Design and Multi-Objective Optimization of a Control Surface Allocation Concept for an Agile and Highly Swept Flying Wing

The aim of the DLR project Mephisto is to establish a multidisciplinary design approach for an effective, agile combat air vehicle by using computational methods and/or simulation-based assessments only. The highly swept generic flying wing configuration MULDICON is equipped with various multifunctional control surfaces and flaps at the trailing edges of the airfoil including split flaps at the trailing edges of the wing tips. Contrary to more conventional aircraft configurations with horizontal and vertical stabilizers (e.g. tube-wing-tail), the combination of this control surface setup and the lack of a tail introduces strong couplings in the forces and moments resulting from each control surface deflection such that simple control allocation strategies (e.g. ailerons for roll, elevator for pitch, etc.) are suboptimal, if even practicable. The control surface allocation concept presented in this paper provides a multi-objective optimized solution for control system inputs that minimizes the control surface deflections as well as the resulting drag while fulfilling the hard constraints in terms of rotational acceleration commands. Furthermore, enabled by modern computational performance and efficient algorithm design, an online optimization was established capable of optimizing the allocation for each time step of a predefined maneuver simulation. This concept grants a controller maximum authority when integrated in the overall aircraft control system.