bluuebunny/crossref_metadata_2025 huggingface dataset:
Towards the Criteria of Genuine Human Enhancement
Authors: Kochetkova Tatjana
Published: October 2024

This chapter explores the long-term implications of converging technologies and their significance for human performance enhancement. First, based on an analysis of the human condition, I consider what types of augmentations constitute a true improvement—what is a genuine human enhancement, as opposed to inadvisable or controversial augmentation? As a criterion for differentiation, I propose a set of human qualities that should be retained in any enhancement. Although this set is incomplete, adherence to these qualities will determine whether such transformations elevate humanity to a new level or potentially destroy it, as some bio-conservatives argue. Secondly, I focus on convergent technologies and examine the possibilities they offer for human performance enhancement. I consider specific types of enhancement and reflect on t several scenarios for the human future based on converging technologies. In conclusion, I discuss the risks and sociopolitical constraints of human enhancement, along with some practical considerations about setting limits.
Human-Machine Collaboration
Authors: Saluja Aparna , Mongia Anupal
Published: October 2024

Robotic assistance is gradually becoming the new norm in the current workplace due to human-robot partnership that enhances human orientations by machine intelligence. This integration facilities the application of automation, artificial intelligent, advanced robotics in various sectors in relation to productivity, efficiency and even safety. Intelligent systems and collaborative robots are integrated into daily work, thus the execution of complex jobs that used to be labor and time consuming become automated, letting human workers to focus on critical and creative work. The former augments the operational effectiveness while the latter fosters more of creative, flexible, and less rigid environment in an organization. Closely associated with the use of robots for repetitive and dangerous undertakings, human positions transform, fuelling immense progress in job definition and work organization.
The Evolution of Human Resources in the Age of Technology
Authors: Subrahmanyam Satya
Published: October 2024

The chapter, “The Evolution of Human Resources in the Age of Technology”, explores the profound impact of technological advancements on HR practices. Beginning with a historical overview, from early mechanization to the digital revolution, the chapter traces the evolution of HRIS and ERP systems. It investigates modern tools such as HCM software, AI-driven recruitment, and cloud computing, emphasizing their transformative effects on recruitment, workforce planning, and employee management. The chapter also examines emerging frontiers like genomics and transhumanism, discussing their potential to personalize health and optimize talent while navigating ethical and privacy considerations. Ultimately, it advocates for proactive adaptation of HR policies and fostering an innovative organizational culture to embrace the future of technology in HR.
Revolutionizing HR Communication
Authors: Devgan Monalisa , Rani Chandni
Published: October 2024

The landscape of Human Resources (HR) communication has undergone a profound transformation, evolving from traditional methods to the integration of cutting-edge AI chatbots. This chapter examines the transition from traditional methods, such as face-to-face meetings, printed notes, and bulletin boards, to the digital revolution. This study investigates the impact of AI chatbots on HR communication by exploring two key questions: First, how do AI chatbots improve the efficiency and effectiveness of HR communication when compared to traditional methods? Second, what are the potential challenges associated with integrating AI chatbots into HR communication processes? The findings aim to provide insights into the benefits and limitations of adopting AI technology in HR. This study is based on qualitative data, drawing from existing conceptual papers, peer-reviewed articles, and websites. This chapter investigates the advantages of AI chatbots, while also addressing concerns about data privacy, security, and the importance of preserving a human touch.
Effects of Vehicle Weight and True Versus Indicated Airspeed on BVI Noise During Steady Descending Flight
Authors:   US Army, Stephenson James ,   NASA Langley Research Center, Greenwood Eric
Published: October 2024

Blade-vortex interaction noise measurements are analyzed for an AS350B helicopter operated at 7000 ft elevation above sea level. Blade-vortex interaction (BVI) noise from four, 6 degree descent conditions are investigated with descents flown at 80 knot true and indicated airspeed, as well as 4400 and 3915 pound take-off weights. BVI noise is extracted from the acquired acoustic signals by way of a previously developed time-frequency analysis technique. The BVI extraction technique is shown to provide a better localization of BVI noise, compared to the standard Fourier transform integration method. Using this technique, it was discovered that large changes in BVI noise amplitude occurred due to changes in vehicle gross weight. Changes in BVI noise amplitude were too large to be due solely to changes in the vortex strength caused by varying vehicle weight. Instead, it is suggested that vehicle weight modifies the tip-path-plane angle of attack, as well as induced inflow, resulting in large variations of BVI noise. It was also shown that defining flight conditions by true airspeed, rather than indicated airspeed, provides more consistent BVI noise signals.
Improving the Performance and Flexibility of Grid-Based Vorticity-Velocity Solvers for General Rotorcraft Flow Analysis
Authors:   Continuum Dynamics Inc, Whitehouse Glen , Silbaugh Benjamin , Boschitsch Alexander
Published: October 2024

