Pub Date : 2021-05-10DOI: 10.4050/f-0077-2021-16797
E. Bachelder, B. Aponso
The concepts and principle developed in this work offer a novel and integrative approach for exploring fundamental issues surrounding pilot performance, handling qualities (HQs), and workload. Fundamental laws of sensory perception are extended to multi-input sensing, showing that multiple sensory inputs add logarithmically. It is proposed rather than being just a sensational response, a pilot’s perception of workload is a skill that is acquired and used for the purpose of modulating system stability (i.e., phase margin) during a tracking task. Evidence is presented indicating than an operator perceives workload and behaves such that workload is linearly related to phase margin (PM). It is also shown that this behavior associated with PM linearization serves to reduce workload. PM-workload linearization would enable a straightforward transformation of workload to PM, allowing PM to be set by the pilot to facilitate loop control. A perceptual transformation of the variables available to the pilot (control activity, error) couples with the behavioral conditioning to complete the linearization between PM and sensed workload. Two contrasting sets of experimental data were used to examine pilot response, indicating that pilot compensation is conducted via both frequency modulation (lead-lag) and temporal modulation (pure time delay). HQ sensing is treated as multi-input perception, where time delay and the lead-lag ratio are the stimuli for compensation sensing, and tracking error is the stimulus for performance sensing. A HQ metric arising from the logarithmic addition of these two sensations is shown to yield promising results. A cost function representing pilot behavioral objectives is developed that serves to modulate the following four items: 1) Tracking error; 2) Workload; 3) Linearity between workload and PM; and 4) Setting a reference PM. The pilot cost function was implemented in an optimal pilot which produced pilot time delay and pilot compensation estimates that closely matched the actual pilot data.
{"title":"A Theoretical Framework Unifying Handling Qualities, Workload, Stability and Control","authors":"E. Bachelder, B. Aponso","doi":"10.4050/f-0077-2021-16797","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16797","url":null,"abstract":"\u0000 The concepts and principle developed in this work offer a novel and integrative approach for exploring fundamental issues surrounding pilot performance, handling qualities (HQs), and workload. Fundamental laws of sensory perception are extended to multi-input sensing, showing that multiple sensory inputs add logarithmically. It is proposed rather than being just a sensational response, a pilot’s perception of workload is a skill that is acquired and used for the purpose of modulating system stability (i.e., phase margin) during a tracking task. Evidence is presented indicating than an operator perceives workload and behaves such that workload is linearly related to phase margin (PM). It is also shown that this behavior associated with PM linearization serves to reduce workload. PM-workload linearization would enable a straightforward transformation of workload to PM, allowing PM to be set by the pilot to facilitate loop control. A perceptual transformation of the variables available to the pilot (control activity, error) couples with the behavioral conditioning to complete the linearization between PM and sensed workload. Two contrasting sets of experimental data were used to examine pilot response, indicating that pilot compensation is conducted via both frequency modulation (lead-lag) and temporal modulation (pure time delay). HQ sensing is treated as multi-input perception, where time delay and the lead-lag ratio are the stimuli for compensation sensing, and tracking error is the stimulus for performance sensing. A HQ metric arising from the logarithmic addition of these two sensations is shown to yield promising results. A cost function representing pilot behavioral objectives is developed that serves to modulate the following four items: 1) Tracking error; 2) Workload; 3) Linearity between workload and PM; and 4) Setting a reference PM. The pilot cost function was implemented in an optimal pilot which produced pilot time delay and pilot compensation estimates that closely matched the actual pilot data.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131996535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-10DOI: 10.4050/f-0077-2021-16709
Rajneesh K. Singh, A. Bagai
Interests in UAS with advanced capabilities, especially in the Groups 1-3 categories is discussed. Potential use cases and exemplary concepts of application are described that illustrate technology challenges that must be addressed to enable extreme UAS performance. Alternative normalized metrics derived from traditional payload, range, and speed are defined, and frameworks that present the state-of-the-art in UAS capabilities are presented. Aircraft cruise, powertrain, and mass fraction efficiencies are assessed to underscore the challenges in enabling radical improvements in performance. The objective is to stimulate ideas for focused basic and applied research in relevant fields to enable transformational improvements in UAS attributes.
