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  • Weitere Quellen  (382)
  • NASA Technical Reports  (382)
  • AIRCRAFT DESIGN, TESTING AND PERFORMANCE  (382)
  • 1980-1984  (382)
  • 1984  (219)
  • 1983  (163)
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  • Weitere Quellen  (382)
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  • NASA Technical Reports  (382)
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  • 1980-1984  (382)
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  • 1
    Publikationsdatum: 2005-03-28
    Beschreibung: Transport fuselage section drop tests provided useful information about the crash behavior of metal aircraft in preparation for a full-scale Boeing 720 controlled impact demonstration (CID). The fuselage sections have also provided an operational test environment for the data acquisition system designed for the CID test, and data for analysis and correlation with the DYCAST nonlinear finite-element program. The correlation of the DYCAST section model predictions was quite good for the total fuselage crushing deflection (22 to 24 inches predicted versus 24 to 26 inches measured), floor deformation, and accelerations for the floor and fuselage. The DYCAST seat and occupant model was adequate to approximate dynamic loading to the floor, but a more sophisticated model would be required for good correlation with dummy accelerations. Although a full-section model using only finite elements for the subfloor was desirable, constraints of time and computer resources limited the finite-element subfloor model to a two-frame model. Results from the two-frame model indicate that DYCAST can provide excellent correlation with experimental crash behavior of fuselage structure with a minimum of empirical force-deflection data representing structure in the analytical model.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: Res. in Struct. and Dyn., 1984; p 347-368
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  • 2
    Publikationsdatum: 2005-03-28
    Beschreibung: The dynamic behavior of aircraft fuselage structures subject to various impact conditions was investigated. An analytical model was developed based on a self-consistent finite element (CFE) formulation utilizing shell, curved beam, and stringer type elements. Equations of motion were formulated and linearized (i.e., for small displacements), although material nonlinearity was retained to treat local plastic deformation. The equations were solved using the implicit Newmark-Beta method with a frontal solver routine. Stiffened aluminum fuselage models were also tested in free flight using the UTIAS pendulum crash test facility. Data were obtained on dynamic strains, g-loads, and transient deformations (using high speed photography in the latter case) during the impact process. Correlations between tests and predicted results are presented, together with computer graphics, based on the CFE model. These results include level and oblique angle impacts as well as the free-flight crash test. Comparisons with a hybrid, lumped mass finite element computer model demonstrate that the CFE formulation provides the test overall agreement with impact test data for comparable computing costs.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Langley Research Center Res. in Struct. and Dyn., 1984; p 325-346
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  • 3
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    In:  CASI
    Publikationsdatum: 2006-02-14
    Beschreibung: The multiobjective programming techniques are important in the design of complex structural systems whose quality depends generally on a number of different and often conflicting objective functions which cannot be combined into a single design objective. The applicability of multiobjective optimization techniques is studied with reference to simple design problems. Specifically, the parameter optimization of a cantilever beam with a tip mass and a three-degree-of-freedom vabration isolation system and the trajectory optimization of a cantilever beam are considered. The solutions of these multicriteria design problems are attempted by using global criterion, utility function, game theory, goal programming, goal attainment, bounded objective function, and lexicographic methods. It has been observed that the game theory approach required the maximum computational effort, but it yielded better optimum solutions with proper balance of the various objective functions in all the cases.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 8 p
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  • 4
    Publikationsdatum: 2006-02-14
    Beschreibung: There are a number of helicopter design problems that are well suited to applications of numerical design optimization techniques. Adequate implementation of this technology will provide high pay-offs. There are a number of numerical optimization programs available, and there are many excellent response/performance analysis programs developed or being developed. But integration of these programs in a form that is usable in the design phase should be recognized as important. It is also necessary to attract the attention of engineers engaged in the development of analysis capabilities and to make them aware that analysis capabilities are much more powerful if integrated into design oriented codes. Frequently, the shortcoming of analysis capabilities are revealed by coupling them with an optimization code. Most of the published work has addressed problems in preliminary system design, rotor system/blade design or airframe design. Very few published results were found in acoustics, aerodynamics and control system design. Currently major efforts are focused on vibration reduction, and aerodynamics/acoustics applications appear to be growing fast. The development of a computer program system to integrate the multiple disciplines required in helicopter design with numerical optimization technique is needed. Activities in Britain, Germany and Poland are identified, but no published results from France, Italy, the USSR or Japan were found.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 13 p
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  • 5
    Publikationsdatum: 2006-02-14
    Beschreibung: An optimization study was performed to develop a minimum weight spreader bar to allow two helicopters to lift the same payload. With this arrangement, the maximum payload that can be lifted is almost doubled without the expense of designing and building a new helicopter. The concept has had some limited use by civil helicopter operators using small helicopters and has been demonstrated in large scale by two CH-54's which successfully lifted a total load of 20 ton. To this point, rather heavy available beams or tower structures have been used for the spreader bar. Since the weight of the bar not only detracts from payload but also adds to the logistics problem, there are more than the usual incentives to minimize weight. Since the design requirement is for classic beam column with uniform side loads resulting from bar weight and aerodynamic drag, the design problem is particularly amenable to optimization. A study has been performed at Sikorsky to establish the minimum weight for a spreader bar sized to carry a load equal to the capacity of two Army BLACK HAWK helicopters. Toward this end, a computer program was written to analyze the spreader bar deflections and stresses and coupled to the NASA developed CONMIN optimization routines.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 12 p
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  • 6
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    In:  CASI
    Publikationsdatum: 2006-02-14
    Beschreibung: The optimization approach discussed is part of an ongoing effort to develop a general automated procedure for rotor blade design. This procedure can be used to determine the necessary geometric, structural, and material properties of a rotor system to achieve desired objectives relating to vibration, stress, and aerodynamic performance. The approach used for helicopter vibration is emphasized. Based on analytical studies performed at the United Technologies Research Center (UTRC), a simplified vibration analysis was developed to be used in conjunction with a forced response analysis in the optimization process. This simplified analysis improves the efficiency of the design process significantly. Results of applying this approach to the design of an existing rotor blade model are presented.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 17 p
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  • 7
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    In:  CASI
    Publikationsdatum: 2006-02-14
    Beschreibung: This discussion summarizes the effort conducted by the BHTI Human Factors and Cockpit Arrangement group for a study and design of the integration of a cockpit control system for the AH 1T (TOW). The resulting design is a culmination of studies that were conducted using the existing configuration as a baseline and complementing it with new equipment and subsystems that fulfill the attack helicopter requirements for the foreseeable future. Of primary concern was the requirement to add a missile control system, with secondary considerations for improved NOE and night operations. In addition, growth capabilities for improved target acquisition, weapons delivery, and precise navigation was considered. Along with the addition of new equipment, the aircraft was assumed to have a central multiplex data bus system for information transfer throughout the aircraft and its subsystems.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Ames Research Center Technical Workshop: Advanced Helicopter Cockpit Design Concepts; p 271-316
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  • 8
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    In:  CASI
    Publikationsdatum: 2006-02-14
    Beschreibung: Nine research areas that are most critical to the issue of cockpits for the single pilot are discussed. Helicopter are addressed in this report. They are as follows: (1) automation priority issues; (2) increased complexity of systems; (3) cockpit workload highest in navigation; (4) auto hover and flight trim controls; (5) voice technology in integrated form; (6) systems must have visual and auditory declutter modes; (7) cockpit should be designed to be NBC resistant; and (8) considerations for spillover to civilian public service.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: Technical Workshop: Advanced Helicopter Cockpit Design Concepts; p 229-238
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  • 9
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    In:  CASI
    Publikationsdatum: 2006-02-14
    Beschreibung: Fundamental development issues, system requirements and improvements are reported for the HH-60D night hawk helicopter. The HH-60D mission requirements are for combat search and rescue (aerospace rescue and recovery service user based at Scott AFB) and special operations (special operations forces based at Hurlburt AFB). Cockpit design, computer architecture and software are described in detail.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Ames Research Center Technical Workshop: Advanced Helicopter Cockpit Design Concepts; p 145-164
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  • 10
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    In:  CASI
    Publikationsdatum: 2006-04-09
    Beschreibung: An analytical study was performed in order to assess relative performance and economic factors involved with alternative advanced fuel systems for future commercial aircraft operating with broad property fuels. Significant results, with emphasis on design practicality from the engine manufacturer' standpoint, are highlighted. Several advanced fuel systems were modeled to determine as accurately as possible the relative merits of each system from the standpoint of compatibility with broad property fuel. Freezing point, thermal stability, and lubricity were key property issues. A computer model was formulated to determine the investment incentive for each system. Results are given.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Lewis Research Center Assessment of Alternative Aircraft Fuels; p 141-158
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  • 11
    Publikationsdatum: 2006-02-14
    Beschreibung: Several problems related to the aeroelastic/aerodynamic optimization of a high speed helicopter compound rotor are discussed. The helicopter fuselage vibration problem, the effects of fuselage vibrations, the source of external and periodic air loads, typical airfoil environments and configurations, rotor dynamics, vibration reduction, and requirements for the rotor design optimization analysis are among the topics covered.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 20 p
