High-altitude balloon OH3VHH-1 launch and flight

The OH3VHH-1 high-altitude balloon flight was a success: the balloon launch was smooth and tracking of the balloon worked mostly without glitches. This post consists mainly of photos, telling the story of the flight from the launch site to the payload recovery. These photos include a large set of high-resolution images from upper atmosphere taken by the Raspberry Pi tracker hardware in the balloon payload.

Latest update: August 3rd, 2021

See the main page for OH3VHH flight for detailed information about the flight hardware and about the radio transmissions emitted by the payload.

Flight videos

See highlights from the flight on the following video clip:


There is also a longer version of the video, including the flight preparations:


Additionally, you can still watch the full YouTube live stream from launch site!

Flight overview

We started preparations at the launch site around 06:00 UTC on Saturday, July 17th, which was the primary planned launch time for the flight. The weather forecast for the day was excellent: sunny, no clouds, temperature rising up to 27C and wind speed of 1-2 m/s near ground level.

The launch site (photo by OH3EYZ)
The launch site (photo by OH3EYZ)

Some quick facts about the flight:

  • Launch location: locator KP21EA30UA in Hämeenlinna, Finland

  • Total flight time: 1 hour 53 minutes

  • Maximum altitude reached: 28357 meters

  • Ascent rate: Up to 7-8 m/s in lower parts of the atmosphere

  • Ascent duration: 1 hour 25 minutes

  • Descent rate: Approximately 10 m/s in lower parts of the atmosphere. Maximum descent rate was 52 m/s right after balloon burst.

  • Descent duration: 27 minutes

Predicted and actual flight path

We used the CUSF Landing Predictor extensively throughout the week before the launch to follow how the weather conditions developed. The predicted flight path we got on Monday (5 days before launch) was only slightly off from the final prediction on the launch day, which was indeed very impressive.

CUSF Landing Predictor indicating a possible landing on a lake
CUSF Landing Predictor indicating a possible landing on a lake

However, as we got closer to the launch day, the wind direction in the upper atmosphere (between altitudes of 10 and 20 kilometers) shifted slightly towards north, which could make the balloon land on an area with several large lakes. This was obviously something we would like to avoid, so that we could safely recover the balloon payload hardware.

Alternative prediction with a higher ascent rate looks a lot better
Alternative prediction with a higher ascent rate looks a lot better

We even considered using an alternate launch site some 20 kilometers south from Hämeenlinna, but eventually ended up with a plan to fill up the balloon with slightly more hydrogen. This would increase the balloon ascent rate from the original plan of 5 m/s to over 7 m/s so that the balloon would simply rise up and burst sooner and avoid the areas with lakes. Our plan to use a higher ascent rate worked perfectly and even the maximum altitude of 28.3 kilometers was higher than the estimate burst altitude of 27 kilometers!

The predicted (yellow) and the actual flight path (cyan)
The predicted (yellow) and the actual flight path (cyan)

APRS tracking

Last 2m APRS position captured by repeaters and IGates
Last 2m APRS position captured by repeaters and IGates

While APRS on the 2-meter band (144.800 MHz) was the main method of tracking the balloon, we only had a 70cm APRS IGate / receiver. This is because we have a very good APRS repeater and IGate coverage in Southern Finland that basically eliminates the need to set up your own receivers. During balloon descent, the last balloon position reports that reached the aprs.fi service had an altitude of under 300 meters, which confirms the APRS coverage.

Mobile 70cm APRS IGate running on Windows
Mobile 70cm APRS IGate running on Windows

The APRS tracker on the 70cm band (432.500 MHz), based on a Vaisala RS41 radiosonde, had quite a lot of issues with inaccurate GPS position information in high altitudes of over 10 kilometers. We do not yet know the exact reason for this, although we suspect it could be a result of some configuration setting for the RS41 GPS chip. After all, the firmware we used in the radiosonde had never been tested in high altitudes. Alternatively, the RF transmissions from other trackers could have interfered with the radiosonde GPS receiver.