{"title":"Considerations for Enabling Extreme Unmanned Aerial Systems Through Advanced Technologies ","authors":"Rajneesh K. Singh, A. Bagai","doi":"10.4050/f-0077-2021-16709","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16709","url":null,"abstract":"\u0000 Interests in UAS with advanced capabilities, especially in the Groups 1-3 categories is discussed. Potential use cases and exemplary concepts of application are described that illustrate technology challenges that must be addressed to enable extreme UAS performance. Alternative normalized metrics derived from traditional payload, range, and speed are defined, and frameworks that present the state-of-the-art in UAS capabilities are presented. Aircraft cruise, powertrain, and mass fraction efficiencies are assessed to underscore the challenges in enabling radical improvements in performance. The objective is to stimulate ideas for focused basic and applied research in relevant fields to enable transformational improvements in UAS attributes.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132473665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-10DOI: 10.4050/f-0077-2021-16846
Mike Gralish
By incorporating sophisticated avionics, intelligent components, and increased interconnectivity with its Integrated Vehicle Heath Management (IVHM) system, the Bell 525 is raising the bar on safety. These features are combined with Bell's MissionLink® desktop application to link the aircraft HUMS data directly to Bell's Interactive Electronic Maintenance Manual (IETM) to manage the Instructions for Continued Airworthiness (ICAs). In flight, the aircraft can self-diagnose and broadcast information on component health and the supporting power or data pathways, allowing ground teams to prepare for corrective actions while the aircraft is still enroute. In the hangar, maintainers utilize the 525 IETM, which contains ICA procedures for locating, inspecting, testing and replacing hundreds of Line Replaceable Units (LRUs). However, unlike typical applications with only logical wiring diagrams, the Bell 525 IETMs can also trace thousands of connectors, and tens of thousands of pins that define the complete wiring pathway for aircraft data and power. If a corrective action is hidden within a harness, connector, junction box, or passthrough and splice, troubleshooting can be accomplished quickly, and the fault site can be rapidly located. This paper presents the technology, operational features, and development procedures that enable efficiency in the 525 maintenance environment.
{"title":"The 525 Interactive Electronic Maintenance Manual - Linking Advanced Avionics and Wiring to Fault Isolation","authors":"Mike Gralish","doi":"10.4050/f-0077-2021-16846","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16846","url":null,"abstract":"\u0000 By incorporating sophisticated avionics, intelligent components, and increased interconnectivity with its Integrated Vehicle Heath Management (IVHM) system, the Bell 525 is raising the bar on safety. These features are combined with Bell's MissionLink® desktop application to link the aircraft HUMS data directly to Bell's Interactive Electronic Maintenance Manual (IETM) to manage the Instructions for Continued Airworthiness (ICAs). In flight, the aircraft can self-diagnose and broadcast information on component health and the supporting power or data pathways, allowing ground teams to prepare for corrective actions while the aircraft is still enroute. In the hangar, maintainers utilize the 525 IETM, which contains ICA procedures for locating, inspecting, testing and replacing hundreds of Line Replaceable Units (LRUs). However, unlike typical applications with only logical wiring diagrams, the Bell 525 IETMs can also trace thousands of connectors, and tens of thousands of pins that define the complete wiring pathway for aircraft data and power. If a corrective action is hidden within a harness, connector, junction box, or passthrough and splice, troubleshooting can be accomplished quickly, and the fault site can be rapidly located. This paper presents the technology, operational features, and development procedures that enable efficiency in the 525 maintenance environment.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"52 9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127572655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-10DOI: 10.4050/f-0077-2021-16778
Z. Unal, I. Yavrucuk
In this study the panel method used in fluid dynamics, is applied to the path planning problem of electric vertical take-off and landing (eVTOL) vehicles in urban environment. For an urban air mobility scenario the path planning problem of these vehicles includes the simultaneous operation of large number of vehicles around complex shaped buildings and architectural structures. Using the panel method, flow around complex shaped obstacles is modeled and calculated stream-lines of the fluid flow are used as trajectories for the eVTOL traffic. Since, streamlines do not cross each other or obstacles, using streamlines as vehicle trajectories guarantees collision free paths for vehicles. Moreover, source and sink elements are used to avoid collision of vehicles with each other in case of emergency, and attract the vehicles to target points. The application of panel method provides a solution to the whole path planning problem for multiple vehicles in a single step. Assuming complete knowledge of the city map, the path of each eVTOL vehicle in an air taxi fleet can be determined simultaneously.
