PICO-Ballooning – By John Ruthroff

In early 2023 I stumbled into Pico-Ballooning, which is the art and science of sending balloons into the mid/upper atmosphere (roughly 45,000 feet above sea level) equipped with amateur radio transmitters and, in some cases, other scientific payloads. These flights are monitored and tracked not only by amateur radio operators, but by the National Oceanic and Atmospheric Administration (NOAA, the parent body of the U.S. National Weather Service) as well as other organizations who study our atmosphere.

The primary intent of this site is to pass along my experiences, to serve as something of a clearinghouse for information I’ve culled from the pico-balloon mailing list, and as a personal diary so I can remember what I’ve done and when.


Sounding balloon being launched by the author, Bosnia – Herzegovina during Operation Joint Endeavor 1997. The radiosonde (it’s a bit of a white smear in this photo) can be seen just to the right of the antennas as a tall skinny white box.

There are many types of balloons used for atmospheric research. The most common is the “sounding” balloon. These are fairly large balloons (a common size is eight feet in diameter when fully inflated) that lift a parachute and a radiosonde into the atmosphere. A radiosonde is an instrument package that samples pressure, temperature, moisture content and wind speed and direction (and possibly other variables) as it rises through the atmosphere. During the flight, the radiosonde radios back to the receiving station, in real time, the information it has gathered.

At some point in the flight, the balloon will burst when the high pressure in the balloon exceeds the strength of the balloon material (usually latex). When the balloon bursts, the parachute opens to slow the descent, and the entire affair heads back to earth.

Sounding balloons are used by civilian weather interests, universities and research institutions, and by the military. In my particular case (U.S. Army) we used sounding balloons to help improve the first-round accuracy of artillery fire.

In pico-ballooning, the balloons are much smaller and are made of a more durable material so they do not burst but find a pressure altitude where they will stop rising and float along with the wind. In this way they are, after their initial climb, horizontally sounding the atmosphere (whereas sounding balloons are pretty much just vertically sampling the atmosphere). Radiosonde sounding balloons have a lifetime of hours, where pico-balloons can stay in the air many months (or years), and circle the globe many times.



A balloon that is popular for this type of activity is manufactured by the Yokohama Balloon Company in Yokohama Japan. Their balloons are not designed for this sort of use (to my knowledge nobody makes a balloon that is, at least at an affordable price). Yokohama makes these balloons for weddings, parties, events and the like. They are not designed or intended to float at high altitudes. However, they do work. When fully inflated they are just shy of 3 feet in diameter. A buyer in the U.S. can get a package of ten of these for $150 which includes shipping. A company names SAG balloons also makes balloons that some in the PBC use. I’m not familiar with their product.


Making the balloon go up requires that it be inflated with a gas that is lighter than air. There are three main choices, hydrogen, “pure” helium, or helium diluted with air, e.g. “party store” helium. In the US this is a mixture of about 80% helium and 20% air. Many po-po the party store helium, but my tests have found it to be quite feasible (see JR16).

Hydrogen is cheaper, flammable, can be easily manufactured, but can be difficult to obtain as it suffers from a bad publicity issue known as “The Hindenburg Disaster”. Helium is an inert gas. It’s considerably more expensive than hydrogen, and is a non-renewable resource. There is no known way to manufacture helium. Helium is formed by radioactive alpha decay inside of rocks, which is an extremely slow process. When it’s gone it’s gone.

Having inflated and flown literally several hundreds of sounding fights using hydrogen I personally consider the hazards overstated. In those “accidents” that I’ve been involved in the only dramatic event was when a balloon would fail during inflation. It would go “POP”, and the hydrogen would go up into the atmosphere. No flame, no explosion, no personal injuries. Nothing but the loss of the balloon and a few cubic meters of hydrogen. The only safety equipment required was safety glasses in the event that a fragment of the balloon might strike an eyeball (that never happened either). We also wore helmets and flak vests, but those were to protect us from other hazards.


The payload is anything attached to the balloon. To do something useful with the balloon a radio transceiver is attached to the balloon. These devices normally receive position information from GPS satellites and retransmit that information to ground stations. One popular device is the U4B manufactured by QRP Laboratories. Another is the JetPack, which is a Raspberry PI Pico soldered to a small circuit board. There are others, some homemade, some manufactured.


There are three options, the Sun, a battery or a combination.

If using only a battery, the useful lifetime of the payload will be short since when the battery runs out of electricity the party’s over.

A solar cell array consisting of seven polycrystalline solar cells. Cracking and breaking these incredibly fragile cells is par for the course.

Combining the two provides the most flexibility but also increases the weight. The sun can charge the battery during the day, and when darkness falls the payload can run, for a while, off the power provided by the battery (in theory at least). The problem with this approach is that it is very cold at 40,000 feet and up. Batteries don’t like the cold and will have very low output for a very short time so for practical purposes this isn’t a viable option.

Some people glue their cells to the airframe. I don’t do this because of the possibility that the temperature change between the assembly area and the cold at 40,000 feet + may crack a cell. I just attach each end of the solar array to the airframe with epoxy, so the cells can “float” and contract a certain amount.

Here is how I make a solar panel.



PB’s and their payloads are very fragile. They don’t react well to moisture, either liquid or solid. Since in most cases the electronics of the payload are open to the weather, they must operate at an altitude that is above the tops of clouds. Much of the time, barring an encounter with a thunderstorm, PB’s do well at 40,000 feet or so. At that altitude the air is very dry so moisture condensing or freezing on the balloon or payload isn’t much of a concern, which is a good thing.

When using the sun (using small solar panels to provide electricity to the payload) the payload has a long-lasting source of power…during the day. Once the sun goes down and the electricity stops flowing, the payload will fall silent until the next sunrise. So it’s a daylight-only operation.


The great equalizer. To get to 45,000 feet and stay there one can’t expect to to bring much along. The total package, balloon, payload, power supply…everything…normally can’t weight more than 3 ounces. That’s the weight of a deck of cards or a small onion. Since nearly half that weight it taken up by the balloon itself, we’re down to lifting a useful payload/power supply combination of 8/10th’s of an ounce, less than the weight of a single AA battery.



