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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Performance analysis of a fault inferring nonlinear detection system algorithm with integrated avionics flight data

This paper presents the performance analysis results of a fault inferring nonlinear detection system (FINDS) using integrated avionics sensor flight data for the NASA ATOPS B-737 aircraft in a Microwave Landing System (MLS) environment. First, an overview of the FINDS algorithm structure is given. Then, aircraft state estimate time histories and statistics for the flight data sensors are discussed. This is followed by an explanation of modifications made to the detection and decision functions in FINDS to improve false alarm and failure detection performance. Next, the failure detection and false alarm performance of the FINDS algorithm are analyzed by injecting bias failures into fourteen sensor outputs over six repetitive runs of the five minutes of flight data. Results indicate that the detection speed, failure level estimation, and false alarm performance show a marked improvement over the previously reported simulation runs. In agreement with earlier results, detection speed is faster for filter measurement sensors such as MLS than for filter input sensors such as flight control accelerometers. Finally, the progress in modifications of the FINDS algorithm design to accommodate flight computer constraints is discussed.

Caglayan, A. K.↗
NASA NTRS2019

Characterization of Thermal Protection Systems: An Analysis of Optical & Thermal Properties

Thermal Protection System Materials & thermal control coatings were characterized by a variety of methodologies including heat flow meter method (HFM), dynamic scanning calorimetry (DSC), fourier transform infrared spectroscopy (FTIR), and Ultra-Violet & Visible light spectroscopy (UV-VIS). Physical properties were measured to aid in the construction of thermal response models for a number a projects including MEDLI and MEDLI2. Comparing pre-flight predictions with actual flight data can allow for a reduction of margins and improve designs. The models enable design of TPS for flight missions and analysis of flight data to understand aerothermal environments experienced on the mission. This presentation reveals critical information: heat capacity (cp vs T), thermal conductivity ( vs T), and emissivity (E vs T) for Super Lightweight Ablative (SLA), Phenolic Impregnated Carbon Ablative (PICA-D), & Heatshield for Extreme Entry Environment Technology (HEEET). These properties were also measured for various thermal control coatings manufactured by AZ Technology. A portion of this work is incomplete and highlights questions to investigate in the future.

Cole, Brian↗
NASA NTRS1972

Analysis of flight test transition and turbulent heating data. Part 1: Boundary layer transition results

The objective of the study was to provide a detailed post flight evaluation of ballistic vehicle flight test boundary layer transition data. A total of fifty-five vehicles were selected for analysis. These vehicles were chosen from a data sampling of roughly two hundred flights and the criteria for vehicle selection is delineated herein. The results of the analysis indicate that frustum transition of re-entry vehicles appears to be nose tip dominated. Frustum related parameters and materials apparently have a second order effect on transition. This implies that local viscous parameters on the frustum should not correlate flight test transition data, and in fact they do not. Specific parameters relative to the nose tip have been identified as the apparent dominant factors that characterize the transition phenomena and a correlation of flight test data is presented.

Martellucci, A.↗
NASA NTRS1975

Analysis of wake vortex flight test data behind a T-33 aircraft

Measurements of the vortex system behind a T-33 aircraft were obtained by a Learjet equipped with a boom carrying a three-wire, hot-wire anemometry probe and other instrumentation. Analysis of the measurements using a computerized geometric method indicated the vortices had a core radius of approximately 0.11 meter with a maximum velocity of 25 meters per second. The hot-wire anemometer was found to be a practical and sensitive instrument for determining in-flight vortex velocities. No longitudinal instabilities, buoyant effects or vortex breakdowns were evident in the data which included vortex wake cross sections from 0.24 to 5.22 kilometers behind the T-33.

Kuhn, G. D.↗
NASA NTRS1988

Current flight test experience related to structural divergence of forward-swept wings

Flight testing the X-29A forward-swept wing aircraft has required development of new flight test techniques to accomplish subcritical extrapolations to the actual structural divergence dynamic pressure of the aircraft. This paper provides current experience related to applying these techniques to analysis of flight data from the forward-swept wing in order to assess the applicability of these techniques to flight test data. The measurements required, maneuvers flown, and flight test conditions are described. Supporting analytical predictions for the techniques are described and the results using flight data are compared to these predictions. Use of the results during envelope expansion and the resulting modifications to the techniques are discussed. Some of the analysis challenges that occurred are addressed and some preliminary conclusions and recommendations are made relative to the usefulness of these techniques in the flight test environment.