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  • 12
    Publikationsdatum: 2006-02-14
    Beschreibung: Formal mathematical programing was applied to the aerodynamic rotor blade design process. The approach is to couple hover and forward flight analysis programs with the general-purpose optimization program CONMIN to determine the blade taper ratio, percent taper, twist distribution, and solidity which minimize the horsepower required at hover while meeting constraints on forward flight performance. Designs obtained using this approach for the blade of a representative Army helicopter compare well with those obtained using a conventional approach involving personnel-intensive parametric studies. Results from the present method can be obtained in 2 days as compared to 5 weeks required by the conventional procedure. Also the systematic manipulation of the design variables by the optimization procedure minimizes the need for the researcher to have a vast body of past experience and data in determining the influence of a design change on the performance.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 12 p
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  • 13
    Publikationsdatum: 2006-02-14
    Beschreibung: The main Army Helicopter Improvement Program (AHIP) mission is to navigate precisely, locate targets accurately, communicate their position to other battlefield elements, and to designate them for laser guided weapons. The onboard navigation and mast-mounted sight (MMS) avionics enable accurate tracking of current aircraft position and subsequent target location. The AHIP crewstation development was based on extensive mission/task analysis, function allocation, total system design, and test and verification. The avionics requirements to meet the mission was limited by the existing aircraft structural and performance characteristics and resultant space, weight, and power restrictions. These limitations and night operations requirement led to the use of night vision goggles. The combination of these requirements and limitations dictated an integrated control/display approach using multifunction displays and controls.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Ames Research Center Technical Workshop: Advanced Helicopter Cockpit Design Concepts; p 121-144
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  • 14
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    In:  CASI
    Publikationsdatum: 2006-04-09
    Beschreibung: The interactions between the design and operation of aircraft fuel systems and the properties of alternative aircraft fuels are discussed. An overview of fuels system research and technology in terms of its rationale, its progress, and future plans is given. The measurement of ambient air temperatures for a wide range of seasonal and geographic variations, design studies on the use of fuels with increased as well as conventional freezing temperatures, the evaluation of fuel heating systems, and the low temperature behavior of fuels are among the topics discussed.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: Assessment of Alternative Aircraft Fuels; p 111-120
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  • 15
    Publikationsdatum: 2006-02-14
    Beschreibung: Several examples of spacecraft systems fires are examined. Much of the design, manufacture, inspection, test, and operation of current high pressure oxygen components and systems has been driven by weight, cost, functional, and schedule requirements. As a result, little coordination has been expended on design for safe operation. While the number of oxygen related fires has not been large, their cost, including program losses and delays, has been very large. Most of these failures need not have occurred.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 13 p
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  • 16
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    In:  CASI
    Publikationsdatum: 2006-04-09
    Beschreibung: The results of a study assessing the impact of using jet fuel with relaxed specification properties on an aircraft fuel system are given. The study objectives were to identify credible values for specific fuel properties which might be relaxed, to evolve advanced fuel system designs for airframe and engines which would permit use of the specified relaxed properties fuels, and to evaluate performance of the candidate advanced fuel systems and the relaxed property fuels in a typical transport aircraft. The study used, as a baseline, the fuel system incorporated in the Lockheed Tristar. This aircraft is powered by three RB.211-524 Rolls-Royce engines and incorporates a Pratt and Whitney ST6C-421 auxiliary power unit for engine starting and inflight emergency electrical power. The fuel property limits examined are compared with commercial Jet A kerosene and the NASA RFP fuel properties. A screening of these properties established that a higher freezing point and a lower thermal stability would impact fuel system design more significantly than any of the other property changes. Three candidate fuel systems which combine the ability to operate with fuels having both a high freeze point and a low thermal stability are described. All candidates employ bleed air to melt fuel freeze-out prior to starting the APU or an inoperable engine. The effects of incorporating these systems on aircraft weight and engine specific fuel consumption are given.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Lewis Research Center Assessment of Alternative Aircraft Fuels; p 159-170
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  • 17
    Publikationsdatum: 2006-02-14
    Beschreibung: Based on initial results obtained from the performance optimization code, a number of observations can be made regarding the utility of optimization codes in supporting design of rotors for improved performance. (1) The primary objective of improving the productivity and responsiveness of current design methods can be met. (2) The use of optimization allows the designer to consider a wider range of design variables in a greatly compressed time period. (3) Optimization requires the user to carefully define his problem to avoid unproductive use of computer resources. (4) Optimization will increase the burden on the analyst to validate designs and to improve the accuracy of analysis methods. (5) Direct calculation of finite difference derivatives by the optimizer was not prohibitive for this application but was expensive. Approximate analysis in some form would be considered to improve program response time. (6) Program developement is not complete and will continue to evolve to integrate new analysis methods, design problems, and alternate optimizer options.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 15 p
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  • 18
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    In:  Other Sources
    Publikationsdatum: 2011-08-18
    Beschreibung: The application of an experimental flight test maneuver autopilot test technique for collecting aerodynamic and structural flight research data on a highly maneuverable aircraft is described in this paper. This technique, which was developed to increase the quality and quantity of data obtained during flight test, was applied to the highly maneuverable aircraft technology (HiMAT) vehicle. A primary flight experiment was to verify the design techniques used to develop the HiMAT aerodynamics and structures. This required the performance of maneuvers for collection of large quantities of high-quality pressure distribution, loads, and wing and canard deflection data. Flight data obtained while executing these research maneuvers are presented to demonstrate the effectiveness of this new technique.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: Journal of Aircraft (ISSN 0021-8669); 21; 776-782
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  • 19
    Publikationsdatum: 2011-08-18
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: Journal of Aircraft (ISSN 0021-8669); 21; 767-775
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  • 20
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    Publikationsdatum: 2011-08-18
    Beschreibung: Rotorcraft noise includes turbofan engine noise components, as well as noise from the main and tail rotors that is conditioned by the aircraft's various operational modes. Both of the rotors generate loading noise and broadband noise. Another noise contributor is blade/vortex interaction noise, which results when shed vortices are encountered by a following blade, releasing impulsive acoustic energy. Attention is presently given to the experimental and developmental initiatives to be made by a NASA/industry five-year program that began in 1983. Aeroacoustic data acquired from experiments conducted in NASA facilities can be used in the development of empirical noise prediction methods, in the improvement of existing noise prediction methodology, in the evaluation of proposed reduced noise designs, and in the establishment of useful scaling relationships for selected noise-generating mechanisms.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: Aerospace America (ISSN 0740-722X); 22; 60-63
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  • 21
    Publikationsdatum: 2011-08-18
    Beschreibung: This short paper will demonstrate that the separation of altitude and flight path angle dynamics using singular perturbation techniques for a transport fuel optimization problem results in an unacceptable oscillation in altitude. A technique for damping this oscillation by adding a penalty term to the cost function for the optimization problem will be discussed. This technique will be compared with a different approach that linearizes the altitude and flight path angle boundary layers.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
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  • 22
    Publikationsdatum: 2011-08-18
    Beschreibung: A procedure based on a modified stepwise regression and several selection criteria is presented for the determination of airplane model structure from flight data. The aerodynamic force and moment coefficients in an airplane model are expresed either as polynomials in output and input variables or as a combination of splines. The procedure is demonstrated in three examples by attempting to determine a local, extended and global model. Some of the resulting models are verified by using the maximum likelihood estimation or by examining model prediction capabilities.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
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  • 23
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    Publikationsdatum: 2011-08-18
    Beschreibung: The AFTI/F-16 flight test program is summarized, and several design issues of general interest are addressed. A brief description is given of the test vehicle, its flight control modes, and the flight envelopes in which testing was performed. Flight test results are summarized by addressing benefits experienced in flight control task-tailoring, handling qualities in mission tasks, aircraft structure considerations, digital flight control system performance, and human factors. Finally, several design issues relevant to future fighter aircraft are examined, including degraded flight control, system complexity, simplex information in redundant systems, and single failure propagation in redundant systems.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
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  • 24
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    Publikationsdatum: 2011-08-19
    Beschreibung: Several recent helicopter vibration reduction research programs are described. Results of studies of blade design parameters in rotor vibratory response and of an advanced blade design for reduced vibration are examined. An optimization approach to develop a general automated procedure for rotor blade design is described, and analytical results for an articulated rotor operating at a steady 160 kt flight condition are reported. The use of a self-adaptive controller to implement higher harmonic control in closed-loop fashion is addressed, and a computer simulation used to evaluate and compare the performance of alternative algorithms included in the generic active controller is discussed. Results are presented for steady level flight conditions, short-duration maneuvers, blade stresses and rotor performance, blade-appended aeroelastic devices, vibratory airloads, wake-induced blade airloads, and airloads from blade motions, the interaction of rotor and fuselage, and the interaction of rotor and empennage.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
