Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “flight state”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,621 records · Page 90
All sourcesNASA NTRSDOE OSTI
NASA NTRS1939

A Glimpse of Scientific Research on Fundamental Problems of Military and Civil Aeronautics

Among the outstanding accomplishments of the last century is man's conquest of the air. That conquest began in 1903 when the Wright brothers made the first successful flight of an airplane at Kitty Hawk, N. C. Five years later the United States Government purchased its first airplane for the use of the Army, and began the training of officers for military flying. During the years immediately preceding the outbreak of the World War the Government and a meager aircraft industry had made important progress, but the Government, practically the only customer, had purchased less than 100 airplanes. In the meantime, leading European nations, sensing acutely the potentialities of aircraft in warfare, had made greater progress and had begun laying the foundations for the new science of aeronautics. The World War gave a remarkable impetus to the development of aeronautics and emphasized the need for organized research on the fundamental problems of flight. By act of Congress approved March 3, 1915, the National Advisory Committee for Aeronautics was created and charged with the duty of supervising, directing, and conducting fundamental scientific research and experiment in aeronautics. With the farsighted support of the Congress the Committee has led the world in the development of unique aeronautical research facilities in its laboratories at Langley Field, Va. The research programs include problems initiated by the Committee and its subcommittees and also investigations requested by the Army, the Navy, and the Civil Aeronautics Authority. The results of researches conducted under one control, serve without duplication of effort, the needs of all branches of aviation, civil and military, and exert a profound influence on the progress of aeronautics by improving the performance, efficiency, and safety of aircraft. A brief description of the results of some of the committee's researches and of the equipment employed will be found in the following pages.

Source record↗
NASA NTRS2004

Modeling and Analysis of Large Amplitude Flight Maneuvers

Analytical methods for stability analysis of large amplitude aircraft motion have been slow to develop because many nonlinear system stability assessment methods are restricted to a state-space dimension of less than three. The proffered approach is to create regional cell-to-cell maps for strategically located two-dimensional subspaces within the higher-dimensional model statespace. These regional solutions capture nonlinear behavior better than linearized point solutions. They also avoid the computational difficulties that emerge when attempting to create a cell map for the entire state-space. Example stability results are presented for a general aviation aircraft and a micro-aerial vehicle configuration. The analytical results are consistent with characteristics that were discovered during previous flight-testing.

Anderson, Mark R.↗
NASA NTRS1998

The Influences of Airmass Histories on Radical Species During POLARIS

The POLARIS mission focused on understanding the processes associated with the decrease of polar stratospheric ozone from spring to fall at high latitudes. This decrease is linked primarily to in situ photochemical destruction by reactive nitrogen species, NO and NO2, which also control other catalytic loss cycles. Steady state models have been used to test photochemistry and radical behavior but are not always adequate in simulating radical species observations. In some cases, air mass history can be important and trajectory models give an improved simulation of the radical species. Trajectory chemistry models, however, still consistently underestimate NO and NO2 abundances compared to measurements along the ER-2 flight track. The Goddard chemistry on trajectory model has been used to test updated rate constants for NO2 + OH, NO2 + O and OH + HNO3, key reactions that affect NO and NO2 abundances. We present comparisons between the modified Goddard chemistry on trajectory model, the JPL steady state model and observations from selected flights.

Pierson, James M.↗
NASA NTRS1986

Boundary layer flow visualization for flight testing

Flow visualization is used extensively in flight testing to determine aerodynamic characteristics such as surface flow direction and boundary layer state. Several visualization techniques are available to the aerodynamicist. Two of the most popular are oil flows and sublimating chemicals. Oil is used to visualize boundary layer transition, shock wave location, regions of separated flow, and surface flow direction. Boundary layer transition can also be visualized with sublimating chemicals. A summary of these two techniques is discussed, and the use of sublimating chemicals is examined in some detail. The different modes of boundary layer transition are characterized by different patterns in the sublimating chemical coating. The discussion includes interpretation of these chemical patterns and the temperature and velocity operating limitations of the chemical substances. Information for selection of appropriate chemicals for a desired set of flight conditions is provided.

