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  • AIRCRAFT
  • Aerodynamics
  • Aircraft Stability and Control
  • GENERAL
  • 2000-2004  (14)
  • 1955-1959
  • 1925-1929
  • 2000  (14)
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Keywords
Years
  • 2000-2004  (14)
  • 1955-1959
  • 1925-1929
Year
  • 1
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    Multidisciplinary Techniques and Novel Aircraft Control Systems (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The Aircraft Morphing Program at NASA Langley Research Center explores opportunities to improve airframe designs with smart technologies. Two elements of this basic research program are multidisciplinary design optimization (MDO) and advanced flow control. This paper describes examples where MDO techniques such as sensitivity analysis, automatic differentiation, and genetic algorithms contribute to the design of novel control systems. In the test case, the design and use of distributed shape-change devices to provide low-rate maneuvering capability for a tailless aircraft is considered. The ability of MDO to add value to control system development is illustrated using results from several years of research funded by the Aircraft Morphing Program.
    Keywords: Aircraft Stability and Control
    Type: AIAA Paper 2000-4848 , Multidisciplinary Analysis and Optimization; Sep 06, 2000 - Sep 08, 2000; Long Beach, CA; United States
    Format: text
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  • 2
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    Multidisciplinary Techniques and Novel Aircraft Control Systems (2000)
    In:  CASI
    Details
    Publication Date: 2019-08-13
    Description: The Aircraft Morphing Program at NASA Langley Research Center explores opportunities to improve airframe designs with smart technologies. Two elements of this basic research program are multidisciplinary design optimization (MDO) and advanced flow control. This paper describes examples where MDO techniques such as sensitivity analysis, automatic differentiation, and genetic algorithms contribute to the design of novel control systems. In the test case, the design and use of distributed shapechange devices to provide low-rate maneuvering capability for a tailless aircraft is considered. The ability of MDO to add value to control system development is illustrated using results from several years of research funded by the Aircraft Morphing Program.
    Keywords: Aircraft Stability and Control
    Type: AIAA Paper 2000-4848 , Multidisciplinary Analysis and Optimization; Sep 06, 2000 - Sep 08, 2000; Long Beach, CA; United States
    Format: application/pdf
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  • 3
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    Langley Wind Tunnel Data Quality Assurance-Check Standard Results (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A framework for statistical evaluation, control and improvement of wind funnel measurement processes is presented The methodology is adapted from elements of the Measurement Assurance Plans developed by the National Bureau of Standards (now the National Institute of Standards and Technology) for standards and calibration laboratories. The present methodology is based on the notions of statistical quality control (SQC) together with check standard testing and a small number of customer repeat-run sets. The results of check standard and customer repeat-run -sets are analyzed using the statistical control chart-methods of Walter A. Shewhart long familiar to the SQC community. Control chart results are presented for. various measurement processes in five facilities at Langley Research Center. The processes include test section calibration, force and moment measurements with a balance, and instrument calibration.
    Keywords: Aerodynamics
    Type: AIAA Paper 2000-2201 , Advanced Measurement Technology and Ground Testing; Jun 19, 2000 - Jun 22, 2000; Denver, CO; United States
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  • 4
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    A Parallel Approach To Optimum Actuator Selection With a Genetic Algorithm (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Recent discoveries in smart technologies have created a variety of aerodynamic actuators which have great potential to enable entirely new approaches to aerospace vehicle flight control. For a revolutionary concept such as a seamless aircraft with no moving control surfaces, there is a large set of candidate locations for placing actuators, resulting in a substantially larger number of combinations to examine in order to find an optimum placement satisfying the mission requirements. The placement of actuators on a wing determines the control effectiveness of the airplane. One approach to placement Maximizes the moments about the pitch, roll, and yaw axes, while minimizing the coupling. Genetic algorithms have been instrumental in achieving good solutions to discrete optimization problems, such as the actuator placement problem. As a proof of concept, a genetic has been developed to find the minimum number of actuators required to provide uncoupled pitch, roll, and yaw control for a simplified, untapered, unswept wing model. To find the optimum placement by searching all possible combinations would require 1,100 hours. Formulating the problem and as a multi-objective problem and modifying it to take advantage of the parallel processing capabilities of a multi-processor computer, reduces the optimization time to 22 hours.
    Keywords: Aircraft Stability and Control
    Type: AIAA Paper 2000-4484 , Guidance, Navigation and Control; Aug 14, 2000 - Aug 17, 2000; Denver, CO; United States
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  • 5
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    Prediction of Hyper-X Stage Separation Aerodynamics Using CFD (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The NASA X-43 "Hyper-X" hypersonic research vehicle will be boosted to a Mach 7 flight test condition mounted on the nose of an Orbital Sciences Pegasus launch vehicle. The separation of the research vehicle from the Pegasus presents some unique aerodynamic problems, for which computational fluid dynamics has played a role in the analysis. This paper describes the use of several CFD methods for investigating the aerodynamics of the research and launch vehicles in close proximity. Specifically addressed are unsteady effects, aerodynamic database extrapolation, and differences between wind tunnel and flight environments.
