This paper describes a joint research campaign conducted by the German Aerospace Center (DLR) and the National Research Council Canada (NRC) to explore methods and techniques to expose rotorcraft pilot-induced oscillations (PIOs) during flight testing. A flight test campaign was conducted at NRC using the Bell 205 experimental aircraft. Results show that, particularly for the lateral axis, ADS-33 tasks can be successfully applied to expose PIO tendencies. Novel subjective and objective criteria were used during the test campaign. PIO prediction boundaries of the objective phase-aggression criteria (PAC) detection algorithm were validated through results obtained. This was the first use of PAC with data recorded in-flight. To collect subjective feedback, the aircraft–pilot coupling (APC) scale was used. This was the first use of the novel scale in-flight and received favourable feedback from the evaluation pilot. Modifications to ADS-33 mission tasks were found to successfully improve the ability to consistently expose PIOs.

The National Research Council of Canada (NRC) Flight Research Laboratory (FRL) is advancing research under its Canadian Vertical Lift Autonomy Demonstration (CVLAD) program. Modular architecture hosted on the NRC Bell 412 Advanced Systems Research Aircraft (ASRA) enables pilot supervised autonomous flight via customized multi-display guidance-cueing. The capability exploits ASRA's full-authority control and safety systems, inertial-radar navigation, state-based digital supervision and is supported by open-source mission planning and digital-twin simulation. To date, ground interfacing (takeoff, landing) trials have been executed in proximity to NRC facilities in Ottawa (Canada) with rich test site variability (surfaces, slopes, obstacles, seasonal variations). Applied knowledge has been generated for autonomous mission execution in broad weather, low-speed, low-altitude, and low obstacle-standoff conditions critical in the vertical lift flight autonomy research domain.

The National Research Council of Canada and Université de Sherbrooke performed flight testing of an Actively Stabilized Slung Load on the NRC Bell 206 Research Aircraft. Hover, Attitude Capture, NRC designed Lateral Precision Hover, and Frequency Sweep mission tasks were performed for Bare Airframe, Passive Water-Filled Barrel and Active Slung Load configurations. Load Mass Ratios of 0.12 with pendulum modes of 1.3 rad/sec were identified for both configurations. Time domain response indicated that both loads remained controllable under excitation by pilot gain, winds, and helicopter-load mode coalescence. Frequency domain analyses confirmed pilot comments indicating HQR-4 handling qualities ratings for bare airframe and stable load behaviors. This degraded to HQR-5 for task execution with load oscillation effects rated at pilot induced oscillation tendency of PIO/T-4. Barrel load HQR degradation related to load inertial and surface area drag effects versus active tether feedback and roll-pitch actuation disharmony of the Active load. Though not optimized, this load’s swing behavior (consistent period and rate) can aid in management of aircraft rate response and pilot compensation. Overall, comparable passive and active test results indicate potential for magneto-rheological actuation to improve slung load mission task performance.

The National Research Council Canada (NRC) and Defence Research and Development Canada (DRDC) have developed modelling and simulation tools intended to de-risk, increase efficiency and standardize Ship Helicopter Operating Limitations (SHOL) testing through the use of modelling and simulation. The Integrated Reality In-Flight Simulation (IRIS) tool is a novel simulator platform where an evaluation pilot (EP) flies a variable stability aircraft while wearing a virtual reality (VR) headset with many elements of the shipboard environment carefully reproduced including the injection of real time turbulence models established from wind tunnel trials. The turbulence and other environmental effects on the aircraft motion are coupled directly into the aircraft in real time, thereby retaining accurate critical proprioceptive and vestibular cueing for the pilot. NRC has recently completed flight test evaluations of the prototype concept. Pilot comments from initial testing indicated that the system required little adaptation, presented no noticeable lag, no attributable propensity to cause motion sickness, and that the turbulence felt realistic.The testing indicated that typical VR deficiencies such as resolution and field of view are not as impactful during close-in shipboard operations, making this application very effective.

Shipboard helicopter operations are much more challenging and complex than land-based operations due to many factors associated with the presence of the ship. To determine those conditions in which safe operations may occur, a First of Class Flight Trial (FOCFT) is conducted for every new ship–helicopter pair. This trial results in a Ship–Helicopter Operating Limit (SHOL) envelope that is used to document operational limits for regular operations. Conducting a FOCFT is a, expensive, and time-consuming task that requires testing all aspects of operations. Modeling and simulation efforts to support shipboard helicopter operations have been ongoing internationally for many years with the intention of de-risking FOCFT and introducing efficiency into the testing process. Canada will be accepting several new ship classes into its fleet over the next two decades. In support of FOCFT for these new ships, modeling and simulation tools are being developed by the National Research Council (NRC) Canada and Defence Research and Development Canada (DRDC) and significant advancements have occurred in the past decade. As part of this work, NRC and DRDC now use a framework and analysis approach that is intended to standardize SHOL testing with the use of modeling and simulation. This paper introduces that framework and gives details on the modeling and simulation tools that can be used to reduce risk and increase efficiency for Canada’s upcoming FOCFTs.