An informal survey of those that have had successful flights indicates that they “stretch” their balloons to prepare them for the rigors of high-altitude existence.

Far from being a difficult task, it can easily be performed with a) a balloon, b) an air pump such as a very inexpensive pump that will inflate a Yokohama in about 2 hours, and deflate it at the same rate. It’s a 12 volt pump, but solder up a wall-wart DC power supply to it and your in business. A 3mm ID vinyl hose fits snugly onto both connectors.

You can find these on Amazon and other places. Works great.

There are many ways to achieve the above. Experimenting is the name of the game.

An example of experimentation is finding a way to fit the inflation hose into the balloon nozzle. You will want to use a small diameter hose as a hose that is too big will pull the nozzle out when you try and remove it (and you will need to remove the hose).

One method is to take a wide rubber band, 1/4 -inch, 3/8th’s of an inch or so, and cut it so you have a long piece of elastic. GENTLY push the hose into the nozzle. If you feel very much friction, your hose is too big. Once the tube is in, tightly wrap the rubber band around the nozzle several turns. When you’ve reached the end of the rubber band, fix it in place. I just twist some insulated wire around it. A tie wrap, Kapton tape, or small diameter parachute cord should work just as well.

View of the nozzle-hose connection on a partly inflated balloon.

I personally have not had great luck using the rubber band method with plastic tubing. I think part of the reason is that the tubing I was inserting in the balloon was a bit to small, so when I would wrap the rubber band around it wouldn’t always clamp completely down on the folded nozzle.

To alleviate this problem I took a piece of brass tube (which is a VERY snug fit in the balloon nozzle) and pushed it over the inflation tube and glued it in place. Now when I wrap the rubber band/tie wrap around the joint there are no leaks. Having said that, many people have had success without having to use a brass sleeve, so this method should not be discounted.

The old inflation setup. Attach the inflation hose to the balloon, affix it in someway to a shower curtain rod, and attach the other hose end to your inflation device. The device hanging in the upper left is a manometer.

A Yokohama balloon may appear to inflate abnormally at first. This is due to the balloon panels sticking to themselves. To fix this, start the inflation process and let the balloon do its thing. When it starts to look strange examine the skin. You’ll find that parts of the balloon have “stuck”.

Partial inflation. To fix, just examine the odd looking areas and gently pull the seams apart.
Once the balloon looks something like this, it’s ready for a moist environment.

When the balloon starts to look fully inflated, but still has some wrinkles, it’s time to “stretch” it. My method of doing so it to inflate the balloon until the small wrinkles along the seams disappear. At that point the balloon is probably around 105 to 110″ in diameter. Clamp the inflation hose shut, turn off the pump and wait from a few hours to several days for the balloon to stretch.

One might think that the balloon will, on its own, deflate itself it a large extent. It won’t. Because the material of which the balloon is made is not very elastic, it has no more propensity to deflate itself than it does to inflate itself. And it has a self-sealing inner nozzle (if you are using a Yokohama with a nozzle).

The inner “self sealing” nozzle of an early model Yokohama. This nozzle has been pulled out of the balloon to be able to better take a photo of it.

The idea is that for conventional (earthbound) use, the balloon is inflated through this nozzle. When the balloon is fully inflated and the inflation tube is removed, the internal pressure will collapse the nozzle upon itself. Probably works great for a one time inflation. But since we need to deflate the balloon after stretching it, then only partly inflate it with lifting gas (more on this later) this nozzle doesn’t self seal. LESSON LEARNED: Yokohama now sells a version of this balloon without the internal nozzle.

A “no nozzle” Yokohama inflation port.

How to deflate? Scroll up some and buy the small inflation pump. It also serves as a deflation pump, just move the air hose from the OUT port to the IN port. It’ll deflate in about 2 hours.

It’s possible to avoid the deflation process all together, and just stretch the balloon with the inflation gas of choice. Bad idea. Unlike a latex sounding balloon, a Yokohama will look very underinflated at launch. It need about 0.07 cubic meters of gas at launch. To fill it to stretching capacity it will take about 0.28 cubic meters. So one would still have to pump out 0.21 cubic meters to launch, a real waste of lifting gas. And, if you are using hydrogen, ask yourself how wise it is to pump hydrogen thru an electric pump that wasn’t made for pumping a flammable gas. It’s your money and time and safety, so choose wisely.

Some will add lifting gas the night before the launch. The issue here is that some of the lifting gas will leak out of the balloon overnight because the hydrogen or helium molecules can penetrate the skin of the balloon at room temperatures. To avoid this I just add lifting gas right before launch. It doesn’t take all that long and eliminates the variable of how much gas will leak through the balloon overnight (as well as having to abort a flight due to a last-minute change of weather, leaving you with a filled and sealed balloon).

Of course there is nothing that says you must launch in the morning. You can launch at night, but depending on your emotional makeup, a night launch means waiting until the next morning to see if your pico will phone home.

Sealing the balloon after adding lifting gas.

In order to not let your lifting gas escape, you need to find a robust way of sealing the nozzle of the balloon. I use a heat sealer.

Heat sealer.

It’s made for sealing cookies and food products (along with many other products) into a plastic bag the resembles cellophane. But it works fine on the trade-secret material used to make Yokohama balloons. You stick the nozzle over the lower “band”, press the hinged top part down, the heating elements come on and melt the material together. It only takes about five seconds. It has a dial that allows you to adjust the heat settings. I put mine on “6” and it seems to work well. There are dozens of these on the open market and they are not all that expensive.

Other methods include epoxy (didn’t work for me), superglue (didn’t work for me), epoxy using a UV light to cure (didn’t work for me), E6000 (didn’t work for me), plastic model glue…do I need to say it again??? Well, you get the idea. Some people just use Kynar® tape or an equivalent. I prefer redundancy, so I heat seal and use tape.

