Pico Balloonery

Flight #11: 12 November 2024
(20m; U4B code 185)

First flight attempted since 2008. 

• Traquito JetPack plus Raspberry Pi Pico RP2040. 

• Traquito Solar System 6-cell solar array. 

• Solid core 18-gauge wire GPS antenna.

• 30-gauge wire-wrap wire upper HF radiator.

• 38-gauge magnet wire lower HF radiator.

• Braided fishing line payload string. 

• Two 32-inch Mylar party balloons inflated for 8 grams net free lift.

Flight #12 hardware pictured. Holy cow are these solar cells fragile! These are the 2 x 5.2 cm polycrystalline cells, $20 USD per 100. And I certainly ended up needing a hundred cells, because I broke them frequently. The Traquito Solar System is a fun design, and very light, but it leaves the cells vulnerable to breakage and it can be difficult to repair (ie., to replace broken cells).

On launch day there was entirely too much wind. I tried to time the release between small gusts, but the balloons blew horizontally anyway. The craft nose-dived into the sidewalk, breaking four solar cells and ending the flight. 

Flight time: zero.

Flight #12: 13 November 2024 4pm EST
(20m; U4B code 187)

Same configuration as Flight #11. 

First successful launch. VERY slow, gentle climb out - may need to adjust fill levels in the future. Apparently released too late in the day to power the Traquito, so no radio traffic the day of the launch.

In fact, aside from initial bench testing, this device was never heard from again. I suspect that either there was not enough lift to sustain the balloon overnight, or it got caught in the rain that came the following day. [Edit: Or the balloon had a leak.]

Worth noting, the 38-gauge magnet wire for the lower side of the HF antenna broke in two places during launch. I'm re-thinking the use of this incredibly fragile wire.

Flight time: unknown.

Flight #11A: 24 November 2024 10:30am EST
(20m; U4B code 185)

Venturing away from the Traquito Solar System array.

• Traquito and upper HF antenna salvaged from Flight #11.

• 8-cell solar array mounted on a 9-inch styrofoam plate.

• 3D printed frame connecting plate to payload string.

• Two 36-inch mylar balloons.

Using a styrofoam plate as the airframe overcomes four issues with the Traquito Solar System. It provides a protective bumper around the fragile solar cells. The cells are mounted loosely (by the wire leads), which helps cushion any contact that does occur. The cells are easier to swap out in the event of breakage. And by using eight cells instead of six, I hope to extend the operational hours of each day. Unfortunately it is also several grams heavier than the Traquito + Solar System combo.

The top image at right shows the craft prepared for transport, with the top roll storing the upper antenna half (blue) and payload string (yellow), and the bottom roll storing the lower half of the HF antenna (copper). 

Also pictured at right is the underside of the plate, with the 3D printed frame (black); the blue and red solar cell leads twisted, soldered, and taped; the GPS antenna (yellow), and the lead for the lower HF antenna (green curl). The lower antenna was originally soldered to the green lead, but was converted to a quick-connect design using half of a F-F jumper wire to connect the magnet wire to the lead. This allows the bottom antenna half to remain disconnected for testing, then attached at launch time, hopefully saving some headaches with the delicate magnet wire unspooling at inconvenient moments.

I launched this one by myself. The balloons took off into clear skies and minimal wind. They went almost straight up after release. No issues with the 38-gauge magnet wire.

At first, the payload would truncate some packets, so no data was being decoded on the ground. Maybe this was due to an intermittent power connection, or maybe the plate was at an angle such that the solar cells fell into shadow? Eventually I began receiving full packets of both positions and telemetry. I used WSPRnet and the Traquito website to track the payload across Virginia and out over the Atlantic Ocean.

After four hours of flight time, the transmissions stopped. It looks as though one of the balloons sprung a leak around 13:15 EST then eventually failed completely, leading to the payload crashing into the Atlantic sometime after 14:28. 

Distance traveled was about 200 miles, roughly 100 of which were out to sea. No circumnavigation this time, but a big success in that I had a clean launch, the payload achieved altitude, and that my gear was able to leave mainland North America (if only just). Party balloons seem like they should work, especially these larger 36-inch ones, as long as they don't leak. 

The maps show the HYSPLIT predicted course, and the actual reception reports from the payload. The altitude graph shows a steady climb until the leak began, then silence.

Total flight time: about 4 hours. 

Flight #13: 4 December 2024 7:50am EST
(20m; U4B code 189)

Continuing to iterate on the design to make the craft less damage-prone and easier to transport.

• Styrofoam plate chassis with (taller) 3D printed frame. 

