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  1. ANALOG SIGNAL CONDITIONING FOR FLIGHT-TEST INSTRUMENTATION , Reference Publication
    Authors: Donald W. Veatch and Rodney K. Bogue
    Report Number: NASA-RP-1159
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The application of analog signal conditioning to flight-tests data acquisition systems is discussed. Emphasis is placed on practical applications of signal conditioning for the most common flight-test data-acquisition systems. A limited amount of theoretical discussion is included to assist the reader in a more complete understanding of the subject matter. Nonspecific signal conditioning, such as amplification, filtering, and multiplexing, is discussed. Signal conditioning for various specific transducers and data terminal devices is also discussed to illustrate signal conditioning that is unique to particular types of transducers. The purpose is to delineate for the reader the various signal-conditioning technique options, together with tradeoff considerations, for commonly encountered flight-test situations.
    Distribution/Availability: Unclassified - Unlimited
    Subject Category: 06
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    Report Date: January 1986
    No. Pages: 173
    Keywords:      Analog data; Data acquisition; Flight tests; Signal processing; Transducers
    Notes: Presented at the AGARD Flight Mechanics Panel, Flight-test Techniques Working Group, AGARDograph 160, Flight-Test Instrumentation Series.


  2. EFFECTS OF WINGLETS ON A FIRST-GENERATION JET TRANSPORT WING. 7: SIDESLIP EFFECTS ON WINGLET LOADS AND SELECTED WING LOADS AT SUBSONIC SPEEDS FOR A FULL-SPAN MODEL , Technical Paper
    Authors: Robert R. Meyer, Jr. and Peter F. Covell
    Report Number: NASA-TP-2619
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The effect of sideslip on winglet loads and selected wing loads was investigated at high and low subsonic Mach numbers. The investigation was conducted in two separate wind tunnel facilities, using two slightly different 0.035-scale full-span models. Results are presented which indicate that, in general, winglet loads as a result of sideslip are analogous to wing loads caused by angle of attack. The center-of-pressure locations on the winglets are somewhat different than might be expected for an analogous wing. The spanwise center of pressure for a winglet tends to be more inboard than for a wing. The most notable chordwise location is a forward center-of-pressure location on the winglet at high sideslip angles. The noted differences between a winglet and an analogous wing are the result of the influence of the wing on the winglet.
    Distribution/Availability: Unclassified - Unlimited
    Subject Category: 02
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    Report Date: September 1986
    No. Pages: 60
    Keywords:      Sideslip; Subsonic speed; Wind tunnel models; Winglets; Angle of attack; Mach number; Pressure distribution; Wing loading


  3. COMPARISON OF PILOT EFFECTIVE TIME DELAY FOR COCKPIT CONTROLLERS USED ON SPACE SHUTTLE AND CONVENTIONAL AIRCRAFT , Technical Memorandum
    Authors: C. M. Privoznik and D. T. Berry
    Report Number: NASA-TM-86030
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: A study was conducted at the Dryden Flight Research Facility of NASA Ames Research Center (Ames-Dryden) to compare pilot effective time delay for the space shuttle rotational hand controller with that for conventional stick controllers. The space shuttle controller has three degrees of freedom and nonlinear gearing. The conventional stick has two degrees of freedom and linear gearing. Two spring constants were used, allowing the conventional stick to be evaluated in both a light and a heavy configuration. Pilot effective time delay was obtained separately for pitch and roll through first-order, closed-loop, compensatory tracking tasks. The tasks were implemented through the space shuttle cockpit simulator and a critical task tester device. A total of 900 data runs were made using four test pilots and one nonpilot (engineer) for two system delays in pitch and roll modes. Results showed that the heavier conventional control stick had the lowest pilot effective time delays. The light conventional control stick had pilot effective time delays similar to those of the shuttle controller. All configurations showed an increase in pilot effective time delay with an increase in total system delay.
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    Subject Category: 08
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    Report Date: February 1986
    No. Pages: 20
    Keywords:      Cockpit simulators; Cockpits; Controllers; Pilot performance; Space shuttles; Time lag


  4. FINITE-ELEMENT REENTRY HEAT-TRANSFER ANALYSIS OF SPACE SHUTTLE ORBITER , Technical Paper
    Authors: William L. Ko, Robert D. Quinn and Leslie Gong
    Report Number: NASA-TP-2657
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: A structural performance and resizing (SPAR) finite-element thermal analysis computer program was used in the heat-transfer analysis of the space shuttle orbiter subjected to reentry aerodynamic heating. Three wing cross sections and one midfuselage cross section were selected for the thermal analysis. The predicted thermal protection system temperatures were found to agree well with flight-measured temperatures. The calculated aluminum structural temperatures also agreed reasonably well with the flight data from reentry to touchdown. The effects of internal radiation and of internal convection were found to be significant. The SPAR finite-element solutions agreed reasonably well with those obtained from the conventional finite-difference method.
    Distribution/Availability: Unclassified - Unlimited
    Subject Category: 34
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    Report Date: December 1986
    No. Pages: 59
    Keywords:      Aerodynamic heating; Finite element method; Heat transfer coefficients; Reentry shielding; Space shuttle orbiters; Thermal analysis


