On Monday, April 4, 2016, at 10:45AM (14:45 UTC), we Launched the Torch! using a 600g weather balloon purchased from High Altitude Science. We used a weather balloon inflator to fill our balloon with approximately 125 cubic feet of helium purchased from AZ Rentals in Tallahassee, FL, which provided us with a little over 3kg of lift (we used both the spring scale included with the inflator, as well as a digital luggage scale, to measure the lift as we inflated the balloon). According to our calculations, this amount of helium would lift our payload (a total of 2kg, including the parachute) at an ascent rate of 4.5 meters per second (thanks to 1 kg of positive lift), thereby Launching the Torch! more than 20,000 meters high in about 80 minutes.
We tied off the weather balloon (as per these instructions) using rubberbands, electrical tape, and duct tape (“I don’t believe in much, but I believe in duct tape”), and then attached a 1.5m parachute at the end of approximately five feet of orange twine purchased from a hardware store (44lb strength). The parachute is designed to stay closed during the ascent, and open automatically after the weather balloon bursts. According to our calculations, it would take approximately 30 minutes for our payload to return to earth. Careful timing of both ascent and descent rates was essential, since we risked the payload landing in the Atlantic Ocean if the payload ascended or descended too slowly.
We used approximately twenty feet of the same twine to attach the parachute to our payload, a 12 inch by 4 inch rectangle of plywood, covered in reflective tape, with eye hooks bolted into each corner. The parachute was attached to a single point (using a carabiner for easy access) that extended to the four corners of the rectangle in an attempt to keep the payload stable during flight. On the top surface of the payload, we attached an Eagle Flight Computer with a Temperature Pressure Sensor and an APRS Radio Transmitter. Combined, these devices would continuously broadcast our payload’s location and altitude, along with current weather conditions, throughout the flight, allowing us to track our travels through near space.
We also attached a SPOT satellite tracker (along with the required annual service plan), which allowed us to track the balloon’s location using satellite networks instead of cellular networks (an essential consideration given our balloon’s projected landing in rural North Florida or South Georgia, where cell phone coverage is less than universal, plus it is against FCC regulations to launch a working cellphone into space). With two devices — the APRS Radio Transmitter and the SPOT Satellite Tracking system — providing GPS coordinates, we hoped to be able to track our balloon in the air and on the ground, in real time.
To help us locate our payload after landing, we installed a short-range (bluetooth) Tile phone finder to help us locate our payload by sound (assuming we could get within 30 feet of the payload). We also included our contact information and details about the project on the payload so that if it was found by someone other than us, they would know what it was and how to contact us in exchange for an reward. Given our presumed landing location, we borrowed a handheld GPS location receiver (which was not sent into space) so that we could track our location on the ground while searching for the payload.
Underneath the payload, we attached a 3D printed GoPro camera rig (based on this design) which included mounts for six cameras pointing in six different directions, thereby providing all the required footage needed for a 360 degree video. For this launch, we decided to only use five cameras (all GoPro Hero 3 cameras), sacrificing a camera pointing up so that we could mount the rig more securely onto the wooden platform (we would later replace the missing video with a blank feed of the sky in near space). To help secure the cameras, we cut a square frame to fit along the bottom edges of the GoPro camera rig, and bolted the frame together with the rig onto the payload platform; we also zip-tied the frame to the platform for added security. Each of our five GoPro cameras was in its own protective case, and we included anti-fog inserts to help keep the camera clear in near space conditions.
Hanging down from the wooden platform, such that they would be visible in front of two of the five included cameras, were two copies of the FSU Torches seal, designed in Autodesk 123D, and printed using our Dremel Idea Builder 3D Printer. The FSU Torches were coated with XTC-3D High Performance Coating, and then painted Garnet and Gold.
We launched our balloon from Florida State University’s intramural fields, which provided a suitable wide-open location devoid of trees or other obstacles that could snag our balloon or payload. We needed a day when the weather was perfect — no surface winds, not a cloud in the sky, and a relatively slow moving jet stream immediately overhead — and Monday, April 4, 2016 was perfect for our needs.
The launch itself went flawlessly, especially considering none of us had done this before (it also helped that had a dress rehearsal the day before, where we did everything except fill the balloon). Working from the ground up, we secured the cameras in the rig (all the GoPro batteries were fully charged and ready to record) but waited to turn them on until we were just about ready to launch (we were worried about how long the batteries would last in flight). Tightening the cameras mounts in the rig was a little tricky, as we didn’t want to snap the plastic, but we managed to secure all five cameras without incident (for good measure, we also secured the camera pointing down with a zip-tie).
Once the cameras were ready to roll, we activated the SPOT Satellite Tracker, Eagle Flight Computer, and APRS Radio Transmitter, and confirmed that everything was working perfectly — special thanks to the Tallahassee Amateur Radio Society for setting up a digipeater close to campus so that we could track our payload from the Intramural Fields. We also made sure that everyone at the launch knew how to track both devices on their phones.
Once the payload was ready, we attached the parachute and began the process of inflating the weather balloon. To prevent any accidental loss of the balloon, we made sure that two extra safety lines were attached to the balloon at all times. Tracking the amount of positive lift as we inflated the balloon was a little tricky as the balloon swayed from side to side as we inflated it, but we used two different scales to find the most accurate measure. Once we had the right amount of helium in the balloon, we tied off the end, attaching the orange twine (leading to the parachute) to the balloon at this time.
At this point, we were ready to launch. We turned the cameras on, disconnected the safety lines, and slowly raised the balloon, step-by-step. We didn’t want to jerk the twine or payload, so we let the balloon go up slowly, working our way down the twine from the balloon to the parachute, then down the parachute to the twine connecting the parachute to the payload (we had a carabiner at both ends of that twine — duct-taped shut for safety), and then down that twine to the carabiner hooked above the payload. At that point the balloon was about fifteen feet overhead, and ready to go. We confirmed that the payload was properly balanced under the parachute (with none of the twine caught up on anything), and let the balloon go — counting down from 3, 2, 1!
We then chased the balloon across North Florida, tracking our payload in real time on our phones. Using both the SPOT satellite tracker and the APRS radio transmitter (http://aprs.fi/) turned out to be a great idea as it gave us confidence that we knew exactly where the balloon was at all time. We constantly tweeted our payload location as we chased it, plus we were broadcasting publicly on K4TLH-11, so many people were tracking our flight at the same time!
We were lucky that the winds were blowing almost exactly due east, so we were able drive almost straight out on I-10, following our balloon in real time. The balloon reached a height of 20333 meters before it popped over Madison, FL, at which point the parachute deployed, and the payload floated back to earth, landing (almost exactly two hours after we launched) in a Potash Mine in White Springs, FL. We are very grateful for the assistance provided by the employees of PotashCorp in locating our balloon, parachute, and payload, without whose help we could never have recovered our cameras.