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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 397 records · Page 22
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Flight test experience with an adaptive control system using a maximum likelihood parameter estimation technique

The flight test performance of an adaptive control system for the F-8 DFBW aircraft is summarized. The adaptive system is based on explicit identification of surface effectiveness parameters which are used for gain scheduling in a command augmentation system. Performance of this control law under various design parameter variations is presented. These include variations in test signal level, sample rate, and identification channel structure. Flight performance closely matches analysis and simulation predictions from previous references.

Hartmann, G.↗
NASA NTRS1984

X-29 flight-research program

The X-29A aircraft is the first manned, experimental high-performance aircraft to be fabricated and flown in many years. The approach for expanding the X-29 flight envelope and collecting research data is described including the methods for monitoring wind divergence, flutter, and aeroservoelastic coupling of the aerodynamic forces with the structure and the flight-control system. Examples of the type of flight data to be acquired are presented along with types of aircraft maneuvers that will be flown. A brief description of the program management structure is also presented and the program schedule is discussed.

Putnam, T. W.↗
NASA NTRS1983

X-29 flight research program

The X-29A aircraft is the first manned, experimental high-performance aircraft to be fabricated and flown in many years. The approach for expanding the X-29 flight envelope and collecting research data is described including the methods for monitoring wing divergence, flutter, and aeroservoelastic coupling of the aerodynamic forces with the structure and the flight-control system. Examples of the type of flight data to be acquired are presented along with types of aircraft maneuvers that will be flown. A brief description of the program management structure is also presented and the program schedule is discussed.

Putnam, T. W.↗
NASA NTRS1991

Design and evaluation of an air traffic control Final Approach Spacing Tool

This paper describes the design and simulator evaluation of an automation tool for assisting terminal radar approach controllers in sequencing and spacing traffic onto the final approach course. The automation tool, referred to as the Final Approach Spacing Tool (FAST), displays speed and heading advisories for arriving aircraft as well as sequencing information on the controller's radar display. The main functional elements of FAST are a scheduler that schedules and sequences the traffic, a four-dimensional trajectory synthesizer that generates the advisories, and a graphical interface that displays the information to the controller. FAST has been implemented on a high-performance workstation. It can be operated as a stand-alone in the terminal radar approach control facility or as an element of a system integrated with automation tools in the air route traffic control center. FAST was evaluated by experienced air traffic controllers in a real-time air traffic control simulation. simulation results summarized in the paper show that the automation tools significantly reduced controller work load and demonstrated a potential for an increase in landing rate.

Davis, Thomas J.↗
NASA NTRS1990

Aircraft radial-belted tire evaluation

An overview is given of the ongoing joint NASA/FAA/Industry Surface Traction And Radial Tire (START) Program being conducted at NASA Langley's Aircraft Landing Dynamics Facility (ALDF). The START Program involves tests using three different tire sizes to evaluate tire rolling resistance, braking, and cornering performance throughout the aircraft ground operational speed range for both dry and wet runway surfaces. Preliminary results from recent 40 x 14 size bias-ply, radial-belted, and H-type aircraft tire tests are discussed. The paper concludes with a summary of the current program status and planned ALDF test schedule.

Yager, Thomas J.↗
NASA NTRS1986

Assessing fatigue

Despite impressive advances in aircraft technology over the past several decades and an overall decline in the airline accident rate since the introduction of turbine-powered aircraft, flight crew performance problems continue to dominate air transport accident statistics. Researchers have offered many hypotheses to explain this finding, and interest in pilot fatigue has stimulated a large volume of laboratory research. Much of this work, however, is difficult to generalize and to apply to the real world of flight operations, and researchers disagree about the extent and operational significance of fatigue-related reductions in pilot performance. As a result, in 1980 Congress asked the National Aeronautics and Space Administration to undertake a comprehensive research program to assess whether fatigue-related problems are prevalent in long- and short-haul flying. The two major goals of this project are: (1) to assess the psychophysiological effects on pilot performance of flying various types of flight and duty cycles, and (2) to determine the operational significance to flight safety and efficiency of flying these flight and duty cycles.

