Longitudinal Trim and Dynamic Stability Analysis of a Seagull-Based Model

Understanding the mechanisms of trim and flight stability in birds is critical to guide the design of bionic micro air vehicles. The complex movements (plunging, sweeping, twisting) and morphing of wings always keeps the flapping flight of birds in dynamic equilibrium, which makes it difficult to determine the critical factors of trim and stability. Hence, a model has been developed that takes real complex movement and the calculation of unsteady aerodynamics into consideration. Two trim methods, including wash-out and forward-sweep, have been used to achieve equilibrium in the longitudinal direction. It is interesting to find that these two methods are both important to realize a larger take-off weight, lower power consumption, and stronger longitudinal stability. This implies that the seagull probably uses both of them to obtain the requirement of equilibrium and stability, which further inspires the design of seagull-inspired micro air vehicles.