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At least 559 records · Page 31

Flight Test Results on the Stability and Control of the F-15 Quiet Spike(TradeMark) Aircraft

The Quiet Spike F-15B flight research program investigated supersonic shock reduction using a 24-ft sub-scale telescoping nose boom on an F-15B airplane. The program primary flight test objective was to collect flight data for aerodynamic and structural models validation up to 1.8 Mach. Other objectives were to validate the mechanical feasibility of a morphing fuselage at the operational conditions and determine the near-field shock wave characterization. The stability and controls objectives were to assess the effect of the spike on the stability, controllability, and handling qualities of the aircraft and to ensure adequate stability margins across the entire research flight envelop. The two main stability and controls issues were the effects of the telescoping nose boom influenced aerodynamics on the F-15B aircraft flight dynamics and air data and angle of attack sensors. This paper reports on the stability and controls flight envelope clearance methods and flight test analysis of the F-15B Quiet Spike. Brief pilot commentary on typical piloting tasks, approach and landing, refueling task, and air data sensitivity to the flight control system are also discussed in this report.

Moua, Cheng M.↗

A data base and analysis program for shuttle main engine dynamic pressure measurements. Appendix C: Data base plots for SSME tests 902-214 through 902-314

A dynamic pressure data base and data base management system developed to characterize the Space Shuttle Main Engine (SSME) dynamic pressure environment is reported. The data base represents dynamic pressure measurements obtained during single engine hot firing tests of the SSME. Software is provided to permit statistical evaluation of selected measurements under specified operating conditions. An interpolation scheme is included to estimate spectral trends with SSME power level. Flow Dynamic Environments in High Performance Rocket Engines are described.

Coffin, T.↗

Implementation and flight tests for the Digital Integrated Automatic Landing System (DIALS). Part 2: Complete set of flight data

Five flight tests of the Digital Automated Landing System (DIALS) were conducted on the Advanced Transport Operating System (ATOPS) Transportation Research Vehicle (TSRV)--a modified Boeing 737 Aircraft for advanced controls and displays research. These flight tests were conducted at NASA's Wallops Flight Center using the Microwave Landing System (MLS) installation on Runway 22. This report is primarily a collection of data plots of all performance variables recorded for the entire five flight tests. A description and source of the performance variables is included. Performance variables include inertial data, air data, automatic control commands, control servo positions, sensor data, DIALS guidance and control parameters, and Kalman filter data. This data illustrates low overshoot captures of the localizer for intercept angles of 20 deg, 30 deg, 40 deg, and 50 deg intercept angles, and low overshoot captures of the glideslope slope for 3 deg, 4.5 deg, and 5 deg glideslopes. Flare maneuvers were successfully performed from the various glideslope angles and good decrab maneuvers were performed in crosswinds of 6 knots. In 18 to 20 knot crosswind conditions rudder limiting occurred which caused lateral drifting although heading alignment was achieved.

Hueschen, R. M.↗

Low-Speed Aerodynamic Data for an 0.18-Scale Model of an F-16XL with Various Leading-Edge Modifications

Using the F-16XL as a test-bed, two strategies for improving the low-speed flying characteristics that had minimal impact on high-speed performance were evaluated. In addition to the basic F-16XL configuration several modifications to the baseline configuration were tested in the Langley 30- X 60-Foot Tunnel: 1) the notched area at the wing leading edge and fuselage juncture was removed resulting in a continuous 70 deg leading-edge sweep on the inboard portion of the wing; 2) an integral attached-flow leading-edge flap concept was added to the continuous leading edge; and 3) a deployable vortex flap concept was added to the continuous leading edge. The purpose of this report is simply to document the test configurations, test conditions, and data obtained in this investigation for future reference and analysis. No analysis is presented herein and the data only appear in tabulated format.

Hahne, Daniel E.↗

Assessment of a 40-kilowatt stirling engine for underground mining applications

An assessment of alternative power souces for underground mining applications was performed. A 40-kW Stirling research engine was tested to evaluate its performance and emission characteristics when operated with helium working gas and diesel fuel. The engine, the test facility, and the test procedures are described. Performance and emission data for the engine operating with helium working gas and diesel fuel are reported and compared with data obtained with hydrogen working gas and unleaded gasoline fuel. Helium diesel test results are compared with the characteristics of current diesel engines and other Stirling engines. External surface temperature data are also presented. Emission and temperature results are compared with the Federal requirements for diesel underground mine engines. The durability potential of Stirling engines is discussed on the basis of the experience gaind during the engine tests.

Cairelli, J. E.↗

A Cloud Detection Neural Network for Above-Aircraft Clouds Using Airborne Cameras

We introduce a method convolutional neural networks to detect the presence of clouds in airborne camera images. We quantify the performance of this Cloud Detection Neural Network (CDNN) using human-labeled validation data where we report a 96% accuracy in detecting clouds in testing datasets for both Zenith- viewing and Forward-viewing models. We assess our performance by comparing the flight-averaged cloud fraction of zenith and forward CDNN retrievals, with that of the prototype hyperspectral total-diffuse Sunshine Pyranometer (SPN-S) instrument’s cloud optical depth data. Comparison of the CDNN with the SPN-S on time specific intervals resulted in 93% accuracy for the zenith- viewing CDNN and 84% for the forward- viewing CDNN. The comparison of the CDNNs with the SPN-S on flight-averaged cloud fraction resulted in an agreement of 0.15 for the Forward CDNN and 0.07 for the Zenith CDNN. We then quantify the ability of the CDNN to identify the presence of clouds above the aircraft using a forward- looking camera mounted inside the aircraft cockpit compared to the use of an All- Sky upward-looking camera that is mounted outside the fuselage on top of the aircraft. We present results from the CDNN based on airborne imagery from the NASA Aerosol Cloud Meteorology Interactions Over the Western Atlantic Experiment (ACTIVATE) and the Clouds, Aerosol and Monsoon Processes- Philippines Experiment (CAMP2Ex). For CAMP2Ex 53% of flight dates had above- aircraft cloud fraction above 50%, while for ACTIVATE 52% and 54% of flight dates observed above-aircraft cloud fraction above 50% for 2020 and 2021, respectively.

