Pub Date : 2021-05-10DOI: 10.4050/f-0077-2021-16808
W. Geyer, Barbara Gordon, C. Mattei, Dwight Robinson
In this work, a statistical time series method that is capable of effective multicopter rotor fault detection, identification, and quantification within a unified stochastic framework is introduced. The proposed framework is based on the functional model based method for fault magnitude estimation tackled within the context of statistical time series approaches. Estimator uncertainties are taken into account, and confidence intervals are provided for the fault magnitude of multicopter rotors. The framework employs functionally pooled (FP) models which are characterized by parameters that depend on the fault magnitude, as well as on proper statistical estimation and decision-making schemes. The validation and assessment is assessed via a proof-of-concept application to a hexacopter flying forward with a constant velocity under turbulence. The fault scenarios considered consist of the front and side rotor degradation ranging from healthy to complete failure with 20% fault increments. The method is shown to achieve fast fault detection, accurate identification, and precise magnitude estimation based on even a single measured signal obtained from aircraft sensors during flight. Furthermore, fault quantification is addressed via the use of both local ( boom acceleration) and global (IMU) sensors, with the signals collected from the boom supporting the identified faulty rotor proven to achieve better performance than the global signals, yet with a shorter signal length.
{"title":"Unified Statistical Framework for Rotor Fault Diagnosis on a Hexacopter via Functionally Pooled Stochastic Models","authors":"W. Geyer, Barbara Gordon, C. Mattei, Dwight Robinson","doi":"10.4050/f-0077-2021-16808","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16808","url":null,"abstract":"\u0000 In this work, a statistical time series method that is capable of effective multicopter rotor fault detection, identification, and quantification within a unified stochastic framework is introduced. The proposed framework is based on the functional model based method for fault magnitude estimation tackled within the context of statistical time series approaches. Estimator uncertainties are taken into account, and confidence intervals are provided for the fault magnitude of multicopter rotors. The framework employs functionally pooled (FP) models which are characterized by parameters that depend on the fault magnitude, as well as on proper statistical estimation and decision-making schemes. The validation and assessment is assessed via a proof-of-concept application to a hexacopter flying forward with a constant velocity under turbulence. The fault scenarios considered consist of the front and side rotor degradation ranging from healthy to complete failure with 20% fault increments. The method is shown to achieve fast fault detection, accurate identification, and precise magnitude estimation based on even a single measured signal obtained from aircraft sensors during flight. Furthermore, fault quantification is addressed via the use of both local ( boom acceleration) and global (IMU) sensors, with the signals collected from the boom supporting the identified faulty rotor proven to achieve better performance than the global signals, yet with a shorter signal length.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"60 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":"133513357","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-0077-2021-16779
Matthew Asper, M. Ricci, J. Sirohi, G. A.
A novel thrust control method for an electrically-driven stacked rotor system is described. The stacked rotor comprises of two two-bladed rotors spinning in the same direction at the same speed, with a fixed axial spacing and variable azimuthal spacing. Changing the azimuthal spacing by around 22° results in a 17% change in the total rotor system thrust. An electromechanical model of the rotor and drive system is developed incorporating a blade element aerodynamic model and field oriented control of two phase-synchronized electric motors, each driving one rotor of the stacked system. The model is validated with measurements on a single, 2m diameter rotor in hover driven by a single electric motor at constant speed as well as during transient rotor speed changes. The validated model is used to explore the behavior of the system in response to a commanded change in rotor azimuthal spacing. At a blade loading of 0.08, and a rotor speed of 1200 RPM, computations indicated that a 5° change in azimuthal spacing could be achieved in less than 0.2s, or less than five rotor revolutions, requiring a transient power increase of 12% the mean power. These results indicate the feasibility of achieving small changes in thrust at a high bandwidth with a small increase in motor power output.