  5. DEVELOPMENT AND FLIGHT TEST OF AN EXPERIMENTAL MANEUVER AUTOPILOT FOR A HIGHLYMANEUVERABLE AIRCRAFT , Technical Paper
    Authors: Eugene L. Duke, Frank P. Jones and Ralph B. Roncoli
    Report Number: NASA-TP-2618
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: This report presents the development of an experimental flight test maneuver autopilot (FTMAP) for a highly maneuverable aircraft. The essence of this technique is the application of an autopilot to provide precise control during required flight test maneuvers. This newly developed flight test technique is being applied at the Dryden Flight Research Facility of NASA Ames Research Center. The FTMAP is designed to increase the quantity and quality of data obtained in test flight. The technique was developed and demonstrated on the highly maneuverable aircraft technology (HiMAT) vehicle. This report describes the HiMAT vehicle systems, maneuver requirements, FTMAP development process, and flight results.
    Distribution/Availability: Unclassified - Unlimited
    Subject Category: 05
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    Report Date: September 1986
    No. Pages: 61
    Keywords:      Automatic control; Automatic pilots; Flight tests; Highly maneuverable aircraft; Aircraft control; Aircraft guidance; Aircraft maneuvers


  6. GROUND VIBRATION TEST RESULTS FOR DRONES FOR AERODYNAMIC AND STRUCTURAL TESTING (DAST)/AEROELASTIC RESEARCH WING (ARW-1R) AIRCRAFT , Technical Memorandum
    Authors: T. H. Cox and G. B. Gilyard
    Report Number: NASA-TM-85906
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The drones for aerodynamic and structural testing (DAST) project was designed to control flutter actively at high subsonic speeds. Accurate knowledge of the structural model was critical for the successful design of the control system. A ground vibration test was conducted on the DAST vehicle to determine the structural model characteristics. This report presents and discusses the vibration and test equipment, the test setup and procedures, and the antisymmetric and symmetric mode shape results. The modal characteristics were subsequently used to update the structural model employed in the control law design process.
    Distribution/Availability: Unclassified - Unlimited
    Subject Category: 05
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    Report Date: January 1986
    No. Pages: 36
    Keywords:      Aeroelasticity; Aircraft design; DAST program; Drone vehicles; Flutter analysis; Vibration


  7. COMBINING AND CONNECTING LINEAR, MULTI-INPUT, MULTI-OUTPUT SUBSYSTEM MODELS , Technical Memorandum
    Authors: E. L. Duke
    Report Number: NASA-TM-85912
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The mathematical background for combining and connecting linear, multi-input, multi-output subsystem models into an overall system model is provided. Several examples of subsystem configurations are examined in detail. A description of a MATRIX (sub x) command file to aid in the process of combining and connecting these subsystem models is contained.
    Distribution/Availability: Unclassified - Unlimited
    Subject Category: 63
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    Report Date: April 1986
    No. Pages: 33
    Keywords:      Computer systems design; Format; Linear equations; Matrices (mathematics); Parallel processing (computers)


  8. COMPARISON OF MEASURED AND CALCULATED TEMPERATURES FOR A MACH 8 HYPERSONIC WING TESTSTRUCTURE , Technical Memorandum
    Authors: R. D. Quinn and R. A. Fields
    Report Number: NASA-TM-85918
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: Structural temperatures were measured on a hypersonic wing test structure during a heating test that simulated a Mach 8 thermal environment. Measured data are compared to design calculations and temperature predictions obtained from a finite-difference thermal analysis.
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    Subject Category: 05
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    Report Date: March 1986
    No. Pages: 140
    Keywords:      Aerodynamic heating; High temperature environments; Hypersonic speed; Mach numbers; Wings


  9. DEVELOPMENT EXPERIENCE WITH A SIMPLE EXPERT SYSTEM DEMONSTRATOR FOR PILOT EMERGENCY PROCEDURES , Technical Memorandum
    Authors: M. VanNorman and D. A. Mackall
    Report Number: NASA-TM-85919
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: Expert system techniques, a major application area of artificial intelligence (AI), are examined in the development of pilot associate to handle aircraft emergency procedures. The term pilot associate is used to describe research involving expert systems that can assist the pilot in the cockpit. The development of expert systems for the electrical system and flight control system emergency procedures are discussed. A simple, high-level expert system provides the means to choose which knowledge domain is needed. The expert systems were developed on a low-cost, FORTH-based package, using a personal computer.
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    Subject Category: 08
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    Report Date: February 1986
    No. Pages: 17
    Keywords:      Artificial intelligence; Avionics; Emergencies; Expert systems; Flight control