Accurate flow prediction is essential to rotorcraft development, and in recent years hybrid CFD methods, where a body-fitted CFD solver is coupled to a vortex method, have been developed to address the cost and vorticity preservation issues associated with full-unsteady rotorcraft simulation. Recent work developing the serial version of the VorTran-M2 grid-based vorticity-velocity method for application to hybrid CFD analysis of rotorcraft addressed critical formulational issues such as maintaining a solenoidal vorticity field, general multi-resolution adaptive gridding, consistent and efficient implementation of the viscous terms and computation of the unsteady pressure contribution. This paper describes the development of a simplified CFD/VorTran-M2 coupling interface and an efficient parallel implementation of this method, with particular emphasis on dynamic domain decomposition. VorTran-M2, an adaptive grid solver, only has cells in regions of significant vorticity. This compact grid representation permits very low cell-counts, but adds significant complexity when developing scalable parallel implementations. Adaptive grid methods are becoming more common in the CFD community, though VorTran-M2 is a particularly extreme example since predictions start with zero cells, rather than from a coarse grid. This lack of initial grid to form the basis of initial domain decomposition combined with increasing problem size and parallelizing the Biot-Savart solution of the Poisson equation, makes efficient scaling challenging and something that is only now being demonstrated.
Numerical Investigation of the Unsteady Loading of a Model Rotor in Hover
Authors:   Arizona State University, Hoffman Justin , Wells Valana
Published: October 2024

The paper describes a numerical study performed using the NASA OVERFLOW code to investigate the unsteady loading components of a rotor in hover. The nominal conditions investigated followed the model rotor test data of Caradonna and Tung, (Ref. 1). Variations to the baseline case included a single-bladed rotor and with and without a central hub. An additional study simulated the experimental setup of Tangler, Wohlfield, and Miley. (Ref. 2) Multiple simulations of the Caradonna and Tung model demonstrated that higher order differencing, together with increasing wake grid resolution, resulted in marked increase in the magnitude of the unsteady components in the rotor thrust convergence history. This was accompananied by a marked increase in the detail of resolution of the rotor wake structure and the appearance of tip vortex instabilities. The simulation of test configurations from the report by Tangler et al. were used to help validate that the higher fidelity model were accurately resolving the nature of the wake structure, especially the presence of helical vortex instabilities. It is found that under the given simulation parameters the tip vortex instability is present but not consistent with experiment. Fourier analysis showed two dominant frequency components of this unsteady loading for cases using adaptive mesh refinement and one dominant frequency in cases using fixed grid systems. Findings suggest that the lower frequency component is due to unsteady wake dynamics near the rotor hub and are unrelated to unsteady vortex dynamics while the higher frequency component is spurious and is demonstrated to be due to the adaptive mesh refinement routine used by the flow solver. Additional numerical experiments were completed to investigate the observed unsteady aerodynamics of a single bladed rotor case which may also be compared to the instability modes predicted for this helical vortex system by Widnall. (Ref. 3) It is postulated that under certain conditions this spurious frequency component due to adaptive mesh refinement may cause an nonphysicial aerodynamic forcing on the rotor system which can potentially pollute numerical simulations of any unsteady phenomenon such as those involving blade dynamics, deformation (Ref. 4), or result in inaccurate noise predictions (Ref. 5) (Ref. 6) when coupling results with aeroacoustic codes such as WOPWOP. (Ref. 7) There is an additional subharmonic signature in the CT convergence history, the source of which is not yet identified. Hanning windowing was used in data processing in attempt to remove this from the single revolution FFT.
Numerical Investigation of Three-Dimensional Effects on Deep Dynamic Stall Experiments
Authors:   Politecnico di Milano, Nilifard Reza , Zanotti Alex , Gibertini Giuseppe , Guardone Alberto , Quaranta Giuseppe
Published: October 2024

Computational Fluid Dynamics simulations were carried out in two and three spatial dimensions to assess the suitability of numerical models for the simulation of deep dynamic stall experiments. The numerical results were compared to pressure measurements and Particle Image Velocimetry flow surveys carried out on a pitching NACA 23012 airfoil. The pitching cycles considered as test cases reproduce the deep dynamic stall condition for a helicopter rotor retreating blade section. The comparison of the airloads curves and of the pressure distribution over the airfoil surface shows that a three-dimensional numerical model can better reproduce the experimental airloads behaviour during the pitching cycles. The three-dimensional simulation results show also a better reproduction of the vortical structures observed by PIV. The solution of the simulation obtained over a three-dimensional grid independent from the wind tunnel geometry highlighted the relevance of three-dimensional effects on the flow field that are mainly due to the intrinsic three-dimensional nature of dynamic stall.
Effects of Reynolds Number and Advance Ratio on the Drag of a Model Helicopter Rotor Hub
Authors:   The Pennsylvania State University, Reich David , Willits Steven , Schmitz Sven
Published: October 2024

