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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Atmospheric analysis for airdata calibration on research aircraft

In-flight airdata calibrations are used to determine the aerodynamic influence of an airplane on pitot-static pressure measurements of altitude and speed. Conventional flight-test calibration techniques are briefly reviewed and meteorological analysis methods for estimating calibration reference values of atmospheric conditions are described. There are cases where some conventional in-flight techniques are not entirely satisfactory for research aircraft because of added equipment requirements or flight envelope and location limitations. In these cases, atmospheric wind and pressure information can be used to complement conventional techniques. Accuracy of the atmospheric measurements and the variability of upper-air winds and pressure values are discussed. Results from several flight research aircraft show that wind reference calibration is generally less accurate than calibration accuracy standards for civil and research aircraft. Examples of pressure reference altimetry derived from meteorological analyses are also presented for a variety of flight research programs. These flight data show that the reference pressure accuracy provided by meteorological analyses is usually within civil aircraft and flight research airdata calibration accuracy standards. Meteorological analyses altimetry is particularly useful when it is not feasible to restrict the test airplane altitude, location, or maneuver envelope.

Ehernberger, L. J.↗
NASA NTRS2016

Real-Time Global Nonlinear Aerodynamic Modeling for Learn-To-Fly

Flight testing and modeling techniques were developed to accurately identify global nonlinear aerodynamic models for aircraft in real time. The techniques were developed and demonstrated during flight testing of a remotely-piloted subscale propeller-driven fixed-wing aircraft using flight test maneuvers designed to simulate a Learn-To-Fly scenario. Prediction testing was used to evaluate the quality of the global models identified in real time. The real-time global nonlinear aerodynamic modeling algorithm will be integrated and further tested with learning adaptive control and guidance for NASA Learn-To-Fly concept flight demonstrations.

Morelli, Eugene A.↗
NASA NTRS1976

YF-16 flight flutter test procedures

The Random Decrement technique (Randomdec) was incorporated in procedures for flight testing of the YF-16 lightweight fighter prototype. Damping values obtained substantiate the adequacy of the flutter margin of safety. To confirm the structural modes which were being excited, a spectral analysis of each channel was performed using the AFFTC time/data 1923/50 time series analyzer. Inflight test procedure included the careful monitoring of strip charts, three axis pulses, rolls, and pullups.

Brignac, W. J.↗
NASA NTRS1987

Dynamic stability and handling qualities tests on a highly augmented, statically unstable airplane

Initial envelope clearance and subsequent flight testing of a new, fully augmented airplane with an extremely high degree of static instability can place unusual demands on the flight test approach. Previous flight test experience with these kinds of airplanes is very limited or nonexistent. The safe and efficient flight testing may be further complicated by a multiplicity of control effectors that may be present on this class of airplanes. This paper describes some novel flight test and analysis techniques in the flight dynamics and handling qualities area. These techniques were utilized during the initial flight envelope clearance of the X-29A aircraft and were largely responsible for the completion of the flight controls clearance program without any incidents or significant delays.

Gera, Joseph↗
NASA NTRS1987

Dynamic stability and handling qualities tests on a highly augmented, statically unstable airplane

Novel flight test and analysis techniques in the flight dynamics and handling qualities area are described. These techniques were utilized at NASA Ames-Dryden during the initial flight envelope clearance of the X-29A aircraft. It is shown that the open-loop frequency response of an aircraft with highly relaxed static stability can be successfully computed on the ground from telemetry data. Postflight closed-loop frequency response data were obtained from pilot-generated frequency sweeps and it is found that the current handling quality requirements for high-maneuverability aircraft are generally applicable to the X-29A.

Gera, Joseph↗
NASA NTRS1987

Dynamic stability and handling qualities tests on a highly augmented, statically unstable airplane

This paper describes some novel flight tests and analysis techniques in the flight dynamics and handling qualities area. These techniques were utilized during the initial flight envelope clearance of the X-29A aircraft and were largely responsible for the completion of the flight controls clearance program without any incidents or significant delays. The resulting open-loop and closed-loop frequency responses and the time history comparison using flight and linear simulation data are discussed.

Gera, Joseph↗
NASA NTRS1998

In-Flight System Identification

A method is proposed and studied whereby the system identification cycle consisting of experiment design and data analysis can be repeatedly implemented aboard a test aircraft in real time. This adaptive in-flight system identification scheme has many advantages, including increased flight test efficiency, adaptability to dynamic characteristics that are imperfectly known a priori, in-flight improvement of data quality through iterative input design, and immediate feedback of the quality of flight test results. The technique uses equation error in the frequency domain with a recursive Fourier transform for the real time data analysis, and simple design methods employing square wave input forms to design the test inputs in flight. Simulation examples are used to demonstrate that the technique produces increasingly accurate model parameter estimates resulting from sequentially designed and implemented flight test maneuvers. The method has reasonable computational requirements, and could be implemented aboard an aircraft in real time.

Morelli, Eugene A.↗
NASA NTRS1988

A discussion of some proposed measurement techniques for hypersonic flight and instrumentation research experiments

Sensors, instrumentation, and test techniques proposed for the Hypersonic Flight Instrumentation and Research Experiment are discussed. The project is concerned with Mach 4 to 16 flight at pressure altitudes of 50,000 to 150,000 feet. The developmental instrumentation for the program includes angle-of-attack sensors, transition sensors, skin-friction sensors, particle sensors, species-concentration sensors, and temperature and heat flux sensors. Support instrumentation (required to monitor basic flight parameters and to supply data from which the performance of the developmental instruments may be evaluated) considered include surface pressure sensors, inertial instrumentation, magnetic attitude sensors, and signal conditioning and data transmission instrumentation.

