Piloted Simulation Evaluation of Tracking Mission Task Elements for the Assessment of High-Speed Handling Qualities

Abstract

Updates to the military rotorcraft handling qualities specification are currently being considered that address the high-speed flight regime envisioned for the Future Vertical Lift platform of the U. S. Army. A team that features industry and academia has developed and evaluated a set of mission task elements (MTEs) that are defined to address vertical takeoff and landing (VTOL) high-speed handling qualities. Following the mission-oriented approach upon which ADS-33E-PRF is based, the MTEs were designed to meet different levels of precision and aggressiveness. Tracking MTEs based on a sum-of-sines (SOS) command signal were defined for precision, aggressive, and precision, nonaggressive applications. The command signals were derived from fixed-wing analogs that have long been used to evaluate aircraft handling qualities. While the precision, aggressive SOS tracking tasks, the primary subject of this paper, are surrogates for air-to-air tracking and nap-of-the-earth tracking, the known forcing function allows for complete open- and closed-loop pilot—vehicle system identification. The MTE objectives, descriptions, and performance criteria were assessed and refined via several checkout piloted simulation sessions. Formal evaluations were then conducted by Army test pilots at four simulator facilities, each featuring a unique high-speed platform including a generic winged-compound helicopter, two tiltrotor configurations, and a compound helicopter with coaxial rotors. To aid in the MTE evaluation process, baseline VTOL configurations were varied to achieve different handling qualities levels. Quantitative measures based on task performance and qualitative measures based on pilot ratings, comments, and debrief questionnaires were used to assess MTE effectiveness. The piloted simulation results demonstrated that the SOS tracking MTEs provided an effective means to discern precision, aggressive handling qualities in high-speed flight.