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- WEB-BASED INSTRUCTION AND LEARNING: RESPONDING TO K-14 CUSTOMER NEEDS , Conference Publication
Authors: Marianne McCarthy , Barbara Grabowski , Tiffany Koszalka and Christa Peck
Report Number: NASA-CP-2003-210722
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: A follow-up working conference was held at Lewis Research Center (now Glenn Research Center) on September 23–25, 1997 to continue discussing issues related to the development of Web-based education materials for the K-14 community. The conference continued the collaboration among the NASA aerospace technology Centers (Ames, Dryden, Langley, and Lewis), NASA Headquarters, the University of Idaho and the Pennsylvania State University. The conference consisted of presentations by the Aeronautics Cooperative Agreement teams, and working sessions that addressed issues identified the most significant issues by consensus. The issues addressed were: classroom access, World Wide Web resources, teacher training, different teaching and learning styles, interactivity, and education standards. The working sessions produced observations and recommendations in each of these areas in order to work toward the goal of making NASA sponsored Web-based educational
resources useful to teachers and students.
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Subject Category: 81
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Report Date: December 2003
No. Pages: 142
Funding Organization: 332-41-00-MI-00-TT-1-00S-000
Keywords: Education; Educational technology; World Wide Web; Classroom access to technology; Teacher training; Aerospace education curricula; Pedagogy; Education standards
Notes: Proceedings of the September Learning Technologies Conference, Lewis Research Center, Cleveland, Ohio, September 23–25, 1997. Marianne McCarthy, NASA Dryden Flight Research Center; Barbara Grabowski, Tiffany Koszalka, and Christa Peck, Pennsylvania State University, University Park, Pennsylvania.
- F/A-18 PERFORMANCE BENEFITS MEASURED DURING THE AUTONOMOUS FORMATION FLIGHT PROJECT , Technical Memorandum
Authors: M. Jake Vachon , Ronald J. Ray , Kevin R. Walsh and Kimberly Ennix
Report Number: NASA-TM-2003-210734
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: The Autonomous Formation Flight (AFF) project at the NASA Dryden Flight Research Center (Edwards, California) investigated performance benefits resulting from formation flight, such as reduced aerodynamic drag and fuel consumption. To obtain data on performance benefits, a trailing F/A-18 airplane flew within the wingtip-shed vortex of a leading F/A-18 airplane. The pilot of the trail airplane used advanced station-keeping technology to aid in positioning the trail airplane at precise locations behind the lead airplane. The specially instrumented trail airplane was able to obtain accurate fuel flow measurements and to calculate engine thrust and vehicle drag. A maneuver technique developed for this test provided a direct comparison of performance values while flying in and out of the vortex. Based on performance within the vortex as a function of changes in vertical, lateral, and longitudinal positioning, these tests explored design-drivers for
autonomous station-keeping control systems. Observations showed significant performance improvements over a large range of trail positions tested. Calculations revealed maximum drag reductions of over 20 percent, and demonstrated maximum reductions in fuel flow of just over 18 percent.
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Subject Category: 05
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Report Date: September 2003
No. Pages: 35
Funding Organization: 706 35 00 E8 28 00 AFF
Keywords: Drag reduction; Flight test techniques; Formation flight; Fuel reduction; Performance
Notes: Presented at the AIAA Atmospheric Flight Mechanics Conference, Monterey, California, August 5–8, 2002.
- GROUND-EFFECT CHARACTERISTICS OF THE TU-144 SUPERSONIC TRANSPORT AIRPLANE , Technical Memorandum
Authors: Robert E. Curry and Lewis R. Owens
Report Number: NASA-TM-2003-212035
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: Ground-effect characteristics of the Tu-144 supersonic transport airplane have been obtained from flight and ground-based experiments to improve understanding of ground-effect phenomena for this class of vehicle. The flight test program included both dynamic measurements obtained during descending flight maneuvers and steady-state measurements obtained during level pass maneuvers over the runway. Both dynamic and steady-state wind-tunnel test data have been acquired for a simple planform model of the Tu-144 using a developmental model support system in the NASA Langley Research Center 14- by 22-ft Subsonic Wind Tunnel. Data from steady-state, full-configuration wind-tunnel tests of the Tu-144 are also presented. Results from the experimental methods are compared with results from simple computational methods (panel theory). A power law relationship has been shown to effectively fit the variation of lift with height above ground for all data sets.