NASA Discipline Space Human Factors↗
NASA NTRS2011

Flight Departure Delay and Rerouting Under Uncertainty in En Route Convective Weather

Delays caused by uncertainty in weather forecasts can be reduced by improving traffic flow management decisions. This paper presents a methodology for traffic flow management under uncertainty in convective weather forecasts. An algorithm for assigning departure delays and reroutes to aircraft is presented. Departure delay and route assignment are executed at multiple stages, during which, updated weather forecasts and flight schedules are used. At each stage, weather forecasts up to a certain look-ahead time are treated as deterministic and flight scheduling is done to mitigate the impact of weather on four-dimensional flight trajectories. Uncertainty in weather forecasts during departure scheduling results in tactical airborne holding of flights. The amount of airborne holding depends on the accuracy of forecasts as well as the look-ahead time included in the departure scheduling. The weather forecast look-ahead time is varied systematically within the experiments performed in this paper to analyze its effect on flight delays. Based on the results, longer look-ahead times cause higher departure delays and additional flying time due to reroutes. However, the amount of airborne holding necessary to prevent weather incursions reduces when the forecast look-ahead times are higher. For the chosen day of traffic and weather, setting the look-ahead time to 90 minutes yields the lowest total delay cost.

Mukherjee, Avijit↗
NASA NTRSDate not supplied

Demonstration of Two Extended Visual Line of Sight Methods for Urban UAV Operations

This report describes two extended visual line of sight (EVLOS) methods developed and utilized during two flight campaigns over the campus of NASA Langley Research Center (LaRC): a chase vehicle method and a radio controlled (RC) pilot handoff method. These campaigns were performed to (a) evaluate small unmanned aerial system (sUAS) flight beyond the visual line of sight (BVLOS) of the ground control station operator and (b) test technologies under development to enable a transition from EVLOS to BVLOS operations. While an autonomous waypoint-based operational approach enabled minimal pilot intervention in both methods, range containment was enforced (a) manually via continual pilot visual monitoring and (b) autonomously via on-board contingency landing autonomy triggerable at the boundary of stay-in geofences. In the thirty-nine flights which utilized the chase vehicle, the pilot followed the sUAS flying a 1.2 km path at 40m altitude over urban streets. In the fifteen flights which utilized pilot handoff, a pilot at one end of a 1.5 km path initiated the flight at 120m altitude over buildings and trees, and at the midway point of the path transferred radio control to a pilot at the other end. In comparison, the chase vehicle method requires less ground crew and simpler avionics, while the pilot handoff method avoids schedule risk arising from street traffic congestion but better replicates actual direct routing for BVLOS flights. Collision risk with another aircraft was introduced in both campaigns and mitigated with the same manual and autonomous methods. Results from these campaigns serve as a basis for planned BVLOS operations at NASA LaRC.

Nicholas Rymer↗
NASA NTRSDate not supplied

Human Factors Research Considerations for Terminal Area Urban Air Mobility Operations

In this presentation, we discuss the human factors research challenges from introducing greater levels of automation in a future air transportation concept called Urban Air Mobility (UAM). UAM is an air transportation concept that aims to provide air transportation services to the daily commuter, as well as emergency response and package delivery. The principal innovation over current day large air transport system is the greater distribution of important safety functions to automated and human agents; these functions include air traffic management, traditionally an air traffic controller responsibility. A central aspect of UAM is the development of an automated air traffic manager, whose primary responsibility is to approve airspace access for vehicle operators. Vehicle operator roles may include onboard and remote pilots, as well as a human manager who will supervise an entire fleet. Alternatively, both fleet manager and vehicle operators can be merged into a single role – a feasible option if UAM aircraft are autonomous. In lieu of tower controllers, vertiport managers, with the assistance of automation, will manage arrival and departure schedules between vertiports, as well as supervise surface operations. Our approach here will be to introduce use cases currently being developed by NASA, and then provide preliminary definitions for each of the roles introduced above and how coordination between them can be configured to support the operations within the use cases described. Subsequently, we review the tools and interfaces being developed to support the various roles. To conclude, we present current human factors work related to defining the roles above and suggest future work to advance the UAM concept.

