Download or read book Development of Handling Qualities Criteria for Rotorcraft with Externally Slung Loads written by and published by . This book was released on 2006 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development of Handling Qualities Criteria for Rotorcraft with Externally Slung Loads written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-20 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: Piloted simulations were performed on the NASA-Ames Vertical Motion Simulator (VMS) to explore handling qualities issues for large cargo helicopters, particularly focusing on external slung load operations. The purpose of this work was based upon the need to include handling qualities criteria for cargo helicopters in an upgrade to the U.S. Army's rotorcraft handling qualities specification, Aeronautical Design Standard-33 (ADS-33E-PRF). From the VMS results, handling qualities criteria were developed fro cargo helicopters carrying external slung loads in the degraded visual environment (DVE). If satisfied, these criteria provide assurance that the handling quality rating (HQR) will be 4 or better for operations in the DVE, and with a load mass ratio of 0.33 or less. For lighter loads, flying qualities were found to be less dependent on the load geometry and therefore the significance of the criteria is less. For heavier loads, meeting the criteria ensures the best possible handling qualities, albeit Level 2 for load mass ratios greater than 0.33. Hoh, Roger H. and Heffley, Robert K. and Mitchell, David G. Ames Research Center NAS2-14360

Download or read book Development of Handling Qualities Criteria for Rotorcraft with Externally Slung Loads written by and published by . This book was released on 2006 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Airworthiness Qualification Criteria for Rotorcraft with External Sling Loads written by and published by . This book was released on 2002 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report presents the results of a study to develop airworthiness requirements for rotorcraft with external sling loads. The report starts with a review of the various phenomena that limit external sling load operations. Specifically discussed are the rotorcraft-load aeroservoelastic stability, load-on handling qualities, effects of automatic flight control system failure, load suspension system failure, and load stability at speed. Based on past experience and treatment of these phenomena, criteria are proposed to form a package for airworthiness qualification. The desired end objective is a set of operational flight envelopes for the rotorcraft with intended loads that can be provided to the user to guide operations in the field. The specific criteria proposed are parts of ADS-33E-PRF; MIL-F-9490D, and MIL-STD-913A all applied in the context of external sling loads. The study was performed for the Directorate of Engineering, U.S. Army Aviation and Missile Command (AMCOM), as part of the contract monitored by the Aerothermodynamics Directorate, U.S. Army AMCOM.

Download or read book Helicopter Flight Dynamics written by Gareth D. Padfield and published by John Wiley & Sons. This book was released on 2018-09-07 with total page 856 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Book The behaviour of helicopters and tiltrotor aircraft is so complex that understanding the physical mechanisms at work in trim, stability and response, and thus the prediction of Flying Qualities, requires a framework of analytical and numerical modelling and simulation. Good Flying Qualities are vital for ensuring that mission performance is achievable with safety and, in the first and second editions of Helicopter Flight Dynamics, a comprehensive treatment of design criteria was presented, relating to both normal and degraded Flying Qualities. Fully embracing the consequences of Degraded Flying Qualities during the design phase will contribute positively to safety. In this third edition, two new Chapters are included. Chapter 9 takes the reader on a journey from the origins of the story of Flying Qualities, tracing key contributions to the developing maturity and to the current position. Chapter 10 provides a comprehensive treatment of the Flight Dynamics of tiltrotor aircraft; informed by research activities and the limited data on operational aircraft. Many of the unique behavioural characteristics of tiltrotors are revealed for the first time in this book. The accurate prediction and assessment of Flying Qualities draws on the modelling and simulation discipline on the one hand and testing practice on the other. Checking predictions in flight requires clearly defined mission tasks, derived from realistic performance requirements. High fidelity simulations also form the basis for the design of stability and control augmentation systems, essential for conferring Level 1 Flying Qualities. The integrated description of flight dynamic modelling, simulation and flying qualities of rotorcraft forms the subject of this book, which will be of interest to engineers practising and honing their skills in research laboratories, academia and manufacturing industries, test pilots and flight test engineers, and as a reference for graduate and postgraduate students in aerospace engineering.

