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At least 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Laser velocimeter applications to high-lift research

The application of the Lockheed-Georgia 2-D laser velocimeter (LV) burst-counter system to the flow field around a 2- and 3-element high-lift airfoil is discussed. The characteristic behavior of the confluent boundary layer (that is, the boundary layer existing downstream of a slot as it approaches and undergoes separation is evaluated. In this application, the LV represents all ideal instruments for nonintrusively probing into the narrow slots and cove areas characterizing mechanical high-lift systems. The work is being performed in the Lockheed-Georgia 10 x 30-inch low-speed test facility using a 9-inch (basic) chord section of the general aviation GAW-1 airfoil. The LV system employs a 4-W argon laser and operates in an off-axis, backscatter mode with a focus length of about 30 inches. Smoke is used as the seeding medium and is injected downstream of the model such that particle uniformity and size are constant upon completion of the tunnel circuit into the test area. The LV system is fully automated by utilizing a MAC-16 minicomputer for positioning, data acquisition, and preliminary data reduction.

Whipkey, R. R.↗
NASA NTRS1982

Development and flight evaluation of an augmented stability active controls concept with a small horizontal tail

A limited authority pitch active control system (PACS) was developed for a wide body jet transport (L-1011) with a flying horizontal stabilizer. Two dual channel digital computers and the associated software provide command signals to a dual channel series servo which controls the stabilizer power actuators. Input sensor signals to the computer are pitch rate, column-trim position, and dynamic pressure. Control laws are given for the PACS and the system architecture is defined. The piloted flight simulation and vehicle system simulation tests performed to verify control laws and system operation prior to installation on the aircraft are discussed. Modifications to the basic aircraft are described. Flying qualities of the aircraft with the PACS on and off were evaluated. Handling qualities for cruise and high speed flight conditions with the c.g. at 39% mac ( + 1% stability margin) and PACS operating were judged to be as good as the handling qualities with the c.g. at 25% (+15% stability margin) and PACS off.

Rising, J. J.↗
NASA NTRS1987

The application of CRM to military operations

The detailed content of the CRM training component of the C-5 Aircrew Training System (ATS) was left to the discretion of the contractor. As a part of determining what the content should be, United Airlines Services Corporation has made an effort to understand how the needs of MAC crews compare with those of civilian airline crews. There are distinct similarities between the crew roles in the cockpits of civilian airliners and military air transports. Many of the attitudes and behaviors exhibited by civil and military crew members are comparable, hence much of the training in the field referred to as Cockpit Resource Management (CRM) is equally appropriate to civil or military aircrews. At the same time, there are significant differences which require assessment to determine if modifications to what might be termed generic CRM are necessary. The investigation enabled the definition and specification of CRM training which is believed to address the needs of the C-5 operational community. The study has concentrated largely on military airlift, but the training objectives and course content of the CRM training are readily adaptable to a wider range of military cockpits than are found in strategic airlift. For instance, CRM training focusing on communication, leadership, situational awareness, and crew coordination is just as appropriate, with some modification, to the pilots manning a flight to Tactical Airlift Command A-7's as it is to the pilots, flight engineers, and loadmasters crewing a C-5.

Cavanagh, Dale E.↗
NASA NTRS1987

Aircrew cooperation in the Royal Air Force

The progressive introduction of modern, high performance aircraft, coupled with a significant increase in the complexity of the operational environment, has highlighted crew co-operation as a critical factor in aircraft safety. Investigation into recent MAC aircraft accidents supports the conclusion reached by NASA and other U.S. research institutions that a positive training program is required to improve resource management in the cockpit and prevent a breakdown under stress of the crew process. Past training and regulation has concentrated on the attainment of individual flying skills, but group skills have been neglected through lack of knowledge and understanding of the group process. This long-standing deficiency is now being addressed in the U.S. by the progressive and widespread introduction of theoretical and practical training programs to improve crew co-operation. The RAF should provide similar training for its aircrews through the adaptation and development of existing training resources. Better crew co-operation would not only reduce the number of RAF aircraft accidents but also improve the morale of the Service.

Adcock, C. B.↗
NASA NTRS1987

Boundary effects on Marangoni-Rayleigh and morphological instabilities

Effects of boundaries (vertical sides) on the Marangoni-Rayleigh problem are reviewed. Spectral crowding and a dimensional singularity when Rayleigh effects are neglected are discussed. In the unbounded case, there is a unique Ma with unique eigenfunction for fixed Ra but infinite Ra for fixed Ma. These infinite values of Ra correspond to vertical cellular modes. In the bounded case, there is infinite Ma for a fixed Ra. The stress free side wall case gives double infinite of Ra for fixed Ma and wave number. Clearly, a dimensional singularity occurs for the Marangoni problem when the side walls go to infinity and a fixed Ra is considered. There is no direct analogy regarding this singularity in the morphological instability problem. Results on the behavior of Mac, Rac with boundary conditions also show only marginal connection to the morphological stability problem.