OH3VHH-1 balloon landing path in aprs.fi with the inaccurate position reports coming from the RS41 radiosonde tracker
OH3VHH-1 balloon landing path in aprs.fi with the inaccurate position reports coming from the RS41 radiosonde tracker

LoRa tracker and signal strength

Mobile LoRa tracker receiver device running the Embedded Radio Tracker software (photo by OH3EYZ)
Mobile LoRa tracker receiver device running the Embedded Radio Tracker software (photo by OH3EYZ)

The LoRa tracker was our backup tracker that we could use in case both of the APRS trackers failed for some reason. The Embedded Radio Tracker software, running on a Raspberry Pi model A+, also handled recording of sensor data and taking of still photographs using the Raspberry Pi HQ camera.

The LoRa modulation performs particularly well in low signal strength scenarios, such as the low-power transmitter in the balloon payload. The map below indicates the RSSI reading for calculated successfully received LoRa packets. The receiver antenna was a simple Diamond AZ-510 dual-band VHF/UHF whip mounted on top of car roof with a magnetic mount.

OH3VHH-1 LoRa tracker received signal strength
OH3VHH-1 LoRa tracker received signal strength

The LoRa receiver was located at the launch site all the time until the balloon landed. Before losing reception, the last LoRa RSSI readings dropped well below -120 dBm when the payload was over 50 km away and its altitude was below 5 kilometers during landing.

DVB-S1 video signal reception

Mobile DVB-S1 reception setup: a circularly polarized 70cm yagi, a low-noise amplifier and a laptop with an RTL-SDR USB receiver
Mobile DVB-S1 reception setup: a circularly polarized 70cm yagi, a low-noise amplifier and a laptop with an RTL-SDR USB receiver

The DVB-S1 live video reception at the launch site worked really well considering this was the first time ever we had used such transmitter on a flight. The video reception was intermittent at times when the payload was spinning and swinging more heavily because of wind, but we did get really smooth video playback during the launch and even from altitudes near 20 kilometers where the wind speed was quite low.

Open Broadcaster Software publishing the DVB-S1 live video stream to YouTube
Open Broadcaster Software publishing the DVB-S1 live video stream to YouTube

Michael OH2AUE, located in Padasjoki, Finland, has shared the following videos about DVB-S video reception.

Video content received directly from the balloon DVB-S transmitter:


Michael’s setup for receiving the DVB-S transmission:

Photos of the launch and the flight

Mikael OH3BHX's car packed and ready for the launch day at OH3AA club
Mikael OH3BHX's car packed and ready for the launch day at OH3AA club

The launch site

Preparing the launch site. Our hydrogen cylinder on the front, ready for action. (photo by OH3EYZ)
Henri OH3JR releasing a small balloon to assess the wind direction and speed. Martti OH1ON in the background. (photo by OH3EYZ)
Henri OH3JR releasing a small balloon to assess the wind direction and speed. Martti OH1ON in the background. (photo by OH3EYZ)
YouTube streaming corner for Mikael OH3BHX (photo by OH3BHX)
YouTube streaming corner for Mikael OH3BHX (photo by OH3BHX)
YouTube stream running. The same laptop was used to receive and decode the DVB-S1 transmission from the balloon using the affordable Nooelec NESDR SMArt USB stick (RTL-SDR). (photo by OH1ON)
YouTube stream running. The same laptop was used to receive and decode the DVB-S1 transmission from the balloon using the affordable Nooelec NESDR SMArt USB stick (RTL-SDR). (photo by OH1ON)

Preparing the payload

Mikael OH3BHX installing new batteries and powering on all the tracking equipment in the balloon payload. (photo by OH3EYZ)
Mikael OH3BHX installing new batteries and powering on all the tracking equipment in the balloon payload. (photo by OH3EYZ)
Mikael OH3BHX and Sami OH3EYZ doing some essential last-minute debugging with the balloon trackers. (photo by OH7Z)
Mikael OH3BHX and Sami OH3EYZ doing some essential last-minute debugging with the balloon trackers. (photo by OH7Z)
Mobile LoRa tracker receiver set up and working. (photo by OH3EYZ)
Mobile LoRa tracker receiver set up and working. (photo by OH3EYZ)

