Proceedings of the Vertical Flight Society 77th Annual Forum最新文献

{"title":"Does Scatter Matter? Improved Understanding of UH-60A Wind Tunnel Rotor Measurements Using Data-Driven Clustering and CREATE-AV Helios","authors":"M. Ramasamy, T. Norman, R. Jain","doi":"10.4050/f-0077-2021-16721","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16721","url":null,"abstract":"\u0000 A data-driven clustering algorithm based on proper orthogonal decomposition was applied to assess the scatter found in the UH-60A wind tunnel airloads measurements. Upon verifying the capability of the algorithm, pushrod loads, blade surface pressure, sectional loads, and torsional moments were analyzed. Spatial eigenmodes resulting from the decomposition provided the optimal basis; projection of the individual cycles on to the high singular value modes allowed visualizing the statistical distribution of data over the entire azimuth. While not all cases showed furcation in the data, bimodal distribution was found in the high thrust cases, where statistically normal distribution is generally assumed. Consequent clustering of the measured cycles produced excellent correlation among clusters found in the pushrod loads, blade surface pressure, and torsional moment that suggest a common source for furcation in the data. The cycles assigned to one group repeatedly showed distinguishable variations from the other group in terms of the presence/absence of a dynamic stall vortex, azimuthal occurrence of stall, chordwise location of separation and reattachment etc. When one of the cluster is smaller in size compared to the other, the conventional phase-average obscured all the intricate features even when the loads are substantially higher than the larger cluster. In general, clustering the data set when warranted showed not only higher peak loads but also lower variance for both the clusters across the entire azimuth compared to the conventional simple phase-average results. Computational simulations were conducted using CREATETM-AV Helios towards understanding the underlying flow field. Misjudged earlier as under/over-predictive when compared with the simple phase-average data, Helios results consistently showed significantly improved correlation with the smaller of the two clusters. Combining the clustered results and the flow visualization provided by Helios, aperiodicity in the spatial location and the strength of both the trim tab vortices and tip vortices have also been hypothesized as potential sources of furcation.\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":"114979028","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":"Floyd Carlson: The Legacy and Contributions of One of America's Greatest Rotary Wing Test Pilots","authors":"Paul J. Fardink","doi":"10.4050/f-0077-2021-16810","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16810","url":null,"abstract":"\u0000 Floyd Carlson was a true pioneer and major contributor in the early development and testing of a broad-range of cutting-edge vertical flight aircraft. His contributions are numerous. Starting with the birth of Bell Helicopter in Gardenville, New York (1942-1945), he performed the first flight of every helicopter Bell designed and built until 1960. His biography mirrors the early history of Bell Helicopter. During this time, Carlson became one of the most experienced and renowned helicopter test pilots in the world, testing aircraft which included the Model 30 (1942); Model 47 (1945); HSL-1 Tandem Rotor Helicopter (1953); XV-3 (1955), forerunner of the XV-15 and V-22 Osprey tiltrotors; and XH-40 (1956), prototype of the iconic UH-1 “Huey.” Floyd Carlson’s passion for aviation began with the guidance of his older brother Milton, whose tragic accident and death left an enduring impact on Floyd’s life as he continued to develop and master the techniques of vertical flight.\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":"115169955","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":"Sustaining Performance and Vigilance during Extended Unmanned Aerial System Operations","authors":"A. Kelley, Amanda M Hayes, Ryan Mackie","doi":"10.4050/f-0077-2021-16751","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16751","url":null,"abstract":"\u0000 Current scheduling of unmanned aerial system (UAS) operators often allows for 8 hour shifts, where operators are typically exposed to low event rate tasks, thus leading to the occurrence of underload. While a long, rich history of vigilance research exists, few studies have examined the threshold at which performance decrements occur in UAS operators in operational settings and the utility of strategies to mitigate vigilance and performance decrements. This study evaluated the performance thresholds relative to time-on-task during a 4 hour simulated UAS mission. Additionally, this study evaluated the effectiveness of countermeasure strategies (secondary task and ambient lighting) on sustaining performance and vigilance during simulated UAS missions. Finally, the study demonstrated patterns of psychophysiological indicators of operator states (comparing high and low workload). Findings suggest that performance begins to decline after 15 minutes on task and plateaus by 45 minutes on task for both workload conditions. There was insufficient evidence to support any of the countermeasures, yet patterns in EEG are consistent with past findings regarding shifts in perceived workload.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"15 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":"123090472","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":"Minimum Weight Design of a Two Speed Dual Clutch Offset Compound Gear Transmission for Rotorcraft Applications","authors":"H. Desmidt, Zhisheng Ai","doi":"10.4050/f-0077-2021-16888","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16888","url":null,"abstract":"\u0000 This paper develops a design code for sizing the major components of a two speed, dual clutch OCG transmission for rotorcraft applications. Furthermore, this design code is integrated into a single main rotor helicopter sizing model to assess any overall system-level performance benefits offered by the two speed transmission. The results of this study show that the two speed variant will always be heavier that the single speed baseline for a given maximum design payload. The results also show that the combined weight of multiple smaller OCG units placed upstream from the combiner stage are significantly lighter than a single OCG located after the combiner. Finally, the results also show that, despite the added weight due to the OCG transmission, the best two speed variant achieved a 20% increase in flight range compared to the single speed baseline carrying the same maximum payload. Hence, the added weight and complexity of the two speed OCG transmission looks like it can indeed \"buy it's way onboard\".\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"59 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":"116794749","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":"The Search for an Ideal Bearingless Main Rotor (BMR) Design ","authors":"D. Schrage","doi":"10.4050/f-0077-2021-16735","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16735","url":null,"abstract":"\u0000 The Main Rotor Hub is the design centerpiece for helicopters and other forms of rotorcraft. It has been a very complex mechanical system design in the past, especially for fully articulated rotor systems. Two major efforts have been made to reduce this complexity. First, was the introduction of elastomeric bearings and dampers which have freed articulated rotor hubs from liquid lubrication and extreme mechanical complexity. This has made them economically feasible for designers and manufacturers of articulated helicopters, such as Boeing and Sikorsky in the U.S; Airbus and Leonardo in Europe; and MIL in Russia. However, the major progress in main rotor hubs has been the continuous movement \"and search\" toward the ideal hingeless and/or bearingless main rotor hubs. Designing the \"Ideal Bearingless Main Rotor (BMR)\" hub has been akin to seeking the \"holy grail.\" One outside critic of the progress made toward the \"Ideal BMR\" over the years has been Thomas A. Hanson, who was involved in early designs of the Lockheed hingeless and bearingless rotor hubs in the 1960s. Having tried to go on his own after Lockheed failed and abandoned their hingeless and baringless rotor hubs, e.g. the XH-51A and the AH-56A Cheyenne, Tom revisited the status of rotorcraft hub design in the 1990s. However, due to the \"not invented here\" syndrome no major helicopter/rotorcraft manufacturer picked up on his innovative solutions. Helicopter/rotorcraft design engineers, especially those addressing aeroelasticity and dynamics, are a very small element in industry and government engineering organizations. The author of this paper was one of these and has been involved in developing, assessing and evaluating helicopter/rotorcraft designs for almost 50 years, e.g. UTTAS, AAH, AH-1 IRB, CH-47D, MDX, OH-58D, and LHX/RAH-66, along with accident investigations. He has also been the Georgia Tech Rotorcraft Design Professor from 1984 to 2019, where he taught and evaluated student design teams. In addition, his D.Sc. research and dissertation thesis under Dr. David A. Peters in 1978 (Schrage, D.P., \"Effect of Structural Parameters on the Flap-Lag Forced response of a Rotor Blade in Forward Flight\") shed new light on the tradeoffs between rotor loads and stability by developing an eigenvalue and modal decomposition approach. This included the evaluation of the Boeing and Sikorsky UTTAS bearingless tail rotors. This paper will review this search for the Ideal BMR and identify the importance it will play in future BMR designs which will be Cyber Physical Vehicle Systems (CPVS) to meet and satisfy the safety and design requirements of these new complex electrical, mechanical and adaptive control systems.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121049486","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":"Prediction of Motion Sickness Onset for Vertical Lift Applications ","authors":"P. Petit","doi":"10.4050/f-0077-2021-16748","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16748","url":null,"abstract":"\u0000 It is foreseen that in the upcoming application of (electric) urban air taxis, the comfort of ride and especially the experience of motion sickness will play a vital role for acceptance amongst passengers and therefore economic success of these vehicles. For this reason accurate motion sickness prediction models are needed, which later can be employed for e.g. kinetosis-low trajectory generation. Established motion sickness models like the ISO 2631 standard however only take into account the vertical translational axis and no rotational axis. For this reason, the 6-DoF Kamiji motion sickness model is selected and modified in order to circumvent unsatisfactory prediction results with this model. Subsequently the parameters of this model are retuned by employing an optimization approach based on published experimental data. It is then shown that with this approach, the modified Kamiji model is better suited for predicting the motion sickness results of this dataset. In the future, this model shall be tested and validated via a series of flight tests with test subjects in DLR’s BO-105 helicopter.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"148 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":"123465905","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":"Aeroacoustic Analysis of Asymmetric Lift-Offset Helicopter in Forward Flight","authors":"Paulo Arias, J. Baeder, Y. Jung","doi":"10.4050/f-0077-2021-16690","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16690","url":null,"abstract":"\u0000 In recent years, the University of Maryland has worked on an asymmetric lift-offset compound helicopter. The configuration consists of a single main rotor helicopter with the addition of two key ways to increase the forward speed: a stubbed wing on the retreating fuselage side, and a slowed down rotor. Experiments and simulations have shown that the novel concept provides improved thrust potential and lift-to-drag ratios in high-speed forward flight. This study aims to determine whether the asymmetric lift-offset configuration also provides aeroacoustic benefits in forward flight in addition to its aerodynamic advantages. The aerodynamic results from previous computational and experimental studies are recreated using the Mercury framework, an in-house CFD solver based on Reynolds-Averaged NavierStokes (RANS). The acoustic analysis is performed using an acoustic code based on the Ffowcs William-Hawkings equation to solve for the noise propagating from the surfaces of the aircraft. It was found that for an advance ratio of 0.5 the wing-lift offset configuration can produce 56.8% more thrust at the same collective angle without any penalties in total noise. When the configurations produce equal thrust it was found that the wing-lift offset case has a 4 dB reduction in maximum overall sound pressure level. At an advance ratio of 0.3 with trim for equivalent thrust between configurations, a 3 dB maximum OASPL reduction was obtained with the inclusion of the wing.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"33 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":"128779520","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":"Multi-Domain Electric Drivetrain Modeling for UAM-Scale eVTOL Aircraft","authors":"Meaghan Podlaski, F. Gandhi, R. Niemiec, L. Vanfretti","doi":"10.4050/f-0077-2021-16893","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16893","url":null,"abstract":"\u0000 This paper presents the modeling and validation of an electric drivetrain through an object-oriented, equation-based framework that includes aerodynamics, electric machine, power electronic converter and battery models at various levels of detail. The proposed drivetrain model considers different losses in the machine and levels of fidelity for the power source and converters. It is simulated with various maneuvers, aiming to show the effects of modeling simplifications on the behavior of UAMs. These studies show that the level of detail in the motors and power system has significant impact on the dynamic response and power consumption of the system. This is most evident in the cases where the system uses a detailed battery model and in the cases where the switching electrical components are used, creating a torque ripple.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"72 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":"129165455","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":"Helicopter rotor blade multiple-section optimization with performance","authors":"Luke D. Allen, Joon W. Lim, R. Haehnel, I. Dettwiller","doi":"10.21079/11681/41031","DOIUrl":"https://doi.org/10.21079/11681/41031","url":null,"abstract":"This paper presents advancements in a surrogate-based, rotor blade design optimization framework for improved helicopter performance. The framework builds on previous successes by allowing multiple airfoil sections to designed simultaneously to minimize required rotor power in multiple flight conditions. Rotor power in hover and forward flight, at advance ratio 𝜇 = 0.3, are used as objective functions in a multi-objective genetic algorithm. The framework is constructed using Galaxy Simulation Builder with optimization provided through integration with Dakota. Three independent airfoil sections are morphed using ParFoil and aerodynamic coefficients for the updated airfoil shapes (i.e., lift, drag, moment) are calculated using linear interpolation from a database generated using C81Gen/ARC2D. Final rotor performance is then calculated using RCAS. Several demonstrative optimization case studies were conducted using the UH-60A main rotor. The degrees of freedom for this case are limited to the airfoil camber, camber crest position, thickness, and thickness crest position for each of the sections. The results of the three-segment case study show improvements in rotor power of 4.3% and 0.8% in forward flight and hover, respectively. This configuration also yields greater reductions in rotor power for high advance ratios, e.g., 6.0% reduction at 𝜇 = 0.35, and 8.8% reduction at 𝜇 = 0.4.","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"39 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":"125458317","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":"Development of Magnesium Laser Powder Bed Fusion to Manufacture Light-weight Components for Vertical Lift Applications","authors":"M. Smit, Antonio Paesano, L. Hoen-Velterop, Maria L. Montero-Sistiaga","doi":"10.4050/f-0077-2021-16814","DOIUrl":"https://doi.org/10.4050/f-0077-2021-16814","url":null,"abstract":"\u0000 This paper describes the work that was conducted to demonstrate the capability to produce high quality representative magnesium products for vertical lift applications by Laser Powder Bed Fusion (LPBF). An important step in the development was the selection of a metal powder with adequate spreadability for LPBF. Optimum process parameters are required for the production of parts featuring low porosity and low roughness. An efficient optimization approach was applied that enabled the selection of process parameters by analysis of an array of thin wall and block samples from one single build job. After the process parameter selection, benchmark parts were produced for evaluating design rules to print magnesium parts. Demonstrator parts were successfully produced based on a representative light-weight component for Vertical Lift application. A very fine homogeneous microstructure was found at the melt-pool and grain scale. After the removal of the parts from the baseplate, some deformation occurred due to residual stresses.\u0000","PeriodicalId":273020,"journal":{"name":"Proceedings of the Vertical Flight Society 77th Annual Forum","volume":"48 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":"121760670","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}