• Flexible polymer solar cells.

• 24-gauge GPS antenna. 

• Quick-connect antennas top and bottom.

• 30-gauge antenna wires top and bottom.

• Familiar Traquito hardware.

• Two 36-inch Mylar balloons.

The flexible cells do not shatter when you drop them, which is a HUGE improvement. But it does take four of them at this size in parallel to produce the current needed to drive the Traquito hardware. At $10 USD per cell, that makes for a fairly expensive tracker. 

The heavier 30-gauge wire-wrap wire for the lower half of the antenna was much stronger than the ultra-skinny 38-gauge magnet wire. This made prepping and launching less stressful.

The launch was perfect - clear skies, no wind at ground level. In the launch photo you can see the shadows of the solar cells on the bottom of the plate, and just make out the bit of blue masking tape at the end of the lower antenna (which has coiled itself into a spring). 

I did not hear from this payload until three hours after launch. This made for a tense morning. I believe the sun's elevation was not high enough to energize the polymer cells until almost mid-day.

The payload did start sending data eventually, and I was able to track its voyage from the Eastern Shore to about 100 miles out into the Atlantic... and right down into the water. Its last report was just 12 miles from Flight #11A's last position. It looks like another leaky balloon doomed this flight. Hopefully Santa will bring me a heat sealer for Christmas.

The night before launching, I wrote my contact information on the styrofoam plate in case someone finds it on a beach somewhere. I'm curious if it will ever find its way back.

Total flight time: about 4 hours 15 minutes.

Flight #14: 25 February 2025
(20m; U4B code 186)

Having used all of my expensive polymer solar cells, I'm back to using the fragile crystalline cells.

• Same design as Flight #11A - Traquito on styrofoam plate and 3D printed frame.

• Quick-connect 30-gauge antennas top and bottom. 

• 28.9g payload.

• 5.7g free-lift (miscalculated) - least amount of lift so far.

• Pre-stretched PartyWoo 50-inch balloon.

• Heat-sealed neck.

• Party Factory Helium (from Germany) .

This was the last Traquito from my original order of five from JLCPCB (one burned up during bench testing).

This balloon =barely= got off the ground. 5.7 grams is not much free lift. My previous flights must have used something like 15g or more of free lift, because they fairly shot upward compared to this one. I thought for sure it would end up in a tree, but it climbed out successfully from the park. 

The first hour's track (plus the HYSPLIT model) make it clear we're heading for Canada. At 28,346 feet and still climbing. Some low clouds moved in after launch, but the balloon was well above them. The balloon stopped transmitting for the night near Long Island.

The next morning, 26 February, the payload came in clearly on 20 meters from the coast of Newfoundland. It had drooped from 32K to 18.8K feet, probably due to rain or mild icing, but climbed out again to 34K as the morning progressed. The balloon made a wide, lazy right-hand turn toward Africa by the afternoon, and was within a couple hundred miles of the Azores as it lost power for the night. 

On the third day, Flight #14 dipped south toward the Canary Islands. Days 5 through 10 saw the balloon pass over Africa and Asia, including a day flying over India when no signals were received. The Pacific crossing took several more days, culminating in a very slow haul the last 1000 miles to Mexico. 

The flight ended in the city of Pueblo, Mexico. Telemetry from the balloon had shown a consistent altitude of over 30,000 feet (except for the first night), so presumably the balloon popped. Locals in Pueblo recovered the airframe, and attempted to contact me via phone (I had written my contact info on the styrofoam plate with a Sharpie). Unfortunately I did not have any fluent Spanish speakers handy, so that amazing connection was never fully realized. 

I had very nearly succeeded in my goal of circumnavigating the Earth, only to fall short by a couple thousand miles. 

Total flight time: 15 days.

Flight #15: 27 March 2025 10:20am EDT
(20m; U4B code 175)

As we're getting into the Spring months, I will be trying to achieve a higher sustained altitude to stay above most weather systems. 

• Mark II platform - smaller and lighter than previous flights (15.7g airframe + flight computer, 4.8g 30-gauge upper antenna, 0.8g 38-gauge lower antenna = 21.3g total payload)

• Frame and flight computer glued into place on bottom of airframe.

• Pre-stretched PartyWoo 50-inch balloon.

• Heat-sealed neck.

• Party Factory Helium (from Germany).

• 7 grams of free lift.

Like Flights #11A and #13, this one ended up in the Atlantic. It transmitted right down to the water, so it seems the balloon drifted down in an orderly manner (suggesting a leak, instead of a burst). Maybe I stretched the balloon too aggressively?

