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 Active Stabilization of Slung Loads in High Speed Flight Using Cable Angle Feedback written by Mariano Scaramal and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Helicopters performing external load missions are subject to instabilities that arise in high speed flight that limit their operational flight envelope. This thesis addresses the problem of active stabilization of slung loads in high speed flight. To demonstrate the method, simulations of a utility helicopter with a dynamic inversion controller (as its automatic flight control system) and a CONEX cargo container were used. An airspeed scheduled controller utilizing cable angle feedback to the primary dynamic inversion controller was designed for the nonlinear coupled system by the classic root locus technique. Nonlinear simulations of straight and level flight at different airspeeds were used to validate the controller performance in stabilizing the load pendulum motions. Controller performance was also evaluated in a complex maneuver and in more demanding scenarios by adding different levels of atmospheric turbulence to the previous cases. The results show that the use of cable angle feedback provides or improves system stability when turbulence is not included in the simulation. When light/moderate turbulence is present sustained limit cycle oscillations are avoided by the use of the controller. For severe turbulence levels, the controller did not provide any significant improvement.

Download or read book Active Arm External Cargo Stabilization System Flight Demonstration written by Theodore S Garnett (Jr) and published by . This book was released on 1976 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: Development of an advanced Active Arm External Load Stabilization System (AAELSS II) for helicopters has been accomplished through analysis, ground test, and flight evaluation of the concept on a CH-47C aircraft. Hydraulically powered arms mounted beneath the helicopter automatically control load motion to provide pendular damping levels in excess of 25% of critical. The system completely eliminates longitudinal pilot-induced oscillation (PIO) tendencies, permitting full envelope instrument meteorological conditions (IMC) flight with heavy external payloads. Potential for precision hover load placement and flight with unstable loads exists. The design is also capable of operating with winchable HLH cargo hoist cable systems. (Author).

Download or read book Design Fabrication and Flight Test of Active Arm External Load Stabilization System for Cargo Handling Helicopters written by J. H. Smith and published by . This book was released on 1973 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Design Fabrication and Flight Test of the Active Arm External Load Stabilization System for Cargo Handling Helicopters written by J. H. Smith and published by . This book was released on 1973 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hi Fidelity Simulation and Prediction of Helicopter Single Point External Load Stabilization written by George E. Ehlers and published by . This book was released on 2001-09-01 with total page 205 pages. Available in PDF, EPUB and Kindle. Book excerpt: The helicopter has been used since its early development for external transport of large or bulky loads to small austere locations. Among the problems encountered as lift capability and airspeeds increased was that of divergent load oscillations due to load aerodynamics. The most problematic are the single point external loads displaying unsteady aerodynamics and coupled yaw-pendulum modes accounting for the instability of cargo containers. However, a lack of simulation models for unsteady aerodynamics renders simulation and analysis incapable of predicting the critical speeds at which such loads become unstable, This thesis attempts to provide a stabilization system for controlling the yaw degree of freedom for the single point external load, Empirical models of the yaw resistance at the hook and of the yaw moments due to vortex shedding were developed and tuned using flight test data and lab measurements Several load stabilization systems were considered, and a horizontal and vertical tail fin assembly was selected. This thesis presents simulation model improvements required for a simulation to match flight results for the load yaw, along with the design, modeling and optimization of the fin stabilization system, and a simulation assessment of the envelope expansion obtained from both passive and active stabilization.

Download or read book Fiscal Year 1978 Authorization for Military Procurement Research and Development and Active Duty Selected Reserve and Civilian Personnel Strengths written by United States. Congress. Senate. Committee on Armed Services and published by . This book was released on 1977 with total page 714 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Introduction to Aircraft Flight Mechanics written by Thomas R. Yechout and published by AIAA. This book was released on 2003 with total page 666 pages. Available in PDF, EPUB and Kindle. Book excerpt: Based on a 15-year successful approach to teaching aircraft flight mechanics at the US Air Force Academy, this text explains the concepts and derivations of equations for aircraft flight mechanics. It covers aircraft performance, static stability, aircraft dynamics stability and feedback control.

Download or read book Jane s All the World s Aircraft written by Frederick Thomas Jane and published by . This book was released on 2004 with total page 924 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fundamentals of Flight written by Richard Shepherd Shevell and published by Pearson Education India. This book was released on 1989 with total page 468 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book CONDUIT A New Multidisciplinary Integration Environment for Flight Control Development written by and published by . This book was released on 1997 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: A state-of-the-art computational facility for aircraft flight control design, evaluation, and integration called CONDUIT (Control Designer's Unified Interface) has been developed. This paper describes the CONDUIT tool and case study applications to complex rotary- and fixed- wing fly-by-wire flight control problems. Control system analysis and design optimization methods are presented, including definition of design specifications and system models within CONDUIT, and the multi-objective function optimization (CONSOL-OPTCAD) used to tune the selected design parameters. Design examples are based on flight test programs for which extensive data are available for validation. CONDUIT is used to analyze baseline control laws against pertinent military handling qualities and control system specifications. In both case studies, CONDUIT successfully exploits trade-offs between forward loop and feedback dynamics to significantly improve the expected handling qualities and minimize the required actuator authority. The CONDUIT system provides a new environment for integrated control system analysis and design, and has potential for significantly reducing the time and cost of control system flight test optimization.

