Flight Test Assessment of Scalable Low-Level Mission Task Elements

Abstract

Low-level flight, defined by high-speed operations near terrain, represents a significant challenge in military rotorcraft missions while providing strategic advantages, such as radar evasion and heightened surprise. Recent conflicts highlight the urgent need for advanced low-level flight capabilities in the design of new rotorcraft. The close proximity to ground obstacles, combined with the complexities of piloting, necessitates precise control and robust handling qualities to prevent accidents. However, existing handling quality standards, such as MIL-DTL-32742, reveal limitations in assessing low-level maneuvers. Given the diverse array of new rotorcraft designs, driven by initiatives like the U.S. Army’s Future Vertical Lift and NATO’s Next Generation Rotorcraft Capabilities, a customized handling qualities evaluation for each design is impractical. In response, a performance-driven strategy has been implemented, scaling Mission Task Elements to align with aircraft performance capabilities. This approach identifies handling quality gaps across the Operational Flight Envelope, concentrating on the aircraft’s effectiveness in achieving task success under varied conditions. Prior simulator studies validate the effectiveness of this method for assessing different configurations. This paper presents flight test results using DLR’s ACT/FHS research helicopter, confirming a set of scalable Mission Task Elements developed at DLR’s AVES and NASA’s VMS simulators. Pilots utilized a Head-Mounted Display for task cueing, eliminating the need for physical infrastructure. The Mission Task Elements proved suitable for evaluating the low-level handling qualities of the ACT/FHS. Although the provided Head-Mounted Display facilitated Handling Qualities evaluations, it encountered some hardware limitations. The scaling for different airspeeds met pilot expectations, and wind compensation functioned as anticipated, enhancing the independence of flight tests from environmental conditions. These findings lead to recommended updates for task descriptions and course cueing requirements, confirming desired performance tolerances.