Total flight time: about 4 hours and 30 minutes. 

Flight #16: 9 April 2025 7:17am EDT
(10m; U4B code 176)

First (and probably last) flight using the 10-meter band. Besides the smaller and lighter antenna halves, same design as Flight #15.

• 2.7g 30-gauge upper antenna, 0.4g 38-gauge lower.

• 16.1g airframe and flight computer.

• 19.2g total payload.

• 7.0g free lift.

Another bee-line to the bottom of the Atlantic.

This flight almost started with a disaster - after launching from the park, the balloon headed directly for the Channel 23 broadcast tower. Somehow it dodged its way through the guy lines and got away without incident. 

There were very few reception reports on 10 meters versus previous flights on 20 meters. IMHO, the 3 grams of weight savings and slight ease-of-handling advantage is not worth the risk of losing contact. 

Total flight time: 4 hours 45 minutes.

Flight #17: 17 April 2025 7:30am EDT
(20m; U4B code 87)

First flight of Mark III platform, wherein the computer circuit board fits into notches in pylons suspended below the 3D-printed frame. This design requires less glue, and provides a sturdier and more consistent structure. I'm also experimenting with omitting the flight string, and connecting the flight computer to the balloon using just the upper antenna wire. 

• Back to 20 meters.

• 17.5g airframe and flight computer.

• 4.7g 30-gauge upper antenna; 0.7g 38-gauge lower.

• 22.9g total payload.

• 7.0g free lift.

I used 22-gauge (or maybe 24?) stranded wire from an Ethernet patch cord to wire the solar cells (not pictured). This wire is easier to strip and to solder, but is much stiffer, springier (and therefore difficult to bend and position), and a bit heavier than the 30-gauge solid wire-wrapping wire I have been using. I was unable to tape this wire to the bottom of the chassis, which may be a factor later. I don't think I'll be using this wire again. 

Launch day was windier than expected. I had to hold the payload by the 3D-printed frame for a minute or so, waiting for a lull in the wind before launching. The lull came, though, and takeoff was otherwise uneventful. 

During the first hour of flight, I was receiving short blips of the warm-up tone on the correct frequency, but no WSPR packets. I suspected an electrical problem (perhaps with that stiff wiring on the solar cells). As the balloon flew on, though, this evened out, and I started receiving data normally. I now suspect that the payload is flying at an angle, and that the solar cells were falling into shadow, cutting power momentarily and resetting the flight computer. 

The rest of the flight showed no issues with lost packets (beyond the normal occasional miss). The balloon flew north toward Greenland, then south to (and through) the Straits of Gibraltar, then turned north through Italy, Switzerland, and Germany, then further north through the Baltic states and into Russia. Another day later it burst and fell into the Siberian wilderness. 

Total flight time was 4 days 21 hours. 

Flight #18: 29 April 2025 7:10am EDT
(20m; U4B code 88)

I haven't done a detailed description of the hardware recently, so here goes.

• Mark III platform, which consists of:

  • Raspberry Pi Pico flight computer, with Traquito Jetpack providing GPS, Si5351-based radio, and software.

  • Styrofoam plate chassis (150mm across).

  • 3D printed frame.

    • Frame features pylons on bottom to suspend flight computer below the chassis (to avoid casting shadows on the solar cells).

  • 8 crystalline solar cells.

    • These are "stitched" onto the styrofoam chassis by passing the power leads through the styrofoam plate. The leads are then twisted together and soldered to make electrical connections, and taped to bottom of chassis. 

  • 30-gauge wire-wrap wire forming the upper HF antenna half (quarter wave on 20m = 204 inches).

  • 38-gauge magnet wire forming the lower HF antenna half (also a quarter wave = 204 inches).

• Notes for this flight:

  • Sticking with the PartyWoo 50-inch silver balloon inflated with Party Factory helium from Hobby Lobby. I stretched the balloon with air, then deflated it, and re-filled it with helium (just enough to get the target lift), heat-sealed the neck in three places, and covered the inlet valve with Kapton tape.

  • Switched back to 30-gauge solid wire to connect the solar cells.

  • Second flight without a flight string (using upper HF antenna half instead of fishing line to attach payload to balloon).

  • 16.4g airframe + 4.9g upper + 1.2g lower antennas = 22.5g payload.

At the suggestion of PicoBalloon community members, I flew this balloon with a much smaller amount of free lift - just 4.5 grams instead of the previous 7.0 grams - in order to (hopefully) avoid bursting the balloon prematurely. My longest-lasting flight had just 5.7g of free lift, so the suggestion to use less helium seems reasonable. 

