In-flight evaluation of active sidestick parameters with respect to handling qualities for rate command and attitude command response types

Abstract

Previous evaluations performed during a cooperative research effort of the DLR Institute of Flight Systems in Germany and the U.S. Army Aeroflightdynamics Directorate (AFDD) showed a significant influence of the dynamic characteristics of active sidesticks on handling qualities of fly-by-wire helicopters and indicated a trend of optimal natural frequency and damping values leading to a first order response model. However this trend could not be validated due to restrictions of the used hardware. An upgrade of the firmware by the manufacturer to expand the allowable configuration envelope now enabled to configure the dynamic characteristics in a significantly enlarged parameter space, so that the response can be considered as a first order system with a time delay. A first flight test campaign at Braunschweig airport with the upgraded stick and with an Attitude Command configuration confirmed the trend to higher frequency and damping values. This paper presents the previous experiments, which were performed with active sidestick (DLR, ACT/FHS) and centerstick (AFDD/RASCAL) inceptors for Rate and Attitude Command response types, the results of a simulator study for RC and AC response types, and the results of the recently conducted campaign at DLR. In all experiments regression analyses were performed based on pilot ratings. These were collected for selected combinations of the dynamic parameters natural frequency and damping in simulation and inflight.