HACT Flight Control System (HFCS) Control Law Overview

This paper overviews the control laws used in the Helicopter Active Control Technology (HACT) Flight Control System (HFCS). The HFCS control laws are designed to surmount fundamental technology barriers identified by the HACT program. These barriers are reviewed along with the HACT program technical approach to address them. The HFCS adds Regime Recognition, Task Tailored Control Laws, and Carefree Maneuvering algorithms to a full authority digital flight control system core that is comprised of the best features of the flight controls used in the Rotorcraft Pilot’s Associate (RPA) program and the RAH-66 Comanche control laws. Working definitions of Regime Recognition, Task Tailored Control Laws, and Carefree Maneuvering are presented. Features and functions considered in preliminary and detailed design are summarized along with the Quality Function Deployment (QFD) approach taken to downselect the HFCS functional capabilities to be demonstrated in flight test and piloted simulation. The evaluation scenarios and metrics used to assess the handling qualities, usable agility, safety, and structural usage benefits offered by the HFCS are described. Piloted simulation and high order linear analysis data are presented to quantify the improvement offered by the HFCS over the HACT program Baseline control laws. This data is used to assess United States (U.S.) progress toward achieving the goals, objectives, and payoffs identified in the Department of Defense (DoD) Rotary Wing Vehicle (RWV) Technology Development Approach (TDA). Potential implementations of HFCS functional capabilities in legacy aircraft equipped with Partial Authority Flight Control Augmentation (PAFCA) systems are identified.