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Viewing 181 to 210 of 61866
1999-10-19
Technical Paper
1999-01-5618
Feng Jiang
This paper examines the capability of the Reynolds-averaged thin-layer Navier-Stokes codes to simulate the results from a two-dimensional aileron effectiveness test. This unique test was carried out in the IAR high Reynolds number wind tunnel and addressed the effects of Reynolds number, Mach number and angle-of-attack on aileron effectiveness. The test results showed a highly nonlinear variation of lift for downward trailing edge deflections. It provides a valuable database for using CFD to determine the adequacy of the corrections applied to the experimental data due to the presence of the wind tunnel walls, and for assessing the current CFD capability to model the flowfield with separation. CFD predictions are obtained by using CFL3D with the Spalart-Allmaras turbulence model and TLNS2D with the modified Johnson-King turbulence model.
1999-10-19
Technical Paper
1999-01-5612
Lawrence W. Lay,, M. Gawad Nagati, James E. Steck
This paper presents a method by which artificial neural networks can be trained and used to identify a possible spin entry, differentiate between an incipient spin and a stabilized spin, and predict required recovery controls. These were then implemented into a simulation and tested using data from actual flight tests conducted by NASA Langley Research Center, to verify that artificial neural networks can successfully be used for this application. The spin avoidance and recovery system functioned properly. In addition, a weighting system was developed to predict possible spin characteristics of aircraft, depending on the relative magnitude of the three principal moments of inertia.
1999-10-19
Technical Paper
1999-01-5625
Steven C. Crow
Starcar 4 is now a road vehicle, ready to be licensed as a motorcycle in the State of Colorado. The vehicle at present is a bare chassis resembling a three-wheel dune buggy. Six people have tested the vehicle so far, and all have pronounced it fun to drive. The vehicle is capable of acceleration up to at least 0.87 g’s, at which point it lifts its nose in a stable “wheelie”. The turning radius is tight, and the vehicle can U-turn on streets measuring 36 ft from curb to curb. Drivers quickly become comfortable with the joystick steering except near zero speeds, when the front wheel tends to flop to one side or the other. The ride is pleasant but stiff at the light weight of the bare chassis, and the steering at road speeds is stiff as well, though not uncomfortably so. The only negative findings are that the steering forces are high at parking lot speeds, and the chassis is about 85 lbs heavier than projected.
1999-10-19
Technical Paper
1999-01-5623
Oliver Bandte, Dimitri N. Mavris, Daniel A. DeLaurentis
A key issue in complex systems design is measuring the ‘goodness’ of a design, i.e. finding a criterion through which a particular design is determined to be the ‘best’. Traditional choices in aerospace systems design, such as performance, cost, revenue, reliability, and safety, individually fail to fully capture the life cycle characteristics of the system. Furthermore, current multi-criteria optimization approaches, addressing this problem, rely on deterministic, thus, complete and known information about the system and the environment it is exposed to. In many cases, this information is not be available at the conceptual or preliminary design phases. Hence, critical decisions made in these phases have to draw from only incomplete or uncertain knowledge. One modeling option is to treat this incomplete information probabilistically, accounting for the fact that certain values may be prominent, while the actual value during operation is unknown.
1999-10-19
Technical Paper
1999-01-5622
Jeremy S. Agte, Jaroslaw Sobieszczanski-Sobieski, Robert R. Sandusky
New optimization methods that are intended as an improvement over traditional design methodology often require the design model itself to be developed in a nontraditional manner. This paper describes the tailoring of a supersonic business jet design model to the Bi-Level Integrated System Synthesis (BLISS) optimization method. Included is a brief discussion of BLISS, the development and implementation of the design model, application of the design constraints, and a survey of favorable results. For discussion purposes, the design model is ‘tailored’ to the optimization method, not vice versa, to illustrate the model’s unique development.