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  • 25
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    Publikationsdatum: 2011-08-19
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: Journal of Aircraft (ISSN 0021-8669); 21; 966-970
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  • 26
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    Publikationsdatum: 2011-08-19
    Beschreibung: The X-29 experimental aircraft, which is a technology integration and evaluation platform for such features as static longitudinal instability, sweptforward wings and three-surface longitudinal control, offers an opportunity to validate the entire aircrft design process through careful correlation and comparison of flight test results with wind tunnel results and design predictions. Attention is presently given to the design features of the aircraft, which encompass supercritical airfoils, digital flight control, and aeroelastically tailored composite wings, as well as to the flight test program that was formulated to investigate the interactions and relative merits of these design features, in light of data gathered by carefully positioned sensors.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: AIAA Student Journal (ISSN 0001-1452); 22; 2-12
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  • 27
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    Publikationsdatum: 2011-08-18
    Beschreibung: The tilt rotor concept is introduced and the performance capabilities and noise characteristics of the XV-15 aircraft are discussed. In hover, the aircraft is lifted by the two wing tip mounted rotors with the nacelles in the vertical position. In this flight mode, the vehicle is a twin rotor helicopter and is controlled by rotor cyclic and collective controls. The aircraft can fly as a helicopter or tilt the nacelle to the propeller mode and operate as a fixed-wing twin turboprop airplane. It is also possible to stop the conversion at any intermediate angle and fly continuously or reconvert. The rotors are powered by two modified T-53 engines and the power train includes a cross shaft located in the wing, to allow for the engine failure case and still retain power to both rotors.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: American Planning Association Proc. of the Monterey Conf. on Planning for Rotorcraft and Commuter Air Transportation; p 24-33
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  • 28
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    Publikationsdatum: 2011-08-18
    Beschreibung: The design concepts, performance capabilities, and projected applications of the Quiet Short-Haul Research Aircraft (QSRA) are discussed. The propulsive lift system of the QSRA provides the lift required for short field operations at low community noise levels. This system consists of four high bipass ratio, geared turbofan engines mounted so that the engine exhaust flows across the upper surface of the wing (upper surface blowing). Large specially shaped flaps behind each engine control the direction of the flow for each phase of flight. A 95 passenger short haul transport based on this technology could operate out of a 2500 foot runway with a combined takeoff and landing 90 EPNdB footprint area of 2.7 sq mi.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: American Planning Association Proc. of the Monterey Conf. on Planning for Rotorcraft and Commuter Air Transportation; p 22-23
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  • 29
    Publikationsdatum: 2011-08-18
    Beschreibung: A program of experimental and analytical research has been performed to demonstrate the effects of rotor and fuselage design parameters on rotor in-plane stability, including aeromechanical stability. The experimental data were obtained from hover and wind-tunnel tests of a scaled advanced bearingless main rotor model. Both isolated-rotor and free-hub conditions were tested. Test parameters included blade built-in cone and sweep angles; rotor inplane structural stiffness and damping; pitch link stiffness and location; and fuselage natural frequency, damping, and inertia. The results show that rotor blade structural damping is one of the most influential design parameters in obtaining acceptable aeromechanical stability margins. Other parameters, such as blade cone angle, pitch link location (rotor delta 3) and anisotropic hub damper configurations, may be used to improve stability margins, but their individual effects are subtle.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
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  • 30
    Publikationsdatum: 2011-08-18
    Beschreibung: Previously cited in issue 12, p. 1701, Accession no. A83-29806
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: Journal of Aircraft (ISSN 0021-8669); 21; 272-277
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  • 31
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    Publikationsdatum: 2011-08-18
    Beschreibung: Previously cited in issue 12, p. 1702, Accession no. A83-29860
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: Journal of Aircraft (ISSN 0021-8669); 21; 209-217
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  • 32
    Publikationsdatum: 2011-08-18
    Beschreibung: The purposes and progress in the Integrated Technology Rotor/Flight Research Rotor (ITR/FRR) Project, a joint effort by the U.S. Army and NASA, are outlined. The project goal is to integrate the disciplines of rotor design, aerodynamics, structures, materials, dynamics, and acoustics, to remove the risks in applying the technology, and to develop an advanced flight research rotor which permits significant variation in the rotor properties. Composite rotors are believed to be capable of displaying infinite fatigue lifetimes with fail-safe characteristics, and bearingless hubs simplify hub designs. The programs will also consider the flight control, propulsion, and structures. Concept definition contracts are presently distributed among five companies, and preliminary designs will lead to model tests in 1984.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: Vertiflite (ISSN 0042-4455); 29; Sept
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  • 33
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    Publikationsdatum: 2011-08-18
    Beschreibung: The failure mechanisms, design lessons, and test equipment employed by NASA in establishing the airworthiness and crashworthiness of aircraft components for commercial applications are described. The composites test programs have progressed to medium primary structures such as stabilizers and a vertical fin. The failures encountered to date have been due to the nonyielding nature of composites, which do not diffuse loads like metals, and the presence of eccentricities, irregular shapes, stiffness changes, and discontinuities that cause tension and shear. Testing to failure, which always occurred in first tests before the design loads were reached, helped identify design changes and reinforcements that produced successful products. New materials and NDE techniques are identified, together with aircraft structural design changes that offer greater protection to the passengers, fuel antimisting agents, and landing gear systems.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: Astronautics and Aeronautics (ISSN 0004-6213); 21; Sept
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  • 34
    Publikationsdatum: 2011-08-18
    Beschreibung: Previously cited in issue 3, p. 325, Accession no. A82-14379
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: (ISSN 0731-5090)
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  • 35
    Publikationsdatum: 2016-06-07
    Beschreibung: The need for numerical design optimization of naval structures is discussed. The complexity of problems that arise due to the significant roles played by three major disciplines, i.e., structural mechanics, acoustics, and hydrodynamics are discussed. A major computer software effort that has recently begun at the David W. Taylor Naval Ship R&D Center to accommodate large multidisciplinary analyses is also described. In addition to primarily facilitating, via the use of data bases, interdisciplinary analyses for predicting the response of the Navy's ships and related structures, this software effort is expected to provide the analyst with a convenient numerical workbench for performing large numbers of analyses that may be necessary for optimizing the design performance. Finally, an example is included that investigates several aspects of optimizing a typical naval structure from the viewpoints of strength, hydrodynamic form, and acoustic characteristics.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 1; 8 p
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  • 36
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: To evaluate the role that optimization can play in structural model refinement, it is necessary to examine the existing environment for the structural design/structural modification process. The traditional approach to design, analysis, and modification is illustrated. Typically, a cyclical path is followed in evaluating and refining a structural system, with parallel paths existing between the real system and the analytical model of the system. The major failing of the existing approach is the rather weak link of communication between the cycle for the real system and the cycle for the analytical model. Only at the expense of much human effort can data sharing and comparative evaluation be enhanced for the two parallel cycles. Much of the difficulty can be traced to the lack of a user-friendly, rapidly reconfigurable engineering software environment for facilitating data and information exchange. Until this type of software environment becomes readily available to the majority of the engineering community, the role of optimization will not be able to reach its full potential and engineering productivity will continue to suffer. A key issue in current engineering design, analysis, and test is the definition and development of an integrated engineering software support capability. The data and solution flow for this type of integrated engineering analysis/refinement system is shown.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 1; 7 p
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  • 37
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: The mathematical statement of the general nonlinear optimization problem is given as follows: find the vector of design variables, X, that will minimize f(X) subject to G sub J (x) + or - 0 j=1,m H sub K hk(X) = 0 k=1,l X Lower I approx less than X sub I approx. less than X U over I i = 1,N. The vector of design variables, X, includes all those variables which may be changed by the ADS program in order to arrive at the optimum design. The objective function F(X) to be minimized may be weight, cost or some other performance measure. If the objective is to be maximized, this is accomplished by minimizing -F(X). The inequality constraints include limits on stress, deformation, aeroelastic response or controllability, as examples, and may be nonlinear implicit functions of the design variables, X. The equality constraints h sub k(X) represent conditions that must be satisfied precisely for the design to be acceptable. Equality constraints are not fully operational in version 1.0 of the ADS program, although they are available in the Augmented Lagrange Multiplier method. The side constraints given by the last equation are used to directly limit the region of search for the optimum. The ADS program will never consider a design which is not within these limits.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 1; 10 p
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  • 38