trial planning↗
NASA NTRS1972

V/STOL tilt rotor aircraft study. Volume 2: Preliminary design of research aircraft

A preliminary design study was conducted to establish a minimum sized, low cost V/STOL tilt-rotor research aircraft with the capability of performing proof-of-concept flight research investigations applicable to a wide range of useful military and commercial configurations. The analysis and design approach was based on state-of-the-art methods and maximum use of off-the-shelf hardware and systems to reduce development risk, procurement cost and schedules impact. The rotors to be used are of 26 foot diameter and are the same as currently under construction and test as part of NASA Tilt-Rotor Contract NAS2-6505. The aircraft has a design gross weight of 12,000 lbs. The proposed engines to be used are Lycoming T53-L-13B rated at 1550 shaft horsepower which are fully qualified. A flight test investigation is recommended which will determine the capabilities and limitations of the research aircraft.

Source record↗
NASA NTRS1972

Capital Requirements for the Air Transport Industry

In recent years the U.S. scheduled airline industry has been involved in the largest re-equipment program that involves the addition of hundreds of new aircraft to the airline fleet. The costs associated with the purchase of this new equipment, along with the other costs involving such matters as the environment and security, are presenting the carriers with significant financial challenges.

James, G. W.↗
NASA NTRS1987

Application of decomposition techniques to the preliminary design of a transport aircraft

A nonlinear constrained optimization problem describing the preliminary design process for a transport aircraft has been formulated. A multifaceted decomposition of the optimization problem has been made. Flight dynamics, flexible aircraft loads and deformations, and preliminary structural design subproblems appear prominently in the decomposition. The use of design process decomposition for scheduling design projects, a new system integration approach to configuration control, and the application of object-centered programming to a new generation of design tools are discussed.

Rogan, J. E.↗
NASA NTRS1986

Application of decomposition techniques to the preliminary design of a transport aircraft

A multifaceted decomposition of a nonlinear constrained optimization problem describing the preliminary design process for a transport aircraft has been made. Flight dynamics, flexible aircraft loads and deformations, and preliminary structural design subproblems appear prominently in the decomposition. The use of design process decomposition for scheduling design projects, a new system integration approach to configuration control, and the application of object-centered programming to a new generation of design tools are discussed.

Rogan, J. E.↗
NASA NTRS1992

Preliminary assessment of the robustness of dynamic inversion based flight control laws

Dynamic-inversion-based flight control laws present an attractive alternative to conventional gain-scheduled designs for high angle-of-attack maneuvering, where nonlinearities dominate the dynamics. Dynamic inversion is easily applied to the aircraft dynamics requiring a knowledge of the nonlinear equations of motion alone, rather than an extensive set of linearizations. However, the robustness properties of the dynamic inversion are questionable especially when considering the uncertainties involved with the aerodynamic database during post-stall flight. This paper presents a simple analysis and some preliminary results of simulations with a perturbed database. It is shown that incorporating integrators into the control loops helps to improve the performance in the presence of these perturbations.