{"title":"Panel-Method-Based Path Planning for eVTOL in Urban Environment","authors":"Z. Unal, I. Yavrucuk","doi":"10.4050/f-0077-2021-16778","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16778","url":null,"abstract":"\u0000 In this study the panel method used in fluid dynamics, is applied to the path planning problem of electric vertical take-off and landing (eVTOL) vehicles in urban environment. For an urban air mobility scenario the path planning problem of these vehicles includes the simultaneous operation of large number of vehicles around complex shaped buildings and architectural structures. Using the panel method, flow around complex shaped obstacles is modeled and calculated stream-lines of the fluid flow are used as trajectories for the eVTOL traffic. Since, streamlines do not cross each other or obstacles, using streamlines as vehicle trajectories guarantees collision free paths for vehicles. Moreover, source and sink elements are used to avoid collision of vehicles with each other in case of emergency, and attract the vehicles to target points. The application of panel method provides a solution to the whole path planning problem for multiple vehicles in a single step. Assuming complete knowledge of the city map, the path of each eVTOL vehicle in an air taxi fleet can be determined simultaneously.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"137 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132605617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-10DOI: 10.4050/f-0077-2021-16780
David A. Coleman, Vishaal Subramanian, Eric Greenwood, V. Lakshminarayan, Moble Benedict, H. Denton, Atanu Halder, Bochan Lee, Carl Runco, Farid Saemi
This paper describes the development and flight testing of a personal air vehicle by team Harmony for the Boeing GoFly X-prize challenge. For the $1mil grand prize, aircraft were scored by compact size, speed, low noise, and endurance. The team chose a coaxial electric helicopter configuration to maximize rotor area and reduce disk loading for efficiency and acoustic benefits. The rotors were designed through an extensive parametric study using an in-house performance code. Air loads were modeled in HPCMP CREATE™-AV Helios for validation, then used in an inhouse acoustics solver to estimate sound pressure levels. A quiet electric power train was developed, as well as a custom 11kWh, 200lb (90.7kg) battery pack. The flight dynamics of the configuration were modeled and the stability analyzed. Structural analysis was utilized in designing key load-bearing parts. Flight control was implemented with dual, independent, electronically coupled swashplates. First, a 1/3rd scale prototype aircraft was developed to validate the design and acoustic predictions. Then a full-scale, 520lb (235.4kg) prototype with an 8.5ft (2.59m) rotor diameter was developed and accumulated 19.5hrs of testing time. During hovering, the sound pressure levels at 50ft (15.24m) were 73dBA, remarkably low for a rotorcraft. The results of this study underscored the endurance limitation of electric flight due to poor battery performance, as well as the need for reliable, lightweight hardware for such applications.
