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This report examines the loss of main rotor control accidents involving RobinsonHelicopter Company R22 helicopters. When similar accidents occurred involving the Robinson R44 helicopters, the scope of the report expanded to includ...
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This report examines the loss of main rotor control accidents involving RobinsonHelicopter Company R22 helicopters. When similar accidents occurred involving the Robinson R44 helicopters, the scope of the report expanded to include those accidents. The safety issues discussed in the report include the need for appropriate measures to reduce the probability of loss of main rotor control accidents; the need for continued research to study flight control systems and main rotor blade dynamics in lightweight, low rotor interia helicopters; the need for operational requirements to be addressed during future certification of lightweight, low rotor inertia helicopters; and the need for the Federal Aviation Administration (FAA) to review and revise, as necessary, its procedures to ensure that internal recommendations, particularly those addressed in special certification reviews, are appropriately resolved and brought to closure.
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July and August 1995 the DLR at Braunschweig conducted flight tests as part of astudy aimed at the evaluation of the Aeronautical Design Standard Handling qualities requirements for military rotorcraft (ADS-33). This standard, whi...
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July and August 1995 the DLR at Braunschweig conducted flight tests as part of astudy aimed at the evaluation of the Aeronautical Design Standard Handling qualities requirements for military rotorcraft (ADS-33). This standard, which was first released as ADS-33C in 1989, is meant to replace the outdated MIL-H-8501A specification. At present, a 1994 D-version of the standard is available. The primary objectives of the DLR study are the following: Gaining experience in testing rotary wing aircraft according to ADS-33. Verifying the applicability of ADS-33 in repeatability, consistency and safety of the proposed maneuvers.
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The objective of the present work was to develop a method for identifyingphysically plausible finite element system models of airframe structures from test data. The assumed models were based on linear elastic behavior with genera...
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The objective of the present work was to develop a method for identifyingphysically plausible finite element system models of airframe structures from test data. The assumed models were based on linear elastic behavior with general (nonproportional) damping. Physical plausibility of the identified system matrices was insured by restricting the identification process to designated physical parameters only and not simply to the elements of the system matrices themselves. For example, in a large finite element model the identified parameters might be restricted to the moduli for each of the different materials used in the structure. In the case of damping, a restricted set of damping values might be assigned to finite elements based on the material type and on the fabrication processes used. In this case, different damping values might be associated with riveted, bolted and bonded elements. The method itself is developed first, and several approaches are outlined for computing the identified parameter values. The method is applied first to a simple structure for which the 'measured' response is actually synthesized from an assumed model. Both stiffness and damping parameter values are accurately identified. The true test, however, is the application to a full-scale airframe structure. In this case, a NASTRAN model and actual measured modal parameters formed the basis for the identification of a restricted set of physically plausible stiffness and damping parameters.
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Georgia Tech's research investigations during the reporting period focused onseveral analytical and experimental tasks in rotorcraft technology. In the area of Rotorcraft Aerodynamics, work continued on the development of numerica...
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Georgia Tech's research investigations during the reporting period focused onseveral analytical and experimental tasks in rotorcraft technology. In the area of Rotorcraft Aerodynamics, work continued on the development of numerical formulations for prediction of viscous flow over rotors and rotor-body combinations without resort to empirical or Lagrangian-based formulations for capturing the tip vortex. Experimental work in transient aerodynamic interactions were aimed at a new capability for, among others, a detailed study of flow separation and reattachment using a basic rotor/wing interaction experiment. In the area of Rotor Dynamics Aeroelasticity, investigations focused on rotor vibration and trim with advanced finite-state wake aerodynamics. In the area of Structures and Materials, dynamic modeling of composite beams was investigated including the edge-zone behavior. Research in robust control theory was devoted to exploring robustness and controller order reduction issues related to the design of rotorcraft flight control systems, development of synthesis techniques for designing full envelope flight controllers without the need for gain scheduling, and neural network based and numerical investigation of a direct adaptive tracking control architecture.
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This project conducted research on tasks related to rotorcraft aerodynamics,dynamics, materials, and structures as approved by the Army Research Office. A total of seven fundamental and multidisciplinary research tasks in rotorcra...
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This project conducted research on tasks related to rotorcraft aerodynamics,dynamics, materials, and structures as approved by the Army Research Office. A total of seven fundamental and multidisciplinary research tasks in rotorcraft materials, structural dynamics, unsteady aerodynamics and aeroelasticity were pursued, each of them highly interactive with at least one of the other tasks in this project.