DuPont™ and Kynar® are trademarks or registered trademarks of affiliates of DuPont de Nemours, Inc.

Note the sliver band on the self-sealing balloon. Some people use solvents to remove this band before sealing. I don’t. Whether that can explain some of my short flights is anyone’s guess.

Different band sealers have different width heating bands, so you may be able to get a third seal in (or maybe only one). The factory heat seal is on both sides of the nozzle, it doesn’t interfere with inflation.

Attaching to transmitter to the balloon.

Since I’m using very thin (30 gauge…about 0.33mm in diameter) magnet wire for antenna elements, I use Kevlar® kite line as strain relief so no stress is put on the wire. The method I use is to start at one end of the antenna wire, lay a length of kite line that is longer than the antenna element (my antenna elements are 194″ long, so I usually cut about a 200″ length of kite line) and wrap a small piece of bare wire around the antenna element and kite line.

DuPont™ and Kevlar® are trademarks or registered trademarks of affiliates of DuPont de Nemours, Inc

Attaching the kite line to the antenna wire. Note the slack in the antenna wire at the bottom.

I then epoxy the connection (I’m all about redundancy) and cut off the ends of the twisted wire. I do this about every 45 inches or so.

For the antenna/kite line to transmitter connection, I again make sure the kite line is taking the load.

Upper antenna element and kite line attachment to the airframe. Note there is no stress on the antenna element. This photo shows a JetPack but the same idea works for any transmitter. The line doesn’t have to be attached to the transmitter, any convenient location will do. All connections are epoxied.

The bottom antenna element is simple, solder it to the transmitter and it just hangs below the transmitter during flight.

The lower antenna element is simply soldered to one of the transmitter antenna leads. Each antenna element is wrapped around a cardboard toilet paper core for easy ground handling. The red dot on the transmitter is nail polish to remind which power lead is positive.

How much lifting gas to add.

As with all other aspects of this endeavor, there are many opinions. But first some basics.

When lifting gas is added to a balloon until it just hovers that’s what you’ll have, a balloon that “just hovers”. That’s no good! We want it to rise. We need to add enough “extra” gas to the balloon so that it will lift the payload to the desired altitude. The term for that is “free lift”. Most people aim for about 40,000 feet, about 8 miles up. At this altitude the balloon is in a relative safe zone where it is above the weather, at least during the cooler months. Summer thunderstorms can reach up to 60,000 feet, but at some point we have to roll the dice and hope our balloon doesn’t run into one.

So, how much “free lift” do we need, and how do we judge when we have it? A good figure is that for an altitude of 40,000 feet or so seven grams of free lift seems to be the magic number. This seven grams is added to the weight of the payload. So, if my payload weighs 14 grams, I add 7 grams to that and come up with 21 grams of what is called “neck lift”.

Neck lift is how much weight you put on the balloon to make it hover at your inflation site and be assured that it will climb to the desired altitude. I have a gram weight set. So I take a plastic bag, put weights in it, and weight it (bag and all) until it weighs (in this example) 21 grams. I then use a piece of tape to tape the bag/weight assembly to the balloon and add lifting gas until the balloon hovers. It pays to be finicky about this process. Too little lift and your balloon ends up in a place, as the ancient mariners said, “where there be monsters” (i.e. too low, where it will run into weather). Too much lifting gas and you risk bursting the balloon.

Some essential things to have to get your inflation right…

A GOOD scale.

I use the one pictured below. There are many manufacturers of quality scales, just find one that has good reviews, can read sub-gram weights and can be calibrated.

If you are on a budget or are not sure how much you want to pursue this sort of activity you can use a food scale. If you do, “your mileage may vary” depending on the quality and accuracy of your food scale.


These are used to calibrate your scale and to set the “neck lift” of the balloon prior to launch.

Summary table of flights

Table is updated every Sunday (more or less). Last update 14 July 2024.

Clicking on the Flight Number link will open details about the flight in a new browser window.

For those flight that are noted to have “went down at night” (except those that transmitted from the ground), no flight time or distance can be reported since the path to the landing point and time of landing are unknown. Losses at night are the most disappointing since determining the cause of the loss is nothing more than an guess.


A typical early-model JR series payload. GPS receiver and HF transmitter (aka “U4B” in in the upper left). Solar cells are blue.

JR01 (my alias for the first KC9IKB flight) was released at 1210 UTC on 27 May 2023 from the CDLF (Crescent Drive Launch Facility, the cul-de-sac outside our house). Launch weight 14 grams.

Its first report back was at 1232 UTC, sun altitude about 22 degrees.

This is a “dry-stretched” late-version Yokohama. Two heat seals were applied to the neck along with Kapton® tape. No other adhesives were used for sealing.

The air frame is white Styrofoam™. Power source is eight (or 7.5) polycrystalline solar cells, 0.5 volts per cell wired in series, in a “flat” (all cells looking up) configuration. No battery. The top antenna (balloon to U4B) is 26 gauge magnet wire, bottom antenna is 30 gauge magnet wire. Antenna wires were not reinforced. Payload weight 14 grams.

Maximum insolation would have been reached around 1743 UTC. I was concerned that the voltage regulator circuit would be damaged by over-voltage. I don’t have a full understanding of how to interpret the voltage shown on the tranquito site (I’m guessing it rolled over) but in any case it has survived its first high-angle sun.

Loss of signal was predicted at 2240 UTC. It occurred at 2332 UTC, sun altitude 15 degrees. Last reported altitude was 38,000 feet, down from 42,000 feet earlier in the day.

The next morning, JR01 was on the ground, or at least in a tree. It had traveled about 110 miles from its last position reported near sunset (when the sun angle was too low to power the solar cells). Probable cause of failure is a gas leak from the balloon.

From the GPS position it appears to be in a tree in the Black River State Forest northeast of LaCrosse Wisconsin. A reasonable scenario, since it is still transmitting days later, is that it landed with the solar cells up and they antenna wires still stretched out. It was last heard from on 10 June 2023.

Below is the flight path of JR01. Distance travelled 419 miles. Time of travel is unknown since it came down at night.

