Analytical Weight Estimators and Optimization for Mechanisms Within a Bio-Inspired Concept Aircraft

This paper presents a method for estimating the weight of mechanisms used within a fullscale concept aircraft equipped with a bio-inspired rotating empennage (BIRE). The aircraft mimics birds, who do not have a vertical stabilizer and rotate their feathers to maintain control to perform agile maneuvers. The selected platform for the BIRE concept is a single-engine, supersonic, tactical aircraft similar to the F-16 Fighting Falcon. The agile tailless aircraft is able to rotate the entire empennage, including the horizontal stabilizers, to provide yaw stability. With the unusual motion, unique mechanisms and structures are required to support a controllable design. Traditional weight estimation methods use empirical methods that are not accurate when applied to novel concepts. Numerical methods, such as finite element analysis, are too complex to include in trade studies. To generate appropriate fidelity estimates, analytical sizing models of the mechanical system for the BIRE were created using first-order principles. The developed weight estimator uses aerodynamic and inertial loads, along with physics-based component selection techniques to inform empirical regression models derived from component vendor information. A controls and aerodynamic informed optimization was implemented to select component alternatives and dimensions that minimize system weight. This mid-fidelity weight estimation has been developed specifically for the BIRE concept but consists of submodels that can be applied to other aircraft mechanisms including shafts, bushings, bearings, gears, and linear and rotary actuators. By removing the vertical stabilizer and incorporating structurally efficient mechanisms, the BIRE concept is expected to decrease fuel consumption due to weight and drag reduction.