  10. FLIGHT AND WIND-TUNNEL MEASUREMENTS SHOWING BASE DRAG REDUCTION PROVIDED BY A TRAILINGDISK FOR HIGH REYNOLDS NUMBER TURBULENT FLOW FOR SUBSONIC AND TRANSONIC MACH NUMBERS , Technical Paper
    Authors: Sheryll Goecke Powers (NASA Ames Research Center), Jarrett K. Huffman (NASA Langley Research Center) and Charles H. Fox, Jr. (NASA Langley Research Center)
    Report Number: NASA-TP-2638
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The effectiveness of a trailing disk, or trapped vortex concept, in reducing the base drag of a large body of revolution was studied from measurements made both in flight and in a wind tunnel. Pressure data obtained for the flight experiment, and both pressure and force balance data were obtained for the wind tunnel experiment. The flight test also included data obtained from a hemispherical base. The experiment demonstrated the significant base drag reduction capability of the trailing disk to Mach 0.93 and to Reynolds numbers up to 80 times greater than for earlier studies. For the trailing disk data from the flight experiment, the maximum decrease in base drag ranged form 0.08 to 0.07 as Mach number increased from 0.70 to 0.93. Aircraft angles of attack ranged from 3.9 to 6.6 deg for the flight data. For the trailing disk data from the wind tunnel experiment, the maximum decrease in base and total drag ranged from 0.08 to 0.05 for the approximately 0 deg angle of attack data as Mach number increased from 0.30 to 0.82.
    Distribution/Availability: Unclassified - Unlimited
    Subject Category: 34
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    Report Date: November 1986
    No. Pages: 143
    Keywords:      Base pressure; Drag reduction; Flight tests; Trailing edge flaps; Turbulent flow; Wind tunnel tests


  11. HIMAT FLIGHT PROGRAM: TEST RESULTS AND PROGRAM ASSESSMENT OVERVIEW , Technical Memorandum
    Authors: Dwain A. Deets, V. Michael DeAngelis and David P. Lux
    Report Number: NASA-TM-86725
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The Highly Manueverable Aircraft Technology (HiMAT) program consisted of design, fabrication of two subscale remotely piloted research vehicles (RPRVs), and flight test. This technical memorandum describes the vehicles and test approach. An overview of the flight test results and comparisons with the design predictions are presented. These comparisons are made on a single-discipline basis, so that aerodynamics, structures, flight controls, and propulsion controls are examined one by one. The interactions between the disciplines are then examined, with the conclusions that the integration of the various technologies contributed to total vehicle performance gains. An assessment is made of the subscale RPRV approach from the standpoint of research data quality and quantity, unmanned effects as compared with manned vehicles, complexity, and cost. It is concluded that the RPRV technique, as adopted in this program, resulted in a more complex and costly vehicle than expected but is reasonable when compared with alternate ways of obtaining comparable results.
    Distribution/Availability: Unclassified - Unlimited
    Subject Category: 05
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    Report Date: June 1986
    No. Pages: 30
    Keywords:      Fighter aircraft; Flight tests; Highly maneuverable aircraft; Remotely piloted vehicles


  12. MODIFIED U.S. ARMY U-8F GROUND VIBRATION TEST , Technical Memorandum
    Authors: M. W. Kehoe
    Report Number: NASA-TM-86741
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The Dryden Flight Research Facility of NASA Ames Research Center conducted a ground vibration test on a modified U.S. Army U-8F airplane. Modifications included new engines, propellers, and engine-mounted truss assemblies. The ground vibration test was conducted using sine dwell, single-point random, and impact excitations. The test was performed to determine modal frequencies, mode shapes, and structural damping coefficients of the airframe and propeller with full and empty fuel tanks. The data presented include frequency response plots, rigid-body and structural modal frequencies, and mode shapes.
    Distribution/Availability: Unclassified - Unlimited
    Subject Category: 05
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    Report Date: August 1986
    No. Pages: 50
    Keywords:      Ground tests; Modal response; Research aircraft; Structural vibration; Vibration tests


  13. APPLICATION OF PARAMETER ESTIMATION TO AIRCRAFT STABILITY AND CONTROL: THE OUTPUT-ERRORAPPROACH , Reference Publication
    Authors: Richard E. Maine and Kenneth W. Iliff
    Report Number: NASA-RP-1168
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The practical application of parameter estimation methodology to the problem of estimating aircraft stability and control derivatives from flight test data is examined. The primary purpose of the document is to present a comprehensive and unified picture of the entire parameter estimation process and its integration into a flight test program. The document concentrates on the output-error method to provide a focus for detailed examination and to allow us to give specific examples of situations that have arisen. The document first derives the aircraft equations of motion in a form suitable for application to estimation of stability and control derivatives. It then discusses the issues that arise in adapting the equations to the limitations of analysis programs, using a specific program for an example. The roles and issues relating to mass distribution data, preflight predictions, maneuver design, flight scheduling, instrumentation sensors, data acquisition systems, and data processing are then addressed. Finally, the document discusses evaluation and the use of the analysis results.
    Distribution/Availability: Unclassified - Unlimited
    Subject Category: 05
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    Report Date: June 1986
    No. Pages: 175
    Keywords:      Aircraft control; Aircraft stability; Flight tests; Parameter identification; Error analysis; Maximum likelihood estimates; Output


  14. IN-FLIGHT EVALUATION OF INCREMENTAL TIME DELAYS IN PITCH AND ROLL , Journal Article
    Authors: D. T. Berry
    Report Number: H-1308
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: No abstract available.
    Distribution/Availability: Unclassified - Unlimited
    Subject Category: 08
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    Report Date: October 1986
    No. Pages: 5
    Keywords:      Aircraft landing; Attitude control; Flight tests; Pilot induced ocillation; Pitching moments; Rolling moments
    Notes: (Guidance, Navigation and Control Conference, Snowmass, CO, August 19-21, 1985, Technical Papers, p. 39-46) Journal of Guidance, Control, and Dynamics (ISSN 0731-5090), vol. 9, Sept.-Oct. 1986, p. 573-577. Previously cited in issue 22, p. 3229, Accession no. A85-45881. Previously cited in issue 22, p. 3229, Accession no. A85-45881.