{"title":"Electromechanical Modeling and Testing of a Novel Electrically Driven Stacked Rotor System","authors":"Matthew Asper, M. Ricci, J. Sirohi, G. A.","doi":"10.4050/f-0077-2021-16779","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16779","url":null,"abstract":"\u0000 A novel thrust control method for an electrically-driven stacked rotor system is described. The stacked rotor comprises of two two-bladed rotors spinning in the same direction at the same speed, with a fixed axial spacing and variable azimuthal spacing. Changing the azimuthal spacing by around 22° results in a 17% change in the total rotor system thrust. An electromechanical model of the rotor and drive system is developed incorporating a blade element aerodynamic model and field oriented control of two phase-synchronized electric motors, each driving one rotor of the stacked system. The model is validated with measurements on a single, 2m diameter rotor in hover driven by a single electric motor at constant speed as well as during transient rotor speed changes. The validated model is used to explore the behavior of the system in response to a commanded change in rotor azimuthal spacing. At a blade loading of 0.08, and a rotor speed of 1200 RPM, computations indicated that a 5° change in azimuthal spacing could be achieved in less than 0.2s, or less than five rotor revolutions, requiring a transient power increase of 12% the mean power. These results indicate the feasibility of achieving small changes in thrust at a high bandwidth with a small increase in motor power output.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"52 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":"133685150","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-0077-2021-16899
Biqiang Xu
Gear load is transmitted by the engaged gear teeth. The load distribution on the engaged tooth surfaces directly determines gear tooth stress status and service life. The contact pattern, gear tooth contact pressure distribution, directly alters the maximum contact and bending stresses, is critical for drive system designs. For a real gear train, the deformations of gear blank, bearing, housing, etc. contribute to contact pressure distribution. It consequently changes local contact pressure and bending stress. To accurately predict the gear contact pressure and bending stress in service, the interaction of whole gear train components needs to be modeled in the gear tooth contact analysis. It is not computational efficient for general purpose FEA packages. Transmission3D (Calyx) is designed for gear contact pattern simulation for given gear tooth surface geometry. When the contact pattern deviates from the design target, how to design a new gear tooth geometry is an open issue and discussed in this paper. Inverse engineering concept with Boussinesq solution is invoked and implemented through Excel macro for gear tooth surface microgeometry design. The design iteration based on this developed method is fast and low cost for gear pattern development.
{"title":"Quick Iteration Algorithm for Cylindrical Gear Contact Pattern Development","authors":"Biqiang Xu","doi":"10.4050/f-0077-2021-16899","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16899","url":null,"abstract":"\u0000 Gear load is transmitted by the engaged gear teeth. The load distribution on the engaged tooth surfaces directly determines gear tooth stress status and service life. The contact pattern, gear tooth contact pressure distribution, directly alters the maximum contact and bending stresses, is critical for drive system designs. For a real gear train, the deformations of gear blank, bearing, housing, etc. contribute to contact pressure distribution. It consequently changes local contact pressure and bending stress. To accurately predict the gear contact pressure and bending stress in service, the interaction of whole gear train components needs to be modeled in the gear tooth contact analysis. It is not computational efficient for general purpose FEA packages. Transmission3D (Calyx) is designed for gear contact pattern simulation for given gear tooth surface geometry. When the contact pattern deviates from the design target, how to design a new gear tooth geometry is an open issue and discussed in this paper. Inverse engineering concept with Boussinesq solution is invoked and implemented through Excel macro for gear tooth surface microgeometry design. The design iteration based on this developed method is fast and low cost for gear pattern development.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"103 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":"125696069","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-0077-2021-16845
B. Jalalahmadi, J. Rios
Sentient has developed a predictive modeling tool for components built using AM to assess their performance, with rigorous consideration of the microstructural properties governing the nucleation and propagation of fatigue cracks. This tool, called DigitalClone® for Additive Manufacturing (DCAM), is an Integrated Computational Materials Engineering (ICME) tool that includes models of crack initiation and damage progression with the high-fidelity process and microstructure modeling approaches. The predictive model has three main modules: process modeling, microstructure modeling, and fatigue modeling. The feasibility and validation of our modeling tool is verified using experimental coupon testing. The predictive tool is able to account for temperature and microstructure variation as the function of process parameters and scanning strategies at various AM processes. The relationship of processmicrostructure in additive manufacturing is successfully linked implicitly in our tool. We simulate the AM build process considering the parameters (laser intensity, laser speed, hatching space, powder layer thickness, orientation of build, etc.) involved during the build process in order to generate the microstructure of AM part which is the outcome of the build process. There is a good agreement between our prediction and the experimental data. The physics-based computational modeling encompassed within DCAM provides an efficient capability to fully explore the design space across geometries and materials, leading to components that represent the optimal combination of performance, reliability, and durability.
