An Affordable Flight Data Recorder for Model Rockets
Payload is a tiny DIY model rocket flight recorder that tracks altitude, thrust, G-forces, and more for about $30 in parts.
Model rocketry certainly doesn’t carry the massive costs of the multi-billion-dollar government programs or commercial aerospace ventures. However, higher-end model rockets and telemetry systems are still quite pricey. If you’re playing around in that world, then you might want to check out Bud Bennett’s project called Payload. It’s a DIY device that records flight data from model rockets, but you won’t have to pay a load of cash for it.
Payload is a very small PCB designed to slide into the payload section of a model rocket and record the key events that happen after launch. That includes altitude, acceleration, rotation, temperature, maximum thrust, burn duration, time to apogee, recovery time, and total flight time. After the rocket is recovered, the user connects the board to a computer or phone over USB and uploads the stored data into a companion app for plotting and analysis.
The PCB measures 12.5 × 30mm, and the finished unit with its miniature 40mAh 1S LiPo battery and 3D-printed enclosure measures approximately 15 × 40 × 9mm. Total weight is around 5 grams, including the battery and enclosure, which makes it light enough for small model rockets.
Bennett built Payload around a PIC16LF18345 microcontroller running at 8MHz. An LPS22HB pressure sensor handles altitude measurements, and an LSM6DSO32 IMU provides acceleration up to ±32g and gyro data up to 2000 dps. The board also includes EEPROM storage, a magnetic arming system, a buzzer, a battery charger, and an MCP2221A USB-UART interface.
There are two planned versions of Payload. The Standard version uses 512 Kb of EEPROM and stores one flight’s worth of data. The Pro version bumps that to 4 Mb, enough for up to eight flights before old data is overwritten. Both versions log fast sensor data after launch detection, then switch to slower one-second sampling during recovery.
Prior to launch, a magnet arms Payload through the rocket body, and the buzzer confirms the armed state. Launch is then detected by acceleration along the automatically determined launch axis. Apogee and landing are detected from altitude data, and after landing the board goes into a low-power sleep mode while beeping periodically to help with recovery.
The companion app works with Windows, Android, and Linux. With a projected component and PCB cost of about $30–$33, Payload looks like a very capable little flight recorder for makers who prefer building their own gear. More details are available in the full project write-up.