Schuster, Lawrence S.↗
NASA NTRS1988

Current flight test experience related to structural divergence of forward-swept wings

Flight testing the X-29A forward-swept wing aircraft has required development of new flight test techniques to accomplish subcritical extrapolations to the actual structural divergence dynamic pressure of the aircraft. This paper provides current experience related to applying these techniques to analysis of flight data from the forward-swept wing in order to assess the applicability of these techniques to flight test data. The measurements required, manuevers flown, and flight test conditions are described. Supporting analytical predictions for the techniques are described and the results using flight data are compared to these predictions. Use of the results during envelope expansion and the resulting modifications to the techniques are discussed. Some of the analysis challenges that occurred are addressed and some preliminary conclusions and recommendations are made relative to the usefulness of these techniques in the flight test environment.

Schuster, Lawrence S.↗
NASA NTRS1972

A generalized method for the identification of aircraft stability and control derivatives from flight test data.

This paper discusses the application of a generalized identification method for flight test data analysis. The method is based on the maximum likelihood (ML) criterion and includes output error and equation error methods as special cases. Both the linear and nonlinear models with and without process noise are considered. The flight test data from lateral maneuvers of HL-10 and M2/F3 lifting bodies are processed to determine the lateral stability and control derivatives, instrumentation accuracies and biases. A comparison is made between the results of the output error method and the generalized ML method for M2/F3 data containing gusts. It is shown that better fits to time histories are obtained by using the generalized ML method.

Mehra, R. K.↗
NASA NTRS1974

Maximum likelihood identification of aircraft stability and control derivatives

Application of a generalized identification method to flight test data analysis. The method is based on the maximum likelihood (ML) criterion and includes output error and equation error methods as special cases. Both the linear and nonlinear models with and without process noise are considered. The flight test data from lateral maneuvers of HL-10 and M2/F3 lifting bodies are processed to determine the lateral stability and control derivatives, instrumentation accuracies, and biases. A comparison is made between the results of the output error method and the ML method for M2/F3 data containing gusts. It is shown that better fits to time histories are obtained by using the ML method. The nonlinear model considered corresponds to the longitudinal equations of the X-22 VTOL aircraft. The data are obtained from a computer simulation and contain both process and measurement noise. The applicability of the ML method to nonlinear models with both process and measurement noise is demonstrated.

Mehra, R. K.↗
NASA NTRS1987

High-angle-of-attack pneumatic lag and upwash corrections for a hemispherical flow direction sensor

As part of the NASA F-14 high angle of attack flight test program, a nose mounted hemispherical flow direction sensor was calibrated against a fuselage mounted movable vane flow angle sensor. Significant discrepancies were found to exist in the angle of attack measurements. A two fold approach taken to resolve these discrepancies during subsonic flight is described. First, the sensing integrity of the isolated hemispherical sensor is established by wind tunnel data extending to an angle of attack of 60 deg. Second, two probable causes for the discrepancies, pneumatic lag and upwash, are examined. Methods of identifying and compensating for lag and upwash are presented. The wind tunnel data verify that the isolated hemispherical sensor is sufficiently accurate for static conditions with angles of attack up to 60 deg and angles of sideslip up to 30 deg. Analysis of flight data for two high angle of attack maneuvers establishes that pneumatic lag and upwash are highly correlated with the discrepancies between the hemispherical and vane type sensor measurements.

Whitmore, Stephen A.↗
NASA NTRS1990

Boundary-layer stability analysis of flight-measured transition data

Correlation of in-flight boundary-layer transition experiments with linear boundary-layer stability theory contributes both to the validation of the numerical methods as well as the analysis of the measured transition process. Transition results obtained in a recent flight experiment, in which the extent of laminar flow and the transition process on the wing of a business-jet fitted with an instrumented glove section were determined, are analyzed. The experiment was conducted at freestream Mach numbers from 0.55 to 0.82, chord Reynolds numbers from 10 to 20 x 10 to the 6th, and leading-edge sweep angles 17 deg to 20 deg. The growth of both Tollmien-Schlichting and crossflow instabilities are predicted using the e exp n method for several flight conditions and the calculated n-factors at transition onset are correlated. Comparison of the measured dominant boundary-layer disturbance frequencies and the predicted unstable frequencies shows fair agreement for several of the flight conditions studied.

Obara, Clifford J.↗
NASA NTRS1986

Ames Research Center Life Sciences Payload - Overview of results of a spaceflight of 24 rats and 2 monkeys

A hardware description and experimental results are reported from the initial STS flight carrying two Research Animal Holding Facility (RAHF) units. The flight was mainly intended for engineering check-out of the RAHF design. The system development and prelaunch preparations are briefly summarized, including the provisions of retrieval teams at alternate landing sites and extensive rehearsals to ensure timely data analysis. The flight revealed a problem with the containment of particulates from the RAHFs and the provision of adequate water for the monkeys. On-board films showed that one of the monkeys experienced motion sickness, from which he recovered after 5 days in space. Necropsy of the subject rats documented suppressed interferon production, loss of muscle mass, an up to 13 percent loss in bone mass (after a one week flight), and a 20 percent decrease in growth-inducing hormone. The volume of data collected is thought to exceed the combined data gathered on all previous U.S. space missions.