  15. AUGMENTOR PERFORMANCE OF AN F100 ENGINE MODEL DERIVATIVE ENGINE IN AN F-15 AIRPLANE , Technical Memorandum
    Authors: James T. Walton and Frank W. Burcham, Jr.
    Report Number: NASA-TM-86745
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The transient performance of the F100 engine model derivative (EMD) augmentor was evaluated in an F-15 airplane. The augmentor was a newly designed 16-segment augmentor. It was tested with a segment-1 sprayring with 90 deg fuel injection, and later with a modified segment-1 sprayring with centerline fuel injection. With the 90 deg injection, no-lights occurred at high altitudes with airspeeds of 175 knots or less; however, the results were better than when using the standard F100-PW-100 engine. With the centerline fuel injection, all transients were successful to an altitude of 15,500 meters and an airspeed of 150 knots: no failures to light, blowouts, or stalls occurred. For a first flight evaluation, the augmentor transient performance was excellent.
    Distribution/Availability: Unclassified - Unlimited
    Subject Category: 07
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    Report Date: May 1986
    No. Pages: 23
    Keywords:      F-15 aircraft; Thrust augmentation; Turbofan engines; Afterburning; Flight tests; Fuel injection


  16. A FLIGHTPATH OVERSHOOT FLYING QUALITIES METRIC FOR THE LANDING TASK , Technical Memorandum
    Authors: D. T. Berry
    Report Number: NASA-TM-86795
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: An analysis was conducted of the attitude and flightpath angle response of configurations used in the Total In-Flight Simulator (TIFS) pitch-rate command systems program. The results show poor correlation between pilot ratings and attitude response and indicate that attitude was not a major influence in the results. A strong correlation was found to exist, however, between the amount of flightpath angle peak overshoot and the pilot ratings. This correlation is similar to the best correlations that have been obtained in recent closed-loop and time-domain analyses but has the advantage of greatly simplified implementation and interpretation.
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    Subject Category: 08
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    Report Date: January 1986
    No. Pages: 11
    Keywords:      Aircraft landing; Aircraft maneuvers; Attitude control; Flight paths; Flight simulators
    Notes: Presented at the AIAA 24th Aerospace Sciences Meeting, Reno, Nevada, 6-9 January 1986.


  17. BUCKLING BEHAVIOR OF RENE 41 TUBULAR PANELS FOR A HYPERSONIC AIRCRAFT WING , Technical Memorandum
    Authors: W. L. Ko, J. L. Shideler and R. A. Fields
    Report Number: NASA-TM-86798
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The buckling characteristics of Rene 41 tubular panels for a hypersonic aircraft wing were investigated. The panels were repeatedly tested for buckling characteristics using a hypersonic wing test structure and a universal tension/compression testing machine. The nondestructive buckling tests were carried out under different combined load conditions and in different temperature environments. The force/stiffness technique was used to determine the buckling loads of the panel. In spite of some data scattering, resulting from large extrapolations of the data fitting curve (because of the termination of applied loads at relatively low percentages of the buckling loads), the overall test data correlate fairly well with theoretically predicted buckling interaction curves. Also, the structural efficiency of the tubular panels was found to be slightly higher than that of beaded panels.
    Distribution/Availability: Unclassified - Unlimited
    Subject Category: 39
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    Report Date: May 1986
    No. Pages: 31
    Keywords:      Buckling; Rene 41; Stiffness matrix; Sweptback wings; Wing loading; Wing panels
    Notes: Presented at the AIAA/ASME/ASCE/AHS 27th Structures, Structural Dynamics and Materials Conference, San Antonio, Texas, 19-21 May 1986.


  18. DEVELOPMENT OF A KNOWLEDGE ACQUISITION TOOL FOR AN EXPERT SYSTEM FLIGHT STATUS MONITOR , Technical Memorandum
    Authors: J. D. Disbrow (Systems Control Technology, Inc.), E. L. Duke (NASA Ames Research Center) and V. A. Regenie (NASA Ames Research Center)
    Report Number: NASA-TM-86802
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: Two of the main issues in artificial intelligence today are knowledge acquisition dion and knowledge representation. The Dryden Flight Research Facility of NASA's Ames Research Center is presently involved in the design and implementation of an expert system flight status monitor that will provide expertise and knowledge to aid the flight systems engineer in monitoring today's advanced high-performance aircraft. The flight status monitor can be divided into two sections: the expert system itself and the knowledge acquisition tool. The knowledge acquisition tool, the means it uses to extract knowledge from the domain expert, and how that knowledge is represented for computer use is discussed. An actual aircraft system has been codified by this tool with great success. Future real-time use of the expert system has been facilitated by using the knowledge acquisition tool to easily generate a logically consistent and complete knowledge base.
    Distribution/Availability: Unclassified - Unlimited
    Subject Category: 61
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    Report Date: January 1986
    No. Pages: 12
    Keywords:      Aircraft control; Computer techniques; Expert systems; Flight control
    Notes: Presented at the AIAA 24th Aerospace Sciences Meeting, Reno, Nevada, January 6-9, 1986.


