Pub Date : 2021-05-10DOI: 10.4050/f-0077-2021-16755
G. Olivares, Domenic L. Barsotti, P. Hooijdonk, L. Gomez, Vincent Robinson, Michiel Unger
Occupant Safety must be an integral part of the overall technical and management processes associated with the design, development, and operation of Urban Air Mobility (UAM) systems. Nowadays the crashworthiness design for aerospace applications under 14 CFR §§ *.561 and *.562 only address the dynamic response of the seat and restraint system during emergency landing conditions. In order to improve the survivability rate of occupants an integrated safety approach is required during the design, development, and operation of Urban Air Mobility (UAM) systems. In this paper, a typical Electric Vertical Take-Off and Landing (eVTOL) under two loading conditions as per 14 CFR §§ 27.727(a) and 27.562(b)(1) is evaluated. For this, a multibody model was developed and optimized using adaptive multivariable optimization algorithms. The results show that multibody and optimization tools in combination with robust design methodologies can significantly reduce the development and certification efforts for eVTOL vehicles.
{"title":"Integrated Occupant Safety for Urban Air Mobility Applications","authors":"G. Olivares, Domenic L. Barsotti, P. Hooijdonk, L. Gomez, Vincent Robinson, Michiel Unger","doi":"10.4050/f-0077-2021-16755","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16755","url":null,"abstract":"\u0000 Occupant Safety must be an integral part of the overall technical and management processes associated with the design, development, and operation of Urban Air Mobility (UAM) systems. Nowadays the crashworthiness design\u0000for aerospace applications under 14 CFR §§ *.561 and *.562 only address the dynamic response of the seat and restraint system during emergency landing conditions. In order to improve the survivability rate of occupants an\u0000integrated safety approach is required during the design, development, and operation of Urban Air Mobility (UAM) systems. In this paper, a typical Electric Vertical Take-Off and Landing (eVTOL) under two loading conditions as\u0000per 14 CFR §§ 27.727(a) and 27.562(b)(1) is evaluated. For this, a multibody model was developed and optimized using adaptive multivariable optimization algorithms. The results show that multibody and optimization tools in\u0000combination with robust design methodologies can significantly reduce the development and certification efforts for eVTOL vehicles.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"31 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":"116566868","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-0077-2021-16811
K. Bartie
With an overall company lifespan of only four years, Vertol Aircraft Corporation continued the tandem-rotor helicopter legacy of its predecessor, Piasecki Helicopter Corp., as well as research, development and testing of other V/STOL aircraft and technologies while concurrently designing two medium-lift transport helicopters that are still in worldwide use and/or production today. During this short timeframe, the company finalized production and deliveries of the H-21C Shawnee/V-44 for the US Army and international customers. The company designed and flew the world’s first tilt-wing VTOL, the NACA/Army/Navy/Vertol VZ-2A. Application of T53 and T58 turbine powerplants led to twin-turbine engine trials and flight tests with experimental H-21 variants. With Vertol’s in-theater customer support, the French Army and Navy introduced the H-21 into combat in Algeria which included the early use of armed, troop-carrying helicopters. The design, test and successful US and worldwide demonstrations of the privately-funded Vertol 107 led to development and certification of the 107-II airliner version and follow-on military transports as the Boeing H-46 Sea Knight. The contract to design and build the YHC-1B was won by Vertol in 1959 and led to the enduring Boeing H-47 Chinook.