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: The purpose of this project was to investigate the use of optimization techniques to improve the flutter margins of the HARM AGM-88A wing. The missile has four cruciform wings, located near mid-fuselage, that are actuated in pairs symmetrically and antisymmetrically to provide pitch, yaw, and roll control. The wings have a solid stainless steel forward section and a stainless steel crushed-honeycomb aft section. The wing restraint stiffness is dependent upon wing pitch amplitude and varies from a low value near neutral pitch attitude to a much higher value at off-neutral pitch attitudes, where aerodynamic loads lock out any free play in the control system. The most critical condition for flutter is the low-stiffness condition in which the wings are moved symmetrically. Although a tendency toward limit-cycle flutter is controlled in the current design by controller logic, wing redesign to improve this situation is attractive because it can be accomplished as a retrofit. In view of the exploratory nature of the study, it was decided to apply the optimization to a wing-only model, validated by comparison with results obtained by Texas Instruments (TI). Any wing designs that looked promising were to be evaluated at TI with more complicated models, including body modes. The optimization work was performed by McIntosh Structural Dynamics, Inc. (MSD) under a contract from TI.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 1; 13 p
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  • 39
    Publikationsdatum: 2016-06-07
    Beschreibung: The work that has been done in the last decade or so in the application of optimization techniques to vehicle design is discussed. Much of the work reviewed deals with the design of body or suspension (chassis) components for reduced weight. Also reviewed are studies dealing with system optimization problems for improved functional performance, such as ride or handling. In reviewing the work on the use of optimization techniques, one notes the transition from the rare mention of the methods in the 70's to an increased effort in the early 80's. Efficient and convenient optimization and analysis tools still need to be developed so that they can be regularly applied in the early design stage of the vehicle development cycle to be most effective. Based on the reported applications, an attempt is made to assess the potential for automotive application of optimization techniques. The major issue involved remains the creation of quantifiable means of analysis to be used in vehicle design. The conventional process of vehicle design still contains much experience-based input because it has not yet proven possible to quantify all important constraints. This restraint on the part of the analysis will continue to be a major limiting factor in application of optimization to vehicle design.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 1; 25 p
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  • 40
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: In optimizing a helicopter configuration, Hughes Helicopters uses a program called Computer Aided Sizing of Helicopters (CASH), written and updated over the past ten years, and used as an important part of the preliminary design process of the AH-64. First, measures of effectiveness must be supplied to define the mission characteristics of the helicopter to be designed. Then CASH allows the designer to rapidly and automatically develop the basic size of the helicopter (or other rotorcraft) for the given mission. This enables the designer and management to assess the various tradeoffs and to quickly determine the optimum configuration.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 1; 19 p
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  • 41
    Publikationsdatum: 2016-06-07
    Beschreibung: Optimum Preliminary Design of Transports (OPDOT) is a computer program developed at NASA Langley Research Center for evaluating the impact of new technologies upon transport aircraft. For example, it provides the capability to look at configurations which have been resized to take advantage of active controls and provide and indication of economic sensitivity to its use. Although this tool returns a conceptual design configuration as its output, it does not have the accuracy, in absolute terms, to yield satisfactory point designs for immediate use by aircraft manufacturers. However, the relative accuracy of comparing OPDOT-generated configurations while varying technological assumptions has been demonstrated to be highly reliable. Hence, OPDOT is a useful tool for ascertaining the synergistic benefits of active controls, composite structures, improved engine efficiencies and other advanced technological developments. The approach used by OPDOT is a direct numerical optimization of an economic performance index. A set of independent design variables is iterated, given a set of design constants and data. The design variables include wing geometry, tail geometry, fuselage size, and engine size. This iteration continues until the optimum performance index is found which satisfies all the constraint functions. The analyst interacts with OPDOT by varying the input parameters to either the constraint functions or the design constants. Note that the optimization of aircraft geometry parameters is equivalent to finding the ideal aircraft size, but with more degrees of freedom than classical design procedures will allow.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: Recent Experiences in Multidisciplinary Analysis and Optimization, Part 1; 15 p
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  • 42
    facet.materialart.
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: The structural design process for large transport aircraft is described. Critical loads must be determined from a large number of load cases within the flight maneuver envelope. The structural design is also constrained by considerations of producibility, reliability, maintainability, durability, and damage tolerance, as well as impact dynamics and multiple constraints due to flutter and aeroelasticity. Aircraft aeroelastic design considerations in three distinct areas of product development (preliminary design, advanced design, and detailed design) are presented and contrasted. The present state of the art is challenged to solve the practical difficulties associated with design, analysis, and redesign within cost and schedule constraints. The current practice consists of largely independent engineering disciplines operating with unorganized data interfaces. The need is then demonstrated for a well-planned computerized aeroelastic structural design optimization system operating with a common interdisciplinary data base. This system must incorporate automated interfaces between modular programs. In each phase of the design process, a common finite-element model for static and dynamic optimization is required to reduce errors due to modeling discrepancies. As the design proceeds from the simple models in preliminary design to the more complex models in advanced and detailed design, a means of retrieving design data from the previous models must be established.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 1; 12 p
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  • 43
    facet.materialart.
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: A Program for an Iterative Aeroelastic Solution (PIAS) is discussed. This will be a modular computer program that combines the use of a finite-element structural analysis code with any linear or nonlinear aerodynamic code. At this point in time, PIAS has been designed but the software has not been written. The idea for this development originated with P. J. (Bud) Bobbitt of the NASA Langley Research Center. There was initial interest in an aeroelastic solution for a separation-induced leading-edge vortex. Some examples of the flow patterns for a low aspect ratio wing are shown. The Leading-Edge Vortex Program, which calculates pressure distributions including the effects of a separation-induced leading-edge vortex, uses an iterative solution method. This led to the concept of an iteration cycle on configuration shape external to the aerodynamic code.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 1; 15 p
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  • 44
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: Military aircraft research opportunities for the future are briefly surveyed. Aircraft control theory, design analysis, systems integration and flight characteristics are discussed.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Langley Research Center NASA Aircraft Controls Research, 1983; p 559-569
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  • 45
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    Publikationsdatum: 2011-08-19
    Beschreibung: A research study was initiated to systematically determine the impact of selected blade tip geometric parameters on conformable rotor performance and loads characteristics. The model articulated rotors included baseline and torsionally soft blades with interchangeable tips. Seven blade tip designs were evaluated on the baseline rotor and six tip designs were tested on the torsionally soft blades. The designs incorporated a systemmatic variation in geometric parameters including sweep, taper, and anhedral. The rotors were evaluated in the NASA Langley Transonic Dynamics Tunnel at several advance ratios, lift and propulsive force values, and tip Mach numbers. A track sensitivity study was also conducted at several advance ratios for both rotors. Based on the test results, tip parameter variations generated significant rotor performance and loads differences for both baseline and torsionally soft blades. Azimuthal variation of elastic twist generated by variations in the tip parameters strongly correlated with rotor performance and loads, but the magnitude of advancing blade elastic twist did not. In addition, fixed system vibratory loads and rotor track for potential conformable rotor candidates appears very sensitive to parametric rotor changes.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
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  • 46
    Publikationsdatum: 2011-08-19
    Beschreibung: Various papers on helicopter rotor technology are presented. The subjects considered include: ground resonance analysis using a substructure modelling approach, aerolastic stability of a bearingless rotor, experimentally determined flutter from two and three-bladed model bearingless rotors in hover, lifting surface theory for a helicopter rotor in forward flight, aeroelastic considerations for torsionally soft rotors, and restructuring of a rotor analysis program. Also discussed are: dynamic inflow and its effect on experimental correlations, flap-lag-torsion instability in forward flight, dynamic stability of a bearingless circulation control rotor blade in hover, dynamic response characteristics of a circulation control rotor model pneumatic system, the relations between vibratory loads and airframe vibrations, coupled rotor body vibrations with in-plane degrees of freedom, helicopter vibration reduction concepts.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
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  • 47
    Publikationsdatum: 2011-08-19
    Beschreibung: The combined effects of blade torsion and dynamic inflow on the aeroelastic stability of an elastic rotor blade in forward flight are studied. The Helicopter Equations for Stability and Loads (HESL) program is extended to derive the governing equations of motion for the blade, and a Lagrangian formulation is used to obtain the equations in generalized coordinates. The program generates the steady-state and linearized perturbation equations in symbolic form and then codes them into FORTRAN subroutines. The coefficients for each equation and for each mode are identified through a numerical program; the latter can also be used to obtain the harmonic balance equations. The governing multiblade equations are derived explicitly using HESL. These equations can accommodate any number of elastic blade modes. Stability results are presented for several hingeless rotor blade structural models, and the influence of dynamic inflow in forward flight with an elastic hingeless rotor is investigated.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
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  • 48
    Publikationsdatum: 2011-08-19
    Beschreibung: A convenient and versatile procedure for modeling and analyzing ground resonance phenomena is described and illustrated. A computer program is used which dynamically couples differential equations with nonlinear and time dependent coefficients. Each set of differential equations may represent a component such as a rotor, fuselage, landing gear, or a failed damper. Arbitrary combinations of such components may be formulated into a model of a system. When the coupled equations are formed, a procedure is executed which uses a Floquet analysis to determine the stability of the system. Illustrations of the use of the procedures along with the numerical examples are presented.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
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  • 49