A 1:17 scale model of a notional rotor hub of a large helicopter was tested in the Pennsylvania State University (PSU) Applied Research Laboratory (ARL) 12-inch test section water tunnel. Objectives of the experiment were to quantify effects of Reynolds number, advance ratio, and hub geometry configuration on the drag and shed wake of the rotor hub. A range of flow conditions were tested, with hub diameter-based Reynolds numbers ranging from 1.06×10⁵ to 2.62×10⁶ and advance ratios ranging from 0.2 to 0.4, as well as non-rotating cases. Three hub geometry configurations were tested with various combinations of components including fairing, blade stubs, spiders, scissors, swashplate, and pitch links. Primary measurements were steady and unsteady hub drag and Particle Image Velocimetry at two downstream locations. Results include time-averaged, phase-averaged, spectral analysis of the unsteady drag, and wake velocity. A strong dependence of steady and unsteady drag on Reynolds number and advance ratio was noted, eluding to the importance of adequate Reynolds scaling for model helicopter rotor hub tests.
Cheeseman Award Paper: Consideration Of Structural Constraints In Passive Rotor Blade Design For Improved Performance
Authors:   US Army AFDD, Lim Joon
Published: October 2024

This design study applied parameterization to rotor blade for improved performance. In the design, parametric equations were used to represent blade planform changes over the existing rotor blade model. Design variables included blade twist, sweep, dihedral, and the radial control point. Updates to the blade structural properties with changes in the design variables allowed accurate evaluation of performance objectives and realistic structural constraints - blade stability, steady moments (flap bending, chord bending, and torsion), and the high g maneuver pitch link loads. Performance improvement was demonstrated with multiple parametric designs. Using a parametric design with the advanced airfoils, the predicted power reduction was 1.0% in hover, 10.0% at μ=0.30, and 17.0% at μ=0.40 relative to the baseline UH-60A rotor, but these were obtained with a 35% increase in the steady chord bending moment at μ=0.30 and a 20% increase in the half peak-to-peak pitch link load during the UH-60A UTTAS maneuver. Low vibration was maintained for this design. More rigorous design efforts, such as chord tapering and/or structural redesign of the blade cross section, would enlarge the feasible design space and likely provide significant performance improvement.
Minimum Loss Load and Twist Distributions for Coaxial Helicopter Rotors in Hover
Authors:   Duke University, Giovanetti Eli , Hall Kenneth
Published: October 2024

We present an approach for determining the optimal (minimum power) torque-balanced coaxial hovering rotor using Blade Element Momentum Theory including swirl. We quantify the effects of the swirl component of induced velocity on performance, optimal induced wash distribution, and optimal blade twist and chord. The optimization accounts for the presence of a finite number of blades using the Prandtl tip loss factor, the effect of profile drag using experimentally or computationally determined drag polars, and the mutual interference between the two rotors using an empirically determined influence coefficient method. We show that including the swirl component of induced wash decreases the optimal figure of merit and has a larger impact at higher disk loadings, as expected. However, at the disk loadings typically found on helicopters, the effect of swirl is relatively small, particularly compared to other physical effects such as mutual interference or tip losses. Additionally, accounting for swirl affects the optimal rotor design near the root of the blade, at locations that would often be part of the root cutout of a realistic rotor.
Multi-point Time-dependent Aero-elastic Adjoint-based Aerodynamic Shape Optimization of Helicopter Rotors
Authors:   University of Wyoming, Mishra Asitav , Mavriplis Dimitri , Sitaraman Jay
Published: October 2024

A formulation for sensitivity analysis of fully coupled time-dependent aeroelastic problems for multipoint design optimization is given in this paper. Both forward sensitivity and adjoint sensitivity formulations are derived that correspond to analogues of the non-linear aeroelastic analysis problem. Both sensitivity analysis formulations make use of the same iterative disciplinary solution techniques used for analysis, and make use of an analogous coupling strategy. The fully coupled aeroelastic analysis formulation is first verified to effectively perform performance predictions of a four bladed HART2 rotor in forward flight started impulsively from rest. Upon successful verification of the fully coupled adjoint formulation, it is used to perform trim and aerodynamic shape design optimization for helicopter rotors in forward flight conditions. The formulation is further extended to perform multi-point blade shape optimization in two simultaneous design points, namely, hover and a forward flight condition.
Comparison of Probabilistic and Fuzzy Multi-Attribute Decision Making Methods for Capturing Uncertainty in Concept Selection
Authors:   Georgia Institute of Technology, Patterson Frank , Schrage Daniel
Published: October 2024

An evolving set of modern conceptual design methods seek to explore the feasibility of a new generation of systems, with new capabilities, to accomplish missions that conventional vehicles cannot be empirically redesigned to perform. These methods attempt to provide a more complete understanding of a concept's design space, and can accurately forecast a design's feasibility in the face of huge uncertainties at the conceptual stage. Modern Multi-Attribute Decision Making (MADM) techniques are evolving to help designers narrow large sets of potential concept architectures while accounting for the uncertainty inherent in early requirements and pre-modeling, expert based assessment. Here, several under-utilized fuzzy MADM methods are introduced and compared to their more recently proposed and utilized probabilistic counterparts. Probabilistic and fuzzy versions of the popular Analytical Hierarchy Process (AHP) and Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) methods are explored, and their results are applied to the selection of a conceptual system architecture for DARPA's VTOL X-Plane program. Various means for visualizing and comparing the resulting ranks and their related uncertainty are discussed.
Conceptual Design of Environmentally Friendly Rotorcraft - A Comparison of NASA and ONERA Approaches
Authors:   NASA Ames Research Center, Russell Carl ,   ONERA, Basset Pierre-Marie
Published: October 2024