The combined data sets have been used to evaluate the test techniques and assess the sensitivity of ground effect to various parameters. Configuration details such as the fuselage, landing gear, canards, and engine flows have had little effect on the correlation between the various data sets. No distinct trend has been identified as a function of either flightpath angle or rate of descent.
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Subject Category: 02
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Report Date: October 2003
No. Pages: 41
Funding Organization: 710-55-04-E8-RR-00-000
Keywords: Aerodynamics; Flight test; Ground effect; Supersonic transport; Tu-144
- ENGINE DAMAGE TO A NASA DC-8-72 AIRPLANE FROM A HIGH-ALTITUDE ENCOUNTER WITH A DIFFUSE VOLCANIC ASH CLOUD , Technical Memorandum
Authors: Thomas J. Grindle and Frank W. Burcham, Jr.
Report Number: NASA-TM-2003-212030
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: The National Aeronautics and Space Administration (NASA) DC-8 airborne sciences research airplane inadvertently flew through a diffuse volcanic ash cloud of the Mt. Hekla volcano in February 2000 during a flight from Edwards Air Force Base (Edwards, California) to Kiruna, Sweden. Although the ash plume was not visible to the flight crew, sensitive research experiments and instruments detected it. In-flight performance checks and postflight visual inspections revealed no damage to the airplane or engine first-stage fan blades; subsequent detailed examination of the engines revealed clogged turbine cooling air passages. The engines were removed and overhauled. This paper presents volcanic ash plume analysis, trajectory from satellites, analysis of ash particles collected in cabin air heat exchanger filters and removed from the engines, and data from onboard instruments and engine conditions.
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Subject Category: 03
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Report Date: August 2003
No. Pages: 27
Funding Organization: 436-14-01-E8-YY-00-DC8
Keywords: Aircraft; Ash; Safety; Turbine; Volcanic
- EVALUATION OF TWO UNIQUE SIDE STICK CONTROLLERS IN A FIXED-BASE FLIGHT SIMULATOR , Technical Memorandum
Authors: Jann Mayer and Timothy H. Cox
Report Number: NASA-TM-2003-212042
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: A handling qualities analysis has been performed on two unique side stick controllers in a fixed-base F-18 flight simulator. Each stick, which uses a larger range of motion than is common for similar controllers, has a moving elbow cup that accommodates movement of the entire arm for control. The sticks are compared to the standard center stick in several typical fighter aircraft tasks. Several trends are visible in the time histories, pilot ratings, and pilot comments. The aggressive pilots preferred the center stick, because the side sticks are underdamped, causing overshoots and oscillations when large motions are executed. The less aggressive pilots preferred the side sticks, because of the smooth motion and low breakout forces. The aggressive pilots collectively gave the worst ratings, probably because of increased sensitivity of the simulator (compared to the actual F-18 aircraft), which can cause pilot-induced oscillations when aggressive
inputs are made. Overall, the elbow cup is not a positive feature, because using the entire arm for control inhibits precision. Pilots had difficulty measuring their performance, particularly during the offset landing task, and tended to overestimate.
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Subject Category: 08
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Report Date: December 2003
No. Pages: 55
Funding Organization: 710-55-24-E8-RR-00-DFR
Keywords: Cooper-Harper Rating; Dynamic Controls, Inc.; Ergonomics; Flying qualities; Handling qualities; Side stick controller
- AGING THEORIES FOR ESTABLISHING SAFE LIFE SPANS OF AIRBORNE CRITICAL STRUCTURAL COMPONENTS , Technical Publication
Authors: William L. Ko
Report Number: NASA-TP-2003-212034
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: New aging theories have been developed to establish the safe life span of airborne critical structural components such as B-52B aircraft pylon hooks for carrying air- launch drop-test vehicles. The new aging theories use the “equivalent-constant- amplitude loading spectrum” to represent the actual random loading spectrum with the same damaging effect. The crack growth due to random loading cycling of the first flight is calculated using the half-cycle theory, and then extrapolated to all the crack growths of the subsequent flights. The predictions of the new aging theories (finite difference aging theory and closed-form aging theory) are compared with the classical flight-test life theory and the previously developed Ko first- and Ko second-order aging theories. The new aging theories predict the number of safe flights as considerably lower than that predicted by the classical aging theory, and slightly lower than those predicted by the
Ko first- and Ko second-order aging theories due to the inclusion of all the higher order terms.