  19. DYNAMICS AND CONTROLS FLIGHT TESTING OF THE X-29A AIRPLANE , Technical Memorandum
    Authors: J. Gera
    Report Number: NASA-TM-86803
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: A brief description of the flight control system of the X-29A forward-swept-wing flight demonstrator is followed by a discussion of the flight test techniques and procedures in the area of flight dynamics and control. These techniques, which evolved during the initial few months of flight testing, are based on integrating flight testing with simulation and analysis on a flight-by-flight basis. A limited amount of flight test results in dynamic stability and handling qualities is also presented.
    Distribution/Availability: Unclassified - Unlimited
    Subject Category: 05
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    Report Date: January 1986
    No. Pages: 13
    Keywords:      Control systems design; Flight control; Flight tests; Swept forward wings; X-29 aircraft
    Notes: Presented at the 24th AIAA Aerospace Sciences Meeting, Reno, Nevada, January 6-9, 1986.


  20. THE ROLE OF A REAL-TIME FLIGHT SUPPORT FACILITY IN FLIGHT RESEARCH PROGRAMS , Technical Memorandum
    Authors: A. L. Moore
    Report Number: NASA-TM-86805
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: This paper presents some of the approaches taken by the NASA Western Aeronautical Test Range (WATR) of Ames Research Center to satisfy the ever-increasing real-time requirements of research projects such as the F-14, F-15, advanced fighter technology integration (AFTI) F-16, YAV-88, and the X-29A. The approaches include the areas of data acquisition, communications (video and audio), real-time processing and display, data communications, and tracking.
    Distribution/Availability: Unclassified - Unlimited
    Subject Category: 09
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    Report Date: January 1986
    No. Pages: 14
    Keywords:      Cockpits; Fighter aircraft; Flight tests; Real time operation; Research aircraft; Satellite transmission
    Notes: Presented at the AIAA Aerospace Sciences Meeting, Reno, Nevada, January 6-9, 1986.


  21. COMPARISON OF THEORETICAL AND FLIGHT-MEASURED LOCAL FLOW AERODYNAMICS FOR A LOW-ASPECT-RATIO FIN , Technical Memorandum
    Authors: J. Blair Johnson and Doral R. Sandlin
    Report Number: NASA-TM-86806
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: Flight test and theoretical aerodynamic data were obtained for a flight test fixture mounted on the underside of an F-104G aircraft. The theoretical data were generated using two codes: a two-dimensional transonic code called code H, and a three-dimensional subsonic and supersonic code called wing-body. Pressure distributions generated by the codes for the flight test fixture, as well as compared with the flight-measured data. The two-dimensional code pressure distributions compared well except at the minimum pressure point and the trailing edge. Shock locations compared well except at high transonic speeds. However, the two-dimensional code did not adequately predict the displacement thickness of the flight test fixture. The three-dimensional code pressure distributions compared well except at the trailing edge of the flight test fixture.
    Distribution/Availability: Unclassified - Unlimited
    Subject Category: 02
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    Report Date: December 1986
    No. Pages: 21
    Keywords:      Computational fluid dynamics; Computer programs; F-104 aircraft; Flight tests; Prediction analysis techniques; Transonic flow


  22. SPACE SHUTTLE LONGITUDINAL LANDING FLYINGQUALITIES , Journal Article
    Authors: B. G. Powers
    Report Number: H-1337
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The Space Shuttle program took on the challenge of providing a manual landing capability for an operational vehicle returning from orbit. Some complex challenges were encountered in developing the longitudinal flying qualities required to land the Orbiter manually in an operational environment. Approach and landing test flights indicated a tendency of pilot-induced oscillation near landing. Changes in the operational procedures reduced the difficulty of the landing task, and an adaptive stick filter was incorporated to reduce the severity of any pilot-induced oscillatory motions. Fixed-base, moving-base, and in-flight simulations were used for the evaluations. Overall, the Orbiter control system and operational procedures produced a good capability to perform routinely precise landings with a large, unpowered vehicle that has a low lift-to-drag ratio.
    Distribution/Availability: Unclassified - Unlimited
    Subject Category: 16
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    Report Date: October 1986
    No. Pages: 7
    Keywords:      Approach and landing tests (STS); Longitudinal control; Manual control; Pilot induced oscillation; Spacecraft control; Spacecraft landing
    Notes: Journal of Guidance, Control, and Dynamics (ISSN 0731-5090), vol. 9, September - October 1986, p. 566-572.