{"title":"History of the Vertol Aircraft Corporation, 1956 to 1960 ","authors":"K. Bartie","doi":"10.4050/f-0077-2021-16811","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16811","url":null,"abstract":"\u0000 With an overall company lifespan of only four years, Vertol Aircraft Corporation continued the tandem-rotor helicopter legacy of its predecessor, Piasecki Helicopter Corp., as well as research, development and testing of other V/STOL aircraft and technologies while concurrently designing two medium-lift transport helicopters that are still in worldwide use and/or production today. During this short timeframe, the company finalized production and deliveries of the H-21C Shawnee/V-44 for the US Army and international customers. The company designed and flew the world’s first tilt-wing VTOL, the NACA/Army/Navy/Vertol VZ-2A. Application of T53 and T58 turbine powerplants led to twin-turbine engine trials and flight tests with experimental H-21 variants. With Vertol’s in-theater customer support, the French Army and Navy introduced the H-21 into combat in Algeria which included the early use of armed, troop-carrying helicopters. The design, test and successful US and worldwide demonstrations of the privately-funded Vertol 107 led to development and certification of the 107-II airliner version and follow-on military transports as the Boeing H-46 Sea Knight. The contract to design and build the YHC-1B was won by Vertol in 1959 and led to the enduring Boeing H-47 Chinook.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"147 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":"121719678","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-0077-2021-16907
Max G. Taylor, Massimiliano Otto, Josh Ehlinger, Jeff Imig
The development lifecycle of software for aircraft systems is dominated by safety and cybersecurity considerations. Software development processes and tools are being continually updated to improve and optimize these critical considerations. While the processes and tools have received continuous updates, changes to the programming languages employed for developing safe and secure software for aircraft systems have evolved at a much slower pace. As of 2017, 63% of Department of Defense (DoD) systems were developed with the C/C++ programming languages (Ref. 1). This is representative of the dominant position that software developed with the C/C++ programming language has in existing aircraft avionics and mission systems. The C language has been around since the 1970s and C++ was first introduced in the late 1980s. These languages are very stable and their extensive supporting ecosystems have helped grow and maintain their expansive use in aerospace and many other domains. The longevity of C/C++ has enabled language, usage, process, and tool tailoring so that the software built with C/C++ can be certified for use in both safety-critical and security-critical environments. The C/C++ ecosystems are stable and mature but have properties that make writing software embedded in aircraft avionics very challenging.
{"title":"Rust for Safe and Secure Avionics and Mission System Software","authors":"Max G. Taylor, Massimiliano Otto, Josh Ehlinger, Jeff Imig","doi":"10.4050/f-0077-2021-16907","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16907","url":null,"abstract":"\u0000 The development lifecycle of software for aircraft systems is dominated by safety and cybersecurity considerations. Software development processes and tools are being continually updated to improve and optimize these critical considerations. While the processes and tools have received continuous updates, changes to the programming languages employed for developing safe and secure software for aircraft systems have evolved at a much slower pace. \u0000\u0000As of 2017, 63% of Department of Defense (DoD) systems were developed with the C/C++ programming languages (Ref. 1). This is representative of the dominant position that software developed with the C/C++ programming language has in existing aircraft avionics and mission systems. The C language has been around since the 1970s and C++ was first introduced in the late 1980s. These languages are very stable and their extensive supporting ecosystems have helped grow and maintain their expansive use in aerospace and many other domains. The longevity of C/C++ has enabled language, usage, process, and tool tailoring so that the software built with C/C++ can be certified for use in both safety-critical and security-critical environments. \u0000\u0000The C/C++ ecosystems are stable and mature but have properties that make writing software embedded in aircraft avionics very challenging. \u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"62 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":"122105857","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-0077-2021-16706
H. Denton, Hao Kang, Moble Benedict, Grant McCurdy
This paper discusses the flight testing and system identification of a compact, re-configurable, rotary-wing micro air vehicle concept capable of sustained hover and could potentially be launched from a 40mm grenade launcher. By launching these energy-constrained platforms to a target area, the mission range could be significantly improved. The vehicles used in the paper has a mass of 345 grams. The vehicle design features coaxial rotors with foldable blades, and a thrust-vectoring mechanism for pitch and roll control. Yaw control was accomplished with a specialized counterrotating motor system composed of two independently controlled motors. A comprehensive set of flight experiments were performed to excite the longitudinal, lateral, directional, and heave modes of the vehicle. A linearized statespace model was derived from the flight test data. The model showed that lateral and longitudinal dynamic modes were decoupled from each other and from the other modes of the vehicle. Due to the axisymmetric nature the vehicle design, the longitudinal and lateral stability and control coefficients and their eigenvalues were nearly identical. All of the aerodynamic damping terms were negative and stabilizing except for the pitch and roll acceleration modes. These two unstable modes necessitated the need for pitch and roll feedback control. The final flight dynamics model was compared against flight test data for each state, and the model shown good agreement with the experimental data.