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Subject Category: 39
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Report Date: December 2003
No. Pages: 40
Funding Organization: 745-30-54-SE-35-00-52B
Keywords: Closed-form aging theory; Discrete aging theory; Equivalent constant stress cycle; Half cycle theory; Number of safe flights
Notes: Errata added April 1, 2004, corrects an error in table 2, page 14.
- EXPERIMENTAL EVALUATION OF HOT FILMS ON CERAMIC SUBSTRATES FOR SKIN-FRICTION MEASUREMENT , Technical Memorandum
Authors: Gregory K. Noffz, Adrienne S. Lavine, and Philip J. Hamory
Report Number: NASA-TM-2003-210742
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: An investigation has been performed on the use of low-thermal conductivity, ceramic substrates for hot films intended to measure skin friction. Hot films were deposited on two types of ceramic substrates. Four hot films used composite- ceramic substrates with subsurface thermocouples (TCs), and two hot films were deposited on thin Macor (registered trademark) substrates. All six sensors were tested side by side in the wall of the NASA Glenn Research Center 8-ft by 6-ft Supersonic Wind Tunnel (SWT). Data were obtained from zero flow to Mach 1.98 in air. Control measurements were made with three Preston tubes and two boundary- layer rakes. The tests were repeated at two different hot film power levels. All hot films and subsurface TCs functioned throughout the three days of testing. At zero flow, the films on the high-thermal conductivity Macor (registered trademark) substrates required approximately twice the power as those on the composite- ceramic
substrates. Skin-friction results were consistent with the control measurements. Estimates of the conduction heat losses were made using the embedded TCs but were hampered by variability in coating thicknesses and TC locations.
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Subject Category: 34
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Report Date: March 2003
No. Pages: 24
Funding Organization: 710 55 04 SE RR 00 FTT
Keywords: Ceramic substrates; Hot film; Hot film calibration; Hot film substrates; Skin friction
Notes: Also presented at the 6th ASME-JSME Thermal Engineering Joint Conference, Hawaii Island, Hawaii, March 16-20, 2003.
- IN-FLIGHT CAPABILITY FOR EVALUATING SKIN-FRICTION GAGES AND OTHER NEAR-WALL FLOW SENSORS , Technical Memorandum
Authors: Trong T. Bui, Brett J. Pipitone and Keith L. Krake
Report Number: NASA-TM-2003-210738
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: An 8-in.-square boundary-layer sensor panel has been developed for in-flight evaluation of skin-friction gages and other near-wall flow sensors on the NASA Dryden Flight Research Center F-15B/Flight Test Fixture (FTF). Instrumentation on the sensor panel includes a boundary-layer rake, temperature sensors, static pressure taps, and a Preston tube. Space is also available for skin-friction gages or other near-wall flow sensors. Pretest analysis of previous F-15B/FTF flight data has identified flight conditions suitable for evaluating skin-friction gages. At subsonic Mach numbers, the boundary layer over the sensor panel closely approximates the two-dimensional (2D), law-of-the-wall turbulent boundary layer, and skin-friction estimates from the Preston tube and the rake (using the Clauser plot method) can be used to evaluate skin-friction gages. At supersonic Mach numbers, the boundary layer over the sensor panel becomes complex, and other means of
measuring skin friction are needed to evaluate the accuracy of new skin-friction gages. Results from the flight test of a new rubber-damped skin-friction gage confirm that at subsonic Mach numbers, nearly 2D, law-of-the-wall turbulent boundary layers exist over the sensor panel. Sensor panel data also show that this new skin-friction gage prototype does not work in flight.