{"title":"Multi-physics Predictive Modeling Platform for Qualification of Material Microstructure and Mechanical Performance of Aerospace Additive Manufacturing Parts","authors":"B. Jalalahmadi, J. Rios","doi":"10.4050/f-0077-2021-16845","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16845","url":null,"abstract":"\u0000 Sentient has developed a predictive modeling tool for components built using AM to assess their performance, with rigorous consideration of the microstructural properties governing the nucleation and propagation of fatigue cracks. This tool, called DigitalClone® for Additive Manufacturing (DCAM), is an Integrated Computational Materials Engineering (ICME) tool that includes models of crack initiation and damage progression with the high-fidelity process and microstructure modeling approaches. The predictive model has three main modules: process modeling, microstructure modeling, and fatigue modeling. The feasibility and validation of our modeling tool is verified using experimental coupon testing. The predictive tool is able to account for temperature and microstructure variation as the function of process parameters and scanning strategies at various AM processes. The relationship of processmicrostructure in additive manufacturing is successfully linked implicitly in our tool. We simulate the AM build process considering the parameters (laser intensity, laser speed, hatching space, powder layer thickness, orientation of build, etc.) involved during the build process in order to generate the microstructure of AM part which is the outcome of the build process. There is a good agreement between our prediction and the experimental data. The physics-based computational modeling encompassed within DCAM provides an efficient capability to fully explore the design space across geometries and materials, leading to components that represent the optimal combination of performance, reliability, and durability.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"50 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":"115784667","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-0077-2021-16788
T. Jusko, Michael Jones
Helicopter operations with winch suspended loads are highly demanding for the flight crew. Without having a direct view on the load, pilots require assistance from a winch operator for load handling to achieve operational requirements (e.g. precise and safe positioning of a suspended person). An automatic load stabilization and positioning system for winching operations has been designed with the aim to reduce pilot and winch operator workload, damp load pendulum motion and to improve the load positioning performance. This system uses the concept of load motion feedback. To allow the winch operator to interact with the automatic positioning functions, a dedicated control interface is used. The system was implemented and evaluated in DLR’s Air Vehicle Simulator (AVES). Three pilots and one winch operator evaluated the system in different control law and crew task configurations in an offshore hoisting scenario. Handling Qualities (HQs) and pilot workload were evaluated using the Cooper-Harper Rating Scale and NASA Task Load Index respectively. The results show that the system can improve HQs, allowing better task performance and lower workload for the pilot and the winch operator when compared to an unassisted configuration.
{"title":"Evaluation of a Slung Load Control System for Piloted Winch Operations","authors":"T. Jusko, Michael Jones","doi":"10.4050/f-0077-2021-16788","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16788","url":null,"abstract":"\u0000 Helicopter operations with winch suspended loads are highly demanding for the flight crew. Without having a direct view on the load, pilots require assistance from a winch operator for load handling to achieve operational requirements (e.g. precise and safe positioning of a suspended person). An automatic load stabilization and positioning system for winching operations has been designed with the aim to reduce pilot and winch operator workload, damp load pendulum motion and to improve the load positioning performance. This system uses the concept of load motion feedback. To allow the winch operator to interact with the automatic positioning functions, a dedicated control interface is used. The system was implemented and evaluated in DLR’s Air Vehicle Simulator (AVES). Three pilots and one winch operator evaluated the system in different control law and crew task configurations in an offshore hoisting scenario. Handling Qualities (HQs) and pilot workload were evaluated using the Cooper-Harper Rating Scale and NASA Task Load Index respectively. The results show that the system can improve HQs, allowing better task performance and lower workload for the pilot and the winch operator when compared to an unassisted configuration.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"44 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":"124738527","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-0077-2021-16795
S. Fasiello, P. Masarati, M. Jump
This paper presents the results of a pilot-in-the-loop experiment performed to investigate the efficacy of a pilot induced oscillation (PIO) or adverse rotorcraft-pilot coupling (RPC) real-time detection method, to be implemented as an in-cockpit warning system. A test pilot performed a number of simulated flights inside the Heliflight-R simulator at the University of Liverpool. Two handling qualities (HQ) mission task element (MTE) maneuvers were chosen, namely Precision Hover and Lateral Reposition. The baseline dynamics were those of a FLIGHTLAB BO105-like helicopter model, as used in previous tests; changes in rate limits were introduced to induce the pilot-vehicle system (PVS) to be more RPC/PIO prone, and to observe pilot’s adaptation to these variations causing system instabilities during the chosen MTEs. To objectively measure the severity of the PIO encountered during the tests, the PhaseAggression Criterion (PAC) has been used. This method has been developed to allow for real-time PIO detection in order to provide the information inside the cockpit. In addition, pilot subjective ratings were collected, by using the HQs, PIO and Pilot Workload rating scales. Overall, the results show a good correlation between objective and subjective evaluations, and that it is possible to detect PIOs in real-time. The information can be provided to the pilot by means of visual, aural or haptic cues, which is the work the authors are currently carrying out.