Snell, S. A.↗
NASA NTRS1999

Overview of the Third Convection and Moisture EXperiment (CAMEX-3)

The Convection And Moisture EXperiment (CAMEX) is a series of field research investigations sponsored by the National Aeronautics and Space Administration (NASA). The third field campaign in the CAMEX series (CAMEX-3) is scheduled for 6 August - 23 September, 1998 to study tropical cyclone development, tracking, intensification, and landfalling impacts using NASA-funded aircraft remote sensing instrumentation. This study will yield high spatial and temporal information of hurricane structure, dynamics, and motion. These data, when analyzed within the context of more traditional aircraft, satellite, and ground-based radar observations, should provide additional insight to hurricane modelers and forecasters who continually strive to improve hurricane predictions. During CAMEX-3, NASA will deploy a high attitude ER-2 and medium altitude DC-8 aircraft from Patrick Air Force Base, Florida. Ground-based instrumentation will also be stationed on Andros Island, Bahamas. Opportunities for coordinated aircraft missions with the National Oceanic and Atmospheric Administration (NOAA) Hurricane Research Division are also being planned. This presentation will provide an overview of the CAMEX-3 missions and key case studies sampled. Data availability and access will also be discussed.

Hood, Robbie↗
NASA NTRS2010

Comparison of Airborne and Ground-Based Function Allocation Concepts for NextGen Using Human-In-The-Loop Simulations

This paper presents an air/ground functional allocation experiment conducted by the National Aeronautics and Space Administration (NASA) using two human-in-the-Loop simulations to compare airborne and ground-based approaches to NextGen separation assurance. The approaches under investigation are two trajectory-based four-dimensional (4D) concepts; one referred to as "airborne trajectory management with self-separation" (airborne) the other as "ground-based automated separation assurance" (ground-based). In coordinated simulations at NASA's Ames and Langley Research Centers, the primary operational participants -controllers for the ground-based concept and pilots for the airborne concept - manage the same traffic scenario using the two different 4D concepts. The common scenarios are anchored in traffic problems that require a significant increase in airspace capacity - on average, double, and in some local areas, close to 250% over current day levels - in order to enable aircraft to safely and efficiently traverse the test airspace. The simulations vary common independent variables such as traffic density, sequencing and scheduling constraints, and timing of trajectory change events. A set of common metrics is collected to enable a direct comparison of relevant results. The simulations will be conducted in spring 2010. If accepted, this paper will be the first publication of the experimental approach and early results. An initial comparison of safety and efficiency as well as operator acceptability under the two concepts is expected.

Wing, David J.↗
NASA NTRS2015

Full-Scale Crash Tests and Analyses of Three High-Wing Single

The NASA Emergency Locator Transmitter Survivability and Reliability (ELTSAR) project was initiated in 2014 to assess the crash performance standards for the next generation of ELT systems. Three Cessna 172 aircraft have been acquired to conduct crash testing at NASA Langley Research Center's Landing and Impact Research Facility. Testing is scheduled for the summer of 2015 and will simulate three crash conditions; a flare to stall while emergency landing, and two controlled flight into terrain scenarios. Instrumentation and video coverage, both onboard and external, will also provide valuable data of airframe response. Full-scale finite element analyses will be performed using two separate commercial explicit solvers. Calibration and validation of the models will be based on the airframe response under these varying crash conditions.

Annett, Martin S.↗
NASA NTRS1986

Aircraft control surface failure detection and isolation using the OSGLR test

The performance of the orthogonal series generalized likelihood ratio (OSGLR) test in detecting and isolating commercial aircraft control surface and actuator failures is evaluated. A modification to incorporate age-weighting which significantly reduces the sensitivity of the algorithm to modeling errors is presented. The steady-state implementation of the algorithm based on a single linear model valid for a cruise flight condition is tested using a nonlinear aircraft simulation. A number of off-nominal no-failure flight conditions including maneuvers, nonzero flap deflections, different turbulence levels and steady winds were tested. Based on the no-failure decision functions produced by off-nominal flight conditions, the failure detection and isolation performance at the nominal flight condition was determined. The extension of the algorithm to a wider flight envelope by scheduling on dynamic pressure and flap deflection is examined. Based on this testing, the OSGLR algorithm should be capable of detecting control surface failures that would affect the safe operation of a commercial aircraft. Isolation may be difficult if there are several surfaces which produce similar effects on the aircraft. Extending the algorithm over the entire operating envelope of a commercial aircraft appears feasible.

Bonnice, W. F.↗