Flight path of JR01. The blue circles are “spot reports”. Once the sun goes down, the device loses power so it can no longer transmit. This part of a flight is represented by a green line.

DuPont™ , Styrofoam™ and Kapton® are trademarks or registered trademarks of E.I. du Pont de Nemours and Company.


Released at 1117 UTC on 30 May 2023. Payload weight 14 grams (rounded to the nearest gram). The same configuration as JR01 except seven solar cells instead of eight, and the balloon was stretched under high humidity. Another less-than-successful attempt. After reaching 42,380 feet, it began a slow descent, taking about 4 hours and 20 minutes before making landfall 4 miles southwest or Monon, Indiana. Unlike JR01 this landing was not favorable as no reports have been heard from it since landfall. Flight time 6 hours 20 minutes, total distance travelled 99 miles.

Probable Cause of Flight Failure: Since it reported all the way down, the issue was not with the electronics. A catastrophic failure of the balloon when it reached altitude is likely.

Altitude profiles of JR03 and JR02


Released at 1141 UTC on 03 June 2023, JR03 has, more or less, the same configuration as JR02 and JR03. Payload weight 14 grams.

The first signal report was received at 1204 UTC at an altitude of 18,300 feet. It continued a steady climb until reaching 40,150 feet, temperature -38 F at 1314 UTC. It then went silent until 1450, when it reported being at 19,800 feet.

JR03 made landfall just south of Bloomington, Indiana. It’s not been heard from since.

Probably Cause of Flight Failure: Balloon failure.

03 June, 2023 – Since “something” is happening upon reaching 40,000 feet, flights will pause while I explore what might be causing these failures. What makes this task difficult is that it’s pretty much impossible to recover the balloon to see what went wrong. Was it a slow leak, did the side split out…questions that without forensic evidence are very difficult to answer.


04 June 2023Going back over every step in the inflation/stretching process I stumbled across what likely went wrong with the above flights. In my notes I had written down to stretch the balloons to .31 millibars. What I SHOULD have written down was to stretch to .31 pounds-per-square-inch (psi). Point 31 millibars is equivalent to .45 psi, way to much pressure. Millibars are metric units (like meters, kilograms and kilometers-per-hour), psi is an English unit (like inches, pounds, miles-per-hour). I tend to think in metric units as it’s the language of meteorology in particular and science in general. So likely I weakened the balloons using this much pressure simply by writing down the wrong measurement system in my notes. LESSON LEARNED: As mentioned before, don’t worry about internal balloon pressure. Just stretch it to 100″ (or more) and hold it at that diameter for several hours.

As an aside, this sort of thing doesn’t just happen to me. In 1983 Air Canada flight 143, a Boeing 767, ran out of fuel at 41,000 feet. The crew thought that the airplane was fueled in metric units (kilograms) when it actuality it was fueled in pounds (English units).

The electronic fuel gages were inoperative, so the backup method of fueling is nothing fancier than sticking a piece of wood into the over-wing fuel ports (a “dripstick”), measuring the depth of the fuel, which is then converted to a liquid measure, and adding (or draining) whatever fuel the particular flight calls for.

Air Canada Flight 143, a Boeing 767

As a rule, large airplanes carry only enough fuel to fly to their destination, fly to their “alternate” airport (where, in case the flight can’t land at its destination due to weather or whatever) then fly for 45 minutes before they would run out of fuel. I have a Flight Dispatcher certificate issued by the FAA, worked for two airlines, and have dispatched dozens of flights using this backup method of measuring fuel. It works just fine if the math is done right.

In this case, it wasn’t.

Because of this confusion between English and metric units, the airplane only had half as much fuel as the flight crew thought it had because the fuelers were thinking in English units, and the crew was thinking in metric units. The crew thought all was fine and well until both engines shutdown due to fuel starvation only halfway to their destination. Through excellent piloting skills and a whole lot of good luck, the crew was able to glide the airplane to a landing. Of the 69 people on board only two passengers were slightly injured and the airplane was damaged, but was repaired and returned to service.


Released at 1425 UTC (1025 AM EDT) on 21 June, JR04 is the first of what I would call a successful flight simply because its lasted several days longer than my previous attempts. Launch weight 14 grams.

The mission of JR04 was simple, just stay alive (technically a “proof of concept flight”).

JR04 hanging from its test stand. It’s suspended from its upper antenna wire, too thin to be seen in this photo.

July 2, 2023 – JR04 was last heard from on 1 July 2023, 90 miles southeast of Oran, Algeria at an altitude of 44,000 feet. An electronics failure is also a possibility, it which case it may still be in the air but not transmitting. It overflew the eastern U.S., the Atlantic Ocean, Portugal, Spain, the Mediterranean Sea, Morocco and Algeria.

Flight path of JR04. The blue spots represent signal reports. Since during darkness the solar cells are not producing power no signal reports are available. The estimated path during the night is represented by the green lines.

Probable Cause of Flight Failure: Since the last report was at 44,000 feet with the sun 70 degrees above the horizon (and plenty of daylight left to have watched it descend due to a balloon failure) this loss was likely caused by a failure in the electronics.


JR05 was released at 1420 UTC (11:20 AM EDT) on 28 June 2023. Payload weight 17 grams. It’s carrying an ambient temperature sensor. The transmitting device aboard all previous flights used a temperature sensor integrated into the radio transmitter circuit board. The job of this temperature sensor is to calibrate the transmitter, not provide the actual air temperature. Since electronics produce heat, the integrated temperature sensor reads the temperature of the circuit board, which will not accurately reflect the actual air temperature.

JR05 shortly after launch. The sky is very hazy due to smoke from the Canadian wildfires. The wire connecting to balloon to the payload can’t be seen due to it being very thin.

Early results from this experiment are mixed.

JR05 passed within 80 miles of Greensboro North Carolina at 0010 UTC. Greensboro is a National Weather Service upper air station, and they release sounding balloons at 0000 and 1200 UTC each day. At the time JR05 was at 42,500 feet, and reporting a temperature of -26 degrees F. The NWS sounding reported a temperature, at the same time and altitude, of -68 degrees F.