{"title":"Evaluation of the Phase-Aggression Criterion for PIO Detection in Real-time ","authors":"S. Fasiello, P. Masarati, M. Jump","doi":"10.4050/f-0077-2021-16795","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16795","url":null,"abstract":"\u0000 This paper presents the results of a pilot-in-the-loop experiment performed to investigate the efficacy of a pilot induced oscillation (PIO) or adverse rotorcraft-pilot coupling (RPC) real-time detection method, to be implemented as an in-cockpit warning system. A test pilot performed a number of simulated flights inside the Heliflight-R simulator at the University of Liverpool. Two handling qualities (HQ) mission task element (MTE) maneuvers were chosen, namely Precision Hover and Lateral Reposition. The baseline dynamics were those of a FLIGHTLAB BO105-like helicopter model, as used in previous tests; changes in rate limits were introduced to induce the pilot-vehicle system (PVS) to be more RPC/PIO prone, and to observe pilot’s adaptation to these variations causing system instabilities during the chosen MTEs. To objectively measure the severity of the PIO encountered during the tests, the PhaseAggression Criterion (PAC) has been used. This method has been developed to allow for real-time PIO detection in order to provide the information inside the cockpit. In addition, pilot subjective ratings were collected, by using the HQs, PIO and Pilot Workload rating scales. Overall, the results show a good correlation between objective and subjective evaluations, and that it is possible to detect PIOs in real-time. The information can be provided to the pilot by means of visual, aural or haptic cues, which is the work the authors are currently carrying out.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"30 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":"125134947","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-0077-2021-16817
Andrew Lavoie
Appropriate consideration of tolerances is critical to the design and manufacture of products that meet customer requirements and defined cost targets. Tolerance analysis is most commonly conducted at the individual part or sub-assembly level utilizing basic stack-up methods (worst-case analysis) to ensure the producibility of the assembled product. A worst-case analysis assumes that each dimension in the stack-up will be manufactured on the extreme end or limit of its assigned tolerance (max or min) in such a way that all tolerances become additive. This usually results in tighter than required drawing tolerances being assigned to guarantee the product can be assembled. Modern day manufacturing processes focus on targeting the nominal dimensional value, so it is safe to assume that a higher number of parts will be produced closer to the nominal value than parts produced at the extreme end of the tolerance range. When evaluating the tolerance stack-up of a larger assembly with many parts additional tolerance analysis methods apply (Root Sum Squared, RSS), and a worst-case analysis becomes more costly and less meaningful. The RSS method of tolerance analysis takes into consideration manufacturing targets and applies normal distribution methods to assess more likely tolerance results, allowing relaxed drawing tolerances to be assigned while still maintaining a high level of confidence in a successful assembly. For analysis of complex systems or installations, tolerance studies using more sophisticated approaches to deal with variation such as Monte Carlo statistical analysis is required. Variational Tolerance Analysis (VTA) tools available today allow a typical Monte Carlo tolerance simulation to be visualized by the designer through 3-dimensional real time manufacturing simulations and sensitivity analysis. This in turn simplifies the development process and allows better identification of tolerance drivers within a large system installation; analysis of the geometric effect of tolerances within the installation; and the ability to quickly iterate the analysis to optimize designs for producibility and lower cost. In this paper, the use of VTA is assessed and quantified to form a business case for further investment by Lockheed Martin. In the course of this work, VTA has been evaluated both before and after final designs were released to manufacturing. Before final designs are released VTA can be used for design optimization (i.e. build before you build simulations), part sequencing studies, or to gain insight into the assembly/installation process enabling advanced planning to take place up front. VTA can also address challenges discovered after final designs have been released to manufacturing and parts are on hand (i.e. during the build) such as: assembly issues, out of spec part disposition, and to inform manufacturing of any special tooling or part rework considerations aiding in corrective action or risk mitigation plans. Cost savings to
