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

{"title":"Towards Full-Scale Fuselage Drag Reduction Computations using Fluidic Oscillators","authors":"Nicholson K. Koukpaizan, A. Glezer, Marilyn J. Smith","doi":"10.4050/f-0076-2020-16460","DOIUrl":"https://doi.org/10.4050/f-0076-2020-16460","url":null,"abstract":"\u0000 Computations were performed to assess the effect of fluidically-oscillating jets on a ROBIN-mod7 helicopter fuselage. The simulations utilize previously experimentally validated methodologies that rely on a new boundary condition formulation at the actuator throats, based on phase-averaged flow variables, which obviates the need to resolve the internal cavities simultaneously with the outer flow. Predictions of the base flow past the helicopter fuselage were validated against experimental and computational data available in the literature. The fluidic oscillator characteristics were then evaluated at different scales and pressure ratios, and invariant quantities were identified. In the flow control evaluation, flow separation was significantly reduced and, in some cases, suppressed. However, drag reduction was not obtained, indicating the sensitivity of the actuation location and operating conditions to the vehicle design and flight orientation.\u0000","PeriodicalId":293921,"journal":{"name":"Proceedings of the Vertical Flight Society 76th Annual Forum","volume":"25 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":"121684999","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":"Experimental Measurement of Sectional Stiffness Properties of Composite Rotor Blades","authors":"Tyler Sinotte, O. Bauchau","doi":"10.4050/f-0076-2020-16367","DOIUrl":"https://doi.org/10.4050/f-0076-2020-16367","url":null,"abstract":"\u0000 This paper describes an experimental-numerical technique for evaluating the full 6 × 6 stiffness matrices for beams based on measured strains using digital image correlation (DIC). The general formulation makes the method well suited for isotropic beams with simple cross-sectional configurations or beams made of anisotropic materials with complex geometries, as typically exhibited in composite rotor blades. A 2-D finite element code, SectionBuilder, is used to generate a finite element mesh of the cross-section and evaluate the warping field, which is then combined with the experimental strain data to calculate the stiffness matrix. A detailed error analysis is performed to allow for the propagation of the experimental errors into the stiffness calculation and provide an uncertainty quantification for use in comprehensive analysis codes. Experimental results are presented for an isotropic beam and two composite rotor blades. Overall, the stiffness properties from the experimental measurements and numerical models showed good agreement and the experimental measurements were able to capture all the expected non-zero stiffness components.\u0000","PeriodicalId":293921,"journal":{"name":"Proceedings of the Vertical Flight Society 76th Annual Forum","volume":"50 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":"124996904","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":"Leveraging Additive Manufacturing for Low-Volume, Out-of-Production Spare Parts","authors":"Thomas Reilly","doi":"10.4050/f-0076-2020-16310","DOIUrl":"https://doi.org/10.4050/f-0076-2020-16310","url":null,"abstract":"\u0000 Additive Manufacturing (AM) and/or 3-D printing has been used for decades for fabrication of prototyping parts to validate design, geometries and kinematics. The ability to rapidly \"grow\" one-off and low-volume parts for evaluation and iterative design development is a perfect use of AM processes. As AM materials and machines advance, the repeatability, reproducibility and quality are maturing. Today, AM parts are moving into limited production applications with opportunity for future design features, competitive pricing, lower weight through design optimization, and potential for \"on-demand\" deliveries. The vast majority of AM parts remain limited to development and prototype phases of a program. As production ramps up, production part fabrications transition to more traditional processes. The higher quantities and schedule demand of production as well as conformity with certified materials and processes still favor traditional manufacturing methods. However, as production ends and the product moves fully into a sustainment phase, the demand for parts plummets (as shown in Figure 1) and subsequent fabrication schedules are dependent on forecasts that are often overwhelmed by \"surprise\" spares orders. In the latter part of the product life cycle, high rate, production-driven manufacturing processes may no longer be optimal and an alternative that permits a transition back to prototyping methods and one-off \"on-demand\" fabrication is needed. \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":"122170052","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":"Estimating Handling Qualities Ratings from Slalom Flight Data: A Psychophysical Perspective","authors":"E. Bachelder, Martine Godfroy-Cooper, B. Aponso, Jeff A. Lusardi","doi":"10.4050/f-0076-2020-16387","DOIUrl":"https://doi.org/10.4050/f-0076-2020-16387","url":null,"abstract":"\u0000 This work examines the handling qualities (HQ) rating scale from a psychophysical perspective, characterizing workload as the response to a stimulus composed of input to the pilot and pilot outputs. Previous work by the author examining three different display tracking tasks indicated that pilot workload is effectively a logarithmic function of tracking error rate and control rate. This approach, called the Spare Capacity OPerations Estimator (SCOPE), is extended to flight and Handling Qualities data collected (109 runs) for the slalom Mission Task Element (MTE) using the U.S. Army’s JUH-60A RASCAL aircraft. Attitude and Rate Command response