What went “wrong” with the temperature reading? There are a few possibilities. The LM335Z temperature sensor on JR05 is rated to -40 degrees F. What happens when the temperature drops below that I don’t know (but I do intend to find out).

Another possibility is that my scaling factor (which converts the raw reading from the temperature sensor into a voltage value that the transmitter can digest) is wrong. The ideal way to test this theory is to cool the temperature sensor gradually until it no longer reports accurately. This is a bit tricky to accomplish. The average food freezer gets to about -18 degrees. The next coldest thing is dry ice, -118 degrees, well below the operational limits of the sensor. Not sure how to do this.

Probable Cause of Flight Failure: Since the last position report didn’t include altitude or voltage information, there’s not enough information to draw a conclusion.

Flight Path of JR05.


JR06 was released at 11Z on 22 July 2023. From the get-go it had a variety of “issues”.

The first spot was reported at 3,400 feet. It climbed to about 5,000 feet at 1006Z, the descended to around 1,700 feet at 1400Z, then climbed again until it reached 40,500 feet at 1926Z. It stayed at that altitude until around 2100Z when it began a slow descent. It came back to earth a few miles east of Canestro, New York.

Probable Cause of Flight Failure: Balloon failure.


17 October, 2023 – JR08 was a “winter” design, modified to meet the low sun angles that we experience in the Northern Hemisphere during the winter months. It carried twenty one solar cells (three banks of seven solar cells) in a triangular arrangement. Each bank of cells was isolated with IN004 diodes so that power from one bank would not flow into the other solar cell bank.

Each solar cell bank was tilted to face about 30 degrees above the horizon to provide more power than a flat-panel facing up array would produce.

JR08 in the assembly room the night before launch.

To keep the airframe level, three Kevlar strings were used and were attached to the antenna so that the airframe would remain, more or less, level.

JR08 was launched the morning of 17 October. Climb out looked normal. I had double-checked weights and free lift, launched in a no-wind condition, no clouds. Yokohama balloon (47g) was “wet” stretched just a few days before. U4B was window tested for several days and operated normally.

It first reported 5 miles east of the launch site at 3,150 feet. Next report was 30 minutes later, 10 miles east of the launch site at 2,362 feet. The reason for this descent is unknown.

The next report was on 18 October at 1024 UTC, just south of Myrtle Beach South Carolina, about 600 miles southeast of the previous position with the sun about 2 degrees up.

During the 18th it sent in multiple reports from around 42,000 feet. The last report of the day was received at sunset, 330 miles east of Savannah, Georgia over the Atlantic.

Shortly after sunrise on the 19th the first report was received at 0704 UTC, sun elevation 3.3 degrees (roughly). No altitude information was received for this or the subsequent report. Temperature was -29 C, which would be consistent with an altitude of 40,000 feet or so.

Flight path of JR08

The next, and last report was received 30 minutes later. Temperature was -23, locating was roughly 70 miles south of the previous report (about 200 miles northwest of the Azores). The temperature increase may indicate that the balloon was descending.

Probable Cause of Flight Failure: Balloon failure.


Launched at 1310 UTC on 16 November 2023, JR09 is a 7-cell flat-panel design. Launch weight 14g (5G free lift). U4B on channel 22, time slot 02.

JR09 completed its first lap around the Earth at 2315 UTC on 26 November 2023, travelling 20,727 miles in 10 day, 10 hours and 5 minutes. It passed within 75 miles of its launch point.

JR09 completed its second lap at about 1042 UTC on 08 December. Miles travelled since launch : 40,929 miles.

Third lap was completed about 07 UTC on 19 December. Miles travelled since launch: roughly 62,500.

Fourth lap completed about 1430 UTC on 28 December. Miles travelled since launch: 84,066.

Fifth lap completed about 2300 UTC on 10 January 2024.

Flight path of JR09 as of 10 January 2024.

One cell broke during launch preparations, so it was actually a 6.75 cell device. Given the low sun angles this time of year I was surprised to see that the voltage at mid-day exceeded 5 VDC (none of my summer flights, when the sun is much higher in the sky, approached 5 VDC).

I left the manometer on the shelf for this flight. The balloon was wet stretched to a diameter of 101.5 inches. I’ve not yet had success using the manometer to reliably determine if the balloon leaks. It could be that the leak is at the hose/nozzle connection, the manometer/hose connection (if not the manometer itself) or the numerous tee connections that make up the inflation plumbing.
LESSON LEARNED: Manometer or high-humidity stretching not required.

This flight is also my first for using a swivel between the balloon and the payload. This may help to reduce airframe rotation, though I’ve not yet though of how to actually test that.

After soldering the solar cell assembly, I applied epoxy over the solder joints in the hope that this would prevent a joint breaking at the cold temperatures found at altitude.

The last difference is that this flight has a Kevlar string running from the airframe to the swivel. I’m using 1/4mm thick magnet wire for the antenna elements. The Kevlar line is slightly shorter than the upper antenna element, so it will take the strain of lifting the payload instead of the antenna wire, which may break if stressed given its thinness.

JR09 has not been heard from since January 16 2024. In its 60 days in the air, it travelled 118,218 miles, and has circled the Earth over five times. The average time to circle the planet was 10-1/2 days.


JR10 was launched at 2236 UTC (about sunset) on 28 November 2023. High winds prevented a launch earlier in the day. The balloon was stretched to 103″ on 11/20. This is a U4B flight which is transmitting on channel 264. Free lift was increased to 6 grams. Other than these differences, it’s pretty much a carbon copy of JR09.

JR10 as of 20 March 2024. JR10 is still flying, but map will no longer be updated due to clutter.

It transmitted as expected until sunset on the 29th. It then went silent until December 16th when it phoned home over Newfoundland after apparently making one lap. It transmitted of a little over two hours, then went silent again until the 27th of December when it reported over Sakhalin Island, Russia. It’s now (20 March) over Kentucky on its eight lap.


