Control Surface Buffet Load Measurement

High performance aircraft experience repeated loads that can vary greatly both in frequency and amplitude depending on such factors as flight condition, maneuvering, and aeroelastic characteristics. Loads are monitored throughout the lifetime of military aircraft and used to estimate remaining structural life. Current airframe sensors are unsuitable for measuring unsteady aerodynamic buffet loads, which can be of significant amplitude and occur at frequencies that excite the aeroelastic dynamics, dramatically decreasing fatigue life. Systems Technology, Inc. and Moog, Inc. propose the Actuator Load Computing System (ALCS), an elegant and logistically attractive solution to this problem that employs onboard flight control actuators as load sensors capable of measuring both high frequency and quasi-steady loads. Since actuators directly measure the forces exerted on a control surface, these loads can be used as a robust reference gauge for what is occurring at the wing or tail surface as a whole. ALCS will leverage a novel frequency response identification technique, Narrowband Signature (NBS), which has proven to be successful with very short duration inputs. Since actuators are employed with all of the control surfaces, ALCS immediately extends itself for use with wings, vertical tails, and horizontal tails without the need for additional hardware.