Unfortunately, the low amount of free lift means a very low departure angle. After release this balloon flew into a tree 150 yards down range, then took off again. The payload was not heard from again for an hour and a half - this led to some premature mourning. Eventually, though, it woke up and began transmitting.

In hindsight, I wish that I had checked the Hysplit model for that day before releasing. It predicted southern travel followed by a bizarre cluster of turns to the northeast. Perhaps another day would have been better.

After its detour through the Bermuda Triangle, this balloon flew most of the way to Africa before disappearing into the Atlantic.

Total flight time was 6 days 23 hours.

Flight #19: 23 May 2025 8:00am EDT
(20m; U4B code 89)

Cutting the styrofoam plate into a square airframe (about 125 x 125mm) instead of a circular one yielded this bat-wing design, which provides better protection for the corners of the solar array. 

• 16.6g airframe + 4.6g + 1.1g antennas = 22.3g payload.

• 4.5g free lift.

• 50-inch silver PartyWoo balloon.

This flight ended before it began when the antenna wrapped itself around a light pole in the parking lot upon launch. 

This makes two flights in a row that encountered objects on the ground before they could climb out. Using low amounts of free lift are causing take-off trajectories to be so low that I worry my launch site may no longer be suitable. 

Total flight time: 10 seconds (approximately).

Flight #20: 24 May 2025 8:15am EDT
(20m; U4B code 50)

Same Mark III design as Flights #18 and #19. 

• 16.2g airframe + 4.7g + 0.8g antennas = 21.7g payload.

• 4.5g free lift.

• 50-inch PartyWoo envelope.

I am using a new spool of #38 wire for the lower antenna of this flight - apparently it is a bit lighter than my previous supply. The styrofoam plate is cut down a bit more, too, which explains the slightly lighter airframe.

This flight took to the sky under an almost dead calm, meaning that it climbed vertically well above the treetops before it started moving horizontally. Even better, it later climbed directly into the jet stream, which whisked the balloon out to sea and over to Europe. 

After several days flying into and out of Russia (including experiencing a GPS spoof over Belarus), this flight eventually ended just south of the outer Aleutian Islands of Alaska. It had crossed the International Date Line, but did not quite make it to landfall in North America.

Total flight time: 8 days 18 hours.

Flight #21: 3 June 2025 7:00am EDT
(20m; U4B code 51)

Another Mark III with a silver PartyWoo 50.

• 16.1g airframe + 4.5g upper + 0.8g lower = 21.4g payload.

• 5.5g free lift.

After filling and sealing the balloon, I trimmed down the quick-connect lead on the lower antenna, saving a full gram. Thus the free lift ended up a gram higher than my target of 4.5g. The 3D-printed frame for this flight is a one-off; it is printed in ABS instead of PETG, making it just a fraction lighter than the other frames.

There was no wind on the morning of the launch, so take-off was uneventful (though uncomfortably close to a light pole again). The payload had some trouble powering up after launch - it was spamming the channel with radio bursts, and would not sustain a tone. This cleared up as the sun rose.

This payload disappeared over China. It is unclear whether it came down or the electronics failed. 

Total flight time: 10 days 15 hours.

Flight #22: 11 June 2025 6:45am EDT
(20m; U4B code 52)

Also a Mark III vehicle with a silver PartyWoo 50.

• 16.1g airframe + 4.5g upper + 1.1g lower = 21.7g payload.

• 4.5g free lift.

The tank I used to fill this balloon was questionable - it seemed to fill the balloon more than normal, as though there was air in the balloon along with the helium. This seems to have affected free lift, too, as this one barely got off the ground. And sure enough, once it had had time to warm up and climb, its altitude topped off at about 20K feet, instead of the 35K feet at which most of my other balloons had flown.

*Plop*. Like so many others, this one burst and landed in the Atlantic Ocean.

Total flight time: 2 days 4 hours. 

Flight #23: 23 July 2025 7:00am EDT
(20m; U4B code 50)

This flight will use the last of my second order of Traquitos. To shake things up a bit, I'm trying to put the entire works on a strict diet to see how much lighter I can get my basic design. This will include:

• Using six solar cells instead of eight.

• Shrinking and lightening both the 3D-printed frame and the styrofoam chassis.

• Using a flight string of light fishing line, and 38-gauge upper and lower antenna halves.

Using these strategies, I should be able to get my payload down to 15 grams, a savings of about 28%. Less payload means less helium, which yields more altitude, which hopefully means fewer encounters with weather.

