MEC 08 - Variable Pitch Ram Air Turbine (VRAT)

This capstone project showcases the design, development, and testing of a variable pitch ram air turbine (VRAT) capable of delivering constant voltage output across a range of wind speeds. In aviation applications, especially during emergency scenarios, ram air turbines (RATs) are deployed to generate electrical power when primary systems fail. Conventional ram air turbines utilize fixed blade angles, causing RPM—and therefore voltage output—to fluctuate with airspeed. To address this, the VRAT features a variable blade-pitch mechanism that adjusts in real-time to changes in wind speed to maintain optimal voltage output. The system is controlled by an Arduino Uno programmed PID controller that continuously monitors the output of the generator, automatically adjusting blade pitch without pilot input. This makes the VRAT well-suited for use in aircraft emergency power systems, where reliability, automation, and voltage stability are critical.

The completed prototype is built around a lightweight aluminium frame and 11 custom-designed parts, including a three-speed transmission, linear/rotary control mechanism, fully articulating blade pitch hubs, turbine blades, and a closed-loop PID control unit. The VRAT was tested in the Centennial College wind tunnel and exceeded expectations in its performance. The VRAT was subjected to wind speeds between 10 and 23 m/s and maintained a consistent output of 2 2V with a variation of +/- 0.4 V across the full range.

Overall, the VRAT combines principles of aerodynamics, mechanical design, control systems, circuit design, power generation, manual machining, 3D printing, and experimental testing to address a real-world challenge in aviation. By providing a constant voltage output across a range of airspeeds, this system enhances the reliability and efficiency of emergency power systems in aircraft. Its autonomous operation, adaptability, and efficiency make it a promising advancement in the field of aerospace auxiliary power solutions.