{"title":"Lichten Award Paper: Variational Tolerance Analysis (VTA) - Design and Manufacturing Optimization Using Statistical Simulation","authors":"Andrew Lavoie","doi":"10.4050/f-0077-2021-16817","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16817","url":null,"abstract":"\u0000 Appropriate consideration of tolerances is critical to the design and manufacture of products that meet customer requirements and defined cost targets. Tolerance analysis is most commonly conducted at the individual part or sub-assembly level utilizing basic stack-up methods (worst-case analysis) to ensure the producibility of the assembled product. A worst-case analysis assumes that each dimension in the stack-up will be manufactured on the extreme end or limit of its assigned tolerance (max or min) in such a way that all tolerances become additive. This usually results in tighter than required drawing tolerances being assigned to guarantee the product can be assembled. Modern day manufacturing processes focus on targeting the nominal dimensional value, so it is safe to assume that a higher number of parts will be produced closer to the nominal value than parts produced at the extreme end of the tolerance range. When evaluating the tolerance stack-up of a larger assembly with many parts additional tolerance analysis methods apply (Root Sum Squared, RSS), and a worst-case analysis becomes more costly and less meaningful. The RSS method of tolerance analysis takes into consideration manufacturing targets and applies normal distribution methods to assess more likely tolerance results, allowing relaxed drawing tolerances to be assigned while still maintaining a high level of confidence in a successful assembly. For analysis of complex systems or installations, tolerance studies using more sophisticated approaches to deal with variation such as Monte Carlo statistical analysis is required. Variational Tolerance Analysis (VTA) tools available today allow a typical Monte Carlo tolerance simulation to be visualized by the designer through 3-dimensional real time manufacturing simulations and sensitivity analysis. This in turn simplifies the development process and allows better identification of tolerance drivers within a large system installation; analysis of the geometric effect of tolerances within the installation; and the ability to quickly iterate the analysis to optimize designs for producibility and lower cost. \u0000In this paper, the use of VTA is assessed and quantified to form a business case for further investment by Lockheed Martin. In the course of this work, VTA has been evaluated both before and after final designs were released to manufacturing. Before final designs are released VTA can be used for design optimization (i.e. build before you build simulations), part sequencing studies, or to gain insight into the assembly/installation process enabling advanced planning to take place up front. VTA can also address challenges discovered after final designs have been released to manufacturing and parts are on hand (i.e. during the build) such as: assembly issues, out of spec part disposition, and to inform manufacturing of any special tooling or part rework considerations aiding in corrective action or risk mitigation plans. \u0000Cost savings to ","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"70 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":"125265120","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-0077-2021-16749
Lori Basham, Justin C. Blankenship, Andrew Koch
The MH-60S NextGen Gunner Seat (NGS) program was established to address serious endurance and chronic injury issues attributed to the legacy seat. This high priority program proceeded at an accelerated pace to meet the fleet’s needs. The program office recognized the important relationships between endurance, injury, anthropometric accommodation, and ergonomics. This paper documents the program’s approach to addressing aircrew accommodation and ergonomics from requirements generation through fielding of the new seat.
{"title":"Anthropometric Accommodation and Ergonomics in the MH-60S NextGen Gunners Seat","authors":"Lori Basham, Justin C. Blankenship, Andrew Koch","doi":"10.4050/f-0077-2021-16749","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16749","url":null,"abstract":"\u0000 The MH-60S NextGen Gunner Seat (NGS) program was established to address serious endurance and chronic injury issues attributed to the legacy seat. This high priority program proceeded at an accelerated pace to meet the fleet’s needs. The program office recognized the important relationships between endurance, injury, anthropometric accommodation, and ergonomics. This paper documents the program’s approach to addressing aircrew accommodation and ergonomics from requirements generation through fielding of the new seat.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"4 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":"134559643","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-0077-2021-16686
James H. Stephenson, B. Cheung, Nikolas S. Zawodny, D. Sargent, B. Sim, Natasha L. Schatzman
Unmanned Aerial Vehicle (UAV) designs typically have aerodynamic configurations that result in complex aerodynamic and acoustic conditions, such as wing and propeller interaction. In response, the Aerodynamic and Acoustic Rotorprop Test (AART) Program was implemented, a primary objective of which was to determine the aerodynamics and acoustics related to an auxiliary propulsor mounted behind an isolated wing in the National Full-Scale Aerodynamics Complex (NFAC) 40-by 80-Foot Wind Tunnel. Three configurations (no wing, half wing, and full wing) were tested, with conditions including variation of the propeller speed, wind tunnel Mach number, and yaw. The acoustic setup, processing, and analysis are discussed along with the known issues for this complex data set. The interaction of upstream bodies and the resulting substantial increase in acoustic emissions are detailed.
