Control Surface Efficiency Analysis and Utilization of an Elastic Airplane for Maneuver Loads Alleviation

摘要

Flexible effect and multi control surfaces bring new challenges to maneuver load analysis and alleviation for modern aircraft. The load alleviation ability evaluation inclusion of flexibility effect becomes the key of control surface utility. Aeroservoelasticity state-space model of flexible aircraft is deduced based on the modal method and the rational function approximation of unsteady aerodynamics. Rigid-body and elastic modes are included in generalized coordinates. The mode displacement method is used to calculate incremental airplane dynamic loads. The control surface zone is divided into a number of elemental chordwise strips and every one is used as one control surface. The alleviation efficiency is assessed one by one for all control surfaces. It is found that the efficient deflection is down for inboard control surfaces and up for outboard ones and the alleviation percent per unit area of outboard zones is higher than inboard ones. Finally an alleviation scheme is carried out by use of an inboard control surface and an outboard one. The result indicates the load peak value and steady-state value both decline and the load oscillation is suppressed. The assessment method can provide useful reference and a basis for the control surface utilization and control scheme design.