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Subject Category: 34
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Report Date: February 2003
No. Pages: 30
Funding Organization: 710-55-04-RR-00-000
Keywords: Boundary layer; Flight test; Flow sensors; F-15B; Skin friction
Notes: Presented at the 41st AIAA Aerospace Sciences Meeting and Exhibit, Jan. 6-9, 2003, Reno NV as AIAA-2003-0741
- EXPLORATORY CALIBRATION OF ADJUSTABLE-PROTRUSION SURFACE-OBSTACLE (APSO) SKIN FRICTION VECTOR GAGE , Technical Memorandum
Authors: Raimo J. Hakkinen , Jeremy S. Neubauer , Philip J. Hamory , Trong T. Bui and Gregory K. Noffz
Report Number: NASA-TM-2003-210739
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: The design of an adjustable-protrusion surface-obstacle (APSO) skin friction vector gage is presented. Results from exploratory calibrations conducted in laminar and turbulent boundary layers at the Washington University Low-Speed Wind Tunnel and for turbulent boundary layers at speeds up to Mach 2 on the ceiling of the NASA Glenn Research Center 8- X 6-ft Supersonic Wind Tunnel are also discussed. The adjustable-height gage was designed to yield both the magnitude and direction of the surface shear stress vector and to measure the local static pressure distribution. Results from the NASA test show good correlation for subsonic and low supersonic conditions covering several orders of magnitude in terms of the adopted similarity variables. Recommendations for future work in this area consist of identifying the physical parameters responsible for the disagreement between the university and NASA data sets, developing a compressibility correction
specific to the APSO geometry, and examining the effect that static pressure distribution and skewed boundary layers have on the results from the APSO.
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Subject Category: 35
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Report Date: February 2003
No. Pages: 25
Funding Organization: WU 710-55-24-SE-RR-00-DFR
Keywords: skin friction; friction measurement; shear stress; stress measurement; boundary layer; Preston tube; pressure measurement; calibrating; wind tunnel tests
Notes: Also presented at 41st AIAA Aerospace Sciences Meeting and Exhibit, Reno, NV, January 6-9, 2003, AIAA-2003-0740.
- THE ACTIVE AEROELASTIC WING PHASE I FLIGHT RESEARCH THROUGH JANUARY 2003 , Technical Memorandum
Authors: David Voracek, Ed Pendleton, Dr. Kenneth Griffin, Eric Reichenbach and Leslie Welch
Report Number: NASA-TM-2003-210741
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: This report describes the technical content of the Active Aeroelastic Wing (AAW) Flight Research Program and discusses the analytical development, aircraft test bed modifications, ground test results, and flight research results through January 2003. The goals of the AAW Flight Research Program are to demonstrate, in full scale, AAW technology, and to measure the aerodynamic, structural, and flight control characteristics associated with the AAW aircraft. Design guidance, derived from the results of this benchmark flight program, will be provided for implementation on future aircraft designs.
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Subject Category: 05
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Report Date: April 2003
No. Pages: 24
Funding Organization: 710 61 14 SE 14 00 AAW
Keywords: Active aeroelastic wing; Aeroelasticity; Flight research; Morphing; Structures
Notes: Presented at the Applied Vehicle Technology Panel (AVT), Symposium on 'Novel and Emerging Vehicle and Vehicle Technology Concepts,' Brussels, Belgium, April 7-9, 2003, AVT-99/RYS-014.
- A FUZZY TECHNIQUE FOR PERFORMING LATERAL-AXIS FORMATION FLIGHT NAVIGATION USING WINGTIP VORTICES , Technical Memorandum
Authors: Curtis E. Hanson
Report Number: NASA-TM-2003-212033
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: Close formation flight involving aerodynamic coupling through wingtip vortices shows significant promise to improve the efficiency of cooperative aircraft operations. Impediments to the application of this technology include intership communication required to establish precise relative positioning. This report proposes a method for estimating the lateral relative position between two aircraft in close formation flight through real-time estimates of the aerodynamic effects imparted by the leading airplane on the trailing airplane. A fuzzy algorithm is developed to map combinations of vortex-induced drag and roll effects to relative lateral spacing. The algorithm is refined using self-tuning techniques to provide lateral relative position estimates accurate to 14 in., well within the requirement to maintain significant levels of drag reduction. The fuzzy navigation algorithm is integrated with a leader-follower formation flight autopilot in a
two-ship F/A-18 simulation with no intership communication modeled. It is shown that in the absence of measurements from the leading airplane the algorithm provides sufficient estimation of lateral formation spacing for the autopilot to maintain stable formation flight within the vortex. Formation autopilot trim commands are used to estimate vortex effects for the algorithm. The fuzzy algorithm is shown to operate satisfactorily with anticipated levels of input uncertainties.