    Keywords: Aerodynamics
    Type: AIAA Paper 2000-4009 , Applied Aerodynamics; Aug 14, 2000 - Aug 17, 2000; Denver, CO; United States
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  • 6
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    Preliminary Study of a Model Rotor in Descent (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: Within a program designed to develop experimental techniques for measuring the trajectory and structure of vortices trailing from the tips of rotor blades, the present preliminary study focuses on a method for quantifying the trajectory of the trailing vortex during descent flight conditions. This study also presents rotor loads and blade surface pressures for a range of tip-path plane angles and Mach numbers. Blade pressures near the leading edge and along the outer radius are compared with data obtained on the same model rotor, but in open jet facilities. A triangulation procedure based on two directable laser-light sheets, each containing an embedded reference, proved effective in defining the spatial coordinates of the trailing vortex. When interrogating a cross section of the flow that contains several trailing vortices, the greatest clarity was found to result when the flow is uniformly seeded. Surface pressure responses during blade-vortex interactions appeared equally sensitive near the leading edge and along the outer portion of the blade, but diminished rapidly as the distance along the blade chord increased. The pressure response was virtually independent of whether the tip-path plane angle was obtained through shaft tilt or cyclic pitch. Although the shape and frequency of the pressure perturbations on the advancing blade during blade-vortex interaction are similar to those obtained in open-jet facilities, the angle of the tip-path plane may need to be lower than the range covered in this study.
    Keywords: Aerodynamics
    Type: NASA/TM-2000-208785 , NAS 1.15:208785 , A-99V0024 , AFDD/TR-99-A-001
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  • 7
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    Design and Evaluation of a New Boundary-Layer Rake for Flight Testing (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A new boundary-layer rake has been designed and built for flight testing on the NASA Dryden Flight Research Center F-15B/Flight Test Fixture. A feature unique to this rake is its curved body, which allows pitot tubes to be more densely clustered in the near-wall region than conventional rakes allow. This curved rake design has a complex three-dimensional shape that requires innovative solid-modeling and machining techniques. Finite-element stress analysis of the new design shows high factors of safety. The rake has passed a ground test in which random vibration measuring 12 g rms was applied for 20 min in each of the three normal directions. Aerodynamic evaluation of the rake has been conducted in the NASA Glenn Research Center 8 x 6 Supersonic Wind Tunnel at Mach 0-2. The pitot pressures from the new rake agree with conventional rake data over the range of Mach numbers tested. The boundary-layer profiles computed from the rake data have been shown to have the standard logarithmic-law profile. Skin friction values computed from the rake data using the Clauser plot method agree with the Preston tube results and the van Driest II compressible skin friction correlation to approximately +/-5 percent.
    Keywords: Aerodynamics
    Type: NASA/TM-2000-209014 , H-2392 , NAS 1.15:209014 , AIAA Paper 2000-0503 , 38th Aerospace Sciences; Jan 10, 2000 - Jan 13, 2000; Reno, NV; United States
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  • 8
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    Flight Test Analysis of the Forces and Moments Imparted on a B737-100 Aircraft During Wake Vortex Encounters (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Several of our major airports are operating at or near their capacity limit, increasing congestion and delays for travelers. As a result, the National Aeronautics and Space Administration (NASA) has been working in conjunction with the Federal Aviation Administration (FAA), airline operators, and the airline industry to increase airport capacity and safety. As more and more airplanes are placed into the terminal area the probability of encountering wake turbulence is increased. The NASA Langley Research Center conducted a series of flight tests from 1995 through 1997 to develop a wake encounter and wake-measurement data set with the accompanying atmospheric state information. The purpose of this research is to use the data from those flights to compute the wake-induced forced and moments exerted on the aircraft The calculated forces and moments will then be compiled into a database that can be used by wake vortex researchers to compare with experimental and computational results.
    Keywords: Aerodynamics
    Type: AIAA Paper 2000-3908 , AIAA Atmospheric Flight Mechanics Conference; Aug 14, 2000 - Aug 17, 2000; Denver, CO; United States
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  • 9
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    Theory and Experiment of Multielement Airfoils: A Comparison (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A detailed comparison of computed and measured pressure distributions, velocity profiles, transition onset, and Reynolds shear stresses for multi-element airfoils is presented. It is shown that the transitional k-zeta model, which is implemented into CFL3D, does a good job of predicting pressure distributions, transition onset, and velocity profiles with the exception of velocities in the slat wake region. Considering the fact that the hot wire used was not fine enough to resolve Reynolds stresses in the boundary layer, comparisons of turbulence stresses varied from good to fair. It is suggested that the effects of unsteadiness be thoroughly evaluated before more complicated transition/turbulence models are used. Further, it is concluded that the present work presents a viable and economical method for calculating laminar/transitional/turbuient flows over complex shapes without user interface.
    Keywords: Aerodynamics
    Type: AIAA Paper 2000-0985 , 38th Aerospace Sciences Meeting; Jan 10, 2000 - Jan 13, 2000; Reno, NV; United States
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  • 10
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    Flight Control Using Distributed Shape-Change Effector Arrays (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Recent discoveries in material science and fluidics have been used to create a variety of novel effector devices that offer great potential to enable new approaches to aerospace vehicle flight control. Examples include small inflatable blisters, shape-memory alloy diaphragms, and piezoelectric patches that may be used to produce distortions or bumps on the surface of an airfoil to generate control moments. Small jets have also been used to produce a virtual shape-change through fluidic means by creating a recirculation bubble on the surface of an airfoil. An advanced aerospace vehicle might use distributed arrays of hundreds of such devices to generate moments for stabilization and maneuver control, either augmenting or replacing conventional ailerons, flaps or rudders. This research demonstrates the design and use of shape-change device arrays for a tailless aircraft in a low-rate maneuvering application. A methodology for assessing the control authority of the device arrays is described, and a suite of arrays is used in a dynamic simulation to illustrate allocation and deployment methodologies. Although the authority of the preliminary shape-change array designs studied in this paper appeared quite low, the simulation results indicate that the effector suite possessed sufficient authority to stabilize and maneuver the vehicle in mild turbulence.
    Keywords: Aircraft Stability and Control
    Type: AIAA Paper 2000-1560 , Structures, Structural Dynamics, and Materials Conference and Exhibit; Apr 03, 2000 - Apr 06, 2000; Atlanta, GA; United States
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