Joseph D Nied↗

Development and evaluation of an automatic labeling technique for spring small grains

A labeling technique is described which seeks to associate a sampling entity with a particular crop or crop group based on similarity of growing season and temporal-spectral patterns of development. Human analyst provide contextual information, after which labeling decisions are made automatically. Results of a test of the technique on a large, multi-year data set are reported. Grain labeling accuracies are similar to those achieved by human analysis techniques, while non-grain accuracies are lower. Recommendations for improvments and implications of the test results are discussed.

Crist, E. P.↗

Tensile Behavior and High-Cycle Fatigue Durability of a SiC/SiC Ceramic-Matrix Composite Without and With Simulated Cooling Holes

High-cycle fatigue (HCF) behavior of a melt-infiltrated, prepreg SiC/SiC composite was investigated using specimens without and with simulated cooling holes at 816 and 1,316 °C. The ceramic-matrix composite (CMC) material used for this study was fabricated by GE Aviation and had a ply configuration of [0/90/0] 3 . HCF tests were conducted with an R-ratio of 0.6 and a cyclic frequency of 30 Hz. Maximum tensile gross-section stresses used in the HCF tests ranged from 152 to 359 MPa. Runout in HCF was defined as 30 million cycles (278 h) at both temperatures. Monotonic tensile tests were conducted at room temperature (RT) on as-received CMC specimens and on HCF runout specimens without and with holes to determine residual tensile strengths. Digital image correlation (DIC) and acoustic emission (AE) techniques were used to monitor progression of damage in RT tensile tests on specimens without and with holes. Fractography was performed on a limited number of specimens without and with holes to determine morphology of fracture surfaces. Representative RT stress-strain behavior, elevated temperature HCF behavior at the two temperatures, and RT residual tensile strengths of HCF runout specimens are documented in this report. Select examples of DIC and AE data from RT tensile tests on specimens without and with holes and typical features observed on fracture surfaces of specimens tested under tensile and HCF conditions are also discussed.

Ceramic matrix composite↗

Analysis of Shockwave Radiation Data in Nitrogen

Data from a pure nitrogen test series in the Electric Arc Shock Tube Facility were previously reported for velocities spanning 6-12 km/s at a free-stream pressure of 0.2 Torr. This test series provides validation data for a range of physical phenomena to investigate, including vibrational relaxation, molecular radiation, nitrogen dissociation and ionization, and atomic radiation and ionization. This paper details analysis of data obtained at a nominal velocity of 10.3 km/s. The spectra are analyzed to extract temperatures and the densities of excited states as a function of position behind the shock. The effect of different methods for calculating state populations and ionization processes is assessed, as is a rigorous assessment of the atomic line lists, with both missing and extra lines identified.

Nitrogen↗

Evaluation of flat-plate collector efficiency under controlled conditions in a solar simulator

The measured thermal efficiencies of 35 collectors tested with a solar simulator, along with the correlation equations used to generalize the data, are presented in this report. The single correlation used is shown to apply to all the different types of collectors tested, including one with black paint and one cover, one with a selective surface coating and two covers, and an evacuated-tube collector. The test and correlation technique is also modified by using a shield so that collectors larger than the simulator test area can also be tested. This technique was verified experimentally for a shielded collector for which the collector shielded area was 31% of the solar simulator radiation area. A table lists all the collectors tested, the collector areas, and the experimental constants used to correlate the data for each collector.

Johnson, S. M.↗

Pressure Distribution Tests on a Series of Clark Y Biplane Cellules with Special Reference to Stability

The pressure distribution data discussed in this report represents the results of part of an investigation conducted on the factors affecting the aerodynamic safety of airplanes. The present tests were made on semispan, circular-tipped Clark Y airfoil models mounted in the conventional manner on a separation plane. Pressure readings were made simultaneously at all test orifices at each of 20 angles of attack between -8 degrees and +90 degrees. The results of the tests on each wing arrangement are compared on the bases of maximum normal force coefficient, lateral stability at a low rate of roll, and relative longitudinal stability. Tabular data are also presented giving the center of pressure location of each wing.

Noyes, Richard W↗

Correlation of Chemical and Physical Test Data for the Environmental Ageing of Tefzel (ETFE)

In a similar approach to that used for the previously issued correlation report for Coflon (CAPP/M.10), this report aims to identify any correlations between mechanical property changes and chemical/morphological changes for Tefzel, using information supplied in other MERL and TRI project reports. Differences identified with Coflon behaviour will be of scientific interest as well as appropriate to project applications, as Tefzel and Coflon are chemical isomers. Owing to the considerable chemical resistance of Tefzel, much of its testing so far has been based on mechanical properties. Where changes have occurred, chemical analysis can now be targeted more effectively. Relevant test data collated here include: tensile modulus and related properties, permeation coefficients, % crystallinity, some crack growth resistance measurements, and other observations where significant. Fluids based on methanol and amine (Fluid G), a mixture of methane, carbon dioxide and hydrogen sulphide gases plus an aqueous amine solution (Fluid F), and an aromatic oil mix of heptane, cyclohexane, toluene and 1-propanol (Fluid I) have affected Tefzel to varying degrees, and are discussed in some detail herein.

Morgan, G. J.↗