E-HAWK Avionics

Part of the E-HAWK project will include developing custom instrumentation and avionics for the aircraft.  The typical internal cumbustion engine instruments will be replaced with sensors and displays to monitor battery voltage (state of charge) and current, motor power, energy consumed, motor and controller temperatures, etc.  In addition to propulsion system monitoring, we will also be looking into additional instrumentation such as altimeter, airspeed indicator, compass, artificial horizon, attitude indicator, etc.  The readily available and inexpensive MEMS sensors offer a number of options.  The RC multirotor hobby has brought much of this technology to the forefront.  A capable multirotor flight controller with gyro, accelerometer, pressure sensors and GPS receiver can be had for < $50.  Add in some custom code and displays and you have yourself a custom “6-pack” instrumentation package found in a traditional cockpit.

With some parts laying around our electronics lab, we were able to put together our first prototype of an Altimeter.  It uses the ubiquitous Arduino (Nano), BMP180 pressure sensor, rotary encoder, and 128×64 OLED display (we’ll be experimenting with other types of displays to find the one with the best readability).  Add in a bit of code and surround it with a custom 3D-printed enclosure.

Our understanding of the FAA rules pertaining to Experimental Amateur-Built Aircraft is that no instrumentation is required for VFR daytime operations therefore no certification will be required.  Of course we will fully test any custom equipment to stringent requirements.

Altimeter prototype comprised of an Arduino Uno, BMP180 Pressure Sensor, 128x64 OLED Display, housed in a 3D-printed enclosure.
Main screen shows altitude, vertical speed, and altimeter setting (QNH) that is adjustable using the rotary dial. This prototype is designed to fit in a standard round 2-1/4" cutout.
CAD rendering of altimeter.
More CAD. We use Onshape for most of our designs. It's been an invaluable tool for our students. It's easy to use, runs in your browser, allows for seamless collaboration, and is free for education.
Parts ready for assembly.
Microcontroller and sensor mounted to perf board. Connectors interfacing with the display and rotary encoder allow for easy assembly/disassembly.
Components installed in 3D-printed housing.
Rear of unit with USB port for power and programming.
We will also begin experimenting with an airspeed indicator. Here is a potential pressure sensor that may work. It's originally designed to work with the Pixhawk series of drone flight controllers.

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