Download or read book Design and Flight Test of a Cable Angle Feedback Control System for Improving Helicopter Slung Load Operations at Low Speed written by Christina Michael Ivler and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The ability of a helicopter to carry externally slung loads makes it very versatile for many civil and military operations. However, the piloted handling qualities of the helicopter are degraded by the presence of the slung load. This dissertation investigates the dynamics, handling qualities requirements, and control aspects of the helicopter/slung load system that contribute to the performance of piloted slung load operations. A control system is developed that integrates measurements of both slung load motions and conventional fuselage feedback to improve the handling qualities for hover/low speed operations. Despite the fact that this technology was developed 40 years ago, it has not been tested in a manned helicopter since the 1970s, due to problems with handling qualities and pilot perception. This dissertation leverages advances in fly-by-wire, complex control design procedures (direct multi-objective optimization), and recently developed work that relates handling qualities to dynamic response (specifications) to successfully flight test cable angle feedback technology in a manned helicopter. The key contributions of this work are developing an understanding of the handling qualities trade-offs for cable angle/rate control system design, implementing an approach to solve the problem with a novel task-tailored control system, and performing extensive piloted flight tests of the control system on a fly-by-wire Black Hawk. The flight tests demonstrated that average precision load set-down time was reduced by 50% for a light load, 30% for a heavy load, and the average handling qualities rating for the external load placement task was improved from Level 2 to Level 1 on the Cooper-Harper rating scale, a significant improvement.

Download or read book Army Research and Development written by and published by . This book was released on 1970 with total page 676 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Human Systems Engineering and Design IHSED 2021 Future Trends and Applications written by Waldemar Karwowski, Tareq Ahram, Mario Milicevic, Darko Etinger and Krunoslav Zubrinic and published by AHFE International. This book was released on 2021-09-25 with total page 1030 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of the 4th International Conference on Human Systems Engineering and Design (IHSED2021): Future Trends and Applications, September 23–25, 2021, University of Dubrovnik, Croatia

Download or read book Army RD A written by and published by . This book was released on 1970 with total page 678 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Army RD A Bulletin written by and published by . This book was released on 1971 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Handling Qualities Requirements and Control Design for High Speed Rotorcraft written by Tom Berger and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The U.S. Department of Defense has established the Future Vertical Lift initiative to develop a family of next-generation vertical lift aircraft that will fly farther, faster, and more efficiently than the current fleet of rotorcraft. To accomplish these goals, advanced rotorcraft configurations beyond the single main rotor/tail rotor design must be considered. Two advanced configurations currently being flight tested in a technology demonstrator program are a lift offset coaxial rotorcraft with a pusher propeller and a tiltrotor. The U.S. Army Aviation Development Directorate has developed generic, high-fidelity flight-dynamics models of these two configurations to provide the government with independent control-system design, handling-qualities analysis, and simulation research capabilities for these types of aircraft in support of the Future Vertical Lift initiative.In an effort to begin defining high-speed handling qualities requirements for these types of advanced rotorcraft configurations, full flight envelope inner-loop explicit model following control systems were designed for both configurations using a multi-objective optimization approach to meet a comprehensive set of stability, handling qualities, and performance requirements. The requirements were chosen from both helicopter and fixed-wing criteria. The control laws for both aircraft were evaluated in a piloted simulation experiment at the NASA Ames Vertical Motion Simulator using a series of high-speed handling qualities demonstration maneuvers. The results from the simulation experiment show overall assigned Level 1 handling qualities for both aircraft which correlates well with the predicted Level 1 handling qualities they were designed to, thus supporting the choice of handling qualities requirements selected during the design process.In addition, outer-loop control laws were also developed for both aircraft in an effort to improve handling qualities and reduce pilot workload. A dynamic inversion control law architecture was used for the outer loops, and again a comprehensive set of stability, handling qualities, and performance requirements was used to optimize the parameters of the control laws. The outer-loop control laws for both aircraft were evaluated in a piloted simulation experiment at the Pennsylvania State University Flight Simulator facility using a subset of the high-speed handling qualities demonstration maneuvers used in the first evaluation. Overall, the outer-loop control laws provided Level 1 handling qualities for the Break Turn and High-Speed Acceleration/Deceleration maneuvers, with improvements seen over the inner-loop control laws. In addition, the outer-loop control laws improved performance and reduced workload during a formation flying task that was developed for this project. However, for pitch attitude capture and tracking tasks, the outer-loop control laws degraded handling qualities as compared to the inner-loop control laws. This was due to the pitch attitude dropback behavior of the outer-loops, even though they were tuned to meet the dropback specification. The results suggest that the amount of allowable dropback should be decreased for high-speed rotorcraft and the outer-loop functionality might be provided as a selectable mode. The set of handling qualities criteria used to optimize the inner- and outer-loop control systems presented here are proposed as a set of requirements to tune high-speed rotorcraft control systems to achieve Level 1 handling qualities.