1999-10-19
Technical Paper
1999-01-5621
F. H. Gern, J. F. Gundlach, A. Ko, A. Naghshineh-Pour, E. Sulaeman, P. -A. Tetrault, B. Grossman, R. K. Kapania, W. H. Mason, J. A. Schetz, R. T. Haftka
This paper details the multidisciplinary design optimization (MDO) of a strut-braced wing aircraft and its benefits relative to the cantilever wing configuration. The multidisciplinary design team is subdivided into aerodynamics, structures, aeroelasticity and synthesis of the various disciplines. The aerodynamic analysis consists of simple models for induced drag, wave drag, parasite drag and interference drag. The interference drag model is based on detailed computational fluid dynamics (CFD) analyses of various wing-strut intersection flows. The wing structural weight is partially calculated using a newly developed wing bending material weight routine that accounts for the special nature of strut-braced wings. The remaining components of the aircraft weight are calculated using a combination of NASA’s Flight Optimization System (FLOPS) and Lockheed Martin Aeronautical System formulas.
1999-10-19
Technical Paper
1999-01-5598
Gary A. Fleming, Hector L. Soto, Bruce W. South, Scott M. Bartram
An instrument development program aimed at using Projection Moiré Interferometry (PMI) for acquiring model deformation measurements in large wind tunnels was begun at NASA Langley Research Center in 1996. Various improvements to the initial prototype PMI systems have been made throughout this development effort. This paper documents several of the most significant improvements to the optical hardware and image processing software, and addresses system implementation issues for large wind tunnel applications. The improvements have increased both measurement accuracy and instrument efficiency, promoting the routine use of PMI for model deformation measurements in production wind tunnel tests.
1999-10-19
Technical Paper
1999-01-5599
James F. Meyers, Joseph W. Lee
While the initial development phase of Doppler Global Velocimetry (DGV) has been successfully completed, there remains a critical next phase to be conducted, namely the determination of an error budget to provide quantitative bounds for measurements obtained by this technology. This paper describes a laboratory investigation that consisted of a detailed interrogation of potential error sources to determine their contribution to the overall DGV error budget. A few sources of error were obvious; e.g., Iodine vapor absorption lines, optical systems, and camera characteristics. However, additional non-obvious sources were also discovered; e.g., laser frequency and single-frequency stability, media scattering characteristics, and interference fringes. This paper describes each identified error source, its effect on the overall error budget, and where possible, corrective procedures to reduce or eliminate its effect.
1999-10-19
Technical Paper
1999-01-5600
James T. Heineck, Stephen M. Walker
Three-component Particle Image Velocimetry (3D PIV) is a fluid velocity measurement technique that has evolved from the laboratory to become a method appropriate for use in large-scale wind tunnel testing. An example application of 3D PIV in a wind tunnel test is described. The PIV technique was applied to characterize the wake of The Ground Transportation System (GTS) model developed for the Department of Energy (DOE) Heavy Vehicle Drag Reduction (HVDR) program. The test was performed in the Ames/Army 7×10 foot wind tunnel. The objective of the PIV measurements was to validate the HVDR computational fluid dynamics code. The PIV method and PIV system are described. Sample truck wake data with and without boattail attachments are shown. 3D PIV system successfully captured the effects of the boattails on the truck wake.
1999-12-01
Technical Paper
1999-01-2988
Luciano B. Abrahão, Sílvio Palácios, Helcio Onusic, José Luis A Moraes Marc Straat, Sergio M. Andreatini
1999-08-17
Technical Paper
1999-01-2893
Yuri A. Krassin
A new application is proposed for a light aircraft in personal transportation - that is of a long range grand tourism vehicle; the role it can perform much better than an automobile. Light aircraft more conventional usage for short ranges is more suitable for business goals. A convertible road to air vehicle (aircar) having a high CL/CD ratio is considered to be the most suitable means of personal transportation in the future. A rather low CL/CD of previously built aircars is considered to be one of the reasons of their failure in the past. A narrow road module having a controlled body tilt and a high aspect ratio wing are proposed as remedies. Simple original equations comparing light aircraft expenses against that of an automobile or an airliner ticket cost are proposed. They show that the light aircraft costing up to $35K per passenger at CL/CD =12 can be competitive with an airliner on a range of up to 2,500 miles and an aircar at CL/CD =20 or more of up to 12,000 miles.