{"title":"Development of \"Aria,\" a Compact, Ultra-Quiet Personal Electric Helicopter","authors":"David A. Coleman, Vishaal Subramanian, Eric Greenwood, V. Lakshminarayan, Moble Benedict, H. Denton, Atanu Halder, Bochan Lee, Carl Runco, Farid Saemi","doi":"10.4050/f-0077-2021-16780","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16780","url":null,"abstract":"\u0000 This paper describes the development and flight testing of a personal air vehicle by team Harmony for the Boeing GoFly X-prize challenge. For the $1mil grand prize, aircraft were scored by compact size, speed, low noise, and endurance. The team chose a coaxial electric helicopter configuration to maximize rotor area and reduce disk loading for efficiency and acoustic benefits. The rotors were designed through an extensive parametric study using an in-house performance code. Air loads were modeled in HPCMP CREATE™-AV Helios for validation, then used in an inhouse acoustics solver to estimate sound pressure levels. A quiet electric power train was developed, as well as a custom 11kWh, 200lb (90.7kg) battery pack. The flight dynamics of the configuration were modeled and the stability analyzed. Structural analysis was utilized in designing key load-bearing parts. Flight control was implemented with dual, independent, electronically coupled swashplates. First, a 1/3rd scale prototype aircraft was developed to validate the design and acoustic predictions. Then a full-scale, 520lb (235.4kg) prototype with an 8.5ft (2.59m) rotor diameter was developed and accumulated 19.5hrs of testing time. During hovering, the sound pressure levels at 50ft (15.24m) were 73dBA, remarkably low for a rotorcraft. The results of this study underscored the endurance limitation of electric flight due to poor battery performance, as well as the need for reliable, lightweight hardware for such applications.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130918707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-10DOI: 10.4050/f-0077-2021-16901
Chad deMontfort, Samuel Forgerson, Brian Harper
Airworthiness for the Future Vertical Lift (FVL) programs will be guided by the Rotorcraft Structural Integrity Program (RSIP) standard, published as MIL-STD-3063. The United States Air Force (USAF) standard that helped to guide RSIP, the Aircraft Structural Integrity Program (ASIP), MIL-STD-1530, has been used by the USAF to guide airworthiness for their helicopter fleets for decades. Mercer Engineering Research Center (MERC) has been supporting these USAF helicopter ASIP programs for several years, often instantiating ASIP requirements on fleets not originally designed to those requirements. MERC believes vital opportunities exist in the early stages of new platforms to inject important lessons learned during the course of this support. For the purposes of this paper, these lessons learned will focus on three primary areas. These areas are 1) identifying and accessing data required for sustainment activities, 2) understanding failure modes of the data and how to handle them appropriately, and 3) efficiently storing and processing of ever-increasing amounts of data. Ultimately, continuous and purposeful communication between development and force management communities is vital to positioning these new fleets as early as possible for the longest phase in their life cycles.
{"title":"Lessons Learned For Application to Rotorcraft Structural Integrity Programs","authors":"Chad deMontfort, Samuel Forgerson, Brian Harper","doi":"10.4050/f-0077-2021-16901","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16901","url":null,"abstract":"\u0000 Airworthiness for the Future Vertical Lift (FVL) programs will be guided by the Rotorcraft Structural Integrity Program (RSIP) standard, published as MIL-STD-3063. The United States Air Force (USAF) standard that helped to guide RSIP, the Aircraft Structural Integrity Program (ASIP), MIL-STD-1530, has been used by the USAF to guide airworthiness for their helicopter fleets for decades. Mercer Engineering Research Center (MERC) has been supporting these USAF helicopter ASIP programs for several years, often instantiating ASIP requirements on fleets not originally designed to those requirements. MERC believes vital opportunities exist in the early stages of new platforms to inject important lessons learned during the course of this support. For the purposes of this paper, these lessons learned will focus on three primary areas. These areas are 1) identifying and accessing data required for sustainment activities, 2) understanding failure modes of the data and how to handle them appropriately, and 3) efficiently storing and processing of ever-increasing amounts of data. Ultimately, continuous and purposeful communication between development and force management communities is vital to positioning these new fleets as early as possible for the longest phase in their life cycles.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131116219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-10DOI: 10.4050/f-0077-2021-16710
A. Kuczek, F. Gandhi, Daniel V. Camp, Z. Chaudhry, Wenping Zhao
High speed rotorcraft experience regions of reverse flow over the inboard sections of blades. In these regions, because of the reverse flow, the rotor blade experiences high drag, large dynamic pitching moments, and the resulting significant vibrations. If the shape of the rotor can be changed “morphed” in the inboard section, a number of these adverse effects can be minimized. This paper outlines the approach to morphing the rotor blade to achieve two desired shapes suited for hover and forward flight. Different elements and associated risk reduction of the morphing system are discussed in details. A key element of a successful morphing structure is a flexible skin which can change shape and at the same time maintain rigidity and stiffness. The approach to achieving these conflicting goals through interleaved and off set layers of elastomers and composite sections, all co-cured in one step, is described. In addition an actuation approach and associated kinematics to achieve the shape change while minimizing actuation forces is also described. Assembly of the full-scale (in the chord-wise direction) prototype hardware of an 18% thick SC325218 airfoil is also included.
