Congratulations to Team Maheswara from Indonesia for winning Honorable Mention, Best Design GSBC 2019! An excerpt from their report is below with more details at the link at the bottom.
Maheswara is a High Altitude Balloon (HAB) that was launched on April 27th 2019. Our team, Maheswara is the only team from Indonesia, South East Asia that participating in this year Global Space Balloon Challenge (GSBC). Our team consist of students of various expertise from Universitas Gadjah Mada that focused on developing radiosonde/high altitude payload. This is our second time to participate in the event and last year we successfully launched our HAB and achieved Second Place Best Design. This year our primary objective for the GSBC Challenge is to develop a better radiosonde chassis and better Antenna Tracking System. For the mission our team developed a radiosonde that can measure atmospheric temperature, humidity, and pressure changes in the atmosphere. The radiosonde also equipped with GPS module so we can track its position, and then the radiosonde will send those measured values to the GCS (Ground Control Segment) using radio transmission. The GPS data is also used to point our ground antenna (The Antenna Tracking System) directly to the payload so that the LOS (Line of Sight) is maintained for maximum data transfer reliability. Our flight successfully reached its maximum altitude at 15814 meters relative from the ground. Unfortunately we encountered technical error in the action camera that we used, the action camera only managed to record a three second video footage and we suspect it is caused due to overheat in the ground and the protection case is not tight enough to protect the camera when its flown from extreme temperature changes. However the rest of the payload data were successfully recovered. Below we further explained in details our goals and design characteristic of the radiosonde.
a. Obtain atmospheric parameter such as Pressure, Temperature, and Humidity.
b. Create and design payload chassis such that it solid enough to withstand impact upon
flight and landing yet light enough, and protect the electronics inside from extreme
c. Provide reliable radio communication at long range for our radiosonde with the ground
control segment using tracking system.
d. To enrich our experience at the edge of the space.
e. To introduce atmospheric parameters research through High Altitude Balloon launch to
wider society in Indonesia since it’s a very uncommon activity for people in our country.
a. Payload Chassis
The chassis was designed by considering several aspects, such as the chassis ability to withstand impact yet lightweight and low cost. The chassis material is chosen not only with the consideration that the material strong enough to withstand impact and lightweight but also can protect its electronic components against atmospheric environments that have extreme temperature changes. From those requirements we chose to made the chassis from Polyfoam (Extruded Polystyrene Foam) because its lightweight property and easy to manufactured. We then combined the Polyfoam with four hollow carbon fiber rod as supporting pillars to help reduce vibrations upon impact when landed. We also wrapped the payload using clear duct tape to prevent water from getting into the electrical parts. Its final weight was 127 grams.
Payload ring is a component that used to hold the radiosonde, action camera and other mission’s stuffs. The payload ring is built from aluminum hollow beam and plywood, to achieve lightweight requirements yet rigid enough. The payload ring take triangular shape so it can distribute the load more balanced and to reduce rotation.
b. Payload Electronics
The electronics for the radiosonde consist of a Lipo battery 7.2V 1000mAh, a GPS module UBLOX M8N, a 433Mhz 100 mW radio transmitter by 3DR, and two sensors: BME 280 (humidity sensor) and BMP 388 (temperature and pressure sensor). For the flight controller unit we use Arduino Micro. These components were carefully selected for optimum reliability.
Antenna Tracking System (ATS) Mechanical Structure of the ATS
Antenna Tracking System (ATS) is a mechanical system that used to track the balloon payload position (horizontal and vertical position).
We build up this antenna tracking system with some
materials such as hollow steel beam, aluminum beam,
acrylic, and gear system. We chose these materials because
they provide rigidity and good stiffness. So, the antenna
system can be used in various area and withstand any
conditions such as windy weather.
The payload chassis that we developed for this year’s flight is much more lightweight and more neat than last year’s chassis. It’s also easier to do troubleshooting. The payload ring that we created help us to better tie up the payload to the parachute and the balloon, the payload ring help to prevent the same mistake from the last year where our payload detach itself from the parachute and the balloon although the balloon hasn’t exploded and free falling from 11000 meters. Both payload chassis and payload ring help to protect the electronics to land safely even the electronics still working fine after flight. But we know our flight is far from perfection, the result from the sensors measurement still show a little bit noisy measurement and the GPS module (only) failed to lock when reaching higher altitude at 11000 meters, we suspect this failure happens because the GPS module couldn’t handle the extreme temperatures in the space. This will become evaluation for us to isolate the GPS module better to keep the module warm. But still the other sensor, the BMP 388 managed to work in extreme temperatures while exceeding its maximum operating temperature ratings and yet the GPS module have the same maximum operating temperature ratings according to the datasheet. Nevertheless our main target is achieved which is to make an Antenna Tracking System that point the ground antenna to the position of the payload automatically. We still don’t know the transmission limit of our radio communication using our Antenna Tracking System, and hopefully next year we can reach higher altitude than before and have better camera to record the flight. Because we can't cram so much information in the report please kindly visit the link below to see our documentation from our launch: