Proceedings of the Vertical Flight Society 76th Annual Forum最新文献

{"title":"Active and Passive Camber Morphing for Helicopter Rotors towards Performance Improvements in Hover and Vertical Flight","authors":"K. Vidyarthi, R. Breuker, M. Pavel, Y. Zahoor, M. Voskuijl","doi":"10.4050/f-0076-2020-16446","DOIUrl":"https://doi.org/10.4050/f-0076-2020-16446","url":null,"abstract":"\u0000 Rotor morphing has been investigated in the past for improvement of rotor performance, either for reduction of rotor power demand or for vibratory load alleviation. The present study investigates the application of camber morphing for improvement of rotor performance in hover and vertical flight conditions, with a particular focus on the combination of camber morphing systems and variable RPM rotors. Camber morphing utilizes a smooth flap at the trailing edge of the rotor blade to modify the camber of blade airfoil sections without excessive drag penalties. Two different camber morphing systems will be investigated in this study, namely the active and passive systems. Passive camber morphing, which combines camber morphing with the variable speed rotor concept is the unique aspect of camber morphing which will be the primary focus of this study. The active system can be actuated at frequencies higher than 1/rev of the rotor and requires external power input for functioning. The passive system can be controlled only by varying the RPM of the rotor and requires no additional energy input. Therefore, the passive system is expected to show larger net performance benefits. Variable RPM rotors in themselves show potential towards the reduction of rotor power demand but are largely ineffective for low-speed applications. The combination of camber morphing and the variable speed rotor shows larger performance benefits than those obtained from the two technologies independent of each other. The two technologies, when combined in passive camber morphing, can remedy each other’s deficiencies and improve the overall rotor performance. The use of camber morphing shows more benefit for operating points at or near the edge of the flight envelope since the rotor blade sections encounter high average angles of attack for these operating points. Vertical climb and hover at high altitude are examples of flight conditions investigated. Overall, passive camber morphing shows a larger performance benefit as compared to the active system.\u0000","PeriodicalId":293921,"journal":{"name":"Proceedings of the Vertical Flight Society 76th Annual Forum","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122372541","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}

{"title":"Endurance Optimization of a Tandem Helicopter with Variable Speed Rotors and a Spark-Ignition Engine","authors":"M. Bouchard, David Laflamme, David Rancourt, Enrick Laflamme","doi":"10.4050/f-0076-2020-16315","DOIUrl":"https://doi.org/10.4050/f-0076-2020-16315","url":null,"abstract":"\u0000 Rotary unmanned aerial vehicles (R-UAV) are becoming commonplace as a solution for maritime surveillance activities due to their vertical take-off and landing (VTOL) capability. Extending flight duration is thus crucial; one approach is to slow down the rotors in flight, which improves their efficiency. An in-house tandem rotorcraft performance model is used to evaluate the benefits of slowed rotors in endurance flight when used in conjunction with a spark-ignition engine. The performance model is validated using experimental data from flight tests in hover and lowspeed flight. A surrogate-based optimization approach determines the flight and engine speeds required for minimal fuel consumption throughout a typical endurance mission. Payload-Endurance and Payload-Range curves for flights at various payload and fuel capacities show overall benefits. Gains up to 25% and 15% in endurance are possible for f lights at standard and maximum fuel capacity. Range is not impacted negatively and sees gains at maximum fuel capacity. The spark-ignition engine plays a beneficial role as it contributes up to 38% of fuel burn reduction.\u0000","PeriodicalId":293921,"journal":{"name":"Proceedings of the Vertical Flight Society 76th Annual Forum","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128957364","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}

{"title":"Concept for an Aeronautical Design Standard (ADS) - Performance Specification for Autonomy Requirements of Military Air Systems","authors":"J. Preston","doi":"10.4050/f-0076-2020-16318","DOIUrl":"https://doi.org/10.4050/f-0076-2020-16318","url":null,"abstract":"\u0000 This concept for an Aeronautical Design Standard for autonomous systems is methodology to determine the acceptable level of supervision for autonomy in military systems. The level of autonomy is directly related to the level of supervision required for the trust in the autonomous system functionality. The approach defines representative Autonomous Task Elements (ATEs), operational considerations, and levels of autonomy. Each ATE is characterized by an objective, description, and performance standards. Performance standards are expressed as metrics related to the trust in the autonomous behavior and the system’s capability to conduct the ATE. The capability of the autonomous system to meet performance standards is expressed as risk. This risk is compared to specified operational / allowable limits. The corresponding acceptable level of autonomy for the ATE is then determined using the probability of failure to meet the limits. The approach for this concept autonomy ADS parallels ADS 33E-PRF for the assignment of Levels of Handling Qualities based on measurable flight performance characteristics.\u0000","PeriodicalId":293921,"journal":{"name":"Proceedings of the Vertical Flight Society 76th Annual Forum","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128129219","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}

{"title":"Coupled Pitch-Lag Hinge for High Inertia Electric Rotors","authors":"Jean-Paul F. Reddinger","doi":"10.4050/f-0076-2020-16327","DOIUrl":"https://doi.org/10.4050/f-0076-2020-16327","url":null,"abstract":"\u0000 As rotor diameter and inertia increases, the quickness of the thrust response to pilot inputs slows, yielding negative implications to handling qualities and limitations on scaling electric propulsion. This study presents a novel approach to alleviating these scaling effects by introducing a pitch-lag coupled hinge to the root of 40\" and 50\" diameter props. The impacts of chordwise hinge placement and hinge angle are examined and compared to a baseline rigid rotor to provide physical understanding of the rotor dynamics. It is shown that a coupled hinge can be designed to maintain propeller efficiency for a design thrust, while increasing the sensitivity of thrust to rotor speed and the maximum thrust of an RPM-limited rotor. Finally, the dynamic implications of this are tested using a first-order motor model. When a 40\" diameter trimmed rotor is set to max throttle, rotors with a coupled hinge angle achieve a 6% higher thrust in 9% less time. The dynamic response improvement scales favorably when the rotor diameter is increased. For the 50\" diameter rotor, the introduction of pitch-lag coupling reduces the time constant of the rotor’s thrust response by 32%.\u0000","PeriodicalId":293921,"journal":{"name":"Proceedings of the Vertical Flight Society 76th Annual Forum","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117127288","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}

{"title":"T55 Gas Turbine Engine Bleed Band Actuator Housing Re-Design","authors":"Wesley Cass","doi":"10.4050/f-0076-2020-16281","DOIUrl":"https://doi.org/10.4050/f-0076-2020-16281","url":null,"abstract":"\u0000 The continual replacement of the bleed band actuator caused a supply shortage resulting in production work stoppage. A re-design effort restored the actuator housing through rework modification of a sleeve repair. The re-design substantion is presented along with the qualification test and manufacturing process. Significant value engineering savings and increased supply readiness resulted from the re-design effort for the U. S. Army. However, the re-designed sleeved actuator housing became costly and inefficient over time and subsequently stopped. The overhaul discrepancy is still present on the newer T55 gas turbine engine model. A review of new repair technology available identified another solution that does not generate hazardous industrial waste. That solution is cold spray technology. Cold spray solid state additive technology is evaluated for re-design of the housing as comparison to the existing sleeve re-design. Cost decrease and manufacturing efficiency increase are both a result from this evaluation. Two cold spray powders presented are options for the re-design housing. While both powders provide a better overall solution to the sleeve re-design, the cold spray hard coat powder appears to provide improved wear resistance, e.g. 20 times better than hexavalent chrome plating.\u0000","PeriodicalId":293921,"journal":{"name":"Proceedings of the Vertical Flight Society 76th Annual Forum","volume":"118 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114056534","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}

{"title":"Redistributed Pseudoinverse Control Allocation for Actuator Failure on a Compound Helicopter","authors":"Praneet Vayalali, M. McKay, F. Gandhi","doi":"10.4050/f-0076-2020-16292","DOIUrl":"https://doi.org/10.4050/f-0076-2020-16292","url":null,"abstract":"\u0000 The present study focuses on applying a redistributed pseudoinverse control allocation method on a 20,110 lb compound helicopter in order to utilize the redundant control effectors in feedback control pre- and post-actuator failure. A range of tolerable positions for locked-in-place actuator failures is established for the aircraft at a cruise speed of 150 knots. A model following linear dynamic inversion control system is implemented for the nonlinear simulation model. Stability margins, phase delay, and bandwidth evaluated for the longitudinal and lateral axis according to ADS-33E specifications show level 1 for most cases except minimum failed aft actuator position (level 2 stability margin) and maximum failed stabilator (level 3 stability margin). Nonlinear simulations are used to examine the control reconfiguration and the aircraft response for failure in the longitudinal axis (swashplate aft actuator and stabilator) and lateral axis (swashplate lateral actuator and ailerons) demonstrating the capability of the redistributed pseudoinverse method. For certain failures, especially for actuators locked in extreme positions, the post-failure response is considerably degraded (showing limit cycle oscillations, actuator saturation, or sluggish response), which was not evident from the handling qualities metrics evaluated from the extracted linear models.\u0000","PeriodicalId":293921,"journal":{"name":"Proceedings of the Vertical Flight Society 76th Annual Forum","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126577480","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}

{"title":"Automated Component Tracking Technologies for Future Vertical Lift","authors":"R. Bharadwaj, J. Moffatt, Hayley Borck","doi":"10.4050/f-0076-2020-16273","DOIUrl":"https://doi.org/10.4050/f-0076-2020-16273","url":null,"abstract":"\u0000 Over the last decade or more there has been a concerted push to move from on condition to predictive maintenance to improve rotorcraft availability and cost competitiveness of sustainment (Ref. 1-2). The US Army, along with industry partners, have been working on the development of prognostics for complete rotorcraft coverage. It has been identified that accurately capturing maintenance actions is needed to improve the accuracy of prognostics for better component health state awareness. Further to achieve the Army's vision for Zero Maintenance rotorcraft and meet the Maintenance Free Operating Period (MFOP) (Ref. 3) requirements for the Future Vertical Lift (FVL) program, it's essential to have an automated configuration management system. To help meet these objectives, the Army and Honeywell are working on the Rotorcraft Automated Component Tracking (RACT) Science and Technology (S&T) development program. This paper discusses the research being conducted to enable the Army's RACT concept done by the Honeywell team and the CCDC AvMC. It identifies the current state of RACT technologies and challenges of integrating such technologies into the rotorcraft environment.\u0000","PeriodicalId":293921,"journal":{"name":"Proceedings of the Vertical Flight Society 76th Annual Forum","volume":"116 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127018010","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}

{"title":"Working Group on eVTOL Noise Assessment","authors":"D. Josephson","doi":"10.4050/f-0076-2020-16405","DOIUrl":"https://doi.org/10.4050/f-0076-2020-16405","url":null,"abstract":"Acceptance of close-proximity eVTOL aircraft depends on public perception that they are quiet in relation to the environment. When they are audible, their influence on community soundscapes must not be intrusive. To solve for that, measurement of \"quiet\" is needed using a physiological model of hearing rather than a sound pressure measurement intended for entirely different applications. While we are starting with baseline noise metrics using earlier methods, we propose a cooperative effort to coordinate development, testing and education about techniques that correlate better with perception of quiet. Two major differences are proposed between current practice and future methods: measure vehicle loudness rather than sound pressure, and measure operations with respect to ambient rather than to meet an arbitrary level for a given land use. These are not new concepts, but require computational resources that until recently were too expensive to be practical.","PeriodicalId":293921,"journal":{"name":"Proceedings of the Vertical Flight Society 76th Annual Forum","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127867449","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}

{"title":"Comparisons of Fully Coupled Aeroelastic Fuselage Simulations to UH-60A Airloads Program Data","authors":"N. Reveles, E. Blades, T. Pierce, H. Yeo","doi":"10.4050/f-0076-2020-16445","DOIUrl":"https://doi.org/10.4050/f-0076-2020-16445","url":null,"abstract":"\u0000 An aeroelastic coupling framework is applied to the UH-60A platform to examine aerodynamic-induced vibrations at four advance ratios spanning the flight envelope. Both one-way and two-way aeroelastic coupling results are examined at each condition. The two-way coupled results are observed to generally predict closer values to measured flight test data on the lifting surfaces of the empennage, and a less pronounced effect is seen in stiffer, nonlifting structure. The effect of aeroelastic coupling subiterations is examined, and they are found to further refine the two-way coupled results, generally improving prediction quality.\u0000","PeriodicalId":293921,"journal":{"name":"Proceedings of the Vertical Flight Society 76th Annual Forum","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127823190","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}

{"title":"Validation and Analysis of Aeroelastic Simulations of the UH-60A Rotor from Pre- to Post-stall Flight Conditions","authors":"F. Richez, Camille Castells, French Aerospace Lab, Amanda L. Grubb, Marilyn J. Smith, R. Jain","doi":"10.4050/f-0076-2020-16469","DOIUrl":"https://doi.org/10.4050/f-0076-2020-16469","url":null,"abstract":"\u0000 Recently aeroelastic simulations of rotors in dynamic stall conditions based on a weak coupling between CFD (Computational Fluid Dynamics) and CA (Comprehensive Analysis) codes have demonstrated their prediction capabilities with good agreement with experimental data, despite the high level of complexity of this phenomenon. These recent studies resulted from a long-term effort to define the requirements, in terms of methods and models, necessary to capture of the complex physics of dynamic stall in rotor environment. However, these previous studies were performed on single test points. In this paper a range of six flight conditions of the UH-60A rotor from pre- to post-stall conditions with three different numerical approaches was examined. This approach permits not only the validation of the numerical methods on a larger set of data, but it provides a thorough analysis of the ability of the numerical methods to predict the onset of stall as the rotor thrust progressively increases. The numerical results show very good agreement on airloads, trim control angles and rotor power. More discrepancies are observed in structural loads although the global trend is captured. The flowfield visualizations from the simulations give a better insight into several regions of flow separation, their evolutions as the rotor thrust increases and the role of Blade Vortex Interaction (BVI) in the trigger of the different stall events.\u0000","PeriodicalId":293921,"journal":{"name":"Proceedings of the Vertical Flight Society 76th Annual Forum","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122406992","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}