Download or read book Flying beyond the stall written by Douglas A. Joyce and published by . This book was released on 2014 with total page 409 pages. Available in PDF, EPUB and Kindle. Book excerpt: The X-31 Enhanced Fighter Maneuverability Demonstrator was unique among experimental aircraft. A joint effort of the United States and Germany, the X-31 was the only X-plane to be designed, manufactured, and flight tested as an international collaboration. It was also the only X-plane to support two separate test programs conducted years apart, one administered largely by NASA and the other by the U.S. Navy, as well as the first X-plane ever to perform at the Paris Air Show. Flying Beyond the Stall begins by describing the government agencies and private-sector industries involved in the X-31 program, the genesis of the supermaneuverability concept and its initial design breakthroughs, design and fabrication of two test airframes, preparation for the X-31's first flight, and the first flights of Ship #1 and Ship #2. Subsequent chapters discuss envelope expansion, handling qualities (especially at high angles of attack), and flight with vectored thrust. The book then turns to the program's move to NASA's Dryden Flight Research Center and actual flight test data. Additional tasking, such as helmet-mounted display evaluations, handling quality studies, aerodynamic parameter estimation, and a "tailless" study are also discussed.The book describes how, in the aftermath of a disastrous accident with Ship #1 in 1995, Ship #2 was prepared for its outstanding participation in the Paris Air Show. The aircraft was then shipped back to Edwards AFB and put into storage until the late 1990s, when it was refurbished for participation in the U. S. Navy's VECTOR program. The book ends with a comprehensive discussion of lessons learned and includes an Appendix containing detailed information.

Download or read book Computers Take Flight A History of NASA s Pioneering Digital Fly By Wire Project written by James E. Tomayko and published by . This book was released on 2000 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Certification of Normal Category Rotorcraft written by United States. Federal Aviation Administration and published by . This book was released on 1985 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Smell of Kerosene written by National Aeronautics and Space Administration and published by Good Press. This book was released on 2023-12-28 with total page 275 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book puts the reader in the pilot's seat for a "day at the office" unlike any other. The Smell of Kerosene tells the dramatic story of a NASA research pilot who logged over 11,000 flight hours in more than 125 types of aircraft. Donald Mallick gives the reader fascinating first-hand description of his early naval flight training, carrier operations, and his research flying career with NASA. After transferring to the NASA Flight Research Center, Mallick became involved with projects that further pushed the boundaries of aerospace technology. These included the giant delta-winged XB-70 supersonic airplane, the wingless M2-F1 lifting body vehicle, and triple-sonic YF-12 Blackbird. Mallick also test flew the Lunar Landing Research Vehicle and helped develop techniques used in training astronauts to land on the Moon.

Download or read book The International Space Station written by Robert C. Dempsey and published by Government Printing Office. This book was released on 2017 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt: Looks at the operations of the International Space Station from the perspective of the Houston flight control team, under the leadership of NASA's flight directors, who authored the book. The book provides insight into the vast amount of time and energy that these teams devote to the development, planning and integration of a mission before it is executed. The passion and attention to detail of the flight control team members, who are always ready to step up when things do not go well, is a hallmark of NASA human spaceflight operations. With tremendous support from the ISS program office and engineering community, the flight control team has made the International Space Station and the programs before it a success.

Download or read book Sierra Hotel flying Air Force fighters in the decade after Vietnam written by and published by DIANE Publishing. This book was released on 2001 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: In February 1999, only a few weeks before the U.S. Air Force spearheaded NATO's Allied Force air campaign against Serbia, Col. C.R. Anderegg, USAF (Ret.), visited the commander of the U.S. Air Forces in Europe. Colonel Anderegg had known Gen. John Jumper since they had served together as jet forward air controllers in Southeast Asia nearly thirty years earlier. From the vantage point of 1999, they looked back to the day in February 1970, when they first controlled a laser-guided bomb strike. In this book Anderegg takes us from "glimmers of hope" like that one through other major improvements in the Air Force that came between the Vietnam War and the Gulf War. Always central in Anderegg's account of those changes are the people who made them. This is a very personal book by an officer who participated in the transformation he describes so vividly. Much of his story revolves around the Fighter Weapons School at Nellis Air Force Base (AFB), Nevada, where he served two tours as an instructor pilot specializing in guided munitions.