[April 23, 2015]

One thing I have wanted for my airplane for some time is an Angle of Attack (AOA) indicator. However, none of the ones out there fit my needs.

1) GRT - Grand Rapids has a sensor-less AOA which figured out the AOA of the wing based on its AHRS and other inputs (They call it dervived AOA). It's OK, but the display can't be put on the dashboard where it would be valuable. Also, there is no connectivity of sound for warning.

2) Advanced Flight System - AFS has a nice AOA system, and it is complete, but it is expensive.

So I decided to see what it would take to roll my own. I built a box which will take three pressure inputs - Pitot, Static and the AOA port on the pitot tube. Using these three pressures, I will output the Airspeed, AOA and altitude. The whole thing is powered by an Arduino Micro microcontroller.

Getting it all plumbed up took some time to make it all fit into my prototype box.

The wiring was very straight forward. Each sensor needed 5V and Ground, and then a return with the analog signal back to the Arduino. I'm pretty impressed with the Arduino - it has a lot of bang for the buck.

The back panel - I am using push connectors.

All assembled and ready to install! I think I have about $100 total into this project so far.

I wrote a simple program that outputs the data of the sensors to a serial port (The Arduino's USB port looks like a serial port to a PC). For testing, I will output the data to a laptop in a delimited format of raw data. The data I am outputting is as follows:

[Milliseconds since Start],[Altitude Sensor],[Airspeed Sensor],[AOA Sensor]

The sensor data is all raw - 1023 is the max value it could be, and that indicated 5V. 0 means 0V. So it's pretty simple math to figure out what voltage I am looking at. Once I have data collected, I can analyze it in excel and plot things out.

I wrote a quick C program that reads the data off of the serial port and adds a date/time/millisecond timestamp to each dataset from the AOA sensor. Now I know exactly when the data was received in local time.



Last Modified: September 4, 2017