Obara, Clifford J.↗
NASA NTRS1989

The insertion of human dynamics models in the flight control loops of V/STOL research aircraft. Appendix 2: The optimal control model of a pilot in V/STOL aircraft control loops

An overview is presented of research work focussed on the design and insertion of classical models of human pilot dynamics within the flight control loops of V/STOL aircraft. The pilots were designed and configured for use in integrated control system research and design. The models of human behavior that were considered are: McRuer-Krendel (a single variable transfer function model); and Optimal Control Model (a multi-variable approach based on optimal control and stochastic estimation theory). These models attempt to predict human control response characteristics when confronted with compensatory tracking and state regulation tasks. An overview, mathematical description, and discussion of predictive limitations of the pilot models is presented. Design strategies and closed loop insertion configurations are introduced and considered for various flight control scenarios. Models of aircraft dynamics (both transfer function and state space based) are developed and discussed for their use in pilot design and application. Pilot design and insertion are illustrated for various flight control objectives. Results of pilot insertion within the control loops of two V/STOL research aricraft (Sikorski Black Hawk UH-60A, McDonnell Douglas Harrier II AV-8B) are presented and compared against actual pilot flight data. Conclusions are reached on the ability of the pilot models to adequately predict human behavior when confronted with similar control objectives.

Zipf, Mark E.↗
NASA NTRS1999

Upper-Stage Flight Experiment

For propulsion applications that require that the propellants are storable for long periods, have a high density impulse, and are environmentally clean and non-toxic, the best choice is a combination of high-concentration hydrogen peroxide (High Test Peroxide, or HTP) and a liquid hydrocarbon (LHC) fuel. The HTP/LHC combination is suitable for low-cost launch vehicles, space taxi and space maneuvering vehicles, and kick stages. Orbital Sciences Corporation is under contract with the NASA Marshall Space Flight Center in cooperation with the Air Force Research Lab to design, develop and demonstrate a new low-cost liquid upper stage based on HTP and JP-8. The Upper Stage Flight Experiment (USFE) focuses on key technologies necessary to demonstrate the operation of an inherently simple propulsion system with an innovative, state-of-the-art structure. Two key low-cost vehicle elements will be demonstrated - a 10,000 lbf thrust engine and an integrated composite tank structure. The suborbital flight test of the USFE is scheduled for 2001. Preceding the flight tests are two major series of ground tests at NASA Stennis Space Center and a subscale tank development program to identify compatible composite materials and to verify their compatibility over long periods of time. The ground tests include a thrust chamber development test series and an integrated stage test. This paper summarizes the results from the first phase of the thrust chamber development tests and the results to date from the tank material compatibility tests. Engine and tank configurations that meet the goals of the program are described.

Anderson, W. E.↗
NASA NTRS2012

On the Transition and Migration of Flight Functions in the Airspace System

Since ~400 BC, when man first replicated flying behavior with kites, up until the turn of the 20th century, when the Wright brothers performed the first successful powered human flight, flight functions have become available to man via significant support from man-made structures and devices. Over the past 100 years or so, technology has enabled several flight functions to migrate to automation and/or decision support systems. This migration continues with the United States NextGen and Europe s Single European Sky (a.k.a. SESAR) initiatives. These overhauls of the airspace system will be accomplished by accommodating the functional capabilities, benefits, and limitations of technology and automation together with the unique and sometimes overlapping functional capabilities, benefits, and limitations of humans. This paper will discuss how a safe and effective migration of any flight function must consider several interrelated issues, including, for example, shared situation awareness, and automation addiction, or over-reliance on automation. A long-term philosophical perspective is presented that considers all of these issues by primarily asking the following questions: How does one find an acceptable level of risk tolerance when allocating functions to automation versus humans? How does one measure or predict with confidence what the risks will be? These two questions and others will be considered from the two most-discussed paradigms involving the use of increasingly complex systems in the future: humans as operators and humans as monitors.

