Distributed Active Load Control System

Abstract

The evolution of air transport towards a sustainable and greener future is a major driver for technology improvements for next generation aircraft. One essential objective here is to decrease the energy consumption per seat-mile, i.e. to increase the aerodynamic efficiency. This is especially relevant in order to make future SAF-fuelled propulsion, hybrid or electric propulsion affordable. With the aim of increasing the aerodynamic efficiency of commercial aircraft, upcoming aircraft designs will incorporate wings with large aspect ratios and spans, incorporating thin wing chords and lightweight structures. This makes the wings more flexible and reacts to external forces with large elastic deformations, while natural frequencies will be overlapping with natural frequencies of rigid body aircraft dynamics. In order to reduce the resulting structural loads, primarily on the wing root, active load alleviation systems are used that make use of the existing control surfaces on the wing. The performance of state-of-the-art load alleviation systems is limited by their sensing capabilities and their centralized architecture. The paper introduces a more effective approach and discusses a related distributed system architecture. The system allows for reduction of loads on the wing and tail structures utilizing remotely arranged accelerometers integrated in remote electronic units (REU). Each of the REUs controls one or more flight control actuators and implements local active load control loops. This enables reaction on the measured acceleration directly at the location where it was sensed. This approach not only provides means for classic gust load alleviation, but also could effectively suppress wing flutter.