OLHZN-2 was the second high altitude weather balloon flight for Overlook Horizon High Altitude Balloons that launched on May 7, 2016 at 11:56am EDT (15:56 UTC). The goal of the second flight was to solidify recovery methods and ensure sensor accuracy throughout the entire flight. This was the first flight that was successfully recovered!!! Our first flight (OLHZN-1) had a few issues that were corrected for this flight. The major issue we needed to resolve was the successful recovery of the payload which was not accomplished in OLHZN-1 due to a insufficient battery pack for the flight. This flight used 8 Energizer Ultimate Lithium batteries that kept the flight fully powered throughout.
Although the flight is considered a success, it wasn’t without issues that need to be improved on for the next launch. The day started off on a good note and we hoped to have our launch procedures down to have a proper countdown for our live viewers. Despite arriving 2 hours early, we still ended up launching almost exactly an hour late… again. This time around, the delays were due to two items. First, we were battling some uncomfortable ground level winds that made filling the balloon stressful and difficult to control which meant the balloon filling procedure took almost 45 minutes alone. Second, while packing the payload for launch, we discovered a fault in the voltage regulator for the extended camera battery we added for this flight. The voltage regulator was supplying too many volts to the camera, which caused the camera’s SD card to fail. Fixing the voltage regulator would have been a time consuming task and our launch window was closing, so we elected to replace 3 out of 6 of our fully charged lithium AA’s with used Alkaline AA’s. The used alkalines we slightly depleted which meant they were outputting a lower voltage that the camera could work with. This worked, but also meant that the camera cut out early in the flight and only lasted to about 40,000 ft. during ascent before losing power.
In addition to that, the launch itself was nearly a disaster due to the strong winds. At liftoff, a strong gust of wind pulled the balloon horizontal which caused the payload not to lift, briefly. The payload crashed into the ground and we heard one of the radio transmissions stop mid-transmission. This was a heartbreaking thought as we thought the flight was over before it was even 1 ft. off the ground. Luckily, the unit continued transmitting. We later discovered that the crash on liftoff caused the battery pack cover to dislodge and we can hear on the liftoff video when the Arduino reboots and goes through its power-up sequence as its lifting off. The Arduino would go on to power cycle (reboot) 14 times throughout the flight due to the batteries being loose with the dislodged cover. It’s amazing that it even kept transmitting.
The balloon traveled to a maximum altitude of 90,141 ft. before bursting at 1:58pm EDT (17:58 UTC). It then came down in a hurry – only 36 minutes! Our next issue occurred when the unit stopped transmitting on the descent at 14,973 ft. and never transmitted again for the final 11 minutes of the flight. We again discovered that this was also due to the aforementioned loose batteries. Of the 14 power cycles (reboots) that occurred during the flight, 11 of them occurred during the final 11 minutes of the flight. This rapid power-cycling meant that the Arduino could not transmit as the software was set to send the first transmission at the 90 second mark after power-up. Since it continuously power cycled, it never reached the 90 second mark.
Fortunately, the backup GPS tracker worked this time and the unit appeared on our GPS app seconds after landing. We were actually hoping to see it land as we were waiting nearly at the predicted landing site. Unfortunately, we missed it as it landed about 1 mile from where we were waiting, but we were pretty close! There’s always next time.