A variometer for thermal soaring models (version 1)

This is a short account of our first attempt at building a lightweight variometer that could transmit a reliable real-time climb/sink feedback signal to aid in RC thermal soaring.

The variometer described is based on the VTI SCP1000 D01 pressure sensor (now discontinued) and the "Pro Mini" Arduino board (8MHz, 3.3V), both sold by Sparkfun.

The prototype version relies on a piezo transducer to produce the audio signals in situ (pictured below). The beeps are then simply picked up by the microphone of an onboard PMR unit (446 MHz walkie-talkie) and monitored from a corresponding unit carried by the pilot on the ground.