Filling up the balloon

Henri OH3JR and Jari OH3UW preparing the hose for filling up the balloon with hydrogen. (photo by OH3BHX)
Henri OH3JR and Jari OH3UW preparing the hose for filling up the balloon with hydrogen. (photo by OH3BHX)
Unfolding the 800g latex balloon, manufactured by Hwoyee. The balloon has to be handled carefully using soft cotton gloves. (photo by OH7Z)
Unfolding the 800g latex balloon, manufactured by Hwoyee. The balloon has to be handled carefully using soft cotton gloves. (photo by OH7Z)
Mikael OH3BHX attaching a custom plastic adapter to the balloon using zip ties. The adapter is used to fill up the balloon and to hold the nylon cord attached to the parachute (in the background) and to the payload enclosure. (photo by OH3EYZ)
Mikael OH3BHX attaching a custom plastic adapter to the balloon using zip ties. The adapter is used to fill up the balloon and to hold the nylon cord attached to the parachute (in the background) and to the payload enclosure. (photo by OH3EYZ)
ari OH3UW filling up the balloon with help of Henri OH3JR. Kari OH3EVO and Martti OH1ON in the background. (photo by OH3BHX)
Jari OH3UW filling up the balloon with help of Henri OH3JR. Kari OH3EVO and Martti OH1ON in the background. (photo by OH3BHX)
Checking the weight of water container that we used to determine the correct amount of hydrogen in the balloon. The balloon is full enough when the balloon is barely able to lift the container. This time we aimed for about 5 kg neck lift to get ~7 m/s ascent rate. (photo by OH1ON)
Checking the weight of water container that we used to determine the correct amount of hydrogen in the balloon. The balloon is full enough when the balloon is barely able to lift the container. This time we aimed for about 5 kg neck lift to get ~7 m/s ascent rate. (photo by OH1ON)
Jari OH3UW and Mikael OH3BHX trying to contain the situation. Wind gusts make filling up the balloon a bit challenging sometimes. (photo by OH1ON)
Jari OH3UW and Mikael OH3BHX trying to contain the situation. Wind gusts make filling up the balloon a bit challenging at times. (photo by OH1ON)
Filling up the balloon does indeed take a long time, so there's plenty of time to take some photos. (photo by OH1ON)
Filling up the balloon does indeed take a long time, so there's plenty of time to take some photos. (photo by OH1ON)
Henri OH3JR taking his turn to continue filling up the balloon. (photo by OH7Z)
Henri OH3JR taking his turn to continue filling up the balloon. (photo by OH7Z)
Jari OH3UW, Henri OH3JR and Mikael OH3BHX doing important team work to make sure the hydrogen gas won't leak from the balloon. (photo by OH3EYZ)
Jari OH3UW, Henri OH3JR and Mikael OH3BHX doing important team work to make sure the hydrogen gas won't leak from the balloon. (photo by OH3EYZ)

Last-minute checks before launch

Mikael OH3BHX powering on the Vaisala RS41 radiosonde converted to an APRS tracker transmitting on the 70cm band. (photo by OH3EYZ)
Mikael OH3BHX powering on the Vaisala RS41 radiosonde converted to an APRS tracker transmitting on the 70cm band. (photo by OH3EYZ)
Time to close the lid of the payload enclosure to make it ready for the flight! (photo by OH3EYZ)
Time to close the lid of the payload enclosure. We are ready for the flight! (photo by OH3EYZ)
Mikael OH3BHX checking that the YouTube stream is running fine and that we're receiving the DVB-S1 video from the balloon payload. (photo by OH7Z)
Mikael OH3BHX checking that the YouTube stream is running fine and that we're receiving the DVB-S1 video from the balloon payload. (photo by OH7Z)
The balloon is finally full and round, also ready for the flight! (photo by OH7Z)
The balloon is finally full and round, also ready for the flight! (photo by OH7Z)