Hellbaum, R. F.↗
NASA NTRS1981

Flight test experience with high-alpha control system techniques on the F-14 airplane

Improved handling qualities of fighter aircraft at high angles of attack can be provided by various stability and control augmentation techniques. NASA and the U.S. Navy are conducting a joint flight demonstration of these techniques on an F-14 airplane. This paper reports on the flight test experience with a newly designed lateral-directional control system which suppresses such high angle of attack handling qualities problems as roll reversal, wing rock, and directional divergence while simultaneously improving departure/spin resistance. The technique of integrating a piloted simulation into the flight program was used extensively in this program. This technique had not been applied previously to high angle of attack testing and required the development of a valid model to simulate the test airplane at extremely high angles of attack.

Gera, J.↗
NASA NTRS1975

Flight Flutter Testing Symposium

Papers presented at the conference are reported. Subjects discussed include: theory, methods and techniques, and flight flutter testing.

Source record↗
NASA NTRS2011

Use of Flexible Body Coupled Loads in Assessment of Day of Launch Flight Loads

A Day of Launch flight loads assessment technique that determines running loads calculated from flexible body coupled loads was developed for the Ares I-X Flight Test Vehicle. The technique was developed to quantify DOL flight loads in terms of structural load components rather than the typically used q-alpha metric to provide more insight into the DOL loads. In this technique, running loads in the primary structure are determined from the combination of quasi-static aerodynamic loads and dynamic loads. The aerodynamic loads are calculated as a function of time using trajectory parameters passed from the DOL trajectory simulation and are combined with precalculated dynamic loads using a load combination equation. The potential change in aerodynamic load due to wind variability during the countdown is included in the load combination. In the event of a load limit exceedance, the technique allows the identification of what load component is exceeded, a quantification of how much the load limit is exceeded, and where on the vehicle the exceedance occurs. This technique was used to clear the Ares I-X FTV for launch on October 28, 2009. This paper describes the use of coupled loads in the Ares I-X flight loads assessment and summarizes the Ares I-X load assessment results.

Starr, Brett R.↗
NASA NTRS1989

Historical review of missile aerodynamic developments

A comprehensive development history to about 1970 is presented for missile technologies and their associated capabilities and difficulties. Attention is given to the growth of an experimental data base for missile design, as well as to the critical early efforts to develop analytical methods applicable to missiles. Most of the important missile development efforts made during the period from the end of the Second World War to the early 1960s were based primarily on experiences gained through wind tunnel and flight testing; analytical techniques began to demonstrate their usefulness in the design process only in the late 1960s.

Spearman, M. Leroy↗
NASA NTRS2004

RTO Technical Publications: A Quarterly Listing

The titles of five reports are listed here, together with an abstract for each. The titles include: 1) 'Spectral Models of Kuiper Belt Objects and Centaurs'; 2) 'Simulation of and for Military Decision Making'; 3) 'Abundance of the Radioactive Be-10 in the Cosmic Radiation up to 2 GeV/nucleon with the Balloon-borne Instrument ISOMAX1998'; 4) 'Optical Air Flow Measurements in Flight'; 5) 'Flight Test Measurement Techniques for Laminar Flow'.

Source record↗
NASA NTRS2007

An Online Resource for Flight Test Safety Planning

A viewgraph presentation describing an online database for flight test safety techniques is shown. The topics include: 1) Goal; 2) Test Hazard Analyses; 3) Online Database Background; 4) Data Gathering; 5) NTPS Role; 6) Organizations; 7) Hazard Titles; 8) FAR Paragraphs; 9) Maneuver Name; 10) Identified Hazard; 11) Matured Hazard Titles; 12) Loss of Control Causes; 13) Mitigations; 14) Database Now Open to the Public; 15) FAR Reference Search; 16) Record Field Search; 17) Keyword Search; and 18) Results of FAR Reference Search.

Lewis, Greg↗
NASA NTRS2018

ARM Pilot Techniques

This presentation discusses lessons learned from flight and technique testing.

outreach↗
NASA NTRS1983

Flight test trajectory control analysis

Recent extensions to optimal control theory applied to meaningful linear models with sufficiently flexible software tools provide powerful techniques for designing flight test trajectory controllers (FTTCs). This report describes the principal steps for systematic development of flight trajectory controllers, which can be summarized as planning, modeling, designing, and validating a trajectory controller. The techniques have been kept as general as possible and should apply to a wide range of problems where quantities must be computed and displayed to a pilot to improve pilot effectiveness and to reduce workload and fatigue. To illustrate the approach, a detailed trajectory guidance law is developed and demonstrated for the F-15 aircraft flying the zoom-and-pushover maneuver.

Walker, R.↗
NASA NTRS1974

NASA Flight Research Center scale F-15 remotely piloted research vehicle program

The NASA Flight Research Center undertook a remotely piloted research vehicle (RPRV) program with a 3/8-scale model of an F-15 aircraft to determine the usefulness of the RPRV testing technique in high-risk flight testing such as spin testing. The results of the first flights of the program are presented. The program has shown that the RPRV technique, including the use of a digital control system, is a viable method for obtaining flight research data. Also presented are some negative aspects that have been learned about the RPRV technique in terms of model size, command frequency, and launch technique.

Layton, G. P.↗