    Publikationsdatum: 2011-08-19
    Beschreibung: The Rotor Systems Research Aircraft (RSRA) is a unique research aircraft designed to flight test advanced helicopter rotor system. Its principal flight test configuration is as a compound helicopter. The fixed wing configuration of the RSRA was primarily considered an energy fly-home mode in the event it became necessary to sever an unstable rotor system in flight. While it had always been planned to flight test the fixed wing configuraion, the selection of the RSRA as the flight test bed for the x-wing rotor accelerated this schedule. This paper discusses the build-up to, and the test of, the RSRA fixed wing configuration. It is written primarily from the test pilot's perspective.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
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  • 50
    Publikationsdatum: 2011-08-19
    Beschreibung: The Rotor Systems Research Aircraft helicopter technology demonstration test bed incorporates an active isolator system which reduces the rotor vibrations that are transmitted to the airframe and allows the simultaneous measurement of all six forces and moments generated by the rotor. The first full system calibration was performed in 1983 to verify the system's static load measurement capabilities; the analysis of the data encompassed multiple linear regressions to determine calibration matrices for different data sets, and a hysteresis removal algorithm for the estimation of in-flight measurement errors. The results obtained indicate that the active isolator system meets most performance predictions.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
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  • 51
    Publikationsdatum: 2011-08-19
    Beschreibung: Wind-tunel testing of a properly scaled aeroelastic model helicopter rotor is considered a necessary phase in the design development of new or existing rotor systems. For this reason, extensive testing of aeroelastically scaled model rotors is done in the Transonic Dynamics Tunnel (TDT) located at the NASA Langley Research Center. A unique capability of this facility, which enables proper dynamic scaling, is the use of Freon as a test medium. A description of the TDT and a discussion of the benefits of using Freon as a test medium are presented. A description of the model test bed used, the Aeroelastic Rotor Experimental System (ARES), is also provided and examples of recent rotor tests are cited to illustrate the advantages and capabilities of aeroelastic model rotor testing in the TDT. The importance of proper dynamic scaling in identifying and solving rotorcraft aeroelastic problems, and the importance of aeroelastic testing of model rotor systems in the design of advanced rotor systems are demonstrated.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
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  • 52
    Publikationsdatum: 2011-08-18
    Beschreibung: Previously cited in issue 13, p. 2021, Accession no. A82-30143
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: (ISSN 0021-8669)
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  • 53
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    Publikationsdatum: 2011-08-18
    Beschreibung: Previously cited in issue 13, p. 2021, Accession no. A82-30146
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: Journal of Aircraft (ISSN 0021-8669); 20; 913-919
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  • 54
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    Publikationsdatum: 2011-08-18
    Beschreibung: Previously cited in issue 19, p. 2977, Accession no. A82-39135
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: Journal of Aircraft (ISSN 0021-8669); 20; 1043-104
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  • 55
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    Publikationsdatum: 2011-08-18
    Beschreibung: This paper examines the relative efficiency of canard, tandem, and aft-tailed aircraft configurations through analysis of an elementary lifting system. Stability and trim requirements are imposed upon the system and its C sub L(max), drag, and structural weight are studied as its geometry varies over a wide range of possible configurations. During the course of the analysis, two general solutions emerge for minimum induced drag as a function of the geometry and the division of lift between the surfaces of such a system - one for fixed span and the other for fixed weight. The conclusion is that the pre-eminence of the conventional aft-tailed configuration has a sound fundamental basis, but that there may be some room for improvement.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: Journal of Aircraft (ISSN 0021-8669); 20; 983-992
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  • 56
    Publikationsdatum: 2011-08-18
    Beschreibung: The primary objective of the advanced fighter technology integration/F-16 (AFTI/F-16) development program is to demonstrate advanced fighter technologies to improve weapon delivery and aircraft survivability. Instrumentation and data processing for monitoring aircraft operation during flight testing is necessary not only for safety-of-flight considerations but also for rapid evaluation of flight test results. The complexity of the AFTI/F-16 aircraft necessitates an extensive capability to accomplish data goals; this paper describes that capability and the resultant product.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
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  • 57
    Publikationsdatum: 2011-08-18
    Beschreibung: Previously cited in issue 17, p. 2685, Accession no. A82-35018
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: (ISSN 0021-8669)
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  • 58
    Publikationsdatum: 2011-08-18
    Beschreibung: Previously cited in issue 05, p. 654, Accession no. A82-16910
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: (ISSN 0731-5090)
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  • 59
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    Publikationsdatum: 2011-08-18
    Beschreibung: Previously cited in issue 19, p. 2977, Accession no. A82-39106
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: (ISSN 0021-8669)
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  • 60
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    Publikationsdatum: 2011-08-18
    Beschreibung: Previously cited in issue 20, p. 3464, Accession no. A81-43156
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: (ISSN 0021-8669)
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  • 61
    Publikationsdatum: 2011-08-18
    Beschreibung: Previously cited in issue 24, p. 4127, Accession no. A81-48618
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: (ISSN 0021-8669)
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  • 62
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    Publikationsdatum: 2011-08-18
    Beschreibung: Previously cited in issue 14, p. 2298, Accession no. A81-32932
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: (ISSN 0021-8669)
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  • 63
    Publikationsdatum: 2011-08-18
    Beschreibung: This paper describes a method for systematic analysis and optimization of large engineering systems, e.g., aircraft, by decomposition of a large task into a set of smaller, self-contained subtasks that can be solved concurrently. The subtasks may be arranged in many hierarchical levels with the assembled system at the top level. Analyses are carried out in each subtask using inputs received from other subtasks, and are followed by optimizations carried out from the bottom up. Each optimization at the lower levels is augmented by analysis of its sensitivity to the inputs received from other subtasks to account for the couplings among the subtasks in a formal manner. The analysis and optimization operations alternate iteratively until they converge to a system design whose performance is maximized with all constraints satisfied. The method, which is still under development, is tentatively validated by test cases in structural applications and an aircraft configuration optimization. It is pointed out that the method is intended to be compatible with the typical engineering organization and the modern technology of distributed computing.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
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  • 64
    Publikationsdatum: 2011-08-18
    Beschreibung: Two sets of wind tunnel tests were performed to examine the relative merits of wing-canard, wing-tail and tailless configurations for advanced fighters. Both sessions focused on variable camber using automated, prescheduled leading and trailing edge flap positioning. The trials considered a modified F-16 tail and canard configuration at subsonic, transonic and supersonic speeds, a 60 deg delta wing sweep, a 44 deg leading edge trapezoidal wing at subsonic and supersonic speeds, vortex flow effects, and flow interactions in the canard-wing-tail-tailless variations. The results showed that large negative stabilities would need to be tolerated in wing-canard arrangements to make them competitive with wing-tail arrangements. Subsonic polar shapes for canard and tailless designs were more sensitive to static design margins than were wing-tail arrangements. Canards provided better stability at supersonic speeds. The static margin limits were a critical factor in control surface selection. Finally, a tailless delta wing configuration exhibited the lowest projected gross take-off weight and drag values.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
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  • 65
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    In:  Other Sources
    Publikationsdatum: 2011-08-18
    Beschreibung: Some historical developments of flight testing of unique aircraft configurations by NASA and the military sector are documented. Several test aircraft are outlined including the M2-F1 (which was the first Space Shuttle concept ever demonstrated, and contributed to the present design), the X-15, the Flying Wing, the Lunar Landing Research Vehicle, the Oblique Wing Research Aircraft, and the Space Shuttle Enterprise. Future test aircraft such as the forward swept wing X-29A Advanced Technology Demonstrator Aircraft, and the X-Wing vehicle are also mentioned. It is noted that the logical preliminary to flight testing is flight simulation, and that flight testing itself is the vital final component of the development, and seems to be the most direct approach to aircraft evaluations.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: AIAA Student Journal (ISSN 0001-1460); 21; 2-7
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  • 66
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    In:  Other Sources
    Publikationsdatum: 2011-08-18
    Beschreibung: NASA has undertaken development and test programs in collaboration with the large transport aircraft construction industry, in order to remove existing barriers to the use of composite material primary structures and to assess their advantages in terms of both acquisition cost and mission performance. These programs are expected to reach design technology readiness for wing and fuselage structures by 1988, paving the way for the validation of design and manufacturing methods in the early 1990s. While composites promise a reduction in fuselage manufacturing costs, it is judged that the relative cost of a metallic wing will be more difficult to surpass. Nevertheless, a 40 percent wing weight saving may more than compensate for increased wing structure cost.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: Aerospace America (ISSN 0740-722X); 22; 58-62
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  • 67
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    In:  Other Sources
    Publikationsdatum: 2011-08-18
    Beschreibung: Technologies developed through NASA's Energy Efficient Transport Program are described. The program was charged with research in advanced aerodynamics and active controls, with the goal of increasing the fuel efficiency of transport aircraft by 15 to 20 percent. Research in aerodynamics was directed toward the development of high-aspect-ratio supercritical wings, winglets, computational design methodology, high-lift devices, propulsion airframe integration, and surface coatings. The active control portion of the program investigated Wing Load Alleviation (WLA) through the use of active controls, drag reduction, and the effect of active pitch controls on fuel consumption. It was found that applying active control functions at the beginning of the aircraft design cycle brings the best benefit, and that if active control and advanced aerodynamic airframe configurations are applied to transport aircraft design concurrently with new lightweight materials, fuel consumption can be reduced by as much as 40 percent.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: Aerospace America (ISSN 0740-722X); 22