{"title":"Aeroacoustic Measurements from the Aerodynamic and Acoustic Rotorprop Test (AART) in the National Full-Scale Aerodynamics Complex (NFAC) 40- by 80-Foot Wind Tunnel ","authors":"James H. Stephenson, B. Cheung, Nikolas S. Zawodny, D. Sargent, B. Sim, Natasha L. Schatzman","doi":"10.4050/f-0077-2021-16686","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16686","url":null,"abstract":"\u0000 Unmanned Aerial Vehicle (UAV) designs typically have aerodynamic configurations that result in complex aerodynamic and acoustic conditions, such as wing and propeller interaction. In response, the Aerodynamic and Acoustic Rotorprop Test (AART) Program was implemented, a primary objective of which was to determine the aerodynamics and acoustics related to an auxiliary propulsor mounted behind an isolated wing in the National Full-Scale Aerodynamics Complex (NFAC) 40-by 80-Foot Wind Tunnel. Three configurations (no wing, half wing, and full wing) were tested, with conditions including variation of the propeller speed, wind tunnel Mach number, and yaw. The acoustic setup, processing, and analysis are discussed along with the known issues for this complex data set. The interaction of upstream bodies and the resulting substantial increase in acoustic emissions are detailed.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"352 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":"131459700","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-0077-2021-16843
Umberto Saetti, J. Rogers
This paper demonstrates the extension of the harmonic decomposition methodology, originally developed for rotorcraft applications, to the study of the nonlinear time-periodic dynamics of flapping-wing flight. A harmonic balance algorithm based on harmonic decomposition is successfully applied to find the periodic equilibrium and approximate linear time-invariant dynamics about that equilibrium of the vertical and longitudinal dynamics of a hawk moth. These approximate linearized models are validated through simulations against the original nonlinear time-periodic dynamics. Dynamic stability using the linear models is assessed and compared to that predicted using the averaged dynamics. In addition, modal participation factors are computed to quantify the influence of the higher harmonics on the flight dynamic modes of motion. The study shows that higher harmonics play a key role in the overall dynamics of f lapping-wing flight. The higher harmonics are shown to induce a vibrational stabilization mechanism that increases the pitch damping and stiffness while reducing the speed stability. This mechanism results in the stabilization of the pitch oscillation mode and thus of the longitudinal hovering cubic. As such, the findings of this study suggest that if a hovering vehicle is excited by periodic forcing at sufficiently high frequency and amplitude, its hovering flight dynamics may become stable.
{"title":"Linear Time-Invariant Models of the Dynamics of Flapping-Wing Flight","authors":"Umberto Saetti, J. Rogers","doi":"10.4050/f-0077-2021-16843","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16843","url":null,"abstract":"\u0000 This paper demonstrates the extension of the harmonic decomposition methodology, originally developed for rotorcraft applications, to the study of the nonlinear time-periodic dynamics of flapping-wing flight. A harmonic balance algorithm based on harmonic decomposition is successfully applied to find the periodic equilibrium and approximate linear time-invariant dynamics about that equilibrium of the vertical and longitudinal dynamics of a hawk moth. These approximate linearized models are validated through simulations against the original nonlinear time-periodic dynamics. Dynamic stability using the linear models is assessed and compared to that predicted using the averaged dynamics. In addition, modal participation factors are computed to quantify the influence of the higher harmonics on the flight dynamic modes of motion. The study shows that higher harmonics play a key role in the overall dynamics of f lapping-wing flight. The higher harmonics are shown to induce a vibrational stabilization mechanism that increases the pitch damping and stiffness while reducing the speed stability. This mechanism results in the stabilization of the pitch oscillation mode and thus of the longitudinal hovering cubic. As such, the findings of this study suggest that if a hovering vehicle is excited by periodic forcing at sufficiently high frequency and amplitude, its hovering flight dynamics may become stable.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"44 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":"115937312","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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