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Subject Category: 08
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Report Date: September 2003
No. Pages: 32
Funding Organization: 710-35-14-SE-45-00-AAR
Keywords: Automatic pilot; Drag reduction; Formation flying; Fuzzy system; Wingtip vortex
- AEROSERVOELASTIC MODEL VALIDATION AND TEST DATA ANALYSIS OF THE F/A-18 ACTIVE AEROELASTIC WING , Technical Memorandum
Authors: Martin J. Brenner and Richard J. Prazenica
Report Number: NASA-TM-2003-212021
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: Model validation and flight test data analysis require careful consideration of the effects of uncertainty, noise, and nonlinearity. Uncertainty prevails in the data analysis techniques and results in a composite model uncertainty from unmodeled dynamics, assumptions and mechanics of the estimation procedures, noise, and nonlinearity. A fundamental requirement for reliable and robust model development is an attempt to account for each of these sources of error, in particular, for model validation, robust stability prediction, and flight control system development. This paper is concerned with data processing procedures for uncertainty reduction in model validation for stability estimation and nonlinear identification. F/A-18 Active Aeroelastic Wing (AAW) aircraft data is used to demonstrate signal representation effects on uncertain model development, stability estimation, and nonlinear identification. Data is decomposed using adaptive orthonormal
best-basis and wavelet-basis signal decompositions for signal denoising into linear and nonlinear identification algorithms. Nonlinear identification from a wavelet-based Volterra kernel procedure is used to extract nonlinear dynamics from aeroelastic responses, and to assist model development and uncertainty reduction for model validation and stability prediction by removing a class of nonlinearity from the uncertainty.
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Subject Category: 08
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Report Date: April 2003
No. Pages: 20
Funding Organization: 710 61 14 SE 14 00 AAW
Keywords: Aeroservoelasticity; Local trigonometric basis; Morlet wavelet; Multiwavelet-based Volterra kernel identification; Robust minimax estimation
Notes: Also presented at the CEAS/AIAA/NVvL International Forum on Aeroelasticity and Structural Dynamics 6/4/03 to 6/6/03, Amsterdam, The Netherlands. Author edited.
- ASYMPTOTIC DISTRIBUTION OF EIGENFREQUENCIES FOR A COUPLED EULER-BERNOULLI AND TIMOSHENKO BEAM MODEL , Contractor Report
Authors: Marianna A. Shubov and Cheryl A. Peterson
Report Number: NASA-CR-2003-212022
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: This research is devoted to the asymptotic and spectral analysis of a coupled Euler- Bernoulli and Timoshenko beam model. The model is governed by a system of two coupled differential equations and a two parameter family of boundary conditions modeling the action of self-straining actuators. The aforementioned equations of motion together with a two-parameter family of boundary conditions form a coupled linear hyperbolic system, which is equivalent to a single operator evolution equation in the energy space. That equation defines a semigroup of bounded operators. The dynamics generator of the semigroup is our main object of interest. For eash set of boundary parameters, the dynamics generator has a compact inverse. If both boundary parameters are not purely imaginary numbers, then the dynamics generator is a nonselfadjoint operator in the energy space. We calculate the spectral asymptotics of the dynamics generator. We find that the spectrum lies in
a strip parallel to the horizontal axis, and is asymptotically close to the horizontal axis - thus the system is stable, but is not uniformly stable.
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Subject Category: 02, 59, 66
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Report Date: November 2003
No. Pages: 78
Funding Organization: UCLA Grant Number NCC4-121
Keywords: Aeroelastic mode; Bending-torsion vibration model; Integro-differential equations; Reflection matrix; Theodorsen function
Notes: UCLA Grant Number NCC4-121; NASA Technical Monitor Kenneth W. Iliff, NASA Dryden Flight Research Center. Other contributors were the National Science Foundation (Division of Mathematical Science and Division of Engineering Sciences), the Advanced Research Program-2002 of Texas, and partial support by two NASA/Texas Space Grant Consortium Fellowships.
