Rocket Control Board – Vladislav Pomogaev

This is the Draco control board, a rocket guidance/steering system that can be used to stabilize as well as record and transmit the flight data of model rockets.

I developed this board for my own personal use for in model rocketry, but wasn’t too sure as to the rocket I would use for it, so I decided to cram it full of features so that I could use it for multiple purposes. Here are some hardware features:

10 servo/general signal outputs for trim servos located on fins
3 detonator circuits for igniting rocket motors or deploying parachute
Camera interface connector for 808 style keychain cameras
Atmega2560 MCU (same as Arduino Mega)
RFM95HW Long-Range (LORA) radio transceiver
Micro SDCard Connector for logging
LSM9DS1TR‎ IMU for accurate positioning and orientation
SAM-M8Q GPS module for recovery tracking
Multi-purpose connector for addon accessories
MS5607 Barometer for altitude monitoring

Half-assembled board; taken during manual component placement. I used a Kapton stencil made by OSH Stencils to apply the solder paste. The GPS soldering was the most anxious part of the build due to being sensitive to the temperature profile. Thankfully I managed to get it soldered with only a hot air gun and warming platform.

Main schematic sheet for the Draco board. A 3.3v to 5v logic-level converter was used to get the MCU to talk to all of the individual components. Sub-sheets were utilized to keep the schematic clean and readable.

PCB layout of the board. The width was constrained to a standard size of inner rocket tube (about 50mm diameter). The final PCB was mounted inside a 3D printed shock mount.

I used the newest version of KiCad (at the time) to create this project. One of the features of KiCad is its ability to model the PCB in 3D, which is something I would later use to create a rocket-mount for the board

KiCad came with some basic 3D models that allowed me to visualize and export the PCB as a 3D CAD file. At the time of making the PCB the export was limited to meshes, but I think it can now export to more relevant file formats.

As well as creating the design using KiCad, I also made a single working prototype of the board for my own use. I got the PCBs made using the ALLPCB service, and assembled it using hot air soldering techniques.

Close up of the a) status LEDs b) detonator circuits c) Buck converter

This board will most likely be later utilized in my rocket or high-altitude balloon projects. The prototype I built worked pretty much first try, except for the IMU, which I had to re-heat and re-solder until it worked.

In addition to use in a flying vehicle, this board also found use as a data recorder and logging tool for my rocket motor test stand. The accessory connector was able to be hooked up to a strain gauge which allowed the board to measure and plot the impulse response of various rocket motors. The files were recorded on the SD card.

In addition to the main Draco board, I also soldered up a second USB-powered board, which contains an Arduino Nano and LORA radio. I will use this board to receive and transmit commands to the Draco board.