    Format: text
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  • 68
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    In:  Other Sources
    Publikationsdatum: 2011-08-18
    Beschreibung: NASA's Aircraft Energy Efficiency (ACEE) program, which began in 1976, has mounted a development effort in four major transport aircraft technology fields: laminar flow systems, advanced aerodynamics, flight controls, and composite structures. ACEE has explored two basic methods for achieving drag-reducing boundary layer laminarization: the use of suction through the wing structure (via slots or perforations) to remove boundary layer turbulence, and the encouragement of natural laminar flow maintenance through refined design practices. Wind tunnel tests have been conducted for wide bodied aircraft equipped with high aspect ratio supercritical wings and winglets. Maneuver load control and pitch-active stability augmentation control systems reduce fuel consumption by reducing the drag associated with high aircraft stability margins. Composite structures yield lighter airframes that in turn call for smaller wing and empennage areas, reducing induced drag for a given payload. In combination, all four areas of development are expected to yield a fuel consumption reduction of 40 percent.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: Aerospace America (ISSN 0740-722X); 22; 54-58
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  • 69
    Publikationsdatum: 2011-08-18
    Beschreibung: Altitude/path angle transitions to fuel-optimal, energy climb and descent paths are examined for subsonic transport aircraft. These transitions are termed boundary layers in singular perturbation theory, the framework used herein to simplify solutions to the state-Euler system. The energy climb and descent paths provide equilibrium or stationary points for the boundary layer system, and thus for moderate transitions, presumed valid for the class of aircraft considered, the boundary layer system may be linearized. This simplification allows derivation of an explicit solution to the two-point boundary-value, boundary layer problem and, as a consequence, yields a nearly optimal control law, in feedback form, for the transitions. Numerical simulation results using the feedback control law are presented for a Boeing 737 airframe (NASA-ATOPS Vehicle) employing twin JT8D-7-7A engines.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
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  • 70
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    In:  Other Sources
    Publikationsdatum: 2011-08-19
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Langley Research Center, Theoretical Aerodynamics Contractors' Workshop, Volume 2; p 365-38
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  • 71
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    In:  Other Sources
    Publikationsdatum: 2011-08-18
    Beschreibung: The efficiency of small transport aircraft can be improved through the adaptation of high altitude turbine engines, and that flights reaching altitudes of 40,000, 60,000, and 80,000 feet can show savings in both flight time and fuel consumption even for trips as short as 500 miles. Studies for a 40-passenger high altitude transport are presented. An increase in structural weight due to larger wing areas, larger engines, and larger engine frontal areas would make the ratio of gross weight to payload look less favorable, but the efficiency of the plane in passenger miles per gallon would increase with altitude. It is also suggested that supercritical airfoils be designed to achieve higher lift coefficients and speeds. A reduction of reduced drag through the use of horizontal or vertical wing tip extensions is also discussed.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
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  • 72
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    In:  Other Sources
    Publikationsdatum: 2011-08-18
    Beschreibung: Prompted by the extensive experience obtained with vortex lift-generating leading edges in the SR-71, Concorde and F-16 supersonic aircraft, development efforts have recently been made toward the use of variable incidence angle delta wing leading edge 'vortex flaps' for supersonic cruise and maneuvering performance improvements in fighter aircraft. Vortex lift flaps have been wind tunnel tested on scale models, and it has been noted that a variety of effects can be obtained through the use of folding, hinged, and tabbed flap designs. Flap planforms can, moreover, be varied in length and in total area, as well as segmented, to yield unique combinations of drag reduction, vortex generation, longitudinal stability, and vortex flow reattachment. It is speculated that the vortex flap may be applicable to multimission fighters, and promote STOL performance.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: Aerospace America (ISSN 0740-722X); 22; 95-99
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  • 73
    Publikationsdatum: 2016-06-07
    Beschreibung: An ongoing program whose goal is to develop an automated procedure that can assist in the preliminary design of aircraft and space structures is described. The approach and capabilities that are to be included in the final procedures are descussed. By using proven engineering software as a basis for the project, a reliable and interdisciplinary procedure is developed. The use of a control language for module sequencing and execution permits efficient development of the procedure and gives the user significant flexibility in altering or enhancing the procedure. The data base system provides reliable and efficient access to the large amounts of interrelated data required in an enterprise of this sort. In addition, the data base allows interfacing with existing pre- and post-processors in an almost trivial manner. Altogether, the procedure promises to be of considerable utility to preliminary structural design teams.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 1; 11 p
    Format: application/pdf
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  • 74
    Publikationsdatum: 2016-06-07
    Beschreibung: The design experience associated with a benchmark aeroelastic design of an out of production transport aircraft is discussed. Current work being performed on a high aspect ratio wing design is reported. The Preliminary Aeroelastic Design of Structures (PADS) system is briefly summarized and some operational aspects of generating the design in an automated aeroelastic design environment are discussed.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 1; 49 p
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  • 75
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: Selection of the best shape of a fillet in a tension bar such that no yielding occurs has long attracted the attention of engineers. Dimensions and notations for the bar and fillet are shown. With symmetry, only the upper half of the bar is considered. The optimal design problem is to find a boundary shape to minimize the total area of the fillet such that no yielding occurs. The classical boundary value problem is reduced to a variational or energy related problem which not only has excellent properties of existence and uniqueness but also provides the mathematical foundation for finite element analysis. The variational formulation may be viewed as the principle of virtual work and the finite element method as a application of the Galerkin method to the variational equation for approximate solution of the boundary value problem.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 1; 15 p
    Format: application/pdf
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  • 76
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: The efficient design of aircraft structure involves a series of compromises among various engineering disciplines. These compromises are necessary to ensure the best overall design. To effectively reconcile the various technical constraints requires a number of design iterations, with the accompanying long elapsed time. Automated procedures can reduce the elapsed time, improve productivity and hold the promise of optimum designs which may be missed by batch processing. Several examples are given of optimization applications including aeroelastic constraints. Particular attention is given to the success or failure of each example and the lessons learned. The specific applications are shown. The final two applications were made recently.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 1; 17 p
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  • 77
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: The objective is to look at optimization as it applies to the design process at a large aircraft company. The design process at Lockheed-Georgia is described. Some examples of the impact that optimization has had on that process are given, and then some areas that must be considered if optimization is to be successful and supportive in the total design process are indicated. Optimization must continue to be sold and this selling is best done by consistent good performance. For this good performance to occur, the future approaches must be clearly thought out so that the optimization methods solve the problems that actually occur during design. The visibility of the design process must be maintained as further developments are proposed. Careful attention must be given to the management of data in the optimization process, both for technical reasons and for administrative purposes. Finally, to satisfy program needs, provisions must be included to supply data to support program decisions, and to communicate with design processes outside of the optimization process. If designers fail to adequately consider all of these needs, the future acceptance of optimization will be impeded.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 1; 16 p
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  • 78
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: Slender wings on supersonic cruise configurations are expected to be thin and highly swept. As a result, edge-separated vortex flow is inevitable and must be accounted for in aerodynamic analysis and design. The present method is based on the method of suction analogy to calculate the total aerodynamic characteristics. The method requires the solution of the attached flow problem, the latter being solved by a low-order panel method in subsonic and supersonic flow. In essence, the lifting pressure is calculated by using a pressure-doublet distribution satisfying the Prandtl-Glauert equation. From the pressure distribution, the leading-edge suction is calculated. The latter is assumed to be the vortex lift through the method of suction analogy. For a cambered wing, the location of vortex-lift action point is important in predicting the aerodynamic characteristics. It is also seen that the effect of camber shape appears nonlinearly in all aerodynamic expressions. To design the camber shape, the camber slope is represented by a cosine Fourier series at each of several spanwise stations. The Fourier coefficients are the design variables. To design a leading-edge flap in the vortex flow (i.e., a vortex flap), the coordinates of corner points and the deflection angle are the design variables. The process of wing design is to determine the camber shape and twist distribution such that an objective function, typically the drag, is minimized, subject to various constraints.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 1; 12 p
    Format: application/pdf
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  • 79
    Publikationsdatum: 2016-06-07
    Beschreibung: Several statistical and information criteria need to be considered when selecting an adequate model. Incorrect stability and control derivates result from inadequate aerodynamic model structure. Stepwise regression is used to determine the structure for an adequate model. Flight data which covers a nonlinear aerodynamic model range may be analyzed as a single data set or partitioned into several distinct sets. Stepwise regression for model structure detemination and parameter estimation was successfully applied to three aircraft types (single engine general aviation, unaugmented modern jet fighter, jet transport).
