Integrated Flight Control Design and Multidisciplinary Optimization

Multi-disciplinary optimization has emerged as a key technology required to make increasingly more sophisticated electric and hybrid-electric aircraft that require advanced CONOPS such as urban air mobility and distributed electric propulsion. Current MDO design results may consider many disciplines in the design resulting in an optimized aircraft, only to be locally re-optimized based on engineering performed post-aircraft configuration lock related to flight control, resulting in less efficient and less capable aircraft. Electric and hybrid-electric aircraft with distributed propulsion provide significant advantages such as significantly reduced stall speeds and improved maintenance cycles. Software weighs nothing, so theres always a push to move the problem downstream for controllers to manage in software, effectively trading bits for atoms. The net result may be the control system requires faster than available actuation, inadequate control authority, or large feedback gains to stabilize unstable dynamics. These issues are costly to uncover late in the system development, since typically flight controller work takes place after the configuration and outer-mode-line (OML) has been locked. It is essential to the success of hybrid and urban air mobility aircraft to include controllability of the aircraft within the aircraft optimization design. After decades of designing and flying flight controllers for new types of hybrid and distributed propulsion aircraft, our goal is to get add a controllability component to MDO to ensure the aircraft designed make the right trades and adjustments for flight controls. Rather than throw a controller MDO cycle into the middle of the aircraft MDO, the controllability problem is broken down into a series of targeted hierarchical Components that contribute to the monolithic optimization suitable for the nonlinear and linear solvers in OpenMDAO.
Benefits: RVLT concepts or slight modifications to the current concepts will allow RVLT to provide NASA with additional key critical technical areas to focus on in the future. New concepts can be quickly iterated and evaluated. AAM can use the controllability tools to understand what closed-loop performance is achievable to be able to form new CONOPS and infrastructure plans. ARMD can use the controllability assessment tools to optimizing the use of motors, rotors and propulsion system powertrain with respect to controller use and limitations. UAM and UAS markets have received significant investments on concept aircraft that may not be able to meet the proposed CONOPS or safety requirements. These tools can be used to evaluate designs and pivot into plausible, but inadequate designs. Technical due diligence could use the tools to compare and evaluate concepts for feasibility.