In the summer of 2020, I started a project to build my own Variometer. I decided to do this because the one I had for my paraglider wasn’t working properly.
My custom Variometer is made using an ESP-8266 microcontroller and has several features: a GPS module for tracking flights and calculating speed, an SD card reader to save flight data, a barometer for measuring air pressure, an accelerometer for accurately measuring changes in height, Bluetooth for connectivity, a buzzer, a 4500 mAh LiPo battery, a battery management system, an old Nokia display, and a 3D-printed case. The sensor data (GPS and accelerometer) in order to estimate the position and velocity during flight was fused using a Kalman filter.
I also planned to use the accelerometer to measure G-forces during flight, but I haven’t implemented that yet.