The "pitch actuator" in action

A project log for WinDIY - HAWT Wind turbine

Mostly 3D printed HAWT windturbine incl. 3D printed disk-generator and brake system.

FabFab 07/05/2020 at 14:040 Comments

So, I successfully tested that the current design for the pitch actuator was a failure. :D

The pitch actuator is the part that moves the threaded rod back and forth, which in turn adjusts the angle of attack of the wing.

The construction itself works exactly as I hoped (see video). Unfortunately, the stepper motor used (the well known 5V stepper 28BYJ-48) is clearly too slow to allow a quick adjustment of the angle. At first I thought "Oh it's not that bad" because it wasn't really meant to have to quickly adjust the angle of attack anyway. After the first complete test run, however, I noticed that a complete trip from end position to end position takes almost ten minutes.

That is a little too long for me. :)

But I already have an idea for improvement. At the beginning I had planned to install only two limit switches for the respective end positions and to determine the position in between by counting the step motor steps relative to the end positions. (Similar to the system used on 3D printers) In the meantime, however, I had the idea of making it possible to query the current position of the threaded rod using a sliding resistor.

This has the practical advantage that I can also use a normal DC motor (probably a "Reely R140") instead of the stepper motor. This creates a significantly higher speed (14000 rpm) and thus higher adjustment speeds. At the same time, the current position can be tracked using the sliding resistor. :)

Now that I know that the design works in principle, I just have to change the motor bracket a bit. :)

Please note that the video below is 20x faster than the original.