In 2011, a task was initiated under the US-French Project Agreement on rotorcraft studies to collaborate on design methodologies for environmentally friendly rotorcraft. This paper summarizes the efforts of that collaboration. The French and US aerospace agencies, ONERA and NASA, have their own software toolsets and approaches to rotorcraft design. The first step of this research effort was to understand how rotorcraft impact the environment, with the initial focus on air pollution. Second, similar baseline helicopters were developed for a passenger transport mission, using NASA and ONERA rotorcraft design software tools. Comparisons were made between the designs generated by the two tools. Finally, rotorcraft designs were generated targeting reduced environmental impact. The results show that a rotorcraft design that targets reduced environmental impact can be significantly different than one that targets traditional cost drivers, such as fuel burn and empty weight.
A Toolbox for Rotorcraft Preliminary Design
Authors:   German Aerospace Center (DLR), Lier Max , Krenik Alex , Kunze Philipp , Kohlgrüber Dieter , Lützenburger Marius , Schwinn Dominik
Published: October 2024

The German Aerospace Center (DLR) developed a toolbox, which is able to reflect the conceptual and preliminary design process of rotorcraft configuration. Such a toolbox is a valuable aid for the design engineer and can be used for the assessment of new technologies with regard to the overall configuration. This toolbox is currently extended to model novel rotorcraft configurations. Automated optimization procedures will be added in the future as well. This paper describes the toolbox layout and data management as well as the various individual tools developed at DLR in detail. Exemplary results of design tasks are given.
Comprehensive Rotorcraft Analysis for Preliminary Design and Optimization
Authors:   ORISE, Avera Michael ,   US Army Research Lab, Kang Hao , Singh Rajneesh
Published: October 2024

A numerical study is conducted to utilize comprehensive rotorcraft analysis code to advanced rotor technologies such as Individual Blade Control for vehicle performance and sizing tasks common to preliminary design methods. A code wrapper was developed for Advanced Rotorcraft Technology Inc's RCAS code with NASA Glenn's open source OpenMDAO, a MDAO tool written in python scripting language. Two cases are presented to demonstrate the utility of the RCAS wrapper. The first case utilizes the RCAS wrapper to run multiple concurrent RCAS trim analyses on a UH-60A rotor for an array of advance ratios and blade loading conditions. The second case integrates the RCAS wrapper with a previously developed OpenMDAO wrapper for NDARC, a preliminary design tool, into a single analysis environment to calculate these same empirical power factors for a UH-60A rotor with an IBC system. The time savings demonstrated by the OpenMDAO analysis environment successfully allows comprehensive analysis to be used to generate on-the-fly analytical characterizations of an IBC system for use in a preliminary design code to assess it's performance impact. Suggestions for future work are made to further exercise the capabilities of this environment and to further integrate it into the preliminary design process.
Joint Common Architecture Demonstration Lessons Learned - Sikorsky/Boeing Perspective
Authors:   US Army, Wigginton Scott ,   The Boeing Company, DuBois Thomas ,   Sikorsky Aircraft, Kinahan Bill , Bereson Andrew
Published: October 2024

The Joint Common Architecture (JCA) Demonstration project exercised the Future Airborne Capability Environment (FACE™) Technical Standard and tools as well as the JCA model-driven approach to gather lessons learned and mature the approaches. Sikorsky/Boeing was selected as one of two vendors to develop a software component and its reusable test component to be integrated onto multiple undisclosed Operating Environments (OEs). The model-driven approach was partially successful but required significantly more detail than was initially provided by the Government. The FACE Standard was effective in enabling portability of the software and the test component onto each OE. FACE Verification was pursued and process improvements were identified. Application of the FACE Transport Services did not introduce timing latencies that would impact safety-critical applications. The quality of the lessons learned throughout this effort highlight the importance of demonstrations involving independent teams in order to mature these approaches.
Investigation of the Rotor Stall Boundary Using CFD/CSD Analysis for Passive Rotor Systems
Authors:   UTRC, Wake Brian ,   Sikorsky Aircraft Corp, Makinen Stephen , Reimann C. , Min Byung-Young , Reed Edward
Published: October 2024