{"title":"Designing a High Speed Morphing Rotor Blade","authors":"A. Kuczek, F. Gandhi, Daniel V. Camp, Z. Chaudhry, Wenping Zhao","doi":"10.4050/f-0077-2021-16710","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16710","url":null,"abstract":"\u0000 High speed rotorcraft experience regions of reverse flow over the inboard sections of blades. In these regions, because of the reverse flow, the rotor blade experiences high drag, large dynamic pitching moments, and the resulting significant vibrations. If the shape of the rotor can be changed “morphed” in the inboard section, a number of these adverse effects can be minimized. This paper outlines the approach to morphing the rotor blade to achieve two desired shapes suited for hover and forward flight. Different elements and associated risk reduction of the morphing system are discussed in details. A key element of a successful morphing structure is a flexible skin which can change shape and at the same time maintain rigidity and stiffness. The approach to achieving these conflicting goals through interleaved and off set layers of elastomers and composite sections, all co-cured in one step, is described. In addition an actuation approach and associated kinematics to achieve the shape change while minimizing actuation forces is also described. Assembly of the full-scale (in the chord-wise direction) prototype hardware of an 18% thick SC325218 airfoil is also included.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133703228","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-10DOI: 10.4050/f-0077-2021-16839
A. Zanoni, A. Cocco, P. Masarati
Aeroelastic rotorcraft-pilot couplings are dynamic phenomena in which the vibrations of a rotorcraft are transmitted through the cockpit, the seat and the control inceptors to the pilot, and the resulting induced motion is involuntarily fed back into the control system. Handling qualities, in terms of ability to complete the desired task, and even safety of f light can be affected by the proneness of the rotorcraft to giving rise to adverse interactions, an unwanted characteristic that can be captured by the so-called biodynamic feedthrough. In this work, a multibody model of the whole upper body, developed by the authors, is used to support the design of the control inceptors. The sensitivity of biodynamic feedthrough to the characteristics of cockpit layout and inceptors is analyzed varying several parameters: the length and inertia of the inceptors, the effect of the trim spring and of the compliance of the seat cushion. The simulations encompass subjects of different anthropometric data, in order to represent possible intra-subject variations. Biodynamic feedthrough at collective and cyclic inceptors, in response to vertical acceleration inputs, is discussed along with single-harmonic, large-magnitude input responses that highlight the presence and importance of nonlinearities.
{"title":"Numerical Investigation on the Role of Control Inceptors Layout in Rotorcraft-Pilot Couplings","authors":"A. Zanoni, A. Cocco, P. Masarati","doi":"10.4050/f-0077-2021-16839","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16839","url":null,"abstract":"\u0000 Aeroelastic rotorcraft-pilot couplings are dynamic phenomena in which the vibrations of a rotorcraft are transmitted through the cockpit, the seat and the control inceptors to the pilot, and the resulting induced motion is involuntarily fed back into the control system. Handling qualities, in terms of ability to complete the desired task, and even safety of f light can be affected by the proneness of the rotorcraft to giving rise to adverse interactions, an unwanted characteristic that can be captured by the so-called biodynamic feedthrough. In this work, a multibody model of the whole upper body, developed by the authors, is used to support the design of the control inceptors. The sensitivity of biodynamic feedthrough to the characteristics of cockpit layout and inceptors is analyzed varying several parameters: the length and inertia of the inceptors, the effect of the trim spring and of the compliance of the seat cushion. The simulations encompass subjects of different anthropometric data, in order to represent possible intra-subject variations. Biodynamic feedthrough at collective and cyclic inceptors, in response to vertical acceleration inputs, is discussed along with single-harmonic, large-magnitude input responses that highlight the presence and importance of nonlinearities.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131404582","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-10DOI: 10.4050/f-0077-2021-16759
Jennifer Baggett, Andrew R. Kreshock, Jinwei Shen
Loads and harmonics calculations for a wind tunnel tiltrotor model built by the U.S. Army are presented. Blade loads are calculated using the comprehensive analysis, CAMRAD II, and the multibody dynamics analysis, Dymore, for helicopter, airplane, and transition modes of flight at various velocity and pylon angles. These calculations were performed for both a gimballed hub and hingeless hub configurations. Mean variations show a primary trend along the radial station is consistent among both hub types. Half peak-to-peak comparisons show excellent agreement based on the analysis in helicopter and airplane mode. During transition flight some deviations occur within the hingeless hub type confiruation. The analytical vibratory blade loads generally match in waveforms for both the gimballed and hingeless hub configurations. Dymore and CAMRAD II show good agreement among the harmonics for both the gimballed and hingeless hub configurations with both the flapwise bending moment and chordwise bending moment cases relatively similar. Good agreement is identified particularly in airplane mode and higher flight speeds.