Callahan, P. X.↗
NASA NTRS1998

Particle Detectors and Data Analysis for Cusp Transient Features Campaign

Grant NAG5-5084 was awarded to support the participation of South West Research Institute (SwRI) in building the energy per unit charge particle detectors for the Cusp Transient Features Campaign and analysis of flight data from these instruments. The detectors are part of an instrumented payload (Rocket 36.152, Dr. R. Pfaff, P.I.) launched from Svalbard on December 3, 1997, into the dark cusp. The particle instruments, a Cusp Electron Detector (CED) and a Cusp Ion Detector (CID), built on this project, provided differential energy and angular measurements along the rocket trajectory throughout the flight.

Sharber, J. R.↗
NASA NTRS1972

Summary analysis of the Gemini entry aerodynamics

The aerodynamic data that were derived in 1967 from the analysis of flight-generated data for the Gemini entry module are presented. These data represent the aerodynamic characteristics exhibited by the vehicle during the entry portion of Gemini 2, 3, 5, 8, 10, 11, and 12 missions. For the Gemini, 5, 8, 10, 11, and 12 missions, the flight-generated lift-to-drag ratios and corresponding angles of attack are compared with the wind tunnel data. These comparisons show that the flight generated lift-to-drag ratios are consistently lower than were anticipated from the tunnel data. Numerous data uncertainties are cited that provide an insight into the problems that are related to an analysis of flight data developed from instrumentation systems, the primary functions of which are other than the evaluation of flight aerodynamic performance.

Whitnah, A. M.↗
NASA NTRS1993

Extraction of stability and control derivatives from orbiter flight data

The Space Shuttle Orbiter has provided unique and important information on aircraft flight dynamics. This information has provided the opportunity to assess the flight-derived stability and control derivatives for maneuvering flight in the hypersonic regime. In the case of the Space Shuttle Orbiter, these derivatives are required to determine if certain configuration placards (limitations on the flight envelope) can be modified. These placards were determined on the basis of preflight predictions and the associated uncertainties. As flight-determined derivatives are obtained, the placards are reassessed, and some of them are removed or modified. Extraction of the stability and control derivatives was justified by operational considerations and not by research considerations. Using flight results to update the predicted database of the orbiter is one of the most completely documented processes for a flight vehicle. This process followed from the requirement for analysis of flight data for control system updates and for expansion of the operational flight envelope. These results show significant changes in many important stability and control derivatives from the preflight database. This paper presents some of the stability and control derivative results obtained from Space Shuttle flights. Some of the limitations of this information are also examined.

Iliff, Kenneth W.↗
NASA NTRS1977

Overview of NASA/Marshall Space Flight Center's program on knowledge of atmospheric processes

The Marshall Space Flight Center (MSFC) is charged with the responsibility to enhance aviation safety through improving understanding of various atmospheric phenomena. A brief discussion is presented concerning the tasks and work being accomplished by MSFC. The tasks are defined as follows: (1) to determine and define the turbulence and steady wind environments induced by buildings, towers, hills, trees, etc., (2) to identify, develop, and apply natural environment technology for the reconstruction and/or simulation of the natural environment for aircraft accident investigation and hazard identification, (3) to develop basic information about free atmosphere perturbations, (4) to develop and apply fog modification mathematical models to assess candidate fog modification schemes and to develop appropriate instrumentation to aquire basic data about fog. To accomplish these tasks MSFC has developed a program involving field data acquisition, wind tunnel studies, theoretical studies, data analysis, and flight simulation studies.

Camp, D. W.↗
NASA NTRS2006

Viking Afterbody Heating Computations and Comparisons to Flight Data

Computational fluid dynamics predictions of Viking Lander 1 entry vehicle afterbody heating are compared to flight data. The analysis includes a derivation of heat flux from temperature data at two base cover locations, as well as a discussion of available reconstructed entry trajectories. Based on the raw temperature-time history data, convective heat flux is derived to be 0.63-1.10 W/cm2 for the aluminum base cover at the time of thermocouple failure. Peak heat flux at the fiberglass base cover thermocouple is estimated to be 0.54-0.76 W/cm2, occurring 16 seconds after peak stagnation point heat flux. Navier-Stokes computational solutions are obtained with two separate codes using an 8- species Mars gas model in chemical and thermal non-equilibrium. Flowfield solutions using local time-stepping did not result in converged heating at either thermocouple location. A global time-stepping approach improved the computational stability, but steady state heat flux was not reached for either base cover location. Both thermocouple locations lie within a separated flow region of the base cover that is likely unsteady. Heat flux computations averaged over the solution history are generally below the flight data and do not vary smoothly over time for both base cover locations. Possible reasons for the mismatch between flight data and flowfield solutions include underestimated conduction effects and limitations of the computational methods.

Edquist, Karl T.↗