• 12.7g airframe (115 x 78mm) + 1.7g upper + 0.7g lower = 15.1g payload.

• 4.5g free lift.

The 3D-printed frame holds the flight computer by one end, so is inherently unbalanced. I tried to compensate for this on the smaller 3x2 chassis by offsetting the frame to one side. I used a bit too much offset, though, so the airframe still does not hang level when suspended by string. This, along with the reduction in solar cell count, may hurt performance at low solar angles. We shall see.

Launch day was windier than advertised, but a lull came along soon enough, and the balloon and payload were on their way. It was hours, though, before anything was heard from the payload. It tried to transmit as scheduled, but the most it could muster were brief blips on the WSJT-X waterfall (instead of the continuous warm-up tone that it should produce). The power budget with six solar cells requires a bit more sunshine than did my other flights, so this was not unexpected.

In an odd twist, this flight headed southwest, opposite the typical west-to-east weather pattern. It continued this track into days two and three, getting as far west as central Texas where it spun in circles for a few days before finally turning back east on day seven.

From Texas, it made its way north, eventually passing through New York, and Maine, and traveling a short ways into Canada. It encountered some weather there, shot up a couple hundred feet above float on a warm updraft, and then (of course) burst and fell to the ground.

Total flight time: 8 days 6 hours.

Flight #24: 22 July 2025 7:45am EDT
(20m; U4B code 50)

After some drama in the pico-balloon community, I'll be flying my new batch of trackers with different firmware (OpenTJP).

• Traquito hardware, PartyWoo 50-inch balloon.

• 16.0g tracker, 4.6g upper, 1.8g lower = 22.4g payload.

• 4.5g free lift.

Clean take-off into a bright sky. The new firmware is chatting away happily...

...or at least it did until the balloon sprang a leak and descended near the Great Dismal Swamp. 

I'm frustrated by the continued failures with the PartyWoo balloons. Hopefully my second shipment of clear cymylar balloons from China will be better (the first shipment got stuck for over a month in customs). 

The OpenTJP firmware seems to be up to the task of running the Traquito, and since it is open source, is more amenable to tinkering. I think I'll stick with it for a while. 

There was some kind of problem with the solar array today - the tracker reported just 4.5 volts instead of the usual 5+. Maybe there was cloud cover? Or a bad cell? Or something related to the new firmware? Of course I have no way to inspect the hardware after launching, so I'll have to keep an eye on this with future trackers. 

Total flight time: 6 hours 30 minutes.

Flight #25: Tentative for Sunday 17 August 2025
(20m, U4B channel 51)

After multiple delays and lost packages, I finally have the balloons, electronics, and helium all ready to go. 

• 14.7g + 4.5g + 0.9g = 20.1g payload.

• 4.5g free lift.

This payload was launched out of sequence (#26 was launched first, while I waited for electronics to arrive). That flight had trouble with the two balloons I used, so I am a little suspicious of the cymylar balloons I have on hand. I will fill the balloon ahead of time, and wait to see if it can maintain its free lift for several days.

Flight #26:  9 August 2025 6:30am EDT
(20m & 30m)

I am finally going to fly the ZachTek WSPR TX Pico that I got for Christmas 2024. This tracker is affectionately known as the "birdhouse" among my family. This will be the fourth flight I have launched from this bottle of helium, and the first I will have flown using a cymylar balloon.

• 13.0g tracker + 4.4g + 0.9g antennas = 18.3g payload.

• 4.5g free lift.

• Clear 60-inch cymylar balloon.

• Transmitting WSPR on both 20 meters and 30 meters.

The first attempt to launch this payload was met by a stiff breeze that had not been forecasted. The second attempt, an hour or so later, was not successful because the balloon had leaked helium overnight, and no longer had any free lift (the balloon stopped rising when it picked up the lower antenna - I had to chase it across the parking lot and haul it back in to fly another day). 

That other day came on the morning of Saturday 9 August 2025. Armed with a new tank of helium, I gassed up one of my cymylar 60-inch balloons and released the "birdhouse" skyward. I had once again lost some lift in the hours before launch; I estimate that I had 4.0 grams or less of free lift. Takeoff was therefore very gradual, but free of any interaction with objects on the ground. 

This tracker never transmitted after it was launched, so its fate is a mystery. 

Total flight time: unknown.

Hardware for future flights

Also for Christmas 2024, I received a QRP Labs U4B. This guy is tiny - just 13 x 33mm once the USB port is snapped off. I had some trouble at first getting the GPS to lock, but per Hans' suggestion, I added the Y-shaped GPS antenna shown, after which receive performance was much improved.