- LAUNCH CONDITION DEVIATIONS OF REUSABLE LAUNCH VEHICLE SIMULATIONS IN EXO-ATMOSPHERIC ZOOM CLIMBS , Technical Memorandum
Authors: Peter H. Urschel and Timothy H. Cox
Report Number: NASA-TM-2003-212023
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: The Defense Advanced Research Projects Agency has proposed a two-stage system to deliver a small payload to orbit. The proposal calls for an airplane to perform an exo-atmospheric zoom climb maneuver, from which a second-stage rocket is launched carrying the payload into orbit. The NASA Dryden Flight Research Center has conducted an in-house generic simulation study to determine how accurately a human-piloted airplane can deliver a second-stage rocket to a desired exo-atmospheric launch condition. A high-performance, fighter-type, fixed- base, real-time, pilot-in-the-loop airplane simulation has been modified to perform exo-atmospheric zoom climb maneuvers. Four research pilots tracked a reference trajectory in the presence of winds, initial offsets, and degraded engine thrust to a second-stage launch condition. These launch conditions have been compared to the reference launch condition to characterize the expected deviation. At each launch
condition, a speed change was applied to the second-stage rocket to insert the payload onto a transfer orbit to the desired operational orbit. The most sensitive of the test cases was the degraded thrust case, yielding second-stage launch energies that were too low to achieve the radius of the desired operational orbit. The handling qualities of the airplane, as a first-stage vehicle, have also been investigated.
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Subject Category: 15
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Report Date: September 2003
No. Pages: 38
Funding Organization: 710-85-14-SE-47-00-DVI
Keywords: Exo-atmospheric zoom climb maneuver; Expendable launch vehicle; Pilot-in-the-loop simulation; Reusable launch vehicle; Transfer orbit
Notes: Also presented at the AIAA Atmospheric Flight Mechanics Conference and Exhibit, Aug. 11–14, 2003, Austin, TX.
- WEB-ENHANCED INSTRUCTION AND LEARNING: FINDINGS OF A SHORT- AND LONG-TERM IMPACT STUDY AND TEACHER USE OF NASA WEB RESOURCES , Technical Publication
Authors: Marianne C. McCarthy , Barbara L. Grabowski and Tiffany Koszalka
Report Number: NASA-TP-2003-212038
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: Over a three-year period, researchers and educators from the Pennsylvania State University (PSU), University Park, Pennsylvania, and the NASA Dryden Flight Research Center (DFRC), Edwards, California, worked together to analyze, develop, implement and evaluate materials and tools that enable teachers to use NASA Web resources effectively for teaching science, mathematics, technology and geography. Two conference publications and one technical paper have already been published as part of this educational research series on Web-based instruction and learning. This technical paper, “Web-Enhanced Instruction and Learning: Findings of a Short- and Long-Term Impact Study,” is the culminating report in this educational research series and is based on the final report submitted to NASA. This report describes the broad spectrum of data gathered from teachers about their experiences using NASA Web resources in the classroom. It also describes
participating teachers’ responses and feedback about the use of the NASA Web-Enhanced Learning Environment Strategies reflection tool on their teaching practices. The reflection tool was designed to help teachers merge the vast array of NASA resources with the best teaching methods, taking into consideration grade levels, subject areas and teaching preferences. The teachers described their attitudes toward technology and innovation in the classroom and their experiences and perceptions as they attempted to integrate Web resources into science, mathematics, technology and geography instruction.
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Subject Category: 81
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Report Date: October 2003
No. Pages: 52
Funding Organization: 332-41-00-* *-NN-00-000
Keywords: Education; Educational technology; Learning technology; Teacher training; World Wide Web
- EVALUATION OF THE X-43A SCRAMJET ENGINE CONTROLLER PEFORMANCE BY MONTE CARLO TECHNIQUE , Technical Memorandum
Authors: Thomas P. Jones and Ethan Baumann
Report Number: NASA-TM-2003-212036
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: A Monte Carlo analysis has been conducted to evaluate the performance of the scramjet engine controller for the X-43A. The Propulsion System Controller (PSC) logic was evaluated to assess the effectiveness of a proposed unstart protection algorithm with regard to preventing engine unstarts and achieving vehicle performance goals. The Monte Carlo data obtained from a high fidelity simulation predicts that utilizing the unstart protection logic significantly reduces the risk of unstart by keeping the isolator margin at or above its desired value. The results also show that the unstart protection algorithm does not significantly reduce the probability of meeting the project’s primary acceleration goal, thus justifying its suitability for use within the X-43A PSC.