Narayanan, R.↗
NASA NTRS1989

Gravity waves and turbulence in the middle atmosphere program (GRATMAP): An overview of gravity wave studies during MAP/MAC

Considerable progress was made in understanding gravity waves and their effects in the middle atmosphere during the MAP and MAC periods. During this time, gravity waves were recognized to play a central role in controlling the large scale circulation and the thermal and constituent structure of this region through wave transports of energy and momentum, a significant induced meridional circulation, and through the action of wave induced turbulence. Both theoretical and observational studies also have contributed to the understanding of the gravity wave spectrum, its temporal and spatial variability, and the processes responsible for wave saturation. As a result, the propagation, interactions, and detailed effects of such motions in the middle atmosphere are beginning to be understood. An overview is provided.

Fritts, D. C.↗
NASA NTRS1989

Dynamics of the upper middle atmosphere (80-110 km) at Tromsoe, June-December 1987, using the Tromsoe/Saskatoon M.F. radar

A real time winds (RTW) system from Saskatoon operated with the Tromsoe M.F. (partial reflection) radar on a continuous basis, June to December 1987. Profiles with 3 km resolution were obtained every 5 minutes with weak ionization, and few geomagnetic disturbances limited the observations normally to 80 to 110 km. However, daily mean winds, tidal characteristics (24, 12 h) such as amplitudes, phases and wavelengths, and gravity wave characteristics (intensities, mean directions) are available throughout this interval, which includes MAC-SINE and Epsilon. This is particularly valuable in defining the background state for some experiments, e.g., rockets, and for comparison with related parameters from the lidar and other radars (EISCAT, SOUSY-VHF). Comparisons with dynamical parameters from Saskatoon (52 N) are made: the zonal circulation was weaker at Tromsoe, tidal amplitudes smaller, and summer 12 h tidal wavelengths shorter (approx. 80 km vs approx. 100 km). The fall transition for this tide occurred in September, earlier than observed elsewhere. Initial comparisons with other experimental systems are also made.

Manson, A. H.↗
NASA NTRS1989

Time-dependent viscous incompressible Navier-Stokes equations - The finite difference Galerkin formulation and streamfunction algorithms

Numerical techniques are developed to solve the Navier-Stokes equations for unsteady incompressible flow. The extension of the finite-difference Galerkin (FDG) method of Stephens et al. (1984) to the continuous-time case in two or three space dimensions is explained, and the numerical implementation of the method is discussed with particular attention to the staggered-MAC-grid primitive-variable discretization, the application of discrete mass balance to avoid problems inherent in FDG schemes, the direct interpretation of the FDG expansion variables as a discrete streamfunction, and a mass-balance approach to two-dimensional problems with throughflow or obstacles. Numerical results are presented graphically for the evolution of asymptotic steady flow in a driven cavity at Reynolds number 400, 1000, or 3200; good agreement with published experimental data is demonstrated, with accurate predictions of secondary-vortex formation from wall bubble recirculations at Reynolds number 1000.

Goodrich, John W.↗
NASA NTRS1990

Graphical interfaces for cooperative planning systems

Based on a cognitive task analysis of 5 airline flight crews in a simulator study, researchers have designed a testbed for studying computer aids for en route flight path planning. This testbed runs on a Mac II controlling three color monitors, and is being used to study the design of aids for both dispatchers and flight crews. Specifically, the research focuses on design concepts for developing cooperative problem-solving systems. We use en route flight planning (selecting alternate routes or destinations due to unanticipated weather, traffic, malfunctions, etc.) as the context for studying the design of such systems. Researchers are currently exploring three questions in this test environment: (1) When interacting with a flight planning aid, how does the role of the pilot influence overall system performance; (2) Can the architecture for a cooperative planning system be built around Sacerdoti's (1983) concept of an abstraction hierarchy, where the pilot can interact with the system at many different levels of detail (but where the computer aid by default handles lower level details that the pilot has chosen not to deat with); and (3) Can graphical displays and direct manipulation of these displays provide perceptual enhancements (Larkin and Simon, 1987) of the pilot's problem-solving activities. Information is given in viewgraph form.

Smith, Philip J.↗
NASA NTRS1991

Solution of the Navier-Stokes equations for a driven cavity

The flow field in a lid driven cavity is determined by integration of the incompressible Navier-Stokes equations. The numerical integration is accomplished via an operator splitting method known as the theta-scheme. This splitting separates the problem into the solution of a quasi-stokes problem and a nonlinear convection problem. Some details of solution methods used for the two subproblems and results obtained for the driven cavity are described. The schemes developed for the quasi-Stokes problem are more advanced at this stage than those for the nonlinear problem. However, the approaches used for both parts are outlined. As a model problem, a two dimensional square cavity with sides of unit length and a lid moving with unit velocity from left to right is considered. The Navier-Stokes equations are discretized in space on a uniform staggered or MAC mesh. The time discretization is accomplished via the theta-scheme.