Coupled computational fluid dynamics and structural dynamics methods offer the potential to significantly improve the ability to predict helicopter rotor performance and unsteady loads. Accurate performance and unsteady loads predictions are necessary for the optimal design of the rotor dynamic components and blades. High-thrust and extreme maneuvering conditions, which are important for design, are especially challenging for the analysis tools to predict accurately due to dynamic stall and its strong coupling with the structural dynamics. Evaluation of complex features such as highly 3D tip shapes, composite structures, and active devices further increases the need for accurate analysis tools. Fundamentally, the CFD/CSD methods capture more relevant physics than the comprehensive analyses using lifting-line, but require significantly more computational time. This paper investigates the use of OVERFLOW/DYMORE to capture the rotor stall boundary and rotor efficiency (L/De). The results are compared with comprehensive analysis (RCAS) and experimental data for a representative rotor. A few variations of these analyses were employed to investigate numerical and physical effects such as grid refinement, and laminar-turbulent transition. The performance results are presented in terms of L/De, which historically has been very difficult to predict based on first principles. Preliminary results are discussed for moving flaps at moderate-thrust conditions. Several potential quantities to identify the rotor stall boundary are examined and discussed; of the quantities considered, the steep fall-off in L/De appears to be the best measure of the rotor stall boundary. Transition modeling and grid refinement improved the correlation of L/De with experimental data; it is believed that further refinements are needed to improve high Mach-number drag.
Coupled CFD/CSD Analysis of an Active-Twist Rotor in a Wind Tunnel with Experimental Validation
Authors:   NASA, Massey Steven ,   US Army, Kreshock Andrew , Sekula Martin
Published: October 2024

An unsteady Reynolds averaged Navier-Stokes analysis loosely coupled with a comprehensive rotorcraft code is presented for a second-generation active-twist rotor. High fidelity Navier-Stokes results for three configurations: an isolated rotor, a rotor with fuselage, and a rotor with fuselage mounted in a wind tunnel, are compared to lifting-line theory based comprehensive rotorcraft code calculations and wind tunnel data. Results indicate that CFD/CSD predictions of flapwise bending moments are in good agreement with wind tunnel measurements for configurations with a fuselage, and that modeling the wind tunnel environment does not significantly enhance computed results. Actuated rotor results for the rotor with fuselage configuration are also validated for predictions of vibratory blade loads and fixed-system vibratory loads. Varying levels of agreement with wind tunnel measurements are observed for blade vibratory loads, depending on the load component (flap, lag, or torsion) and the harmonic being examined. Predicted trends in fixed-system vibratory loads are in good agreement with wind tunnel measurements.
Evaluation of the Second Transport Rotorcraft Airframe Crash Testbed (TRACT 2) Full Scale Crash Test
Authors:   NASA Langley Research Center, Annett Martin , Littell Justin
Published: October 2024

Two Transport Rotorcraft Airframe Crash Testbed (TRACT) full-scale tests were performed at NASA Langley Research Center's Landing and Impact Research Facility in 2013 and 2014. Two CH-46E airframes were impacted at 33-ft/s forward and 25-ft/s vertical combined velocities onto soft soil, which represents a severe, but potentially survivable impact scenario. TRACT 1 provided a baseline set of responses, while TRACT 2 included retrofits with composite subfloors and other crash system improvements based on TRACT 1. For TRACT 2, a total of 18 unique experiments were conducted to evaluate ATD responses, seat and restraint performance, cargo restraint effectiveness, patient litter behavior, and activation of emergency locator transmitters and crash sensors. Combinations of Hybrid II, Hybrid III, and ES-2 Anthropomorphic Test Devices (ATDs) were placed in forward and side facing seats and occupant results were compared against injury criteria. The structural response of the airframe was assessed based on accelerometers located throughout the airframe and using three-dimensional photogrammetric techniques. Analysis of the photogrammetric data indicated regions of maximum deflection and permanent deformation. The response of TRACT 2 was noticeably different in the longitudinal direction due to changes in the cabin configuration and soil surface, with higher acceleration and damage occurring in the cabin. Loads from ATDs in energy absorbing seats and restraints were within injury limits. Severe injury was likely for ATDs in forward facing passenger seats.
Selectable Profile Energy Absorber System for Rotorcraft Troop Seats
Authors:   Safe Inc., Desjardins Stanley ,   Labun LLC, Labun Lance ,   US Army, Woodhouse Jin , Belden Leda
Published: October 2024

A selectable profile energy absorber (SPEA) system was developed for crashworthy helicopter troop seats. This system combines information from an on-seat sensor and the aircraft data bus to tailor the energy absorber force profile not only to the weight of the occupant, but also to the predicted crash severity. The development testing was conducted using a vertical seat orientation on a drop tower under the U.S. Army Aircrew Survivability Technologies Project. This second Transport Rotorcraft Airframe Crash Testbed (TRACT 2) presented the opportunity for Safe, Inc. to independently test the SPEA system on a troop seat in an airframe undergoing a combined vertical and forward crash impact. The SPEA system is designed to use the lowest possible EA force profile considering the available stroking distance. Despite a component failure, the SPEA delivered a peak lumbar force of 572 lbf in a 50th-percentile male ATD and stroked 10 of an available 12 inches.
Performance Evaluation of Crash-Recording Technologies in a Full-Scale CH-46 Airframe Crash Test
Authors:   NAWCAD PAX RIVER, Bark Lindley , Willis Robert
Published: October 2024

