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1. March 2021 Berkeley Picoballoon Launches

   As part of the San Francisco High Altitude Balloon group, Martin W6MRR has been experimenting with picoballoons. Picoballoons are different than regular amateur radio balloons in that are designed to be neutrally buoyant at around 40k feet. This requires payloads that are much lighter than traditional balloons, and different balloon materials that won't stretch or break. This altitude was picked because it is above airplanes and weather, but still in the jetstream, where they can float around the world in a matter of weeks. Our goal is to circumnavigate the globe at least once.

   Picoballoons use either Mylar or plastic material in their construction. More traditional Amateur radio balloons, like from our previous launch use latex, which expand dramatically at altitude, then bursts. Latex balloons also break down under ultraviolet light, and are much more expensive than plastic balloons.

   Early picoballoon launches just used 2m APRS for sending position information. However, the APRS frequencies in Europe and the rest of the world are different than the North American standard of 144.390 MHz, so balloons that crossed the Atlantic needed ...

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2. High-Altitude Balloon Launch from Davis

   The SF-HAB group got together in the beginning of August to do another high-altitude balloon launch. The purpose was to test out a new 3D GoPro camera to see how well it would perform at altitude. We also had a LoRA transciever onboard, which we are thinking about using as a remote cutdown device that we would fly on future launches.

   The jet stream in July was really unsettled, so we delayed for a few weeks while the winds picked up a bit and shifted heading. Watching the predictions from HABHUB gave us a good idea when to launch. This was one of our predictions before launch.

   

   Unfortunately, I really goofed up when doing the launch predictions. As you can see in the above screenshot, I used the default ascent rate of 3.5 m/s, which is about 680 ft/min. We normally target 1000 ft/min, so this prediction has the balloon going much further than what we were looking for.

   I realized my mistake and ran some more predictions, plus the winds changed slightly overnight, so we ...

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3. High-Altitude Balloon Launch from the Berkeley Marina

   After the success of the KD4STH launch in September, we decided to do it again! A new group formed for San Francisco High Altitude Balloons (SF-HAB), and we started scheming. The hardware and time stars finally aligned on Sunday March 8th, and we decided to launch from the Berkeley Marina. Unbeknownst to us, this was only a few days before the whole world shut down due to COVID-19. Great timing!

   

   

   The balloon was a Kaymont 3kg balloon, and we used an entire K-sized tank of hydrogen for lift. Unlike some previous launches, we didn't use weights to carefully measure/specify the ascent rate, we just used the whole tank. During the chase, we calculated our ascent rate at about 1400 ft/min, which was faster than our target of 1000 ft/min. Faster ascent means the balloon is not being pushed around by the wind as much, but it will burst at a lower altitude if the balloon is overfilled. Since this was a 3kg balloon, it was not overfilled.

   

   The primary mission of this launch was to fly a ...

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