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA Aircraft Controls Research, 1983; p 155-170
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  • 80
    Publikationsdatum: 2016-06-07
    Beschreibung: The Flight Optimization System (FLOPS) is an aircraft configuration optimization program developed for use in conceptual design of new aircraft and in the assessment of the impact of advanced technology. The modular makeup of the program is illustrated. It contains modules for preliminary weights estimation, preliminary aerodynamics, detailed mission performance, takeoff and landing, and execution control. An optimization module is used to drive the overall design and in defining optimized profiles in the mission performance. Propulsion data, usually received from engine manufacturers, are used in both the mission performance and the takeoff and landing analyses. Although executed as a single in-core program, the modules are stored separately so that the user may select the appropriate modules (e.g., fighter weights versus transport weights) or leave out modules that are not needed.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 1; 18 p
    Format: application/pdf
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  • 81
    Publikationsdatum: 2016-06-07
    Beschreibung: The complete aircraft design process can be broken into three phases of increasing depth: conceptual design, preliminary design, and detail design. Conceptual design consists primarily of developing general arrangements and selecting the configuration that optimally satisfies all mission requirements. The result of the conceptual phase is a conceptual baseline configuration that serves as the starting point for the preliminary design phase. The conceptual design of an aircraft involves a complex trade-off of many independent variables that must be investigated before deciding upon the basic configuration. Some of these variables are discrete (number of engines), some represent different configurations (canard vs conventional tail) and some may represent incorporation of new technologies (aluminum vs composite materials). At Lockheed-Georgia, the sizing program is known as GASP (Generalized Aircraft Sizing Program). GASP is a large program containing analysis modules covering the many different disciplines involved fin defining the aricraft, such as aerodynamics, structures, stability and control, mission performance, and cost. These analysis modules provide first-level estimates the aircraft properties that are derived from handbook, experimental, and historical sources.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 1; 21 p
    Format: application/pdf
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  • 82
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: More than twenty five years have elapsed since it was recognized that a rather general class of structural design optimization tasks could be properly posed as an inequality constrained minimization problem. It is suggested that, independent of primary discipline area, it will be useful to think about: (1) posing design problems in terms of an objective function and inequality constraints; (2) generating design oriented approximate analysis methods (giving special attention to behavior sensitivity analysis); (3) distinguishing between decisions that lead to an analysis model and those that lead to a design model; (4) finding ways to generate a sequence of approximate design optimization problems that capture the essential characteristics of the primary problem, while still having an explicit algebraic form that is matched to one or more of the established optimization algorithms; (5) examining the potential of optimum design sensitivity analysis to facilitate quantitative trade-off studies as well as participation in multilevel design activities. It should be kept in mind that multilevel methods are inherently well suited to a parallel mode of operation in computer terms or to a division of labor between task groups in organizational terms. Based on structural experience with multilevel methods general guidelines are suggested.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization Part 1; 17 p
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  • 83
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: Research applicable to commercial aircraft is briefly discussed. Display devices, fly by wire control systems, and systems compatibility are among the topics discussed.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA. Langley Research Center NASA Aircraft Controls Research, 1983; p 511-517
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  • 84
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: The Theoretical Mechanics Branch has as one of its long-range goals to work toward solving real-time trajectory optimization problems on board an aircraft. This is a generic problem that has application to all aspects of aviation from general aviation through commercial to military. Overall interest is in the generic problem, but specific problems to achieve concrete results are examined. The problem is to develop control laws that generate approximately optimal trajectories with respect to some criteria such as minimum time, minimum fuel, or some combination of the two. These laws must be simple enough to be implemented on a computer that is flown on board an aircraft, which implies a major simplification from the two point boundary value problem generated by a standard trajectory optimization problem. In addition, the control laws allow for changes in end conditions during the flight, and changes in weather along a planned flight path. Therefore, a feedback control law that generates commands based on the current state rather than a precomputed open-loop control law is desired. This requirement, along with the need for order reduction, argues for the application of singular perturbation techniques.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA Aircraft Controls Research, 1983; p 209-219
    Format: application/pdf
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  • 85
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    In:  CASI
    Publikationsdatum: 2017-10-02
    Beschreibung: The simulation requirements for investigation of pilot-induced-oscillation (PIO) characteristics during the landing phase are discussed. Orbiters simulations and F-8 digital fly-by-wire aircraft tests are addressed.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: AGARD Ground and Flight Testing for Aircraft Guidance and Control; 7 p
    Format: text
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  • 86
    Publikationsdatum: 2017-10-02
    Beschreibung: A new laboratory, AIRLAB, recently completed at the NASA Langley Research Center was developed as a focus for conducting research on fault-tolerant electronic systems for flight-crucial applications. The laboratory was conceived and implemented to enhance the utilization of aeronautical research for improving the performance of future aerospace vehicles. Advanced vehicles will require highly reliable digital electronic systems to perform flight-crucial functions which if lost, would cause total failure of the vehicle. Techniques to form the basis for a validation methodology that can be used to determine the performance and reliability of advanced digital systems are being developed. Included are the development of analytical models, emulation techniques, and experimental procedures. The techniques and methods are verified using these specimens of fault-tolerant computers and systems and the capabilities of AIRLAB.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: AGARD Ground and Flight Testing for Aircraft Guidance and Control; 12 p
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  • 87
    Publikationsdatum: 2017-10-02
    Beschreibung: Advances in computer technology which may have an impact on computational mechanics and flight vehicle structures technology were reviewed. The characteristics of supersystems, highly parallel systems, and small systems are summarized. The interrelations of numerical algorithms and software with parallel architectures are discussed. A scenario for future hardware/software environment and engineering analysis systems is presented. Research areas with potential for improving the effectiveness of analysis methods in the new environment are identified.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: AGARD The Influence of Large Scale Computing on Aircraft Struct. Design; 29 p
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  • 88
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    In:  CASI
    Publikationsdatum: 2017-10-02
    Beschreibung: This lecture describes some of the experimental research pertaining to transonic configuration development conducted by the Transonic Aerodynamics Branch of the NASA Langley Research Center. Discussions are presented of the following: use of florescent oil films for the study of surface boundary layer flows; the severe effect of wind tunnel wall interference on the measured configuration drag rise near the speed of sound as determined by a comparison between wind tunnel and free air results; the development of a near sonic transport configuration incorporating a supercritical wing and an indented fuselage, designed on the basis of the area rule with a modification to account for the presence of local supersonic flow above the wing; a device for improving the transonic pitch up of swept wings with very little added drag at the cruise condition; a means for reducing the large transonic aerodynamic interference between the wing, fuselage, nacelle and pylon for a for a fuselage mounted nacelle having the inlet above the wing; and methods for reducing the transonic interference between flows over a winglet and the wing.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: AGARD Spec. Course on Subsonic(Transonic Aerodyn. Interference for Aircraft; 9 p
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  • 89
    Publikationsdatum: 2017-10-02
    Beschreibung: An experimental investigation in flight was performed to explore the feasibility of using LEBU (Large-Eddy-Breakup) devices to reduce the drag of aircraft. Two geometrical shapes of ribbons were used, and the development of local skin friction was monitored downstream. The aircraft was a swept-wing attack aircraft, and the flights covered the entire subsonic regime from M=0.92 down to stall conditions; flight altitudes were 1, 4.5, 7 and 10 km to explore various combinations of angle of attack, Mach - and Reynolds numbers. Some information was obtained concerning the turbulence characteristics downstream, and a discussion of the downstream amplification due to the drag at the device is also presented.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: AGARD Improvement of Aerodynamic Performance Through Boundary Layer Control and High Lift Systems; 16 p