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Subject Category: 07
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Report Date: October 2003
No. Pages: 21
Funding Organization: 745-30-54-SE-50-00-43A
Keywords: Engine control; Monte Carlo; Scramjet; Unstart; X-43
Notes: Presented at the AIAA/ASME/SAE/ASEE Joint Propulsion Conference, July 20–23, 2003, Huntsville, Alabama, AIAA 2003-5192.
- REAL-TIME STABILITY AND CONTROL DERIVATIVE EXTRACTION FROM F-15 FLIGHT DATA , Technical Memorandum
Authors: Mark S. Smith , Timothy R. Moes and Eugene A. Morelli
Report Number: NASA-TM-2003-212027
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: A real-time, frequency-domain, equation-error parameter identification (PID) technique was used to estimate stability and control derivatives from flight data. This technique is being studied to support adaptive control system concepts currently being developed by NASA (National Aeronautics and Space Administration), academia, and industry. This report describes the basic real-time algorithm used for this study and implementation issues for onboard usage as part of an indirect-adaptive control system. A confidence measures system for automated evaluation of PID results is discussed. Results calculated using flight data from a modified F-15 aircraft are presented. Test maneuvers included pilot- input doublets and automated inputs at several flight conditions. Estimated derivatives are compared to aerodynamic model predictions. Data indicate that the real-time PID used for this study performs well enough to be used for onboard parameter estimation.
For suitable test inputs, the parameter estimates converged rapidly to sufficient levels of accuracy. The devised confidence measures used were moderately successful.
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Subject Category: 08
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Report Date: September 2003
No. Pages: 35
Funding Organization: 745-20-00-SE-40-00-IFS
Keywords: F-15; Frequency domain; Parameter identification; Real-time; Stability and control derivatives
Notes: Presented at the AIAA Atmospheric Flight Mechanics Conference, Austin, Texas, August11–14, 2003, AIAA-2003-5701.
- INTEGRATION OF ONLINE PARAMETER IDENTIFICATION AND NEURAL NETWORK FOR IN-FLIGHT ADAPTIVE CONTROL , Technical Memorandum
Authors: Jacob J. Hageman , Mark S. Smith and Susan Stachowiak
Report Number: NASA-TM-2003-212028
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: An indirect adaptive system has been constructed for robust control of an aircraft with uncertain aerodynamic characteristics. This system consists of a multilayer perceptron pre-trained neural network, online stability and control derivative identification, a dynamic cell structure online learning neural network, and a model following control system based on the stochastic optimal feedforward and feedback technique. The pre-trained neural network and model following control system have been flight-tested, but the online parameter identification and online learning neural network are new additions used for in-flight adaptation of the control system model. A description of the modification and integration of these two stand-alone software packages into the complete system in preparation for initial flight tests is presented. Open-loop results using both simulation and flight data, as well as closed-loop performance of the complete system in a
nonlinear, six-degree-of- freedom, flight validated simulation, are analyzed. Results show that this online learning system, in contrast to the nonlearning system, has the ability to adapt to changes in aerodynamic characteristics in a real-time, closed-loop, piloted simulation, resulting in improved flying qualities.
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Subject Category: 08
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Report Date: October 2003
No. Pages: 22
Funding Organization: 745-20-00-SE-40-00-IFS
Keywords: F-15 Aircraft; Indirect Adaptive Control; Intelligent Flight Control System; Neural Network; Parameter Identification
Notes: Also presented at the AIAA Atmospheric Flight Mechanics Conference, Austin Texas, Aug. 11–14, 2003. AIAA-2003-5700
- FLIGHT INVESTIGATION OF PRESCRIBED SIMULTANEOUS INDEPENDENT SURFACE EXCITATIONS FOR REAL-TIME PARAMETER IDENTIFICATION , Technical Memorandum
Authors: Timothy R. Moes , Mark S. Smith and Eugene A. Morelli
Report Number: NASA-TM-2003-212029
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: Near real-time stability and control derivative extraction is required to support flight demonstration of Intelligent Flight Control System (IFCS) concepts being developed by NASA, academia, and industry. Traditionally, flight maneuvers would be designed and flown to obtain stability and control derivative estimates using a postflight analysis technique. The goal of the IFCS concept is to be able to modify the control laws in real time for an aircraft that has been damaged in flight. In some IFCS implementations, real-time parameter identification (PID) of the stability and control derivatives of the damaged aircraft is necessary for successfully reconfiguring the control system. This report investigates the usefulness of Prescribed Simultaneous Independent Surface Excitations (PreSISE) to provide data for rapidly obtaining estimates of the stability and control derivatives. Flight test data were analyzed using both equation-error and output-error
PID techniques. The equation-error PID technique is known as Fourier Transform Regression (FTR) and is a frequency-domain real-time implementation. Selected results were compared with a time-domain output-error technique. The real-time equation-error technique combined with the PreSISE maneuvers provided excellent derivative estimation in the longitudinal axis. However, the PreSISE maneuvers as presently defined were not adequate for accurate estimation of the lateral-directional derivatives.
