In aerospace engineering, the first few seconds of flight are the most precarious. Most research rockets use fixed fins for stability; however, fins require high-velocity airflow to be effective. This creates a "stability gap" during takeoff and slow-speed maneuvers when the vehicle is not yet moving fast enough for aerodynamic surfaces to provide control.
The Portal Space student team in Norway is addressing this gap with a custom Thrust Vector Control (TVC) mechanism. Instead of relying on airflow over fins, this system physically tilts the propulsion unit to steer the vehicle from the bottom up. While the mechanism is designed for the high-stakes environment of rocket flight, the team is currently utilizing a propeller-based design for their prototype to allow for rapid testing and iteration.
Technical Specifications: For more info about the specific product used in this application, you can check out our L16 Actuator Product Page
The Engineering Challenge: Speed vs. Stability
Building a steering system is a balancing act. If the movement is too slow, the computer corrections will lag behind the physical tilt of the vehicle, leading to a crash where the system over-corrects until it spins out of control.
The Portal Space team used heavy simulations to find the right amount of correction. The hardware had to be light enough for flight but fast enough to match the high-speed demands of the flight software. They selected the L16-50-35-6-R for several technical reasons:
- Speed: The 35:1 gear ratio is the fastest version of this actuator, providing the rapid response times needed for real-time steering adjustments.
- Compatibility: Because the R-series acts as a linear replacement for a standard servo, it is designed for compatibility with systems that output a standard PWM signal.
- Form Factor: The compact size allows it to fit within the tight constraints of a 3D-printed housing.
The Prototype: Mechanics and Control
The Portal Space vehicle uses a 3D-printed cradle to hold the propulsion assembly. The L16-R is mounted vertically to push and pull this cradle, tilting the thrust source in different directions. This versatile mechanism is effective for both rocket engines and propeller assemblies, as the physics of vectoring the thrust remains the same.
Precision Feedback
The L16-R features an internal potentiometer that provides the flight computer with constant position feedback. This ensures the system knows the exact angle of the thrust vector at all times, proving that the physical assembly can execute the software commands required for stable flight.
The project is now moving into an optimization phase focused on reducing overall vehicle weight to improve the thrust-to-weight ratio and performing general optimization of the physical assembly. Actuonix is proud to support student research that pushes the boundaries of aerospace engineering. This level of integration moves the vehicle beyond traditional fixed stability and into the realm of dynamic control, where fundamental flight characteristics are managed in real-time.
Technical FAQ: Portal Space & Thrust Vectoring
Why was the 35:1 gear ratio specifically chosen for this project?
The 35:1 gear ratio is the fastest configuration available for the L16. In thrust vectoring, the physical actuator must move as fast as the flight software's calculations; if the actuator is too slow, the system will lag, leading to over-correction and a potential crash.
How does the L16-R integrate with standard flight controllers?
The L16-R is designed as a direct linear replacement for a standard rotary servo. It accepts a standard PWM (Pulse Width Modulation) signal, which is the universal language for most hobbyist and professional flight controllers.
What is the benefit of the internal potentiometer in this application?
The internal potentiometer provides closed-loop position feedback. This allows the flight computer to verify that the thrust cradle has actually reached the commanded angle, ensuring the system knows the exact angle of the thrust vector at all times.
Moving From Theory to Application
At the end of the day, understanding how linear motion integrates with mechanical leverage is key to setting your project up for long-term success. While it’s tempting to simply pick a high-power actuator and hope for the best, the most reliable designs are those that take care to select the most appropriate actuator for the application.
If you need assistance selecting a product that meets your application requirements, please contact our sales team for assistance.