{"title":"Comparison of Wind Tunnel Tiltrotor Loads of Two Hub Types Under Different Pylon Angles with Multibody Dynamics Analyses ","authors":"Jennifer Baggett, Andrew R. Kreshock, Jinwei Shen","doi":"10.4050/f-0077-2021-16759","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16759","url":null,"abstract":"\u0000 Loads and harmonics calculations for a wind tunnel tiltrotor model built by the U.S. Army are presented. Blade loads are calculated using the comprehensive analysis, CAMRAD II, and the multibody dynamics analysis, Dymore, for helicopter, airplane, and transition modes of flight at various velocity and pylon angles. These calculations were performed for both a gimballed hub and hingeless hub configurations. Mean variations show a primary trend along the radial station is consistent among both hub types. Half peak-to-peak comparisons show excellent agreement based on the analysis in helicopter and airplane mode. During transition flight some deviations occur within the hingeless hub type confiruation. The analytical vibratory blade loads generally match in waveforms for both the gimballed and hingeless hub configurations. Dymore and CAMRAD II show good agreement among the harmonics for both the gimballed and hingeless hub configurations with both the flapwise bending moment and chordwise bending moment cases relatively similar. Good agreement is identified particularly in airplane mode and higher flight speeds.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115431223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-10DOI: 10.4050/f-0077-2021-16804
James Hunt, TJ Martin, Thomas Samper
Vibration monitoring of dynamic components is an important part of ensuring aircraft safety and has been used to determine the health of rotating components since the inception of the modern day helicopter. Some vibration checks have not changed from the time that a specific helicopter was placed into service and others have been modified with the addition of Health and Usage Monitoring Systems (HUMS) with the goal to improve them. A seeded fault test on an MH-47 aircraft was conducted to directly compare modified vibration checks to the legacy checks, identify a method to decrease vibrations, and minimize maintenance. Data was collected using Modernized Signal Processing Unit (MSPU) which replaced the Aviation Vibration Analyzer (AVA) for rotor smoothing and all drivetrain vibration checks. While this paper will present lessons learned, it will also provide successful HUMS benefits. This paper will demonstrate that HUMS can not only maintain legacy vibration checks but improve them as well with changes that enhance airworthiness and reduce maintenance burden. This is an example of how HUMS continues to evolve as we press forward in the pursuit of providing aircraft users with the best tools possible.
{"title":"An Investigation of Legacy Vibration Checks on Modern H-47 Chinook Systems via Seeded Fault Testing","authors":"James Hunt, TJ Martin, Thomas Samper","doi":"10.4050/f-0077-2021-16804","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16804","url":null,"abstract":"\u0000 Vibration monitoring of dynamic components is an important part of ensuring aircraft safety and has been used to determine the health of rotating components since the inception of the modern day helicopter. Some vibration checks have not changed from the time that a specific helicopter was placed into service and others have been modified with the addition of Health and Usage Monitoring Systems (HUMS) with the goal to improve them. A seeded fault test on an MH-47 aircraft was conducted to directly compare modified vibration checks to the legacy checks, identify a method to decrease vibrations, and minimize maintenance. Data was collected using Modernized Signal Processing Unit (MSPU) which replaced the Aviation Vibration Analyzer (AVA) for rotor smoothing and all drivetrain vibration checks. While this paper will present lessons learned, it will also provide successful HUMS benefits. This paper will demonstrate that HUMS can not only maintain legacy vibration checks but improve them as well with changes that enhance airworthiness and reduce maintenance burden. This is an example of how HUMS continues to evolve as we press forward in the pursuit of providing aircraft users with the best tools possible.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115932675","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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