Morris, Allan Terry↗
NASA NTRS2003

International Space Station Internal Thermal Control System Cold Plate/Fluid-Stability Test: Two Year Update

Operation of the Internal Thermal Control System (ITCS) Cold Plate/Fluid-Stability Test Facility commenced on September 5, 2000. The facility was intended to provide advance indication of potential problems on board the International Space Station (ISS) and was designed: - To be materially similar to the flight ITCS. - To allow for monitoring during operation. - To run continuously for three years. During the first two years of operation the conditions of the coolant and components were remarkably stable. During this same period of time, the conditions of the ISS ITCS significantly diverged from the desired state. Due to this divergence, the test facility has not been providing information useful for predicting the flight ITCS condition. Results of the first two years are compared with flight conditions over the same time period, showing the similarities and divergences. To address the divergences, the test facility was modified slightly to more closely match the flight conditions, and to gain insight into the reasons for the divergence. Results of the modifications are discussed and provide insight into the development of the conditions on orbit.

Paul Wieland↗
NASA NTRS1975

Motor activity of astronauts in unsupported state

The performance quality of movements away and approaches to an airlock by astronauts was tested during parabolic flights for weightlessness simulation. Coordination of movement, orientation and performance capacity of the astronauts were not singificantly disrupted. Observed physiological shifts are characterized by an increase in pulse and respiration rate and an increase in arterial pressure under g-forces, a gradual decrease in these indices during repeated stays in weightlessness or during the prolonged effect of it, by a reduction of the length of postrotational nystagmus and counterrotation illusions under weightless conditions.

Kasyan, I. I.↗
NASA NTRS1994

Commercial investigation results for the generic bioprocessing apparatus flown on United States Microgravity Laboratory-1

The Generic Bioprocessing Apparatus (BPA) payload was developed by BioServe to support the commercial flight development needs of our specialized consortia comprised of business, academic, and government entities. The consortia have commitments to explore commercial opportunities in bioprocessing, biomedical models, and closed agricultural systems. In addition, some members of BioServe have interests in the development and/or qualification of enabling flight hardware used in life sciences space flight testing. Some business and academic entities have interests in more than one of these consortia. To aid in payload development, flight, and analysis, each consortium member contributes resources ranging from proprietary expertise and materials, to hardware and cash. Professionals from business, academia, and government often interact with each other via graduate research assistants who do much of the 'hands-on' payload preparation and subsequent data analyses. The GBA supported research, testing, and development activities for each different BioServe consortium. It produced an environment in which professionals from diverse backgrounds came together with a single focus. And, it provided a truly novel learning environment for a youthful new cadre of space professionals committed to the exploration of commercial opportunities presented by space. Since the GBA supported a large number of different experiments, this paper briefly describes the payload characteristics and the essential operations of the payload. A summary of the experiments is presented. Finally, a few of the experiments are described in detail highlighting some novel effects of space flight on life science systems. Portions of the reported work have or will appear in appropriate archival journals as cited in the bibliography. In several instances, data collected from USML-1 have been supplemented with related data collected on more recent STS missions.

Stodieck, Louis S.↗
NASA NTRS2002

Thermal Stir Welding: A New Solid State Welding Process

Thermal Stir Shielding is a revolutionary new welding process developed at NASA's Marshall Space Flight Center in Huntsville, AL. Thermal stir welding is similar to friction stir welding in that it joins similar or dissimilar materials without melting the parent material. However, unlike friction stir welding, the heating and stirring functions are independent allowing more degrees of freedom for greater process control. This paper introduces the mechanics of the thermal stir welding process. In addition, weld mechanical property data is presented for selected alloys as well as metallurgical analysis.