1999-10-19
Technical Paper
1999-01-5588
R. A. Faerber, T. G. Sharpe, T. J. Etherington, S. S. Chappell, T.R. Barnes, T. L. Vogl, S. M. Zellers, D. H. Hartley, J. A. Klein, R. D. Jinkins
Tomorrow’s flight deck will contain avionics similar in nature to today’s aircraft. However, tomorrow’s avionics display formats and the manner in which pilots will interact with and control those displays will be significantly different. These differences will be for the benefit of the pilot and allow him/her to intuitively interact with their equipment, increase their performance, and heighten the safety of all passengers aboard. This paper will highlight some of the advanced avionics display formats and control technologies that the Human Interface Technology Group of Rockwell Collins, Inc. Advanced Technology Center (ATC) have been investigating over the last year and provide recommendations for future research efforts.
1999-10-19
Technical Paper
1999-01-5587
Ratan Khatwa, Robert L. Helmreich
Executive Summary This document is the final report of the Data Acquisition and Analysis Working Group (DAAWG) of the Flight Safety Foundation (FSF) Approach-and-landing Accident Reduction (ALAR) Task Force (Appendix D contains the complete listing of participants). The DAAWG was established in August 1997 to independently analyze data that may lead to the identification and/or resolution of approach-and-landing safety issues. Activities pursued by the DAAWG included: high-level analyses of 287 fatal accidents; detailed case studies of 76 accidents and serious incidents; and the assessment of key crew behavioral markers isolated in the occurrences and in the line audits of about 3,300 flights. The DAAWG is also conducting an economic analysis of the cost of approach-andlanding accidents (ALAs) to the industry (in progress).
1999-10-19
Technical Paper
1999-01-5590
Laurent Moussault
This paper presents an approach to pilots’ situation awareness (SA) that focuses on temporal issues. This approach must be complemented by other factors such as spatial awareness. The temporal aspects of SA are important for the flying task, for computer interaction, and for human communication. The presence of these three domains together inside the cockpit leads to difficulties with time management. Temporal aspects in human-computer interaction (HCI) are investigated in the context of aviation SA. Useful tools for their evaluation and anticipation are proposed. Finally, psychological, cognitive and philosophical studies on time consciousness that enable the investigation of relevant attributes of complex dynamic systems such as aircrafts are presented.
1999-10-19
Technical Paper
1999-01-5591
Christopher D. Wickens, John Helleberg, Xidong Xu
In two experiments, strategic conflict avoidance maneuvers of 32 licensed pilots were analyzed when they flew a series of missions in a low fidelity (Experiment 1) and a high fidelity (Experiment 2) flight simulator, rendering an outside view and a cockpit display of traffic information. On various legs of the mission, aircraft generating traffic conflicts intruded from above, below and at the same altitude as ownship at various azimuth orientations. Pilot maneuvers were categorized in terms of the dimension of maneuver (vertical, lateral, airspeed), and the direction of change within that maneuver. Decision analysis revealed a strong tendency of pilots to use simple one dimensional maneuvers, and of these, to prefer vertical over lateral and airspeed maneuvers. Airspeed maneuvers in particular were avoided.
1999-10-19
Technical Paper
1999-01-5559
Steven M. Nash, Stuart E. Rogers
An overset grid approach is used to analyze a 3-element trapezoidal wing high-lift configuration. A new software system was developed to automate the overset computational fluid dynamics process. A three-dimensional grid resolution study is conducted, and comparisons of numerical results are made to experimental data which were obtained after the simulations. Comparisons between numerical and experimental data are in good agreement for the lift coefficient over a wide range of angles of attack, up to and including CLmax. Comparisons of chordwise distributions of the pressure coefficient between numerical and experimental data are in good agreement for all three elements, except the lift is under-predicted for the tip region when the wing is near CLmax.
1999-10-19
Technical Paper
1999-01-5558
Dimitri J. Mavriplis
A Reynolds-averaged Navier-Stokes solver based on unstructured mesh techniques for analysis of high-lift configurations is described. The method makes use of an agglomeration multigrid solver for convergence acceleration. Directional agglomeration and implicit line-smoothing is employed to relieve the stiffness associated with highly stretched meshes. A GMRES technique is also implemented to speed convergence at the expense of additional memory usage. The solver is parallelized on shared and distributed memory machines using the MPI message passing library. Convergence and scalability results are illustrated for various high-lift test cases.
