Balua – Braga


This launch was done in Braga, on April 4 (Friday), between 13 and 17 hours. This launch was made in collaboration with the students and professors of Escola Secundária D. Maria II. This School was celebrating 50 years of existence and this launch was part of the celebration activities conducted by the school.

cartaz 50 anos



  1. Obtain good images and video.




  • Payload = 904g
  • Parachute = 70g
  • Filled Balloon = 1000g
  • Total = 1904g


  • SPOT Tracking System
  • Radiometrix HX1 – VHF transmitter hard-tuned to 144.8 MHz
  • UHF beacon hard tuned to 434.480MHz


  • Venus638FLPx GPS module
  • 1 pressure sensor
  • 1 3-axis accelerometer
  • 1 magnetic compass


  • 6x AA Lithium Energizer batteries.


How it works


The main flight computer was a custom PCB with an ATmega328 running the arduino bootloader. Also on-board is a 3.3V voltage regulator and a Radiometrix HX1 (VHF transmitter, hard-tuned to 144.8 MHz which outputs 300mW (draining 120mA at full RF). The flight computer also connects to the Venus638FLPx module and receives data from 2 temperature sensors, a pressure sensor, a magnetometer and a 3-axis accelerometer. All data is stored on an on-board microSD card. All systems are powered by 6x AA Lithium Energizer batteries. A buzzer was also fitted to facilitate locating the payload.  Lastly, a chemical heater was embedded within the payload casing.

As a backup system we have a SPOT satellite GPS Messenger. This equipment is placed in a special casing that allows it to rotate and always face north.

We also have a beacon that gives a beep in UHF every second (a type of beacon used often in animal tracking). This beacon is used by us in conjugation with a yagi antenna to track the balloon when we are close by (it was important in Barcelos).


The ATmega328 running the arduino bootloader is programmed in C language and the main software loop runs on the following instructions:

  • Reads gps data and parses it,
  • Reads sensors and converts data,
  • Sends data through the HX1
  • Stores data to the microSD card.


Estimated Flight Plan





Pictures and Video

Pictures and/or movies can be found in the gallery section here.

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