Pilot Workload and Performance Assessment for a Coaxial-Compound Helicopter and Tiltrotor During Aggressive Approach

Abstract

The Combat Capability Development Command (DEVCOM) Aviation & Missile Center (AvMC) Technology Development Directorate (TDD) has developed high-fidelity flight-dynamics models of generic Future Vertical Lift (FVL) configurations to provide the government with independent control-system design, handling-qualities analysis, and simulation research capabilities for advanced high-speed rotorcraft. Two of these generic models are a lift offset coaxial helicopter with compound thrust provided through a pusher propeller (herein referred to as Coaxial) and Tiltrotor aircraft. This paper examines a study where an aggressive visual approach maneuver using the two aircraft models was flown and evaluated at the NASA Ames Vertical Motion Simulator (VMS) facility. Sixteen pilots participated in the experiment, spanning the U.S. military branches and a wide range of platform and mission experience. Based on observed aircraft response and workload analysis, this paper proposes a pilot control model for the high-speed approach. Workload and performance comparisons between the two generic FVL aircraft models without the additional outer-loop augmentation for the high-speed approach are presented, corroborating the model’s predictions, and supporting the case for augmenting Tiltrotor flight path control through coordinated nacelle angle and rotor thrust. A single-axis workload estimation technique previously developed by the author, called the Spare Capacity OPerations Estimator (SCOPE), is extended to multiple inputs for the current work and compared with the pilot workload ratings that were recorded in real-time during each approach.