{"title":"System Identification of a Thrust-vectoring, Coaxial-rotor-based Gun-launched Micro Air Vehicle in Hover","authors":"H. Denton, Hao Kang, Moble Benedict, Grant McCurdy","doi":"10.4050/f-0077-2021-16706","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16706","url":null,"abstract":"\u0000 This paper discusses the flight testing and system identification of a compact, re-configurable, rotary-wing micro air vehicle concept capable of sustained hover and could potentially be launched from a 40mm grenade launcher. By launching these energy-constrained platforms to a target area, the mission range could be significantly improved. The vehicles used in the paper has a mass of 345 grams. The vehicle design features coaxial rotors with foldable blades, and a thrust-vectoring mechanism for pitch and roll control. Yaw control was accomplished with a specialized counterrotating motor system composed of two independently controlled motors. A comprehensive set of flight experiments were performed to excite the longitudinal, lateral, directional, and heave modes of the vehicle. A linearized statespace model was derived from the flight test data. The model showed that lateral and longitudinal dynamic modes were decoupled from each other and from the other modes of the vehicle. Due to the axisymmetric nature the vehicle design, the longitudinal and lateral stability and control coefficients and their eigenvalues were nearly identical. All of the aerodynamic damping terms were negative and stabilizing except for the pitch and roll acceleration modes. These two unstable modes necessitated the need for pitch and roll feedback control. The final flight dynamics model was compared against flight test data for each state, and the model shown good agreement with the experimental data.\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":"125862220","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-0077-2021-16881
Nicolas Jäckel, J. Andert, Abdulsamed Karaduman, C. Granrath, Bernhard Rumpe, L. Wachtmeister
Ground-bound transport systems in major cities are increasingly encountering their limits. Vertical Take-Off and Landing systems, in short VTOL systems, possibly autonomous and electrified, are a promising way to utilize urban space for public transportation. In this context, the application of the Compositional Unified system-Based Engineering (CUBE) methodology, enables the use of Model-Based Systems Engineering (MBSE) to develop suitable VTOLs. This methodology can be used to move from abstract artifacts to concrete architecture and from system to subsystem development. In this paper, the CUBE methodology is presented using a feature-driven specification to demonstrate its general applicability. The model-based description of the System of Interest (SoI, i.e., the VTOL system) from an abstract use case to a technical architecture is exemplified using three features. This methodology approaches the creation of system- and feature-based models with a tailored level of abstraction to better manage complexity.
{"title":"Feature-Driven Specification of VTOL Air-Taxis with the Use of the Model-Based System Engineering (MBSE) Methodology CUBE","authors":"Nicolas Jäckel, J. Andert, Abdulsamed Karaduman, C. Granrath, Bernhard Rumpe, L. Wachtmeister","doi":"10.4050/f-0077-2021-16881","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16881","url":null,"abstract":"\u0000 Ground-bound transport systems in major cities are increasingly encountering their limits. Vertical Take-Off and Landing systems, in short VTOL systems, possibly autonomous and electrified, are a promising way to utilize urban space for public transportation. In this context, the application of the Compositional Unified system-Based Engineering (CUBE) methodology, enables the use of Model-Based Systems Engineering (MBSE) to develop suitable VTOLs. This methodology can be used to move from abstract artifacts to concrete architecture and from system to subsystem development. In this paper, the CUBE methodology is presented using a feature-driven specification to demonstrate its general applicability. The model-based description of the System of Interest (SoI, i.e., the VTOL system) from an abstract use case to a technical architecture is exemplified using three features. This methodology approaches the creation of system- and feature-based models with a tailored level of abstraction to better manage complexity.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"46 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":"121717517","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-0077-2021-16739
Christopher J. Silva, W. Johnson
A toolchain and process for conceptual design of VTOL rotorcraft, employing low- and mid-fidelity tools is presented. The approach is capable of providing more quantitatively-credible trades between noise, size, and cost metrics than the methods commonly used for conceptual design. In addition to a general conceptual design tool, the approach employs comprehensive analysis for trim, blade motion, and airloads; these are then used by acoustic analysis software to develop source sound, propagate it, and calculate noise metrics. A key aspect of the approach is flexibility to assess varied aircraft types and different technologies and design features. Vehicles are sized using a representative Urban Air Mobility design mission. Demonstration cases are presented for a single main rotor helicopter, quadrotor, sideby-side helicopter, and lift+cruise aircraft. Noise metrics used for demonstration are the FAA/EASA certification Effective Perceived Noise Levels for takeoff, flyover, and approach. The concept aircraft in this study are shown to achieve reductions in noise relative the initial design points, with changes in mission performance and cost as a consequence. Many of the designs are predicted to be tens of EPNdB quieter in the certification metrics than existing helicopters.