Distribution/Availability: Unclassified - Unlimited
Subject Category: 08
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Report Date: October 2003
No. Pages: 36
Funding Organization: 745-20-00-SE-40-00-IFS
Keywords: Equation error; Intelligent flight control; Output error; Parameter identification; Stability and control derivatives
Notes: Also presented at the AIAA Atmospheric Flight Mechanics Conference and Exhibit, Austin, Texas, August 11–14, 2003.
- A POWERFUL FRIENDSHIP: THEODORE VON KÁRMÁN AND HUGH L. DRYDEN , Technical Memorandum
Authors: Michael Gorn
Report Number: NASA-TM-2003-212031
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: During their long personal friendship and professional association, Theodore von Karman (1882-1963) and Hugh L. Dryden (1898-1965) exercised a pivotal if somewhat elusive influence over American aeronautics and spaceflight. Both decisive figures in organizing scientists and engineers at home and abroad, both men of undisputed eminence in their technical fields, their range of contacts in government, academia, the armed forces, industry, and professional societies spanned the globe to an extent unparalleled then as now. Moreover, because they coordinated their activities closely, their combined influence far exceeded the sum of each one’s individual contributions. This paper illustrates their personal origins as well as the foundations of their friendship, how their relationship became a professional alliance, and their joint impact on the world of aeronautics and astronautics during the twentieth century.
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Report Date: September 2003
No. Pages: 15
Funding Organization: 953-20-00-GA-TT-00-000
Keywords: Aeronautical history; Hugh L. Dryden; National Advisory Committee for Aeronautics (the NACA); Science advising; Theodore von Kármán
Notes: Presented at the 41st AIAA Aerospace Sciences Meeting Exhibit, Reno, Nevada, January 6-9, 2003, AIAA-2003-0289.
- MODELING AIRCRAFT WING LOADS FROM FLIGHT DATA USING NEURAL NETWORKS , Technical Memorandum
Authors: Michael J. Allen and Ryan P. Dibley
Report Number: NASA-TM-2003-212032
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: Neural networks were used to model wing bending-moment loads, torsion loads, and control surface hinge-moments of the Active Aeroelastic Wing (AAW) aircraft. Accurate loads models are required for the development of control laws designed to increase roll performance through wing twist while not exceeding load limits. Inputs to the model include aircraft rates, accelerations, and control surface positions. Neural networks were chosen to model aircraft loads because they can account for uncharacterized nonlinear effects while retaining the capability to generalize. The accuracy of the neural network models was improved by first developing linear loads models to use as starting points for network training. Neural networks were then trained with flight data for rolls, loaded reversals, wind- up-turns, and individual control surface doublets for load excitation. Generalization was improved by using gain weighting and early stopping. Results are presented
for neural network loads models of four wing loads and four control surface hinge moments at Mach 0.90 and an altitude of 15,000 ft. An average model prediction error reduction of 18.6 percent was calculated for the neural network models when compared to the linear models. This paper documents the input data conditioning, input parameter selection, structure, training, and validation of the neural network models.
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Subject Category: 05
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Report Date: September 2003
No. Pages: 19
Funding Organization: 710 61 14 SE 14 00 AAW
Keywords: Aeroelastic research wings; F-18 aircraft; Flight simulation; Loads (forces); Neural nets
Notes: Also presented at the SAE World Aviation Congress, Montreal, Quebec, Canada, September 11, 2003
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