Alleviation of Atmospheric Flow Disturbance Effects on Aircraft Response

Abstract

Since the air is the element of flying, air motion is an essential parameter in aeronautics. This paper gives an overview of the results of offline simulations, full flight simulator studies and results from in-flight simulation experiments to investigate the alleviation of atmospheric flow disturbance effects on aircraft response. The studies are part of the DLR project “Weather and Flying” aiming at the improvement of flight operation and safety in adverse weather conditions. Gusts and turbulence strongly affect the passenger comfort and the safety of aircraft. Another important air mass motion adversely affecting aircraft operation is wake vortex. This well known hazardous flow field is produced by aircraft themselves. Active control technology can be applied to alleviate these flow disturbance effects on aircraft motion in case of an encounter. DLR is developing the Integrated Ride and Loads Improvement System (IRLIS) to cope with the phenomena mentioned above. It can be shown that the aircraft response encountering natural and aircraftinduced (wake vortex) turbulence can be improved significantly by a feed-forward controller. Based on a forward-looking sensor, the controller generates aerodynamic surface deflections to counter the vertical accelerations generated by gusts as well as the roll response induced by lift variations along the wing span. For this investigation it is assumed that a LIDAR sensor is able to provide the necessary flow field information ahead of the a/c. In addition to the standard control surfaces (elevator, aileron and rudder) the a/c is supposed to be equipped with special flaps for independent direct lift control. Simulation results show a clear tendency that IRLIS can significantly improve the situation in adverse atmospheric flow fields.