Two CH-46 airframe crash tests were conducted at NASA-Langley Research Center. During the first test, as a result of densely measured accelerations, it became apparent that the crash environment for military helicopters is almost never as well defined as it could be. Crash recorders were installed in a second CH-46 airframe for a second crash test. The recorders performed quite well and captured the differing crash environment for different locations in the airframe. It is believed that technology has advanced to bring crash recorders that are small, inexpensive, effective, and accurate. Therefore, implementation of crash recording capability should be considered for military aviation.
Crash Dynamic Model for Rotorcraft Adaptive Seat Energy Absorber Evaluation
Authors:   US Army, Murugan Muthuvel ,   University of Cincinnati, Tabiei Ala ,   Innovital Systems, Hiemenz Gregory
Published: October 2024

This research study focuses on the finite-element based nonlinear dynamic model development and analysis for virtual evaluation of adaptive seat dampers for enhanced occupant protection during vertical crash landings of a helicopter. The current state-of-the-art helicopter crew seat has passive safety mechanisms that are highly limited in their capability to optimally adapt to each type of crash scenario due to variations in both occupant weight and crash severity level. While passive crash energy absorbers work well for a single design condition (50th percentile male occupant and fixed crash severity level), they do not offer adequate protection across a broad spectrum of crash conditions by minimizing the load transmitted to the occupant. This study reports the development of a finite-element based seat-occupant system level model using LS-DYNA for rotorcraft crash injury simulation. This finite element simulation model of a seated occupant with five-point belt and stroking seat is used to study occupant kinematics and spinal injury assessments to support crash sled evaluations of seat energy absorbers. The injury criteria and tolerance levels for the biomechanical effects are discussed for each of the adult-sized occupants with respect to thoracic lumbar loads. The desired objective of this analytical model development is to develop a tool to study the performance effectiveness of adaptive seat energy absorbers for enhancing rotorcraft occupant crash protection.
Reusable Energy Absorbing Lab (REAL) Seat
Authors:   NAVAIR, Knott Michael , Hall Brandon
Published: October 2024

Energy absorbing seats have played a critical role in increasing the survivability of rotary wing mishaps in both military and civilian rotorcraft. By using various methods of energy absorption, crashworthy seats limit occupant exposure to potentially injurious spinal loading and whole-body accelerations during a mishap. When testing aircrew-mounted equipment, or while conducting experiments on crashworthy seating systems, the costs associated with using a new or refurbished crashworthy seating system can prove to be cost prohibitive. To alleviate this cost burden and provide for substantially more iterative design support testing, a completely reusable Energy Absorbing (EA), crashworthy seat was desired. The Reusable Energy Absorbing Lab (REAL) Seat was developed to address this need. Through the Naval Innovative Science and Engineering (NISE) Workforce Development (WFD) program, a project was established to develop and validate the REAL Seat. The objective of the REAL Seat is to provide a capable, reusable EA seat that can be used as a Fleet representative test bed for simulating the use of a crashworthy seat. The REAL Seat is designed to simulate the kinematics of military crashworthy seating systems. It complies with MIL-S-85510 and MIL-S-58095, which are the legacy military standard baselines for cabin and cockpit crashworthy seating systems, respectively. By using a pneumatic-actuated braking system, the REAL Seat absorbs kinetic energy of the occupant and seat mass similar to that of an actual production crashworthy seating system. The REAL Seat can accommodate occupant sizes ranging from the 5th percentile female up to the fully equipped 95th percentile male (119-275lbs). The seat can use a variety of restraint systems and seat cushions, allowing it to simulate the use a range of seating systems. The system has been successfully tested and has shown that it adequately represents the crashworthy seating systems presently fielded in military aircraft.
Mission Utility of a Tactile Display in Rotary Wing Operations
Authors:   University of Canberra, McGrath Braden ,   Aviation Development Directorate - AATD, Cox Jeffrey ,   US Army Aviation Missile Cmd, McKay Joe ,   US Army Aeromedical Research Laboratory, Rupert Angus
Published: October 2024

Over the last decade, the foremost helicopter issue reported by the military operating in desert environments is the inability to maintain control of the aircraft in degraded visual environments (DVE). A DVE mishap is a special subset of the Spatial Disorientation (SD) mishap. SD is defined as the inability of the pilot to correctly perceive the position, motion or attitude of the aircraft relative to the earth or other significant objects. The US military organization has been developing improved man-machine interfaces that increase pilots’ awareness of spatial orientation, including the use of non-visual tactile display technology for orientation information. A series of flight tests have shown the potential of tactile displays to improve aircrew spatial awareness and reduce aircrew workload, especially in DVE. The combined conclusions and recommendations of the test events support further flight-testing in a US Army UH-60M in DVE conditions and the associated engineering efforts to address reliability and maintainability to ensure US Army fleet-wide operational suitability. To take advantage of the potential risk reduction and performance enhancements of tactile cueing in current and emerging platforms, a multi-sensory system that integrates tactile cueing with advanced visual and audio displays, coupled with automatic or user-selected switching between these sensory modalities is paramount.
Investigation of Tip-Vortex Modifications on Rotor Loads and Performance
Authors:   Indian Institute of Technology Kanpur, A. Abhishek , R. Rahul
Published: October 2024