{"title":"Practical Conceptual Design of Quieter Urban VTOL Aircraft","authors":"Christopher J. Silva, W. Johnson","doi":"10.4050/f-0077-2021-16739","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16739","url":null,"abstract":"\u0000 A toolchain and process for conceptual design of VTOL rotorcraft, employing low- and mid-fidelity tools is presented. The approach is capable of providing more quantitatively-credible trades between noise, size, and cost metrics than the methods commonly used for conceptual design. In addition to a general conceptual design tool, the approach employs comprehensive analysis for trim, blade motion, and airloads; these are then used by acoustic analysis software to develop source sound, propagate it, and calculate noise metrics. A key aspect of the approach is flexibility to assess varied aircraft types and different technologies and design features. Vehicles are sized using a representative Urban Air Mobility design mission. Demonstration cases are presented for a single main rotor helicopter, quadrotor, sideby-side helicopter, and lift+cruise aircraft. Noise metrics used for demonstration are the FAA/EASA certification Effective Perceived Noise Levels for takeoff, flyover, and approach. The concept aircraft in this study are shown to achieve reductions in noise relative the initial design points, with changes in mission performance and cost as a consequence. Many of the designs are predicted to be tens of EPNdB quieter in the certification metrics than existing helicopters. \u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"32 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":"124888941","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-0077-2021-16891
P. Darmstadt, Mihir Mistry, Andrew Arkebauer, Allan Beiderman, Ephraim Chen, C. Dillard, Sheevangi Pathak
The objective of the current work was to develop an all-electric distributed propulsion and flight control (DPFC) architecture that will have no more than 10-9 catastrophic failures per flight hour (pfh). The DPFC architecture was broken into four system design teams, the (i) electrical power and distribution system, (ii) drive and power system, (iii) thermal management system (TMS), and (iv) flight control system (FCS). System designs were updated and iterated upon, working with reliability and safety analysis teams, to develop compliant designs. The firm designs were reflected in a preliminary system safety assessment (PSSA) for initial verification of compliance. Additionally, design and analysis excursions are presented in which aircraft attributes were modified to investigate sensitivities to propulsion type, number of rotors, and control schemes. Excursion results found that all aircraft evaluated likely have paths to comply with the stringent, probabilistic catastrophic failure criteria. However, S&C models showed large power transients that must be addressed and PSSA results show that future work is needed in single load path structures, high voltage power storage and distribution, and in motor/rotor overspeed protection.
{"title":"Distributed Electric Propulsion and Flight Control Concept to Meet EASA SC-VTOL-01 10-9 Catastrophic Failure Criteria","authors":"P. Darmstadt, Mihir Mistry, Andrew Arkebauer, Allan Beiderman, Ephraim Chen, C. Dillard, Sheevangi Pathak","doi":"10.4050/f-0077-2021-16891","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16891","url":null,"abstract":"\u0000 The objective of the current work was to develop an all-electric distributed propulsion and flight control (DPFC) architecture that will have no more than 10-9 catastrophic failures per flight hour (pfh). The DPFC architecture was broken into four system design teams, the (i) electrical power and distribution system, (ii) drive and power system, (iii) thermal management system (TMS), and (iv) flight control system (FCS). System designs were updated and iterated upon, working with reliability and safety analysis teams, to develop compliant designs. The firm designs were reflected in a preliminary system safety assessment (PSSA) for initial verification of compliance. Additionally, design and analysis excursions are presented in which aircraft attributes were modified to investigate sensitivities to propulsion type, number of rotors, and control schemes. Excursion results found that all aircraft evaluated likely have paths to comply with the stringent, probabilistic catastrophic failure criteria. However, S&C models showed large power transients that must be addressed and PSSA results show that future work is needed in single load path structures, high voltage power storage and distribution, and in motor/rotor overspeed protection.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"51 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":"124808306","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-0077-2021-16760
James R. Sutherland, A. Datta
This paper covers the design, fabrication, testing, and modeling of a family of Froude-scale tiltrotor blades. They are designed with the objective of gaining a fundamental understanding of the impact of a swept-tip on tiltrotor whirl flutter. The goal of this paper is to describe the development the blades needed for this purpose. The rotor is three bladed with a diameter of 4.75 feet. The blades have a VR-7 profile, chord of 3.15 inches, and linear twist of-37° per span. The swept-tip blades have a sweep of 20° starting at 80% R. The blade properties are loosely based on the XV-15 design. A CATIA and Cubit based high-fidelity 3-D finite element model is developed. It accurately represents the fabricated blade and is analyzed with X3D. Experiments in a vacuum chamber were carried out to prove the structural integrity of the blades. Measured frequencies and strains were validated with X3D predictions proving the fidelity of the 3-D model. Thus, even though the wind tunnel facilities were closed due to COVID-19, hover and forward flight calculations for the blade stress could be performed numerically, using the high-fidelity 3-D structural model. The results prove the blades have sufficient structural integrity and stress margins to allow for wind tunnel testing.