Launched at 2225 UTC on 29 November 2023 near sunset due to high winds during the day. It’s an experiment with an over-stretched balloon (stretched to 105.5 inches), 8g of free lift, 19 g payload weight. No manometer was used.

After crossing Italy heading north, it went silent on December 3 2023 and reappeared on March 23 2024. My guess is this silent period had to do with it being too far north during winter. It then transmitted more-or-less consistently until March 31st 2024, when it went silent over southern China. Best guess is that it made about 11 laps.


Launched at 1815 UTC on 20 December 2023, it’s a no-nozzle Yokohama stretched to 107 inches and held at that diameter for 72 hours. Jetpack tracker. Free lift 6 grams payload weight 24 grams. Ten solar cells (five each bank wired in parallel) for redundancy.

It didn’t get far. It went down (but still transmitting) on the 21st of December 2023 in the strip-mining country of West Virginia. Maximum recoded altitude was 4,000 feet near sunset on launch day. What happened at night is anyone’s guess.

Flight path of JR12.

Probably Cause of Flight Failure: Since it transmitted from the ground, balloon failure terminated the flight.


Released at 1430 UTC 13 December 2024, channel 273, payload weight 18.7g, free lift 6 g. The 47g Yokohama balloon was stretched to 105″ at room temperature and humidity (70 degrees F and 40% RH). Traquito JetPack.

Problems from the start. Launched under a clear sky with plenty of sun, it didn’t phone home until over 100 miles downrange at an altitude of 22,000 feet. It’s last transmission of the day, near local sunset, was from 40,000 fee over West Virginia. Then silence until 4,700 miles later over Algeria just after sunrise at 41,617 feet on the 16th of December. It transmitted 17 spots that day and was next heard over western Turkey on the 17th where it transmitted 15 spots then went silent.

Probably Cause of Flight Failure: Unknown.


JR14 was launched on 08 January 2024 at 1635 UTC. It’s a no-nozzle Yokohama stretched to 116″ and held at that diameter until the morning of launch (about 5 days). Five grams of free lift, 16.7 g payload weight, 22 g neck lift. JetPack tracker, channel 291, seven polycrystalline solar cells facing the zenith.

With our crummy weather having no end in sight, I took the risk of launching through a few cloud layers. The surface observation, closest to launch time from the nearest airport was:

KIND 081654Z 13015KT 10SM FEW018 BKN230 OVC300 03/M02 A3025 RMK AO2 SLP250 T00331017

So, a broken layer1 of clouds at 23,000 feet, and an overcast layer2 at 30,000 feet.

My thought is that any ice that is picked up in the clouds (both these layers were fairly thin) would sublimate at higher altitudes due to lower air pressure, the very dry air, and increased incoming solar radiation. Either I was right, or lucky, as the first spot this morning (09 Jan) was at 44,000 feet.

JR 14 Flight Path as of late March 2024. Map will no longer be updated.


Those that have been doing this for awhile and have had the proper combination of skill and luck have had some flights circumnavigate the planet. JR14 has circumnavigated many times, but as of 08 June 2024 its been circling not the planet, but Mexico!

Path of JR14 from 08 June to 05 July 2024. The green arrows show the direction of motion.

The JR15 series will be battery-powered flights to examine the feasibility of launching thru cloud cover.

The batteries will be two lithium cells removed from an EBL 1200ma non-rechargeable 9 volt lithium battery.

Window testing these batteries with a Jetpack showed that they would power the Jetpack for about 21 hours. Of course this is at room temperature, these optimistic results can’t be expected at altitude.

Erratic temperatures caused by the Sun moving in and out of clouds during window testing (the window faces south).


First attempt at a single battery-only flight (no solar cells). Launched at 1555 UTC 22 March 2024. Yokohama stretched to 110″, Jetpack on channel 247, no conformal coating was used. The nearest surface aviation observation (7 miles away) reported a overcast layer at 8,500 feet at the time of launch. No PIREPS were available reporting cloud tops. It likely suffered a balloon failure upon reaching 40,000 feet.

Why to avoid using Helium.

Helium is a gas that is produced by alpha-decay by radioactive elements in the Earth. It is a non-renewable resource. Nobody has found a way to synthesize it. When it’s gone it’s gone.

The issue with using helium is that it has other more important uses, such as cooling the magnets in MRI imagers and NMR imagers, both are important medical applications. Other applications include medical and scientific research, uses that are much more important then floating balloons. Of course the pico-balloon community is just a tiny fraction of the issue, and it’s understandable for those that can’t get access to hydrogen or only intend to make a few flights to want to use it. Conservation of helium, like many other efforts to, so to speak “save the planet”, can be viewed as symbolism, but is none-the-less important.

JR15a in final preparation. The two cardboard tubes have the upper and lower antenna wires wrapped around them for easy transportation. The battery has “247” on it (the transmit channer number).

The short flight of JR15. The green line is the launch, the red line is the last spot received. Due to the brevity of the flight it’s difficult to draw many conclusions.


Still analyzing date.


Launched at 1702 UTC 31 March 2024 this flight is an experiment using “party” helium as the lifting gas. Party helium is the type one buys at party stores for inflating small balloons. It’s roughly 80% helium and 20% air so it has nowhere the lifting power of hydrogen or high-purity helium. The flight was powered by to lithium batteries wired in parallel (no solar panel) as it’s meant to be a short-lived experiment.

JR15c on the scale. The batteries and antenna elements have not yet been attached.
JR15c telemetry. Data left of the Launch (green) line is pre-flight testing, which was done with a bench power supply not batteries.

The results were surprising. There was a signal dropout lasting an hour. While unusual, it’s not unheard of. The wind speed and temperature are consistent with upper-air observations taken that day.

Helium One (JR16)

Launched at 1200 UTC 06 April 2024, this flight tests the commonly held belief that “party store” helium is not suitable for pico-ballooning.