This paper studies the influence of tip vortex modification on the airloads and performance of the helicopter for high speed steady level flight and unsteady maneuver using a lifting-line based comprehensive analysis. The tip vortex modification is modeled inside the free wake model of the comprehensive analysis in three different ways: (1) the location of tip vortex release point is altered, keeping the strength constant, (2) strength of the tip vortex is diminished by certain factor while keeping the release location constant, and (3) both the release location and strength of the vortex are altered simultaneously. The modification of tip vortex release location is observed to have significant influence on rotor power during both steady and unsteady flight conditions analyzed. Moving the tip vortex outboard of blade tip by 5%, 10%, 15% and 20% of chord in the simulation resulted in power reduction ranging from 11.5%-18.5%, 20%-32.5%, 28%-46% and 35%-59% respectively for the unsteady pull-up maneuver.
Experimental Validation of Tailboom Vibration Control Using Fluidic Flexible Matrix Composite Tubes
Authors:   Pennsylvania State University, Miura Kentaro ,   Bell Helicopter Textron Inc., Romano Peter , Krott Matthew , Smith Edward , Rahn Christopher
Published: October 2024

Rotorcraft tailbooms experience driveline component wear and structural fatigue, while causing passenger discomfort due to vibration excitation from the rotors, separated flow behind the rotor hub, vehicle maneuvers, and wind gusts. Fluidic Flexible Matrix Composite (F²MC) tubes, a new class of passive fluidic vibration treatments, are tested on a representative tailboom structure. Two pairs of F²MC tubes are mounted to the top and bottom of the tailboom and interconnected via a fluidic circuit with a tunable orifice to form a tuned vibration absorber. Experimental frequency responses are obtained to demonstrate that the tuned vibration absorber reduces response amplitude at the first vertical bending mode by over 70%, and that a partially closed orifice leads to a damped absorber that adds nearly 8% damping to the first mode. A model of a tailboom with F²MC tubes is developed and validated with the experimental results. The effect of fluid pre-pressure and tailboom forcing amplitude are studied.
Do We Really Need To Study Rotorcraft as Linear Periodic Systems?
Authors:   Politecnico di Milano, Tamer Aykut , Masarati Pierangelo
Published: October 2024

This work discusses the application of Lyapunov Characteristic Exponents as a means of generalizing rotorcraft stability analysis. Stability estimation of linear time invariant and linear time periodic systems relies on eigenanalysis of special state transition matrices and implies simplifications on the nonlinear non-autonomous equations that govern rotorcraft stability. Lyapunov Characteristic Exponents provide quantitative information on the stability of nonlinear non-autonomous dynamical systems. Stability estimation using Lyapunov Characteristic Exponents does not require a special reference solution and agrees with the eigensolution of linear time invariant and Floquet-Lyapunov analysis of linear time periodic systems. Thus, they represent a natural generalization of conventional stability analysis. The Discrete QR method is used to practically estimate the Lyapunov Characteristic Exponents. The method is applied to rotorcraft related problems. Results are correlated with usual methods for linear time invariant and time periodic problems when possible.
Development, Testing and Validation of Transport Category Procedures for the AW609 Tiltrotor
Authors:   Agusta Westland, Schaeffer Joseph , Belt David , Campbell Kip , Colombo Alessandro
Published: October 2024

Transport Category Certification requires the ability to safely land or continue flight after an engine failure during all phases of flight. The maximum transport category gross weight is a key parameter that can strongly influence the success of an aircraft. Due to its unique configuration, the tiltrotor offers unique challenges and abilities for surviving an engine failure during its critical mission phase. Challenges include energy management and thrust maintenance for a low inertia, high disk-loading rotor. Unique capabilities include rapid acceleration due to tilting of the thrust vector via the nacelles, which is a powerful method of improving takeoff performance and ground clearance for continued flight after a single engine failure. With its fly by wire flight control system and integrated engine controls architecture, the AW609 offers an unparalleled ability to evaluate, tune, and improve transport category performance, specifically during the critical flight phases of takeoff and landing. This paper will summarize the development and initial evaluation of transport category performance on the AW609 tiltrotor. It includes a brief discussion of the control architecture, a summary of simulation correlation, and a summary of flight test findings.
Design and Flight Test of a Hybrid External Load Stabilization System for an H-6 Helicopter Testbed
Authors:   The Boeing Company, Patterson Byron , Enns Russell , King Carl , Kashawlic Bryan , Mohammed Stephen , Lukes and
Published: October 2024

