Our Next Generation High Altitude Balloon Payload Platform

What Is High Altitude Ballooning – High Altitude Balloons are generally un-crewed balloons, usually filled with helium or hydrogen, that are released into the stratosphere, generally attaining between 18 and 37 km above sea level. High Altitude Balloons are known to have attained altitudes of close to 53 km (32.9 mi; 173,900 ft).

High Altitude Balloons have been used extensively by meteorological organizations around the world as weather balloons for purposes of obtaining measurements of key environmental variables i.e. wind speeds, temperature, humidity, pressure, etc. This data is used to model weather conditions and provide weather predictions. Meteorological organizations tend to launch such weather balloons at-least once a day from various locations across their countries for purposes of data collection. Here’s in Melbourne the BoM or Bureau of Meteorology launches weather balloons twice a day, every day.

Hobby groups, Universities, Defence organizations, research organizations are known to use High Altitude Balloons as platforms to perform various scientific experiments including using it for purposes of measuring current meteorological conditions during scheduled events e.g. launch of a space craft, etc. If you are interested in learning more about High Altitude Ballooning then head over to our resources page and check out the links there – https://hack2.live/high-altitude-ballooning/

Our Launch History – The EMDRC High Altitude Balloon Group has been launching High Altitude Balloons since 2022, have had 3 launches so far, all of them based out of Ararat, Country Victoria. Our learning journey was unique in many different ways, we received our flight instrument from CASA (Civil Aviation Safety Authority) just before the pandemic hit. As a result our flight schedule, flight preparation activities were severely impacted. We managed to keep flight preparation and testing going through the rest of 2021 and 2022 before finally being able to launch in September 2022.

The EMDRC (Eastern & Mountain District Radio Club) High Altitude Balloon group has come a long way, worked together as a team to overcome many different challenges, has a few runs on the board and has launches scheduled across 2023 with some ambitious projects in the wings e.g. design, build and launch of our custom payload platform.

Current High Altitude Balloon Payload Platform – We currently have two different types of payloads we fly on our flights with a third option to be tested out soon –

1. RS41 Radiosonde – Our primary flight payload is the RS41 Radiosonde, launched twice a day by the Bureau of Meteorology here in Melbourne (located & retrieved post flight) but now reprogrammed with the Horus binary firmware.
   • The RS41 has an on-board GPS, temperature and humidity sensor
   • The RS41 transmits on the 70 cm band
2. Wenet payload – Our secondary payload is based on the AREG Wenet project spearheaded by Mark VK5QI.
   • The Wenet payload consists of a Styrofoam box that houses all the electronics.
   • The payload includes a Raspberry Pi along with a daughter board consisting of 2 radio modules.
   • Raspberry Pi Zero W with a 32GB high performance SD card on-board
   • Power provided by 3 Energizer Ultimate High Performance AA batteries
   • USB GPS connected to the Raspberry Pi Zero which provides location details
   • Raspberry Pi Camera to capture still shots as the payload ascends and descends along the flight path
3. Flextrack – This High Altitude Balloon platform was initially designed and built by Dave Ackerman out of the UK and is now sold through the Uputronics website. This consists of –
   • Raspberry Pi Zero W main-board connected to a Raspberry Pi Camera
   • Raspberry Pi Zero W with a 32GB high performance SD card on-board
   • Power provided by 3 Energizer Ultimate High Performance AA batteries
   • Seprate Flextrack daughter board with the following capabilities.
   • Communications module on the daughter board that includes a LoRA module (915-928MHz in Australia)
   • On-board GPS with GPS antenna required to provide location details

We chose to invest in the Flextrack High Altitude Balloon platform long before we made acquaintance with Mark VK5QI, the father of High Altitude Ballooning in Australia and author of auto_Rx, Wenet, HorusGUI, etc. Across the three flights we have flown so far we have chosen to only fly with our RS41 and Wenet payload, however we are considering flying the Flextrack at the next payload to see how it performs.

Why Consider A New Platform – So with all of those options why would we even consider a new High Altitude Balloon platform you might ask. I guess the answer you would get is, because we can. So while a custom High Altitude Balloon platform isn’t a necessity, it’s an opportunity for the EMDRC High Altitude Balloon Group to push the boundaries, develop new skills, expand our High Altitude Balloon capabilities and design-build-fly our own custom payload platform that offers enhanced capabilities in a small package.

The new High Altitude Balloon platform is going to be based on the Raspberry Pi CM4 module which is powered by the BCM2711 Quad-Core Cortex A72 Arm 64Bit SoC with each of the cores clocked at 1.5Ghz. The high level schematic above suggests the different modules the new High Altitude Balloon payload platform might include. The platform is being designed by Trystan CJ and will be tested out by a number of others across the group with significant input provided by Mark VK5QI.

The Raspberry Pi RP2040 which powers the Raspberry Pi Pico has been included as a micro-controller to allow offloading of radio communications, interacting with GPS including recording data from sensors, etc. The HAB platform will allow for the RP2040 to be disabled allowing the main Raspberry Pi CM4 to drive the GPS, sensors and radio communications.

What Features, Capabilities With the New Platform Provide – Here’s an initial view of the capabilities provided by the new High Altitude Balloon platform. The final feature set hasn’t been locked in yet and is subject to change.

1. Raspberry Pi CM4
   • Broadcom BCM2711 quad-core Cortex-A72 (ARM v8) 64-bit SoC @ 1.5GHz
   • Options for 1GB, 2GB, 4GB or 8GB LPDDR4-3200 SDRAM
   • Options for 0GB (“Lite”), 8GB, 16GB or 32GB eMMC Flash memory
   • 2.4 GHz, 5.0 GHz IEEE 802.11 b/g/n/ac wireless, Bluetooth 5.0, BLE;
2. Raspberry Pi Pico integrated, can be programmed to manage sensors, GPS, radio, etc.
3. Onboard sensors i.e. temperature, pressure, etc.
4. Additional sensors can be connected via a daughter board
5. Powered by multiple AA batteries
6. Two UHF radios on the main-board
7. Onboard GPS
8. HDMI connector
9. 2 x MIPI CSI connectors allowing the use of 2 cameras

What Are Our Timelines – We’ve been chatting about the new High Altitude Balloon platform for a while, with Trystan being a major supporter and the platforms primary designer. We are hoping to have the platform up and running June/July and tested out in preparation for flight August/September 2023. Those timelines are what we are aiming for and subject to change.

So if you are keen to know more about the High Altitude Balloon Group, understand how you could contribute to the design, build, test of the new payload platform, or just chat with rest of the High Altitude Balloon group then head over to discord and let’s get chatting. Here’s the URL for getting onto discord is – https://discord.gg/4FkrKJeNt5.

Drop us a note and let us know if you have any questions, comments or suggestions. You can reach us at trevor at hack2 dot live.