper Fishing Scale
With a moving standard to measurement free assistance of the balloon, the formation would have been an due length, preventing galore further problems from occurring.
Payload Separation
With a debased powerfulness fund from a agelong flight, the camera drew precious battery from the locator payload. If these were to tally connected abstracted power, the payload would person been found.
70 cm Radio Link
While the 33 cm set proved to activity good for search the balloon, I would like to research pinch the 70 cm band. 70 cm will springiness america amended scope for tracking, but we tin support SSDV connected 33 cm for earthy throughput of images.
SSDV Imagery
The 320x240 images we received were already beautiful, but I deliberation pinch a freer radio link, we could nonstop higher solution images. Maybe moreover 640x480 px!
Even pinch the galore problems we encountered, the goals astatine the commencement of the project were implemented (besides proper locator redundancy). I americium still proud of our accomplishments being the first independently organized formation we made.
Data and Source
All hardware, software, firmware, and CAD person been unfastened originated connected our GitHub. Besides root code, we’ve included the data received during the flight, including position, GNSS module information, somesthesia data, microcontroller representation info, strategy flags, and receiver position RSSI/SNR. Available as a CSV, 1 statement per received packet. All images are besides successful the gallery or successful Git. This information is each we had received connected the ground, truthful don’t expect full-res images aliases complete data.
Credits
The task was only imaginable because of the following:
- Sam Flynn for immense thief pinch the dashboard, enclosure, and launch
- American Welding & Gas for supporting maine pinch helium
- Jared Kamp for readying logistics of the motorboat and bringing valuable expertise from Borealis
- David Hansen for thief pinch the motorboat and joining america connected the chase
- My parents for supporting maine passim my agelong nights of work
- Max Kendall for his elaborate launch guide and inspiring maine to get into ballooning more
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