The European ACT Programme: A Collaborative Approach to Handling Qualities Evaluation and Control Law Design

A European collaborative programme in Active Control Technology is currently underway to define a common approach to certain aspects of ACT helicopter flight control systems. This paper concentrates on the work of the Handling Qualities team comprising participants from ECD, ECF, WHL, DRA, DLR and ONERA. The detailed preparatory work undertaken during the first year is briefly reviewed, followed by a description of the ground and airborne simulation activities to support both handling qualities and control law design. A common set of Mission Task Elements (MTE’s) were used, two for hover and low speed, and two for high speed, concentrating initially on the pitch and roll axes. These were specifically chosen to address a range of handling parameters, which could be related to handling qualities criteria. A series of questionnaires was developed for the trials, accompanied by a "Glossary of Terms" providing a standard set of definitions. Simulation activities have included a comparison of the simulators at DRA Bedford, ECF Marignane, ECD Ottobrunn, together with a handling qualities trial at DRA Bedford. ECF and ECD/DLR have performed simulation trials using specific non-linear models prior to the flight evaluation of the control laws (Rate Command and Altitude Command) developed under the programme. WHL have developed Translational Rate Command (TRC) laws, initially for ground simulation, which are designed to operate throughout the flight envelope. Flight trials have been conducted to gather handling qualities data and a first evaluation of rate command laws has been performed using the standard set of MTE’s, with both the Dauphin 6001 and DLR BO105-S3. Results are shown which illustrate the use of both ground and airborne simulation in the design and development of active control laws.