A future helicopter vehicle management system must include technologies to minimize the impact of externally slung loads on the helicopter's controllability. Two proposed technologies, active cargo hooks (ACH) and stabilization through the flight control system, termed the Flight Control Load Stabilization (FCLS), are developed. A hybrid combination of the two technologies is also explored. The design and simulation of the technologies culminates in the flight testing of the ACH and FCLS, with the hybrid mode being flown for the first time. The results showed the ACH system significantly improving load damping which in turn resulted in significant improvements in several key metrics such as handling qualities and maneuver completion time. In contrast, the FCLS and hybrid approaches did not show the same expected benefits in flight. Post flight investigation revealed an error in the modeling, which may help explain the discrepancies. With this correction made and gains retuned, the next flight test planned for early 2015 will reassess the FCLS and hybrid technologies.
Augmented Systems for a Personal Aerial Vehicle Using a Civil Light Helicopter Model
Authors:   University of Pisa, Geluardi Stefano ,   Max Planck Institute for Biological Cybernetics, Nieuwenhuizen Frank ,   Korea University, Bülthoff Heinrich , Pollini Lorenzo
Published: October 2024

This paper presents the implementation of classic augmented control stategies applied to an identified civil light helicopter model in hover. Aim of this study is to enhance the stability and controllability of the helicopter model and to improve its Handling Qualities (HQs) in order to meet those defined for a new category of aircrafts, Personal Aerial Vehicles (PAVs). Two control methods were used to develop the augmented systems, H∞ control and µ-synthesis. The resulting augmented systems were compared in terms of achieved robust stability, nominal performance and robust performance. The robustness was evaluated against parametric uncertainties and external disturbances modeled as real atmospheric turbulences that might be experienced in hover and low speed flight. The main result achieved in this work is that classical control techniques can augment a linear helicopter model to match PAVs responses at low frequencies. As a consequence, the achieved HQs performance resemble those defined for PAVs pilots. However, both control techniques performed poorly for some specific uncertainty conditions demonstrating unsatisfactory performance robustness. Differences, advantages and limitations of the implemented control architectures with respect to the considered requirements are described in the paper.
Preliminary Investigation into Rotorcraft Pilot Strategy and Visual Cueing Effects in the Shipboard Environment
Authors:   U.S. Naval Test Pilot School, Tritschler John ,   Naval Air Systems Command, Pritchard James , O'Connor John , Arteche David , Wallace Ryan , Eksuzian Daniel
Published: October 2024

The present work reports the results of a research investigation into the handling qualities of a ship approach and landing task. The investigation was performed via fixed-base, pilot-in-the-loop flight simulation and included six test pilots with extensive operational and test experience in the shipboard environment. Representative approach/landing tasks were flown with three different response types to the field and to multiple spots on a LHA. The ship was stationary and there was no simulated ship airwake, so the fundamental differences between the field and ship approaches were limited to visual cueing. Traditional subjective handling qualities ratings were supplemented with multiple other analysis techniques, including: (i) approach profile analysis, (ii) pilot eye tracking analysis, and (iii) pilot control activity analysis. The results show that there are multiple fundamental differences caused by differences in visual cueing between field and ship approaches. Such differences are seen in the overall approach profiles as well as in the pilot gaze patterns. Additionally, subjective assessments indicated that pilots preferred higher degrees of aircraft stabilization in the shipboard environment than in the field environment, though there were not significant differences between pilot control techniques in these environments for a given aircraft response type.
Augustine's Law and Unit Cost Growth in the Rotorcraft Industry
Authors:   The Boeing Company, Streich Eric
Published: October 2024

One of the most famous of Augustine's Laws involved the ever-escalating costs of aircraft over time. Law Number XVI states, "In the year 2054, the entire defense budget will purchase just one aircraft. This aircraft will have to be shared by the Air Force and Navy 3- 1/2 days each per week except for leap year, when it will be made available to the Marines for the extra day." This particular reference involved tactical aircraft but the same trend can be observed for other types of military hardware. This paper addresses and attempts to explain this phenomenon as it applies to the rotorcraft industry. For example, increasing demand for more survivable rotorcraft, and more survivable payloads that must be carried by rotorcraft (eg., HMMWVs, soldier body armor, etc.), result in not only higher unit costs but in higher mission costs.
Blade Root Integrated Fibre Bragg Grating Sensors - A Highly Redundant Data Source For Future HUMS
Authors:   Technische Universitaet Muenchen (TUM), Hajek Manfred , Manner Stephanie , Suesse Soeren
Published: October 2024

Fiber Bragg Gratings (FBG) show an excellent potential for accurate strain measurement in aerospace and other applications. This paper will describe an approach to derive remaining useful lifetime values for dynamically loaded components by using FBG strain sensor data from helicopter blades. A complete chain of transformations is presented together with a substantiation approach for certification. The transformation chain is based on properties of piece-wise linear mechanical systems for which observability conditions are fulfilled. For this class of problems, FBG measurement values can be used to calculate rotor hub loads and how they are transferred to dynamic components. Before the results are used to calculate the so-called remaining useful life, failure analyses are necessary in order to evaluate the required level of redundancy on sensor level. An experimental set up is presented based on a bearingless main rotor blade root with embedded FBGs. First lab tests raise confidence in the acquired signal accuracy and availability which demonstrates enough potential to let lifetime calculations derive from them. In order to finally comply with regulatory constraints, the complete setup needs to have an architecture with satisfactory data integrity.