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  • 90
    Publikationsdatum: 2017-10-02
    Beschreibung: A simple airborne flight management descent algorithm designed to define a flight profile subject to the constraints of using idle thrust, a clean airplane configuration (landing gear up, flaps zero, and speed brakes retracted), and fixed-time end conditions was developed and flight tested in the NASA TSRV B-737 research airplane. The research test flights, conducted in the Denver ARTCC automated time-based metering LFM/PD ATC environment, demonstrated that time guidance and control in the cockpit was acceptable to the pilots and ATC controllers and resulted in arrival of the airplane over the metering fix with standard deviations in airspeed error of 6.5 knots, in altitude error of 23.7 m (77.8 ft), and in arrival time accuracy of 12 sec. These accuracies indicated a good representation of airplane performance and wind modeling. Fuel savings will be obtained on a fleet-wide basis through a reduction of the time error dispersions at the metering fix and on a single-airplane basis by presenting the pilot with guidance for a fuel-efficient descent.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: AGARD Ground and Flight Testing for Aircraft Guidance and Control; 17 p
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  • 91
    Publikationsdatum: 2018-12-01
    Beschreibung: A computationally efficient body analysis is developed and coupled with a comprehensive helicopter analysis to calculate the body-induced aerodynamic effects on rotor performance and loads. A modified slender body theory is used as the body model. With the objective of demonstrating the accuracy, efficiency, and application of the method, the analysis at this stage is restricted to axisymmetric bodies at zero angle of attack. By comparing with results from an exact analysis for simple body shapes, it is found that the modified slender body theory provides an accurate potential flow solution for moderately thick bodies, with only a 10-20 percent increase in computational effort over that of an isolated rotor analysis. The computational ease of this method provides a means for routine assessment of body-induced effects on a rotor. Results are given for several configurations that typify those being used in the NASA Ames 40 x 80-ft Wind Tunnel and in the rotor-body interference tests being conducted at NASA Ames.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
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  • 92
    Publikationsdatum: 2018-12-01
    Beschreibung: The results of a simulation validation program of the XV-15 tilt-rotor research aircraft are detailed, covering such simulation aspects as the mathematical model, visual system, motion system, cab aural system, cab control loader system, pilot perceptual fidelity, and generic tilt rotor applications. Simulation validation was performed for the hover, low-speed, and sideward flight modes, with consideration of the in-ground rotor effect. Several deficiencies of the mathematical model and the simulation systems were identified in the course of the simulation validation project, and some were corrected. It is noted that NASA's Vertical Motion Simulator used in the program is an excellent tool for tilt-rotor and rotorcraft design, development, and pilot training.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
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  • 93
    Publikationsdatum: 2018-12-01
    Beschreibung: The development of laminar-flow technology for commercial transport aircraft is discussed and illustrated in a review of studies undertaken in the NASA Aircraft Energy Efficiency (ACEE) program since 1976. The early history of laminar-flow-control (LFC) techniques and natural-laminar-flow (NLF) airfoil designs is traced, and the aims of ACEE are outlined. The application of slotted structures, composites, and electron-beam-perforated metals in supercritical LFC airfoils, wing panels, and leading-edge systems is examined; wind-tunnel and flight test results are summarized; studies of high-altitude ice effects are described; and hybrid LFC/NLF designs are characterized. Drawings and photographs are provided.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
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  • 94
    Publikationsdatum: 2018-12-01
    Beschreibung: An overview of laminar flow control (LFC) technology developments is presented, along with a description of NASA's broadened program concerning laminar flow concepts for commercial transports. Topics covered include developments in LFC airfoils, wing surface panels, and leading-edge systems, as well as the effects of high altitude ice particles and insect impacts. It is suggested that the electron beam perforated titanium surface is superior to the Dynapore surface. The Douglas LFC wing design, the Krueger flap, the Lockheed, and the Douglas leading-edge concepts are covered. Future research includes an evaluation of a hybrid LFC concept, which combines LFC suction in the leading-edge region with natural laminar flow over the wing box.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 95
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2019-06-28
    Beschreibung: Presented is a procedure for using the FLEXSTAB External Structural Influence Coefficients (ESIC) computer program to produce the structural data necessary for the FLEXSTAB Stability Derivatives and Static Stability (SD&SS) program. The SD&SS program computes trim state, stability derivatives, and pressure and deflection data for a flexible airplane having a plane of symmetry. The procedure used a NASTRAN finite-element structural model as the source of structural data in the form of flexibility matrices. Selection of a set of degrees of freedom, definition of structural nodes and panels, reordering and reformatting of the flexibility matrix, and redistribution of existing point mass data are among the topics discussed. Also discussed are boundary conditions and the NASTRAN substructuring technique.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA-TM-84897 , NAS 1.15:84897
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 96
    Publikationsdatum: 2019-06-28
    Beschreibung: An evaluation was made of laminar flow control (LFC) system concepts for subsonic commercial transport aircraft. Configuration design studies, performance analyses, fabrication development, structural testing, wind tunnel testing, and contamination-avoidance techniques were included. As a result of trade studies, a configuration with LFC on the upper wing surface only, utilizing an electron beam-perforated suction surface, and employing a retractable high-lift shield for contamination avoidance, was selected as the most practical LFC system. The LFC aircraft was then compared with an advanced turbulent aircraft designed for the same mission. This comparison indicated significant fuel savings and reduced direct operating cost benefits would result from using LFC.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA-CR-159251 , NAS 1.26:159251 , ACEE-01-FR-3132
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 97
    Publikationsdatum: 2019-06-28
    Beschreibung: The Hybrid Heavy Lift Helicopter (HHLH) is a potential candidate vehicle aimed at providing heavy lift capability at low cost. This vehicle consists of a buoyant envelope attached to a supporting structure. Four rotor systems are also attached to the supporting structure. Nonlinear equations of motion capable of modeling the dynamics of this multi-rotor/support frame/vehicle system have been developed and used to study the fundamental aeromechanical stability characteristics of this class of vehicles. The mechanism of coupling between the blades, supporting structure and rigid body modes is identified and the effect of buoyancy ratio (buoyant lift/total weight) on the vehicle dynamics is studied. It is shown that dynamics effects have a major role in the design of such vehicles. The analytical model developed is also useful for studying the aeromechanical stability of single rotor and tandem rotor coupled rotor/fuselage systems.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 98
    Publikationsdatum: 2019-06-28
    Beschreibung: The purpose of the analysis is to determine if inflow turbulence distortion may be a cause of experimentally observed changes in sound pressure levels when the rotor mean loading is varied. The effect of helicopter rotor mean aerodynamics on inflow turbulence is studied within the framework of the turbulence rapid distortion theory developed by Pearson (1959) and Deissler (1961). The distorted inflow turbulence is related to the resultant noise by conventional broadband noise theory. A comparison of the distortion model with experimental data shows that the theoretical model is unable to totally explain observed increases in model rotor sound pressures with increased rotor mean thrust. Comparison of full scale rotor data with the theoretical model shows that a shear-type distortion may explain decreasing sound pressure levels with increasing thrust.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 99
    Publikationsdatum: 2019-06-28
    Beschreibung: A real time computer program was implemented on a F-15 jet fighter to monitor in-flight engine performance of a Digital Electronic Engine Controlled (DEES) F-100 engine. The application of two gas generator methods to calculate in-flight thrust real time is described. A comparison was made between the actual results and those predicted by an engine model simulation. The percent difference between the two methods was compared to the predicted uncertainty based on instrumentation and model uncertainty and agreed closely with the results found during altitude facility testing. Data was obtained from acceleration runs of various altitudes at maximum power settings with and without afterburner. Real time in-flight thrust measurement was a major advancement to flight test productivity and was accomplished with no loss in accuracy over previous post flight methods.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA-CR-176997 , NAS 1.26:176997
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 100
    Publikationsdatum: 2019-06-28
    Beschreibung: Modifications to a multi-degree-of-freedom flexible aircraft take-off and landing analysis (FATOLA) computer program, including a provision for actively controlled landing gears to expand the programs simulation capabilities, are presented. Supplemental instructions for preparation of data and for use of the modified program are included.
    Schlagwort(e): AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Materialart: NASA-CR-166069 , NAS 1.26:166069 , TAO-33842
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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