  23. FLIGHT TEST OF A RESIDENT BACKUP SOFTWARE SYSTEM , Technical Memorandum
    Authors: D. A. Deets, W. P. Lock and V. A. Megna (Draper (Charles Stark) Lab.)
    Report Number: NASA-TM-86807
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: A new fault-tolerant system software concept employing the primary digital computers as host for the backup software portion has been implemented and flight tested in the F-8 digital fly-by-wire airplane. The system was implemented in such a way that essentially no transients occurred in transferring from primary to backup software. This was accomplished without a significant increase in the complexity of the backup software. The primary digital system was frame synchronized, which provided several advantages in implementing the resident backup software system. Since the time of the flight tests, two other flight vehicle programs have made a commitment to incorporate resident backup software similar in nature to the system described in this paper.
    Distribution/Availability: Unclassified - Unlimited
    Subject Category: 08
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    Report Date: January 1986
    No. Pages: 12
    Keywords:      Control systems design; Fault tolerance; Flight control; Flight tests; Fly by wire control; Redundancy


  24. DECOUPLING CONTROL SYNTHESIS FOR AN OBLIQUE-WING AIRCRAFT , Technical Memorandum
    Authors: G. S. Alag (University of Western Michigan), R. W. Kempel and J. W. Pahle
    Report Number: NASA-TM-86801
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: Interest in oblique-wing aircraft has surfaced periodically since the 1940's. This concept offers some substantial aerodynamic performance advantages but also has significant aerodynamic and inertial cross-coupling between the aircraft longitudinal and lateral-directional axes. This paper presents a technique for synthesizing a decoupling controller while providing the desired stability augmentation. The proposed synthesis procedure uses the concept of a real model-following control system. Feedforward gains are selected on the assumption that perfect model-following conditions are satisfied. The feedback gains are obtained by using eigensystem assignment, and the aircraft is stabilized by using partial state feedback. The effectiveness of the control laws developed in achieving the desired decoupling is illustrated by application to linearized equations of motion of an oblique-wing aircraft for a given flight condition.
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    Subject Category: 08
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    Report Date: June 1986
    No. Pages: 12
    Keywords:      Aircraft control; Asymmetry; Automatic control; Cross coupling; Decoupling; Feedfoward control; Flight control; Lateral control; Longitudinal control; Oblique wings
    Notes: Presented at the American Control Conference, Seattle, Wash., 18-20 Jun. 1986.


  25. REAL-TIME OPEN-LOOP FREQUENCY RESPONSE ANALYSIS OF FLIGHT TEST DATA , Conference Paper
    Authors: J. T. Bosworth and J. C. West (USAF, Flight Test Center)
    Report Number: H-1340
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: A technique has been developed to compare the open-loop frequency response of a flight test aircraft real time with linear analysis predictions. The result is direct feedback to the flight control systems engineer on the validity of predictions and adds confidence for proceeding with envelope expansion. Further, gain and phase margins can be tracked for trends in a manner similar to the techniques used by structural dynamics engineers in tracking structural modal damping.
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    Report Date: April 1986
    No. Pages: 11
    Keywords:      Flight control; Flight tests; Frequency response; Linear prediction; Real time operation; X-29 Aircraft
    Notes: AIAA, AHS, CASI, DGLR, IES, ISA, ITEA, SETP, and SFTE, Flight Testing Conference, 3rd, Las Vegas, Nevada, Apr. 2-4, 1986.


  26. SUMMARY OF RESULTS OF NASA F-15 FLIGHT RESEARCH PROGRAM , Technical Memorandum
    Authors: F. W. Burcham, Jr., G. A. Trippensee, D. F. Fisher and T. W. Putnam
    Report Number: NASA-TM-86811
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: NASA conducted a multidisciplinary flight research program on the F-15 airplane. The program began in 1976 when two preproduction airplanes were obtained from the U.S. Air Force. Major projects involved stability and control, handling qualities, propulsion, aerodynamics, propulsion controls, and integrated propulsion-flight controls. Several government agencies and aerospace contractors were involved. In excess of 330 flights were flown, and over 85 papers and reports were published. This document describes the overall program, the projects, and the key results. The F-15 was demonstrated to be an excellent flight research vehicle, producing high-quality results.
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    Report Date: April 1986
    No. Pages: 34
    Keywords:      Aircraft control; Aircraft stability; F-15 aircraft; Flight tests; Propulsion system performance; Research aircraft
    Notes: Presented at the AIAA 3rd Flight Testing Conference, Las Vegas, Nevada, April 2-4, 1986.


  27. X-29A ADVANCED TECHNOLOGY DEMONSTRATOR PROGRAM OVERVIEW , Conference Paper
    Authors: W. J. Sefic and W. Cutler
    Report Number: H-1342
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The present discussion of the X-29A forward-swept wing experimental aircraft's functional flight program and concept evaluation program gives attention to the program management structure for a test team that encompasses NASA, the U.S. Air Force, and the prime contractor for the X-29A. The preflight, flight-functional, envelope-expansion and flight research test objectives of the program are also noted, together with the qualitative characterizations obtained to date for both a limited envelope flight control system and one for an expanded envelope.
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    Report Date: April 1986
    No. Pages: 16
    Keywords:      Aircraft performance; Flight tests; Project management; X-29 aircraft; Aircraft stability; Flight control; Flight simulation; Telemetry
    Notes: AIAA, AHS, CASI, DGLR, IES, ISA, ITEA, SETP, and SFTE, Flight Testing Conference, 3rd, Las Vegas, NV, Apr. 2-4, 1986.


