贝尔直升机德事隆

The Army requires rotorcraft drive systems to operate for 30 minutes following a loss of lubrication event to make an emergency landing. Coatings research has shown great promise for loss of lubrication, but coating repeatability and quality control is a primary hurdle. The Army partnered with Acree Technologies via a Small Business Innovation Research (SBIR) effort to develop an optimized gear coating for loss of lubrication. The research culminated in a system level transmission experiment that maintained flight relevant torque and speed through a helicopter gearbox without oil for three hours. The authors decided to shutdown the experiment for inspection after three hours of operation without oil because the temperature and vibration signals maintained steady state conditions without signs of failure. Teardown analysis showed the transmission gear surfaces did not scuff, scanning electron microscope analysis showed coating remained on the gear teeth, and cross-sectional SEM analysis showed a measurable coating thickness remaining on the gear teeth after three-hours of operation without oil.

A common-open data exchange standard for rotorcraft health and usage monitoring systems (CODEX-HUMS), SAE Aerospace Standard AS7140, was issued in September 2025. This standard provides a definition for the CODEX-HUMS open data format produced or used by an on-board or off-board system. The centerpiece of the standard is the data model. This paper describes how the two main data types, stream and batch data, are defined and modeled distinctly by AS7140. The batch data model, targeted at high-frequency, short-duration recorded data, features and delineates a "source", an "indicator", and a "status" element. The streaming data model, intended for lower-frequency, longer-duration HUMS data, covers events and parametric data. The data model is structured by defined data collections to describe the data collected or supporting metadata specifying details about the system or underlying data. In particular, there are definition-type entities and recorded data-type entities. This data model is designed to be flexible and efficient in order to accommodate existing HUMS as well as future HUMS development that support legacy and new rotorcraft platforms.

This paper focuses on system identification of a small, flying-wing UAS using the frequency response method. A flight test procedure is designed to address the unique challenges encountered when conducting system identification for a small flying-wing UAS with elevon controls. These challenges include increased susceptibility to atmospheric disturbances, limited yaw maneuverability, and visual line-of-sight safety requirements. Frequency sweeps are used as control inputs to excite the longitudinal and lateral-directional dynamics over a designed frequency range. Reduced-order transfer functions are first identified to gain initial information on key dynamics and to provide comparison with different models. Then, decoupled longitudinal and lateral-directional state space models are identified from flight data. The models are validated in the time-domain through comparison with doublet maneuver flight data, showing an excellent fit between the dynamic models and flight data. Finally, nondimensional stability and control derivatives and their confidence intervals are computed from the state space models for comparison with other modeling methods.

Mission engineering and reliability engineering are systems engineering disciplines used throughout product development and sustainment of a system. This paper highlights the commonalities and differences between the two disciplines of mission and reliability engineering. Mission engineering generally lacks standardization and precision of analysis due to less guidance documentation, uncertainty, and data limitations. Reliability analysis can improve the results of mission engineering analysis and thus, should be embedded within mission engineering. A recommendation is to include reliability as a component of the system Measures of Success (MOSs), Measures of Effectiveness (MOEs), and Measures of Performance (MOPs). Additional recommendations are centered around how reliability is represented in a mission engineering architecture and determining a logical approach to improve mission engineering decision capability and outcomes. Conclusions focus on an integrated approach to measuring system and mission effectiveness throughout system design and sustainment.

Active Inceptors in fly-by-wire aircraft offer new possibilities for control law reconfigurability, haptic cueing and system redundancies. Based on recent active inceptor research, new requirements for force-feel characteristics are proposed. Results are obtained from a simulation campaign investigating the influence of dynamic force-feel characteristics on the overall air-vehicle handling qualities (HQs). For this study, a rate-command type controller is evaluated in a pilot-in-the-loop simulation facility. Five mission task elements (MTEs) are flown with a range of force-feel characteristics (stick damping and stick natural frequency). Pilot comments on the active inceptors indicate clear differences and preferences between inceptor configurations. Generally, inceptor configurations with lower damping and higher natural frequency are preferred. Some minor differences, with respect to the MTEs flown, were noted and these may be explored in more detail in future research.