Jim Heaney's Ultralogger Is an Arduino-Compatible Rocketry Avionics Logger for High-Power Launches

Industrial engineering student Jim Heaney has developed a custom Arduino-compatible avionics package, dubbed the Ultralogger, for high-power model rocketry — weighing in at just 6.4g (0.23oz).

"The Ultralogger is small enough to fit into a 17mm tube, making it a viable option for small Estes and similar rockets. However, the sensor package and memory allow this board to fly up to 100,000 feet above sea level and reach accelerations up to 200g while still recording data," Heaney writes of the project. "The board can log up to 20Hz data for 20 minutes, with a manually-configurable data rate to maximize recordings on longer flights."

The board is based on a Microchip ATtiny1616 microcontroller, which is programmed through the Arduino IDE using the community MegaTinyCore. Also on the board are a pair of sensors for monitoring the flight: a MEAS Switzerland MS5607 pressure and temperature sensor, used to track the rocket's altitude; and an Analog Devices ADXL375 accelerometer to track acceleration.

"I started out with the sensors and built up from there," Heaney explains. "The accelerometer and altimeter I used in this board are ones that I want to use on future, larger, more complex avionics packages, but I needed a way to better quantify their performance at the small-scale first to know if they'd work for what I wanted to do. Beyond that, my next driver was physical size. Smaller rockets are cheaper and easier to launch, so if I could squeeze this into a 17mm versus, say, a 25mm body tube, I could launch maybe 50 per cent more for the same cost/amount of time."

A major part of the Ultralogger's design is flexibility: if a particular model rocket lacks an avionics bay, the unit can be attached directly to a parachute. There's no removable storage, to avoid issues with microSD cards or similar shaking loose during flight, with three I2C EEPROM chips used instead — and all settings, including data retrieval in CSV format, can be done over the board's micro-USB interface via a standard serial connection.

"Weight with battery comes in at 6.4 grams [around 0.23oz]," Heaney says of the finished device. "Can log temperature (either F or C), altitude (either above sea level or ground level, in either feet or meters), acceleration (vertical, in gs), and battery voltage (in volts, to two decimal places). The functionality is also there to measure acceleration in X and Y, but that is not too useful in a rocket. It can measure up to 20 times per second, with the limiting factor being the EEPROM."

More information on the project is available in Heaney's Reddit thread; while a planned write-up had not appeared on his website at the time of writing, other avionic board designs are detailed in its place for the curious.