Party store helium is the type of helium that one can buy at a party or craft store. It’s normally used to inflate party balloons. The containers (at least in the U.S.) say that they hold “not less than 80% helium”, and the other 20% being air.

Party store helium has many unknowns. What is the exact ratio of helium to air? What purity is the helium before being combined with the air? Is the air dry? I don’t suspect that there are many stringent regulations concerning the above issues, and the mixture could likely vary from batch-to-batch. However, for those that can’t obtain Hydrogen, don’t plan to do many flights, or figure that the price of Helium is out-of-reach, party-store helium may be an option.

Altitude profile of Helium One (JR 16), a “party store helium” balloon.

A Yokohama balloon was used carrying a Jetpack and seven solar cells. Payload weight 20.35 g, free lift 4 g, neck lift 24.35 g.

JR16 appears to have met its fate over the Middle East. It had the bad luck to be passing over Lebanon/Jordan/Israel the night of 13-14 April 2024 when Iran fired a few hundred cruise missiles at Israel. There was a lot of hardware flying about that night. It’s likely a coincidence since cruise missiles fly fairly low, but JR16 hasn’t been heard from since.

Flight path of Helium One.


This is a battery-only flight meant to examine the feasibility of launching thru a cloud layer. Tracker was a JetPack with two 3.3 volt Lithium Ion batteries wired in series, producing a measured 6.2 volts at launch. The manufacturer of the JetPack doesn’t advise using more than 5 volts, but it seemed quite happy with 6.2 volts. Payload weight 30.9g, neck lift 35.9g, hydrogen, channel 597. No conformal coating was applied. Yokohama dry stretched to around 104 inches.

As the flight was not intended to stay up for long (and hog a channel) it was decided to use batteries. When the batteries died, the flight will be, for practical purposes, over. Turns out something else brought it down.

JR17 just before launch. Kapton tape holds the two batteries to the JetPack.

At the time of launch the nearest two airports were reporting an overcast layer of clouds a about 7,000 feet. Interpolating between the four nearest radiosonde observation stations, the freezing level was at 10,000 feet, and remained at that height for the remainder of the flight.

JR17 Flight profile. Upper plot is altitude, lower plot is reported temperature from the JetPack. The red line is the measured base of the overcast cloud layer.

The temperature values make no sense. NWS radiosonde observations show that the freezing level was about 11,000 feet. The tracker was reporting a freezing level of near 20,000 feet. Could this effect be both the heat of the tracker processor plus the heat generated from the batteries plus the heat of the Sun? While it’s not factually known what the cloud tops were (no PIREP reports reporting cloud tops were available) the JetPack designer said the reported temperature should be a few degrees above ambient. My un-rigorous testing showed about 5 degrees F above ambient. Sunlight hitting the tracker and the batteries adding some heat may be the explanation. A future flight will have batteries well-spaced from the tracker processer, and the tracker shielded from direct sunlight.

This particular balloon was questionable, as I had reason to suspect it had a leak. Since this flight wasn’t supposed to last long anyway, losing the balloon/payload wasn’t much of a disappointment.


Launched 08 May 2024 at 1555 UTC. Yokohama, party store helium, JetPack, payload weight 19.23 g, free lift 6 g, neck lift 25.1 g., channel 153.

Made a beginners mistake. I set the JetPack for 10 meters a week or so ago for testing and then put it back on the shelf. The morning of launch day I set the channel correctly, but neglected to set the band back to 20 meters. So it’s transmitting on 10 meters with a 20 meter antenna.

Or it “was” transmitting. A leaky seal on the balloon seems to be responsible for its demise. It spent a few hours at 38,000 feet and then began a slow descent. Probably in a field near Scranton or Allentown, PA.

JR18 Flight Path.

JR18 Altitude Profile (not to scale with image of flight path).


Launched 1130 UTC on 17 May 2024. Yokohama balloon with party-store helium. U4B, no conformal coating, channel 247. Payload weight 24.6 g, Neck lift 36.6 g. Power was provided by two ER14350 3.6 volt batteries wired in series producing 7.2 volts (no load).

This flight was an experiment of launching into clouds.

Batteries were used to ensure the flight would be short. I was interested in how it would act as it ascended thru the cloud layers. Since I didn’t think this thru clearly, I didn’t get the data I wanted. The first spot was at 6,000 feet. I’ll try a different strategy next time.

JR19 with batteries.

The weather shortly before launch was:

KUMP 171135Z AUTO 22004KT 2SM BR BKN005 OVC009 18/17 A2983 RMK AO2 CIG 003V008 T01780175

KUMP is Indianapolis Metropolitan Airport, 7 miles southeast from the launch site.

In plain English the above means a broken layer of clouds at 500 feet and an overcast layer at 900 feet. “BR” means mist, but I didn’t feel any at launch.

Two other airports, Indianapolis Executive (KTYQ, nine miles west) and Indianapolis Eagle Creek (KEYE, 13 miles southwest) also reported similar low overcast.

Altitude profile of JR19.

The “stair stepping” I’ve not seen previously and have no explanation for.

Even more confusing is the voltage profile.

Voltage profile of flight JR19.

Helium Two (JR20)

Launched at 1056 UTC on 23 May 2024, this is a second flight using party store helium. Jetpack, 7 solar cells, 8 grams free lift, channel 120. Disappeared at night over the Mediterranean Sea after 4 days.

Helium Three (JR21)

Launched at 1120 UTC on 31 May 2024, this is a third flight using party store helium. Jetpack, 7 solar cells, 5 grams free lift, channel 575. Started a late-afternoon descent of 115 feet per minute about 11 UTC on the 5th of June a few hundred miles northeast of Crete. Transmissions terminated near local sunset. Its not been heard from again.

Helium 3. The rats nest of string are the three Kevlar strings that (are supposed) to keep the platform level. The JetPack is mounted of the other side of the channel number, 575.

What’s up with “party store” helium”?

It’s been an interesting experience with party-store helium. Three flights launched…three flight that have “terminated early”. All ended within 5 to 7 days of launch, and all ended over the Mediterranean. It’s a bit difficult to buy off on this being a coincidence, but stranger things have happened. In the next day or so I’ll send “Helium Four” up.