Balloon launch

Jari OH3UW and Mikael OH3BHX tying the nylon cord from the balloon around the payload enclosure. Sami OH3EYZ waiting impatiently for launch in the background. (photo by OH1ON)
Jari OH3UW and Mikael OH3BHX tying the nylon cord from the balloon around the payload enclosure. Sami OH3EYZ waiting impatiently for launch in the background. (photo by OH1ON)
Sami OH3EYZ probably thinking "What's taking so long?" (photo by OH3BHX)
Sami OH3EYZ probably thinking "What's taking so long?" (photo by OH3BHX)
Jari OH3UW looking at the payload ready for flight, wondering if the thing is really going to work :) (photo by OH3EYZ)
Jari OH3UW looking at the payload ready for flight, wondering if the thing is really going to work :) (photo by OH3EYZ)
Finally letting the balloon fly! (photo by OH7Z)
Finally letting the balloon fly! (photo by OH7Z)
With a high ascent rate, these photos had to be taken quickly! (photo by OH7Z)
With a high ascent rate, these photos had to be taken quickly! (photo by OH7Z)
Seppo OH7Z, Rami OH3RAMI, Kari OH3EVO and Martti OH1ON gathering around to check the live video stream from the balloon. (photo by OH3EYZ)
Seppo OH7Z, Rami OH3RAMI, Kari OH3EVO and Martti OH1ON gathering around to check the live video stream from the balloon. (photo by OH3EYZ)
70cm APRS IGate receiving tracking data from the RS41 radiosonde and publishing it on the Internet. (photo by OH3BHX)
70cm APRS IGate receiving tracking data from the RS41 radiosonde and publishing it on the Internet. (photo by OH3BHX)
Mikael OH3BHX and Jari OH3UW taking a break after a successful launch. The 70cm circularly polarized yagi is carefully aimed at the balloon for video reception. (photo by OH3EYZ)
Mikael OH3BHX and Jari OH3UW taking a break after a successful launch. The 70cm circularly polarized yagi is carefully aimed at the balloon for video reception. (photo by OH3EYZ)

Recovery

We knew the location where the balloon payload landed quite accurately based on 2m APRS tracking results. There was even a road leading to a mobile network antenna tower nearby, but the forest where the payload landed was very dense. (photo by OH3BHX)
We knew the location where the balloon payload landed quite accurately based on 2m APRS tracking results. There was even a road leading to a mobile network antenna tower nearby, but the forest where the payload landed was very dense. (photo by OH3BHX)
The payload was somewhere there in the forest. We tried to get a more accurate GPS location, but only the 70cm APRS tracker gave us any readings and it was still giving us very inaccurate reports with the location hopping around up to 50 meters. Chase car antennas in the foreground. (photo by OH3BHX)
The payload was somewhere there in the forest. We tried to get a more accurate GPS location, but only the 70cm APRS tracker gave us any readings and it was still giving us very inaccurate reports with the location hopping around up to 50 meters. Chase car antennas in the foreground. (photo by OH3BHX)
The only choice was to simply go out there. The forest was super dense and it was difficult to move around there. Mosquitoes and horseflies didn't help us either. :) (photo by OH3BHX)
The only choice was to simply go out there, Sami OH3EYZ leading the way. The forest was super dense and it was difficult to move around there. Mosquitoes and horseflies didn't help us either. :) (photo by OH3BHX)
"WTF is this? Are we lost? :)" Mikael OH3BHX trying to locate the payload transmitter direction using a handheld yagi antenna and an SDR receiver connected to a laptop. (photo by OH3EYZ)
"WTF is this? Are we lost? :)" Mikael OH3BHX trying to locate the payload transmitter direction using a handheld yagi antenna and an SDR receiver connected to a laptop. (photo by OH3EYZ)
"There it is!" Using the yagi antenna to find the direction did help us and we eventually stumbled upon the payload. (photo by OH3BHX)
"There it is!" Using the yagi antenna to find the direction did help us and we eventually stumbled upon the payload. (photo by OH3BHX)
The payload was in excellent condition, only the wing we used to stabilize movement for smoother video had broken off. Even the QFH antenna was in good shape as the payload had landed sideways. Landing on its side was also the reason why the trackers had lost GPS fix, as the GPS antennas are on the top of the payload. (photo by OH3BHX)
The payload was in excellent condition, only the wing we used to stabilize movement for smoother video had broken off. Even the QFH antenna was in good shape as the payload had landed sideways. Landing on its side was also the reason why the trackers had lost GPS fix, as the GPS antennas are on the top of the payload. (photo by OH3BHX)
The parachute was on a branch of a small tree, also in perfect condition. (photo by OH3BHX)
The parachute was on a branch of a small tree, also in perfect condition. (photo by OH3BHX)
The balloon remnants -- or more likely the whole balloon, as it looked like no parts of it were missing. (photo by OH3BHX)
The balloon remnants -- or more likely the whole balloon, as it looked like no parts of it were missing. (photo by OH3BHX)
A quick look inside the payload revealing that the tracking hardware and the cameras survived the landing. Both video cameras were still recording! (photo by OH3BHX)
A quick look inside the payload revealing that the tracking hardware and the cameras survived the landing. Both video cameras were still recording! (photo by OH3BHX)
Driving back home in picturesque countryside landscape after over an hour of wandering around in the forest. (photo by OH3BHX)
Driving back home in picturesque countryside landscape after over an hour of wandering around in the forest. (photo by OH3BHX)