types as well as various forcefeel configurations were tested. Based on flight data observation a novel and intuitive action model is proposed for the slalom MTE whereby the pilot operates on the relative angle between the ground track and the upcoming cone’s location (effectively the cone’s location on the windscreen relative to the aircraft nose, assuming a no-wind environment). Proximity to an approaching cone determines which of two strategies is active: maintaining a constant relative angle or maintaining the relative angular rate constant. A method is proposed for mapping Handling Qualities (HQ) ratings to flight data performance and the workload estimate, offering the possibility for easing the requirement that a pilot trained in HQ evaluation fly test maneuvers. Applying this approach to the slalom maneuver produced good correlation between actual and estimated HQ ratings over the varying aircraft and inceptor feel system dynamics.\u0000","PeriodicalId":293921,"journal":{"name":"Proceedings of the Vertical Flight Society 76th Annual Forum","volume":"2013 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":"125667014","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":"Trade-off between Maneuver Performance and Component Load Limiting","authors":"C. Mballo, J. V.","doi":"10.4050/f-0076-2020-16400","DOIUrl":"https://doi.org/10.4050/f-0076-2020-16400","url":null,"abstract":"\u0000 In this paper, two competing model predictive component load limiting control (LLC) architectures, viz., command limiting and control limiting, are developed and evaluated for performance in nonlinear model simulations. Reduced order time invariant linear models of coupled body-rotor-inflow dynamics are used for real-time prediction of rotor system component harmonic loads. The trade-off between maneuver performance and component load limiting is compared between the proposed command limiting architecture and a previously studied control limiting architecture. Nonlinear simulation results show that the maneuver performance degradation in the presence of component load limiting with a command limiting architecture is less severe when compared with a control limiting architecture.\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":"121339408","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":"A Virtual Reality Approach to Piloted Flight Simulation","authors":"P. Masarati, M. Daniele, G. Quaranta, A. Zanoni, P. Milano","doi":"10.4050/f-0076-2020-16300","DOIUrl":"https://doi.org/10.4050/f-0076-2020-16300","url":null,"abstract":"\u0000 A pilot-in-the-loop simulation environment aimed at increasing pilot visual cues without the need of expensive visualization hardware is presented. The proposed solution relies on Virtual Reality (VR) to enhance the pilot immersion in the simulated environment. The project is integrated in the development of the complete simulation framework FRAME-Sim, focused on simulating rotorcraft in early conceptual design stages, and therefore relying on physics-based multibody simulation of the rotorcraft flight dynamics and free/open source software. FRAME-Sim visual environments that are being used include products available to the market as well as homemade solutions developed to obtain the highest level of versatility during the simulation.\u0000","PeriodicalId":293921,"journal":{"name":"Proceedings of the Vertical Flight Society 76th Annual Forum","volume":"59 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":"114952257","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":"XV-15 Tilt Rotor Research Aircraft Photogrammetry and Metrology Measurement","authors":"H. Cummings, M. Dominguez, E. Solis, Christopher J. Silva, B. Bowman, S. Burek","doi":"10.4050/f-0076-2020-16278","DOIUrl":"https://doi.org/10.4050/f-0076-2020-16278","url":null,"abstract":"\u0000 A new measurement capability was created by combining photogrammetry and metrology techniques to accurately measure one half of the XV-15 Tilt Rotor Research Aircraft at the Smithsonian’s Udvar-Hazy museum. The challenges imposed by the fuselage and surrounding environment at Udvar-Hazy were overcome by careful application of photogrammetry and metrology techniques. Data analyses and processing included the use of multiple reverse engineering programs to accurately generate a complete 3-dimensional water-tight geometry of the aircraft and rotor blade. This paper describes the photogrammetry and metrology measurement systems, technology and hardware set-up, data analysis and processing methods, future work, and lessons learned. In addition, selected measurement results of the fuselage and rotor blade are presented.\u0000","PeriodicalId":293921,"journal":{"name":"Proceedings of the Vertical Flight Society 76th Annual Forum","volume":"46 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":"129588857","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":"Design, Development and Flight Testing of a Gun-Launched Rotary-Wing Micro Air Vehicle","authors":"H. Denton, Moble Benedict, Hao Kang, Vikram Hrishikeshavan","doi":"10.4050/f-0076-2020-16477","DOIUrl":"https://doi.org/10.4050/f-0076-2020-16477","url":null,"abstract":"\u0000 This paper describes the development and flight testing of a compact, re-configurable, rotary-wing micro air (MAV) vehicle capable of sustained hover and could potentially be launched from a 40mm grenade launcher. Launching the vehicle as a projectile over the target area could significantly improve the mission range for these energy-constrained platforms. The MAV design features coaxial rotors with foldable blades, and a thrust-vectoring mechanism for pitch and roll control. Yaw control was accomplished by using a specialized counter-rotating motor system comprised of two independently controlled motors. Passive unfolding of the coaxial rotor blades in flight utilizing centrifugal force was demonstrated. A cascaded feedback