The helium I was using on my first helium flights was advertised as “a mixture of no less than 80% helium and air”. These flights have not turned out well which is documented above.

Helium Four will be using a different tank of helium. This tank does not have the “80/20” disclaimer on it. So what does it contain…I don’t know. I would doubt it’s 100% helium as the cost is roughly the same as the 80/20 mix, but I don’t know the significance of that. Helium Four may help resolve the issue.

Helium 3.5 (JR22)

Helium 3.5 was launched at 1049 UTC 12 June 2024 (about 25 minutes after sunrise). Yokohama stretched to 105 inches, JetPack on 20 meters, 7 solar cells, upper antenna element reinforced with Kevlar string, payload weight 18 grams, neck lift 23 grams, channel 162.

It checked-in at 1332 UTC from 27,000 feet. The sun angle on the solar array was 33 degrees, a little higher than I expected, but not unreasonable. It then climbed to 36,000 feet and then began a 130 foot per minute descent. It’s now likely on the ground few miles south of Sutton, West Virginia (EM98PP). Weather was not a factor along the flight path.

Flight path of Helium Four.
Altitude profile of the flight of Helium Four.

The descent profile is consistent with a slow leak in the balloon. What caused the leak can only be guessed.

I’m not ready to blame this on party-store helium. The only thing different from recent launches is that the balloon sat partially gassed overnight as I ran out of gas and had to go buy another tank. I can’t think of any reason that would be a factor. A defective balloon can’t be ruled out, or the possibility that I didn’t seal the balloon properly.

So, I need to ponder this a bit. Since I still have a nearly full tank of party-store helium, I will try again.

Helium Four (JR23)

Released on 30 June 2024, Helium Four was filled with a tank of helium that didn’t have the disclaimer of “no less than 80% helium” printed on it. What that means I don’t know. Does is have more helium in it? I’m working an experiment to determine that, but at the moment I don’t have an answer to that question.

Helium Four is a Yokohama balloon, JetPack tracker, solar panel with seven solar cells, channel 422, 5 grams of free lift. It was likely brought down by thunderstorms off the east coast of Japan the night of 10/11 July 2024.


Were you the first person to do this – No.

Is it legal – Yes, and “Maybe”.

The U.S. Federal Aviation Administration has no problem with these flights, but the Federal Communications may have. A licensed amateur operator operating on any amateur radio band is required to have a “control operator” to monitor the legality of the transmission and to cease the transmission if the transmission is in violation of any FCC rules. But at what altitude does the FCC cease to have jurisdiction? And the FCC has no jurisdiction over international waters, or over any foreign country.

So lets say that I launch at sunset. Since there won’t be sufficient sunlight to “energize” the solar panel, no transmission will happen until the next morning by which time my balloon could well be over international waters (this has happened several times). My balloon is no longer is U.S. airspace and is no longer subject to FCC regulations. So far so good.

But in my balloon’s trip around the world, it’s certain to pass over many countries that may have their own regulations concerning transmission over amateur radio frequencies. Could Iran, Germany, China, Spain Russia or North Korea bring me to court for violating their regulations?

And what about if my balloon makes a trip around the globe and enters U.S. airspace, still transmitting. Am I responsible for these so-called “illegal” transmission (since there is no control operator to stop the transmission)?

My (self-serving) opinion is “No” since the U.S., China, India, Russia, North Korea, South Korea, to name just a few, have launched satellites that routinely travel over other countries with, or without their permission. There is no international agreement on the altitude limit of any countries airspace, nor on what frequencies they can transmit. Should I, as an individual, be held to a higher standard than my own government, or any other government?

How much does each flight cost – about $25 to $75 in materials.

Can it carry a camera (part 1) – No (well, not yet anyway). Even the smallest lightest camera is far too heavy.

Can it carry a camera (part 2) – Even if it could, it wouldn’t have much luck sending the pictures back. Images and video take huge amounts of bandwidth. The protocol for picoballoon flights is WSPR (Weak Signal Propagation Reporter). While it has very good range, the transmission rate is very slow.

There are other protocols that can be used, but none support video transmission as of this writing.

Are there regulatory requirements – Yes. One needs to have an amateur radio license to legally transmit in the United States. It’s not against either U.S. Federal Aviation Administration or Federal Communications Commission regulations to fly the balloon, but the balloon has to have a transmitter attached so one knows where it is and what data is is collecting. Other countries may have other requirements which are beyond the scope of my comments.

Can it be recovered after it lands – Yes and no. Once the balloon and payload are down they normally stop transmitting. It would be extremely difficult to find (but some have done it). Since it only transmits Madienhead grid square coordinates, a search area would be VERY large.

What happens if an airplane hits it (part 1) – Nothing. It’s made out of lightweight materials such as Styrofoam*, a circuit board that will fit into a tablespoon, wire and a few other components. An average House Sparrow weighs more.

*Styrofoam™ is a registered trademark of E.I. du Pont de Nemours and Company.

Other “trackers” are a bit larger and heavier (the Traquite JetPack for example) but not by any measurable degree. They do about the same thing. I’ve come to favor the JetPack since the makers of the U4B have not yet updated the firmware to make it useful for sending down data from additional sensors.

There are other trackers, but I have not used, and are unfamiliar, with them.

What happens if a bird hits it – I would think that a bird beak would puncture the balloon and that is the end of the flight.

How does a typical flight end – Eventually the balloon will either break, run into a thunderstorm or some other high-altitude weather event (tropical storm, hurricane) that will bring it down. An electronics failure will also “end” the flight for practical purposes, since when the transmitter stops the flight can’t be tracked.

If the balloon pops, how long does it take the thing to reach the ground – in my experience, roughly four to eight hours. When the balloon pops, it acts like a small parachute and, given the very light weight of the payload, it will descend very very slowly, roughly one mile per hour.

How much power does it use – in low power mode 121 milliwatts.

To be continued…