Photos from the flight

Henri OH3JR and Jari OH3UW as photographed by the Raspberry Pi tracker moments before launch.
Parola and lake Lehijärvi soon after launch.
Parola and lake Lehijärvi soon after launch.
Flying over Hämeenlinna city center
Flying over Hämeenlinna city center
Some kind of foggy layer in the atmosphere above altitude of 10 km producing beautiful color gradients.
Some kind of foggy layer in the atmosphere above altitude of 10 km producing beautiful color gradients.
Photo with the highest altitude of 28.2 km, moments before the balloon burst.
Photo with the highest altitude of 28.2 km, moments before the balloon burst.
Falling down through the fog again.
Falling down through the fog again.
Lake Vesijärvi and city of Lahti.
Lake Vesijärvi and city of Lahti.
Lake Vesijärvi and city of Lahti.
Lake Vesijärvi and city of Lahti.
Remnants of the balloon hanging from the parachute.
Remnants of the balloon hanging from the parachute.
Remnants of the balloon hanging from the parachute.
Remnants of the balloon hanging from the parachute.
Moment before landing.
Moment before landing.
The payload landed sideways.
The payload landed sideways.
The payload being recovered :)
The payload being recovered :)

Afterthoughts

In spite of some challenges during the launch, most things went really smoothly. And most importantly, the payload did not end up landing on a lake! We had a great launch day and awesome weather. Much fun was had! :)

We did have issues with both APRS trackers: 2m Trackuino had trouble getting GPS fix near ground and 70cm RS41 had GPS issues in high altitudes, which was totally unexpected. We still don’t know what the reason could be — maybe some kind of misconfiguration of the GPS chip or possibly RF interference from other tracker transmissions?

The DVB-S live video transmission from the balloon (along with the YouTube stream) was a unique feature that got many people interested in following the flight — even though we had only a couple of people attempting to receive the DVB-S signal eventually. Sharing instructions earlier for setting up reception could have helped to gather a wider audience.

YouTube live-streaming of the launch event was a success with over 200 viewers watching the stream simultaneously and an active discussion going on in the chat. Admittedly, we could have done our commentary in a slightly more organized way. :)

Finally, launch preparations took a lot longer than planned, as we had to carefully switch on all tracker devices and cameras before closing lid of the payload enclosure — just to make sure we won’t miss anything like potentially forgetting to enable recording of video or lose the payload because of tracker not being powered on! This was a real challenge especially with the video cameras, which require access to all of the buttons around the camera enclosure. Additionally, the uncertainty with the Trackuino 2m APRS tracker GPS fix caused some delays.

Me ready to embrace the might of the balloon! (photo by OH1ON)
Me ready to embrace the might of the balloon! (photo by OH1ON)

Huge thanks to both Jari OH3UW and Sami OH3EYZ for working on this project with me. Additionally, I want to thank all people involved in the launch, and more specifically Henri OH3JR for offering his help with the balloon launch and Seppo OH7Z for getting us computer accessories to fix our YouTube streaming setup!

Lessons learned and ideas for future launches

  • Use unique APRS SSID suffix in the call sign for each APRS tracker. Having two trackers use the same call sign made tracking difficult in aprs.fi.

  • We could add a video overlay of flight data in the YouTube live stream to indicate balloon altitude and GPS position details

  • Adding external atmospheric sensors to Raspberry Pi could provide us more accurate temperature data

  • We could use dedicated, mobile APRS IGates for 2m and 70cm instead of trying to set up one "in case it is needed for tracking"

  • Having a separate recovery team to chase the balloon soon after launch would allow live-streaming the descent using the DVB-S video.

  • Add a Geiger tube as a new sensor in the payload. Detecting level of radiation vs altitude would be interesting.

Follow us for updates

NOTE: We will be publishing videos from the flight in the coming days!

See the main page for OH3VHH flight for detailed information about the flight hardware and about the radio transmissions emitted by the payload.

You can also follow me on Twitter at @mikaelnou where I will share updates regarding the OH3VHH flight!