NOTE: the prices below where compiled before COVID and we have unfortunately observed quite an increase during the last few years with some of the items doubling in price…
This is the list of required components:
Raspberry Pi 3 B+. We have completed all of our test with a Pi3 B+. We have not tested with a RPi4 but there is no reasons why it would not work properly although the RPi4 possesses a more power-hungry processor and does requires more power to operate reducing available battery time if the device is not plugged in the airplane. The RPi4 also generates more heat then the 3 B+ and additional cooling may have to be considered during hot summer days.
A Raspberry Pi 3 B+ cost approximately $38 US.
We also recommend installing the software and booting from a USB flash drive instead of an SD card. This is optional but a USB device tends to cost less for the same size and they are less susceptible to data corruption during power transitions. During testing we used a SanDisk 32GB Ultra Fit USB Flash Drive with no SD card installed. Approx $10-15 US on Amazon.
USB GPS module. We recommend the Stratux GPY2.0 u-blox 8 USB GPS unit. We have tested numerous GPS modules including cheap serial GPS and an Adafruit Ultimate GPS HAT but they were unfortunately interfering with the cellular module serial communication and configuring the GPS to use the RPi I2C bus did not produce acceptable output as we observed numerous dropped data. There is also an external USB version shown below but although we found the cable length to be a little too long it is still a valid option. The GPY2.0 GPS costs around $20 US.
Raspberry Pi cellular communication 4G/LTE/GSM HAT. We recommend at least a 4G unit but if your country still supports 2G these modules are less expensive and they work well. We have tested both the Waveshare 4G and 2G GSM modules. Approx $72 US for the 4G/LTE and $28 US for 2G GSM.
Since the data transfer rate between Blackbox and its server is minimal (a few data points every 6 seconds) the total on-line time is minimal and during test we recorded a maximum of 1 Mb / hour data transfer rate.
GeeekPi Raspberry Pi GPIO Extension Board. This is optional, we use it to stack more than one HAT onto the RPi3, which is the case for our prototype. Approx. $10 US.
An IMU + Baro module. We have tried numerous types of IMU sensors, including MPU6050, MPU9250, Adafruit BNO08XX, BMP388, Adafruit BMP390, etc., but we found that one of the easiest to configure, requiring no soldering and combining both an IMU and a Baro sensor, is the BerryIMU HAT. Our recommendation would be to use a BerryIMU Version 3 (without GPS) and connect it via a Raspberry Pi QWIIC connector & cable sold on Amazon. The Berry IMU V3 will supply your project with an accelerometer, a gyroscope, a magnetometer and a barometric sensor. Approx $28 US online.
Case enclosure. We are currently working on a specific and printabled 3D case design that will provide easy access to the SD card and the RPi connections but meanwhile we are using an ABS Plastic Electrical Project Case with adequate dimensions (6.2″x3.5″x2.4″)(158 x 90 x 60 mm). Approx $7 US.
The Blackbox prototype looked like this when fully assembled:
Total cost of hardware, including a SanDisk Ultra 32GB microSDHC SD card (around $13 US):
- $135 US with a GSM 2G or
- $175 US with a 4G/LTE
You will also require a sim card and a data only plan (sometimes called “tablet plan” by providers) to allow continuous communication with the Blackbox webserver. The data transmitted by Blackbox during a one-hour flight is quite nibble, while conducting live tests we observed a rate of approx. 1 Mb / hour. A starter data plan with around 100 Mb per month will be sufficient for most installations and these plans, depending on your location, should cost you anywhere from $4 to $10 US per month. In Canada, using Videotron, we subscribed to a $5.00 CAN per month plan that can be cancel at any time if needed.