Download or read book Flight Simulation of the Model 347 Advanced Tandem rotor Helicopter written by U.S. Army Air Mobility Research and Development Laboratory. Eustis Directorate and published by . This book was released on 1974 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Flight Test Identification and Simulation of a UH 60A Helicopter and Slung Load written by and published by . This book was released on 2001 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: Helicopter slung-load operations are common in both military and civil contexts. Helicopters and loads are often qualified for these operations by means of flight tests, which can be expensive and time consuming. There is significant potential to reduce such costs both through revisions in flight-test methods and by using validated simulation models. To these ends, flight tests were conducted at Moffett Field to demonstrate the identification of key dynamic parameters during flight tests (aircraft stability margins and handling-qualities parameters, and load pendulum stability), and to accumulate a data base for simulation development and validation. The test aircraft was a UH-60A Black Hawk, and the primary test load was an instrumented 8- by 6- by 6-ft cargo container. Tests were focused on the lateral and longitudinal axes, which are the axes most affected by the load pendulum modes in the frequency range of interest for handling qualities; tests were conducted at airspeeds from hover to 80 knots. Using telemetered data, the dynamic parameters were evaluated in near real time after each test airspeed and before clearing the aircraft to the next test point. These computations were completed in under 1 min. A simulation model was implemented by integrating an advanced model of the UH-60A aerodynamics, dynamic equations for the two-body slung-load system, and load static aerodynamics obtained from wind-tunnel measurements. Comparisons with flight data for the helicopter alone and with a slung load showed good overall agreement for all parameters and test points; however, unmodeled secondary dynamic losses around 2 Hz were found in the helicopter model and they resulted in conservative stability margin estimates.

Download or read book External Load Stabilization Across the Flight Envelope Using an Active Cargo Hook written by Ajay Singh and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Helicopters must carry out a variety of missions, ranging from military to civilian uses. Missions mayinvolve delivery of a payload from one location to another. Some loads are externally attached to thehelicopter by cables. In this configuration, the loads are referred to as slung loads. Due to the couplingbetween the slung load aerodynamics and inertial forces, loads dynamics can become unstable whenairspeed increases. Slung load instabilities limit the flight operations of a rotorcraft. Because limitingflight speeds reduce the operational efficiency of the rotorcraft, methods for stabilizing external loadsin forward flight are the subject for research. In recent years, the dynamics and control of slung loadswere studied using analysis, dynamic wind tunnel tests, and flight tests.The research presented in this thesis investigated a control design methodology and its feasibilityto stabilize an external load across the flight envelope, including high speed flight. The capability of anactive cargo hook (ACH) to provide external load stabilization in high speed flight is studied. The ACHis an electromechanical device that can slide longitudinally and laterally along the base of the fuselage.Previous work used the ACH to directly control the loads roll and pitch but only during hover and lowspeed flight. Previous studies results proved promising.The test load and helicopter simulated in this thesis is a CONEX cargo container and a UH-60 BlackHawk helicopter, respectively. During high speed flight, the load can become unstable, exhibiting sustainedperiodic motion, or limit cycle oscillations, which can degrade helicopter handling qualities. Previousstudies observed the load dynamics in a wind tunnel. The findings showed the excessive swingingand rotation in the slung load are due to its nonlinear dynamics.The control methodology first examined designed a full-state feedback (FSF) linear-quadratic regulator(LQR) controller. In this controller, the load states and cargo hook longitudinal and lateral positionsare used as inputs to the controller with the commanded cargo hook longitudinal and lateral positionsas outputs. Results showed high damping in the loads attitude response with little saturation in theACH stroke and stroke rate. The full-state LQR controller demonstrated success in stabilizing the slungload.The FSF controller, however, requires sensors to measure the loads states real-time. A more practicalapproach is using a reduced order model (ROM) using relative cable angle feedback (RCAF). With RCAF,the relative cable angles can be measured real-time, requiring less sensors and measurements. Thereduced order model is used to design an LQR controller for the ACH. The inputs for the controllerare the relative cable angles, relative cable angular rates, and ACH positions. The results demonstratedbetter performance than the FSF LQR controller, stabilizing the load approximately 20 percent quicker.The loads damping of the RCAF controller is higher than the FSFs and the ACH does not saturate instroke or stroke rate. The settling time of the load was also improved significantly. Furthermore, thecontrollers robustness was tested through applying a Dryden Turbulence model in the simulations. TheRCAF was able to appropriately stabilize the load through low, mild, and severe turbulence levels.

Download or read book Monthly Catalog of United States Government Publications Cumulative Index written by United States. Superintendent of Documents and published by . This book was released on 1976 with total page 1408 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Monthly Catalog of United States Government Publications written by and published by . This book was released on with total page 1388 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Monthly Catalog of United States Government Publications written by United States. Superintendent of Documents and published by . This book was released on 1979 with total page 1250 pages. Available in PDF, EPUB and Kindle. Book excerpt: February issue includes Appendix entitled Directory of United States Government periodicals and subscription publications; September issue includes List of depository libraries; June and December issues include semiannual index