1999-10-19
Technical Paper
1999-01-5564
R.C.J. Ruigrok, R.N.H.W. van Gent, J.M. Hoekstra
This paper describes the initial results of a simulation experiment in which the human factors implications of three Mixed Equipage, Integrated Air-Ground, Free Flight Air Traffic Management (ATM) scenarios were investigated. The experiment primarily addressed how to accommodate a fleet of mixed equipped aircraft, with and without Airborne Separation Assurance System (ASAS), in a transitional free flight era in which both air and ground players have defined responsibilities. All three transitional ATM operational concepts evaluated, were designed with the idea that equipping aircraft should be immediately beneficial to the airlines.
1999-10-19
Technical Paper
1999-01-5563
Brian Hilburn, Wouter D. Pekela
This paper presents selected results of four experiments into air traffic control (ATC) aspects of free flight (FF). The first two examined basic human performance implications of FF, in terms of workload and ability to monitor traffic. The third explored the potential for improved ATC displays to benefit controllers under FF traffic patterns. The fourth experiment examined methods for accommodating mixed equipage, such as during a transitional FF era in which both FF capable and FF incapable aircraft would be expected to share the same airspace. The first three experiments involved controllers operating in “open-loop” simulations, with computer-generated traffic and simulated pilot responses. In the final experiment, pilots and controllers were linked in real-time sessions.
1999-10-19
Technical Paper
1999-01-5566
Eric Hoffman, Karim Zeghal, Gildas Courtet
The Evolutionary Air-ground Co-operative ATM Concepts (EACAC) study of the Freer-Flight project investigates the delegation by the controller to the pilot, of some tasks related to separation assurance. Starting from the analogy of visual clearances, EACAC investigates the possibility of giving electronic clearances. One of the issues of the study deals with the appropriate assistance scheme to be provided to the pilot, considering the proposed concept of limited delegation. The “scales of separations” is one of the levels of assistance envisaged. Two models of turns and their appropriateness for lateral scales of effects are investigated. The scales of separations implementing these models will be evaluated by pilots, first through a cockpit environment in a stand-alone mode (end 1999), and then using a cockpit simulator in a real-time simulation with controllers (mid 2000).
1999-10-19
Technical Paper
1999-01-5565
Karim Zeghal, Eric Hoffman, Jean-Pierre Nicolaon, Anne Cloerec, Isabelle Grimaud
This paper presents the initial evaluation of the EACAC study, which is investigating delegation by the controller to the pilot of some tasks related to separation assurance. The concept is applied in managed airspace for two classes of application: crossing and passing in enroute, and sequencing in Terminal Manoeuvring Area. The concept relies on two key points discussed in the paper: “limited delegation” and “flexible use of delegation”. The initial evaluation using a simplified ATC environment has been set up to get “feedback” from both controllers and pilots, and to assess the operational feasibility and potential interest of the concept. The overall feeling about the method is “promising” with a “great potential”, and could reduce workload. The notion of “flexible use of delegation” would enable the gradual growth of confidence and would also provide flexibility to use the method under different conditions (traffic, airspace, practice level).
1999-10-19
Technical Paper
1999-01-5567
Walter W. Johnson, Vernol Battiste, Sheila Holland Bochow
Cockpit displays need to be substantially improved to serve the goals of situational awareness, conflict detection, and path replanning, in Free Flight. This paper describes the design of such an advanced cockpit display, along with an initial simulation based usability evaluation. Flight crews were particularly enthusiastic about color coding for relative altitude, dynamically pulsing predictors, and the use of 3-D flight plans for alerting and situational awareness.
1999-10-19
Technical Paper
1999-01-5576
Marianne Mosher, Michael E. Watts, Michael Barnes, Jorge Bardina
A processing system has been developed to meet increasing demands for detailed noise measurement of aircraft in wind tunnels. Phased arrays enable spatial and amplitude measurements of acoustic sources, including low signal-to-noise sources not measurable by conventional measurement techniques. The Microphone Array Phased Processing System (MAPPS) provides processing and visualization of acoustic array measurements made in wind tunnels. The system uses networked parallel computers to provide noise maps at selected frequencies in a near real-time testing environment. The system has been successfully used in two subsonic, hard-walled wind tunnels, the NASA Ames 7- by 10-Foot Wind Tunnel and the NASA Ames 12-Foot Wind Tunnel. Low level airframe noise that can not be measured with traditional techniques was measured in both tests.