{"title":"Fabrication, Testing, and 3-D Comprehensive Analysis of Swept Tip Tiltrotor Blades","authors":"James R. Sutherland, A. Datta","doi":"10.4050/f-0077-2021-16760","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16760","url":null,"abstract":"\u0000 This paper covers the design, fabrication, testing, and modeling of a family of Froude-scale tiltrotor blades. They are designed with the objective of gaining a fundamental understanding of the impact of a swept-tip on tiltrotor whirl flutter. The goal of this paper is to describe the development the blades needed for this purpose. The rotor is three bladed with a diameter of 4.75 feet. The blades have a VR-7 profile, chord of 3.15 inches, and linear twist of-37° per span. The swept-tip blades have a sweep of 20° starting at 80% R. The blade properties are loosely based on the XV-15 design. A CATIA and Cubit based high-fidelity 3-D finite element model is developed. It accurately represents the fabricated blade and is analyzed with X3D. Experiments in a vacuum chamber were carried out to prove the structural integrity of the blades. Measured frequencies and strains were validated with X3D predictions proving the fidelity of the 3-D model. Thus, even though the wind tunnel facilities were closed due to COVID-19, hover and forward flight calculations for the blade stress could be performed numerically, using the high-fidelity 3-D structural model. The results prove the blades have sufficient structural integrity and stress margins to allow for wind tunnel testing.\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":"130073496","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-0077-2021-16830
Praneet Vayalali, F. Gandhi, M. McKay
The present study provides a comparison of an adaptive versus a robust baseline pseudoinverse control allocation method on a 20,110 lb compound helicopter post-actuator failure. Failure scenarios such as locking of the main rotor swashplate actuators and aerosurface actuators are taken into consideration in forward flight. A range of tolerable positions for locked-in-place actuator failures is established for the aircraft at a cruise speed of 150 knots. A full authority model following linear dynamic inversion control architecture is implemented for the nonlinear simulation model. Stability margins, phase delay, bandwidth, and disturbance rejection specifications for the aircraft were evaluated under different actuator failures with adaptive and robust control allocations. Nonlinear simulations are used to examine the benefits and drawbacks of an adaptive and robust control allocation schemes when the aircraft is subjected to different actuator failure at their extreme positions.
{"title":"Fault-Tolerant Control Allocation on a Compound Helicopter in Cruise","authors":"Praneet Vayalali, F. Gandhi, M. McKay","doi":"10.4050/f-0077-2021-16830","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16830","url":null,"abstract":"\u0000 The present study provides a comparison of an adaptive versus a robust baseline pseudoinverse control allocation method on a 20,110 lb compound helicopter post-actuator failure. Failure scenarios such as locking of the main rotor swashplate actuators and aerosurface actuators are taken into consideration in forward flight. A range of tolerable positions for locked-in-place actuator failures is established for the aircraft at a cruise speed of 150 knots. A full authority model following linear dynamic inversion control architecture is implemented for the nonlinear simulation model. Stability margins, phase delay, bandwidth, and disturbance rejection specifications for the aircraft were evaluated under different actuator failures with adaptive and robust control allocations. Nonlinear simulations are used to examine the benefits and drawbacks of an adaptive and robust control allocation schemes when the aircraft is subjected to different actuator failure at their extreme positions.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"64 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":"130490401","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-0077-2021-16872
Francisco Javier., S. Roncero, M. Reyes
Increasing attention is being paid recently to eVTOL (electric Vertical Take-Off and Landing) vehicles for different applications, such as Search and Rescue. Convertible aircraft such as tilt-rotors seem to be one of the most promising concepts. The dynamics modeling and simulation of these vehicles is very challenging due to their wide flight envelope (from hovering to horizontal flight) and to the reduced amount of available data. This paper presents a model for the dynamics of a Bi-Rotor Convertible Aircraft, the ProVANT-EMERGENTIa, with a general formulation of the forces and moments acting over it. The equations are simplified to determine longitudinal flight trim conditions using wind tunnel identified aerodynamic and propulsive models. Trimmable flight envelope maps were successfully calculated considering the aircraft state variables (flight path angle, airspeed, and angle of attack) and the longitudinal control inputs (control surfaces deflection, propeller orientation, and throttle lever position). The flight envelope was found to be limited either by the saturation of the control surfaces deflection when the pitch moments were too large, or by the throttle lever when the propeller air incidence angle was too low. The size and shape of the envelope was impacted by the flight path angle: more limited for climb conditions due to the excess of Thrust demanded and of the greater pitch moments involved; less restricted for descents because of the opposite reasons.
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