  28. AEROELASTIC CONTROL OF OBLIQUE-WING AIRCRAFT , Technical Memorandum
    Authors: J. J. Burken, G. S. Alag and G. B. Gilyard
    Report Number: NASA-TM-86808
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The U.S. Navy and NASA are currently involved in the design and development of an unsymmetric-skew-wing aircraft capable of 65 deg wing sweep and flight at Mach 1.6. A generic skew-wing aircraft model was developed for 45 deg wing skew at a flight condition of Mach 0.70 and 3048 m altitude. At this flight condition the aircraft has a wing flutter mode. An active implementable control law was developed using the linear quadratic Gaussian design technique. A method of modal residualization was used to reduce the order of the controller used for flutter suppression.
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    Report Date: June 1986
    No. Pages: 12
    Keywords:      Flight tests; Flutter analysis; Gauss equation; Linear equations; Oblique wings; Quadratic equations; Reduced order filters; Vibration damping; Wing oscillations
    Notes: Presented at the American Control Conference, Seattle, Wash., 18-20 Jun. 1986.


  29. X-29A TECHNOLOGY DEMONSTRATOR FLIGHT TEST PROGRAM OVERVIEW , Technical Memorandum
    Authors: W. J. Sefic and C. M. Maxwell
    Report Number: NASA-TM-86809
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: An overview of the X-29A functional flight program and concept evaluation program is presented, including some of the unique and different preparations for the first flight. Included are a discussion of the many organizational responsibilities and a description of the program management structure for the test team. Also discussed are preflight ground, flight functional envelope expansion, and flight research test objectives and qualitive results to date for both a limited-envelope flight control system and an expanded-envelope system. The aircraft, including the instrumentation system and measurements, is described. In addition, a discussion is included regarding the use of major support facilities, such as ground and flight simulators, the NASA Western Aeronautical Test Range and mission control center, and the Grumman automated telemetry station. An overview of the associated real-time and postflight batch data processing software approaches is presented. The use of hardware-in-the-loop simulation for independent verification and validation and mission planning and practice is discussed. Also included is a description of the flight-readiness review, the airworthiness and flight safety review, work scheduling, technical briefings, and preflight and postflight crew briefings. The configuration control process used on the X-29A program is described, and its relationship to both simulation and aircraft operations is discussed. An X-29A schedule overview is presented with an outline of a proposed follow-on program.
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    Report Date: May 1986
    No. Pages: 17
    Keywords:      Aircraft performance; Flight tests; Research aircraft; Swept forward wings; X-29 aircraft


  30. EFFECT OF TIME DELAY ON FLYING QUALITIES: AN UPDATE , Technical Memorandum
    Authors: R. E. Smith and S. K. Sarafian
    Report Number: NASA-TM-88264
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: Flying qualities problems of modern, full-authority electronic flight control systems are most often related to the introduction of additional time delay in aircraft response to a pilot input. These delays can have a significant effect on the flying qualities of the aircraft. Time delay effects are reexamined in light of recent flight test experience with aircraft incorporating new technology. Data from the X-29A forward-swept-wing demonstrator, a related preliminary in-flight experiment, and other flight observations are presented. These data suggest that the present MIL-F-8785C allowable-control system time delay specifications are inadequate or, at least, incomplete. Allowable time delay appears to be a function of the shape of the aircraft response following the initial delay. The cockpit feel system is discussed as a dynamic element in the flight control system. Data presented indicate that the time delay associated with a significant low-frequency feel system does not result in the predicted degradation in aircraft flying qualities. The impact of the feel system is discussed from two viewpoints: as a filter in the control system which can alter the initial response shape and, therefore, the allowable time delay, and as a unique dynamic element whose delay contribution can potentially be discounted by special pilot loop closures.
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    Report Date: August 1986
    No. Pages: 13
    Keywords:      Aircraft performance; Electronic equipment; Flight characteristics; Flight control; Input; Loops; Man machine systems; Pilot performacne; Time lag
    Notes: Presented at the AIAA Guidance, Navigation and Control Conference, Williamsburg, Virginia, 18-20 Aug. 1986.