1999-10-19
Technical Paper
1999-01-5540
Lynne Martin, Jeannie Davison, Judith Orasanu, Chesley Sullenberger
Despite efforts to design systems and procedures to support “correct” and safe operations in aviation, accidents still occur and errors in human judgment are found to be contributing factors. In this paper we examine how the wider aviation system may play a role in decision processes. Our strategy was to examine a collection of identified decision errors (National Transportation Safety Board [NTSB], 1994) through the lens of an aviation decision process model and to search for common patterns. The second and more difficult task was to determine what might account for those patterns. The decision process model suggests that decisions with undesirable outcomes can arise in two major ways: either through misassessment of the situation - a problem with situation awareness, or through judgment of the best course of action.
1999-10-19
Technical Paper
1999-01-5541
Jacqueline A. Duley, Scott M. Galster, Raja Parasuraman, Anthony J. Smoker
Increases in technological capability permit us to obtain more information with improved accuracy from the systems and actors in the NAS. Collaborative Decision Making is a philosophy of redistributing information such that airspace users and service providers can act cooperatively to solve problems in areas such as flow control, and ground or weather delays. Designers are creating new tools to access this information and provide it to the users and ATC. We are concerned with the controller interface to this information and its incorporation of these new tools. We recommend a human-centered approach to the development of an effective interface.
1999-10-19
Technical Paper
1999-01-5537
Reiner Onken
This paper presents a concept which is needed to warrant a highest possible degree of situation awareness of the flight crew as well as a workload level which is as close as possible to the satisfactory one. This concept offers the solution to counteract susceptibiliy to pilot errors, typical for lack of attention or knowledge limitations in certain flight situations. This concept is founded on cognitive system engineering in order to really accomplish allocation of automation as a complement to the human pilot crew when needed in favor of flight safety and mission effectiveness. This technology enables a cockpit design in order to systematically comply with the requirements of ’ Human-Centered Automation (HCA)’ . It even allows to quantify at which degree these requirements are met. The underlying approach behind the concept has become real by the development of the cockpit assistant system prototype family CASSY/CAMA as described in this paper.
1999-10-19
Technical Paper
1999-01-5556
George W. Thorpe
Aircraft potable (drinking) water systems haven’t changed significantly in the last half-century. These systems consist of cylindrical water tanks pressurized by bleed air from the jet engines, with insulated stainless steel distribution lines. What has changed recently is the increase in the possibility of aircraft picking up contaminated drinking water at foreign and domestic stops. Customer awareness of these problems has also changed - to the point where having reliable drinking water is now a competitive issue among airlines. Old style potable water systems that are used on modern aircraft are high maintenance and exacerbate the growth of microbes because the water is static much of the time. The integrity of some pressurized water tanks are also a concern after years of use. Cost-effective mechanical and biological solutions exist that can significantly reduce the amount of chemicals added and provide good potable water.
1999-10-19
Technical Paper
1999-01-5557
Shahyar Z. Pirzadeh
The application of an unstructured grid methodology on a three-dimensional high-lift configuration is presented. The focus of this paper is on the grid generation aspect of an integrated effort for the development of an unstructured- grid computational fluid dynamics (CFD) capability at the NASA Langley Research Center. The meshing approach is based on tetrahedral grids generated by the advancing-front and the advancing-layers procedures. The capability of the method for solving high-lift problems is demonstrated on an aircraft model referred to as the energy efficient transport configuration. The grid generation issues, including the pros and cons of the present approach, are discussed in relation to the high-lift problems. Limited viscous flow results are presented to demonstrate the viability of the generated grids. A corresponding Navier-Stokes solution capability, along with further computations on the present grid, is presented in a companion SAE paper.
Viewing 181 to 210 of 61866

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