control strategy was implemented on a 1.7 gram custom-designed autopilot. Systematic wind tunnel tests were conducted with the vehicle on a single degree of freedom stand, which proved the ability of the controller to reject wind gusts up to 6 m/s and stabilize the vehicle during the powered axial descent phase. Different phases of the gun-launched flight sequence were independently verified through targeted flight tests. Free f light testing conducted both indoors and outdoors verified that the vehicle could hover and fly forward in moderate winds. In-flight drop tests were conducted by throttling down the vehicle from a high altitude to attain high axial decent speeds followed by recovery using the rotor thrust to aggressively brake the descent and achieve a stable hover. Finally, the vehicle was launched vertically from a pneumatic cannon followed by a stable projectile phase utilizing the f ins, passive rotor unfolding, and final transition to a stable hover from arbitrarily large attitude angles demonstrating the robustness of the controller, as well as all the sub-systems of the vehicle operating in perfect harmony.\u0000","PeriodicalId":293921,"journal":{"name":"Proceedings of the Vertical Flight Society 76th Annual Forum","volume":"2007 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":"130618970","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":"Simulation and Characterization of Variable-Voltage Hybrid-Electric Powertrains","authors":"Brent T Mills, A. Datta","doi":"10.4050/f-0076-2020-16412","DOIUrl":"https://doi.org/10.4050/f-0076-2020-16412","url":null,"abstract":"A phenomenological simulation for a variable-voltage hybrid-electric powertrain was developed and compared with test data acquired on a 4 hp powertrain to understand the fundamental characteristics of such a system. The powertrain was modeled component by component, and compared with over 500 experimental data points, from the engine alone to the engine generator, to the engine-generator with four distributed propulsors. The principal conclusion of the predictive simulation and the experimental data was that generator voltage is a key parameter that needs careful control relative to rotor speed. For any operating state -- defined by rotor torque and RPM -- the generator voltage should be minimized to minimize engine specific fuel consumption. In general the system is influenced more by the engine generator than electric motors. Hence greater rotor torque and lower rotor RPM is desired. It was found that steady state performance can be confidently predicted with the engine model, if the thermal efficiency is calibrated with engine data. The overall understanding gained from this work is that the optimal operation of hybrid-electric powertrains in VTOL is closely coupled with controls and rotor aeromechanics as well as engine gas dynamics and thermodynamics, but can be captured with relatively simple phenomenological models.","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":"131231460","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":"Restoring Practical Single Engine IFR to the Marketplace","authors":"Erik Oltheten","doi":"10.4050/f-0076-2020-16343","DOIUrl":"https://doi.org/10.4050/f-0076-2020-16343","url":null,"abstract":"\u0000 Attempting to pick through bad weather - becoming disoriented in diminished visibility or striking a wire or obstacle at low altitude - remains one of the major causes of fatal helicopter accidents. It is more common than engine failure, more common than mechanical failures, and more common than systems failures. While some feel the answer involves more tools to enable low-flying helicopters to avoid terrain and obstacles, a better solution is to keep helicopters safely away from terrain and obstacles using instrument flight rules (IFR) when weather conditions demand. For single engine helicopters, which form the largest population of helicopters, this means finding cost effective ways to provide them with safe and practical IFR capability. IFR capability is commonplace in airplanes, even among entry-level and training aircraft. An IFR rating is typically the first rating sought after an airplane pilot receives their license. For helicopters, there is currently not a parallel culture of shifting to the safety of IFR operations when weather demands. The reasons are complex, but a significant factor affecting this culture today is that the entryl evel IFR rotorcraft is generally a twin-turbine-engine helicopter. By the time a helicopter pilot gets to this level of machine, he or she is typically well versed in the \"alternate\" methods of weather avoidance. Unfortunately, even IFR rated helicopter pilots tend to default to a practice of attempting to fly below the weather using visual flight rules (VFR). Increasing the availability of IFR-capable helicopters by restoring practical, low-cost IFR solutions to single engine rotorcraft is the first step in a process intended to change the rotorcraft safety culture. This paper describes a 5-year effort by associations, industry, and regulators to remove the obstacles to certifying low-cost IFR helicopters. By mid-year 2019, two single-engine helicopters were certified for IFR operations, ending an absence of more than 20 years from the marketplace, but these were newly-manufactured aircraft. The remaining challenge is to apply what has been done in order to allow cost-effective retrofits of IFR capability to the existing fleet of VFR helicopters. The hope is that, with the trail now blazed, others will follow, and we will see even more single-engine rotorcraft with IFR capability and fewer weather-related accidents.\u0000","PeriodicalId":293921,"journal":{"name":"Proceedings of the Vertical Flight Society 76th Annual Forum","volume":"35 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":"132159840","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}