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During DESERT STORM, Army Aviation established that it has matured as a combatarm. When employed in close combat, aviation is deadly and decisive. Aviation forces can deliver decided combat power to formidable operational depths, ...
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During DESERT STORM, Army Aviation established that it has matured as a combatarm. When employed in close combat, aviation is deadly and decisive. Aviation forces can deliver decided combat power to formidable operational depths, poising itself as the principal maneuver arm of AirLand Battle operations in the nineties. During DESERT STORM, Army Aviation operations demonstrated how rotary-wing aircraft can accelerate the tempo of conventional combat. The executive summary in the U.S. Army Aviation Center's DESERT SHIELD/DESERT STORM After Action report stated, We won the war, but in many areas, we did not win in the most efficient and effective way. The study discusses the state of the equipment immediately before and during DESERT SHIELD and DESERT STORM. It relates the technical and tactical proficiency of Apache crews to their combat effectiveness. The study relates high-intensity mission schemes and fleeting skills to training issues....Desert Storm, Desert Shield, Army aviation, AH-64A, Apache, Helicopter, Hellfire missile.
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When a rotating blade system moves under certain operating conditions, each bladewill impinge on the tip vortices shed by itself or other blades. This impingement is called a blade-vortex interaction, or BVI. Although the blade an...
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When a rotating blade system moves under certain operating conditions, each bladewill impinge on the tip vortices shed by itself or other blades. This impingement is called a blade-vortex interaction, or BVI. Although the blade and trailing tip vortices interact with many different orientations, one of the two extremes, either parallel or perpendicular interaction, is usually modeled. A parallel interaction has the largest concurrent interaction with the blade, as a result this case is given the most attention. One of the most commonly studied occurrences of blade-vortex interactions is associated with low-speed descending rotorcraft flight. BVI occurs when the tip vortices shed by the blades intersect the plane of the rotor. BVI cause local pressure changes over the blades which are responsible, in part, for the acoustic signature of the rotorcraft. The local pressure changes also cause vibrations which lead to fatigue of both the blades and the mechanical components driving the blades.
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This memorandum is the RAE/FS8 recommendation for a specification to define UKMOD requirements for the lightning protection of aircraft. It has been written to be appended to a JAC paper proposing changes to the lightning content ...
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This memorandum is the RAE/FS8 recommendation for a specification to define UKMOD requirements for the lightning protection of aircraft. It has been written to be appended to a JAC paper proposing changes to the lightning content of DEF STAN 00-970 and is in five parts covering background and advisory material, certification, design and testing requirements. This memorandum has been prepared as an essential step in the production of a JAC paper recommending changes to the lightning content of DEF STAN 00-970. The document has been written to the direction of RAE/FS(F)8 and in its final form will give RAE recommendations for a new specification which will define Great Britain MOD requirements (Design, Test and Certification) for the lightning protection of UK Military Aircraft. This specification provides the design and evaluation requirements to ensure that UK Military aircraft comply with the lightning protection requirements of DEF STAN 00-970. It shall apply to all fixed and rotary wing aircraft as decided by the Aircraft Project Director.
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This document establishes procedures and methods for determining the physicalcharacteristics of aviation materials undergoing technical testing. These procedures cover techniques for obtaining physical characteristics data for air...
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This document establishes procedures and methods for determining the physicalcharacteristics of aviation materials undergoing technical testing. These procedures cover techniques for obtaining physical characteristics data for aircraft (both fixed and rotary wing), avionics, electronics and communications equipment; aircraft subsystems and associated equipment; ground support equipment; and personnel equipment. Other tests required will be performed in accordance with the appropriate common Test Operations Procedures (TOP).
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The Spectrum is a fully modular, quick change air ambulance life support systemused in both fixed and rotary wing aircraft. The unit provides 115VAC/60 Hz electrical power, medical air and oxygen, and vacuum. The Spectrums evaluat...
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The Spectrum is a fully modular, quick change air ambulance life support systemused in both fixed and rotary wing aircraft. The unit provides 115VAC/60 Hz electrical power, medical air and oxygen, and vacuum. The Spectrums evaluation came at the request of Brig Gen P.K. Carlton, HQ AETC/SG to expand the role of C-21 Learjets involvment in aeromedical evacuation. Aeromedical Research staff members within the Systems Research Branch, considers the unit conditionally acceptable for use in the aeromedical evacuation environment providing all modifications to the unit have been met.
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