Semeraro, B. D.↗
NASA NTRS1990

Documentation for the token ring network simulation system

A manual is presented which describes the language features of the Token Ring Network Simulation System. The simulation system is a powerful simulation tool for token ring networks which allows the specification of various Medium Access Control (MAC) layer protocols as well as the specification of various features of upper layer ISO protocols. In addition to these features, it also allows the user to specify message and station classes virtually to any degree of detail desired. The choice of a language instead of an interactive system to specify network parameters was dictated by both flexibility and time considerations. The language was developed specifically for the simulation system, and is very simple. It is also user friendly in that language elements which do not apply to the case at hand are ignored rather than treated as errors.

Peden, Jeffery H.↗
NASA NTRS1991

Status report on the land processes aircraft science management operations working group

Since its inception three years ago, the Land Processes Aircraft Science Management Operations Working Group (MOWG) provided recommendations on the optimal use of the Agency's aircraft in support of the Land Processes Science Program. Recommendations covered topics such as aircraft and sensor usage, development of long-range plans, Multisensor Airborne Campaigns (MAC), program balance, aircraft sensor databases, new technology and sensor development, and increased University scientist participation in the program. Impacts of these recommendations improved the efficiency of various procedures including the flight request process, tracking of flight hours, and aircraft usage. The group also created a bibliography focused on publications produced by Land Processes scientists from the use of the aircraft program, surveyed NASA funded PI's on their participation in the aircraft program, and developed a planning template for multi-sensor airborne campaigns. Benefits from these activities are summarized.

Lawless, James G.↗
NASA NTRS1990

Improved evaluation of optical depth components from Langley plot data

A simple, iterative procedure to determine the optical depth components of the extinction optical depth measured by a solar radiometer is presented. Simulated data show that the iterative procedure improves the determination of the exponent of a Junge law particle size distribution. The determination of the optical depth due to aerosol scattering is improved as compared to a method which uses only two points from the extinction data. The iterative method was used to determine spectral optical depth components for June 11-13, 1988 during the MAC III experiment.

Biggar, S. F.↗
NASA NTRS1990

A testbed for the evaluation of computer aids for enroute flight path planning

A simulator study of the five airline flight crews engaged in various enroute planning activities has been conducted. Based on a cognitive task analysis of this data, a flight planning workstation has been developed on a Mac II controlling three color monitors. This workstation is being used to study design concepts to support the flight planning activities of dispatchers and flight crews in part-task simulators.

Smith, Philip J.↗
NASA NTRS1990

Effects of uniaxial stress on magnetoacoustic emission and magnetoacoustic responses in steel

Results of magnetoacoustic emission (MAE) and magnetoacoustic (MAC) measurements performed with an unembrittled HY-80 steel specimen are presented. The MAE measurements were obtained by applying an ac magnetic field of 20 Hz parallel to the uniaxial stress axis. The effects of tensile stress were shown to monotonically decrease the peak amplitude of the MAE burst, and they were consistent with the predicted trend based on the tensile stress-induced domain alignment. The effects of compressive stress were found to increase the peak amplitude of the MAE burst initially and to eventually decrease as the magnitude of compressive stress increased.

Namkung, M.↗
NASA NTRS1991

MACHYDRO-90 - The microwave aircraft experiment for hydrology

MACHYDRO-90 is a multisensor aircraft campaign (MAC) that was held in central Pennsylvania over an eleven day period in July 1990. The emphasis of the campaign was on the microwave measurements of soil moisture, although other aspects of hydrology and microwave-target interactions were also studied. A description is given of the experiment, its organization, and the meteorological conditions during the eleven days. Preliminary results are also presented from PBMR (Push-Broom Microwave Radiometer) and SAR (synthetic aperture radar) measurements of soil moisture. These results are portrayed in the context of the hydrology, which, during this experiment, exhibited dry and wet extremes.

Engman, Edwin T.↗
NASA NTRS1992

Method of characterizing residual stress in ferromagnetic materials using a pulse histogram of acoustic emission signals

The invention is a method and apparatus for characterizing residual uniaxial stress in a ferromagnetic test member by distinguishing between residual stresses resulting from positive (tension) forces and negative (compression) forces by using the distinct and known magnetoacoustic (MAC) and a magnetoacoustic emission (MAE) measurement circuit means. A switch permits the selective operation of the respective circuit means.

Namkung, Min↗