Ding, R. Jeffery↗
NASA NTRSDate not supplied

NASA Armstrong State of Discipline

- AFRC’s Overview Statement - AFRC is NASA's primary center for high-risk, atmospheric flight research and ground testing on modified or unique research vehicles and test articles - AFRC’s L&D Facility - Flight Loads Lab (FLL): High-bay test area with flight line access for large-scale structural & thermal testing of aerospace structures for component and airframe qualification/airworthiness & research - AFRC’s L&D Expertise - Mainly supports projects in the Aeronautics Research Mission - Aeroelasticity, Model Tuning, FEM & Flutter Analysis Airworthiness Clearance support - Modal Testing, Mass Property Testing & Flight Testing

Natalie Spivey↗
NASA NTRS2010

Optimizing Flight Departure Delay and Route Selection Under En Route Convective Weather

This paper presents a linear Integer Programming model for managing air traffic flow in the United States. The decision variables in the model are departure delays and predeparture reroutes of aircraft whose trajectories are predicted to cross weather-impacted regions of the National Airspace System. The model assigns delays to a set of flights while ensuring their trajectories are free of any conflicts with weather. In a deterministic setting, there is no airborne holding due to unexpected weather incursion in a flight s path. The model is applied to solve a large-scale traffic flow management problem with realistic weather data and flight schedules. Experimental results indicate that allowing rerouting can reduce departure delays by nearly 57%, but it is associated with an increase in total airborne time due to longer routes flown by aircraft. The computation times to solve this problem were significantly lower than those reported in the earlier studies.

Mukherjee, Avijit↗
NASA NTRS1988

Free-flying experiment to measure the Schawlow-Townes linewidth limit of a 300 THz laser oscillator

Recent advances in laser diode-pumped solid state laser sources permit the design and testing of laser sources with linewidths that approach the Schawlow-Townes limit of 1 Hz/mW of output power. Laser diode pumped solid state ring oscillators have been operated with CW output power levels of 25 mW at electrical efficiencies that exceed 6 percent. These oscillators are expected to operate for lifetimes that approach those of the laser diode sources which is now approaching 20,000 hours. The efficiency and lifetime of these narrow linewidth laser sources will enable space measurements of gravity waves, remote sensing applications (including local range rate and measurements), and laser sources for frequency and time standards. A free-flight experiment, 'SUNLITE', is being designed to measure the linewidth of this all-solid-state laser system.

Byer, R. L.↗
NASA NTRS2007

NASA Global Hawk: A Unique Capability for the Pursuit of Earth Science

For more than 2 years, the NASA Dryden Flight Research Center has been preparing for the receipt of two Advanced Concept Technology Demonstration Global Hawk air vehicles from the United States Air Force. NASA Dryden intends to establish a Global Hawk Project Office, which will be responsible for developing the infrastructure required to operate this unmanned aerial system and establishing a trained maintenance and operations team. The first flight of a NASA Global Hawk air vehicle is expected to occur in 2008. The NASA Global Hawk system can be used by a variety of customers, including U.S. Government agencies, civilian organizations, universities, and state governments. Initially, the main focus of the research activities is expected to be Earth science related. A combination of the vehicle s range, endurance, altitude, payload power, payload volume, and payload weight capabilities separates the Global Hawk unmanned aerial system from all other platforms available to the science community. This report describes the NASA Global Hawk system and current plans for the NASA air vehicle concept of operations, and provides examples of potential missions with an emphasis on science missions.

Naftel, J. Chris↗
NASA NTRS2007

NASA Global Hawk: A Unique Capability for the Pursuit of Earth Science

For more than 2 years, the NASA Dryden Flight Research Center has been preparing for the receipt of two Advanced Concept Technology Demonstration Global Hawk air vehicles from the United States Air Force. NASA Dryden intends to establish a Global Hawk Project Office, which will be responsible for developing the infrastructure required to operate this unmanned aerial system and establishing a trained maintenance and operations team. The first flight of a NASA Global Hawk air vehicle is expected to occur in 2008. The NASA Global Hawk system can be used by a variety of customers, including U.S. Government agencies, civilian organizations, universities, and state governments. A combination of the vehicle s range, endurance, altitude, payload power, payload volume, and payload weight capabilities separates the Global Hawk unmanned aerial system from all other platforms available to the science community.

Naftel, J. Chris↗