Exploration of Unconventional Aircraft Designs: A Flight Analysis of a Red-Tailed Hawk

The objective of this project was to analyze the flight of a red-tailed hawk in order to figure out how it remains stable in flight, and to determine if it had any advantages over conventional aircraft that could be implemented into future aircraft design. The analysis was performed by solving a six degree of freedom model (6DOF) in MATLAB with the use of Simulink. The twelve equations of motion that describe the 6DOF had to be built in Simulink, and parameters describing the bird’s performance and geometry had to be found and implemented as well. In preparation for the project, a lot of research was conducted to see what others had come across and how they thought birds remain stable. Research was also conducted in order to better describe the red-tailed hawk in the model. The research was focused on the aerodynamics of birds, and ranged from finding lift curve slopes to finding the physical mechanisms behind how birds control themselves and remain stable. In the absence of a live red-tailed hawk specimen that could be studied, pictures and videos were used to obtain flight performance and geometric characteristics. Preliminary results from the model modeling the hawk’s open loop response showed that even with a configuration that was statically longitudinally stable, the bird’s velocity was unbounded and showed oscillations with large changes in magnitude. Since the velocity was unbounded, the position was also unbounded and both were reaching values that were unrealistic. The bird’s pitch rate was also constantly increasing. These results indicated that the hawk must be closing the loop and a controller for pitch rate and pitch angle had to be modeled. The gains of the controller were chosen to target the Butterworth poles. Integration of the controller into the existing model was successful and results showed that the rates and angles were controlled. Based on those results, it was confirmed that the bird was actively controlling itself to maintain orientation during descent. With a viable model constructed, it opens up the possibility of studying more aspects of the bird’s flight, such as lateral stability. For future study, there is opportunity to refine the aerodynamics model, explore lateral stability, and model the hawk’s guidance system as it hunts for prey.