  31. SIMULATION STUDIES OF ALTERNATE LONGITUDINAL CONTROL SYSTEMS FOR THE SPACE SHUTTLE ORBITER IN THE LANDING REGIME , Technical Memorandum
    Authors: B. G. Powers and S. K. Sarrafian
    Report Number: NASA-TM-86815
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: Simulations of the space shuttle orbiter in the landing task were conducted by the NASA Ames-Dryden Flight Research Facility using the Ames Research Center vertical motion simulator (VMS) and the total in-flight simulator (TIFS) variable-stability aircraft. Several new control systems designed to improve the orbiter longitudinal response characteristics were investigated. These systems improved the flightpath response by increasing the amount of pitch-rate overshoot. Reduction in the overall time delay was also investigated. During these evaluations, different preferences were noted for the baseline or the new systems depending on the pilot background. The trained astronauts were quite proficient with the baseline system and found the new systems to be less desirable than the baseline. On the other hand, the pilots without extensive flight training with the orbiter had a strong preference for the new systems. This paper presents the results of the VMS and TIFS simulations. A hypothesis is presented regarding the control strategies of the two pilot groups and how this influenced their control systems preferences. Interpretations of these control strategies are made in terms of open-loop aircraft response characteristics as well as pilot-vehicle closed-loop characteristics.
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    Report Date: January 1986
    No. Pages: 14
    Keywords:      Flight control; Flight simulation; Orbital maneuvers; Pilot training; Space flight training; Space shuttles
    Notes: Presented at the AIAA Atmospheric Flight Mechanics Conference, Williamsburg, Virginia, 18-20 Aug. 1986.


  32. VALIDATION OF A NEW FLYING QUALITY CRITERION FOR THE LANDING TASK , Technical Memorandum
    Authors: D. T. Berry and S. K. Sarrafian
    Report Number: NASA-TM-88261
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: A strong correlation has been found to exist between flight path angle peak overshoot and pilot ratings for the landing task. The use of flightpath overshoot as a flying quality metric for landing is validated by correlation with four different in-flight simulation programs and a ground simulation study. Configurations tested were primarily medium-weight generic transports. As a result of good correlation with this extensive data base, criterion boundaries are proposed for landing based on the flight path peak overshoot metric.
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    Report Date: January 1986
    No. Pages: 10
    Keywords:      Aircraft landing; Aircraft performance; Flight characteristics; Flight paths; Flight simulation; Pilot performance
    Notes: Presented at the AIAA Atmospheric Flight Mechanics Conference, Williamsburg, Virginia, 18-20 Aug. 1986.


  33. BIBLIOGRAPHY FOR AIRCRAFT PARAMETER ESTIMATION , Technical Memorandum
    Authors: Kenneth W. Iliff and Richard E. Maine
    Report Number: NASA-TM-86804
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: An extensive bibliography in the field of aircraft parameter estimation has been compiled. This list contains definitive works related to most aircraft parameter estimation approaches. Theoretical studies as well as practical applications are included. Many of these publications are pertinent to subjects peripherally related to parameter estimation, such as aircraft maneuver design or instrumentation considerations.
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    Report Date: October 1986
    No. Pages: 22
    Keywords:      Aircraft design; Flight tests; Maximum likelihood estimates; Parameter identification


  34. EIGENSYSTEM SYNTHESIS FOR ACTIVE FLUTTER SUPPRESSION ON AN OBLIQUE-WING AIRCRAFT , Technical Memorandum
    Authors: G. S. Alag (University of Western Michigan), J. J. Burken (NASA Hugh L. Dryden Flight Research Center) and G. B. Gilyard (NASA Hugh L. Dryden Flight Research Center)
    Report Number: NASA-TM-88275
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The application of the eigensystem synthesis technique to place the closed-loop eigenvalues and shape the closed-loop eigenvectors has not been practical for active flutter suppression, primarily because of the availability of only one control surface (aileron) for flutter suppression. The oblique-wing aircraft, because of its configuration, provides two independent surfaces (left and right ailerons), making the application of eigensystem synthesis practical. This paper presents the application of eigensystem synthesis using output feedback for the design of an active flutter suppression system for an oblique-wing aircraft. The results obtained are compared with those obtained by linear quadratic Gaussian techniques.
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    Report Date: August 1986
    No. Pages: 9
    Keywords:      Ailerons; Eigenvalues; Eigenvectors; Flutter analysis; Oblique wings
    Notes: Presented at the AIAA Guidance, Navigation and Control Conference, Williamsburg, Virginia, 18-20 Aug. 1986.


  35. MODEL-FOLLOWING CONTROL FOR AN OBLIQUE-WING AIRCRAFT , Technical Memorandum
    Authors: G. S. Alag, R. W. Kempel, J. W. Pahle, J. J. Bresina and F. Bartoli
    Report Number: NASA-TM-88269
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: A variable-skew oblique wing offers a substantial aerodynamic performance advantage for aircraft missions that require both high efficiency in subsonic flight and supersonic dash or cruise. The most obvious characteristic of the oblique-wing concept is the asymmetry associated with wing-skew angle which results in significant aerodynamic and inertial cross-coupling between the aircraft longitudinal and lateral-directional axes. A technique for synthesizing a decoupling controller while providing the desired stability augmentation. The proposed synthesis procedure uses the cncept of explicit model following. Linear quadratic optimization techniques are used to design the linear feedback system. The effectiveness of the control laws developed in achieving the desired decoupling is illustrated for a given flight condition by application to linearized equations of motion, and also to the nonlinear equations of six degrees of freedom of motion with nonlinear aerodynamic data.
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    Report Date: August 1986
    No. Pages: 13
    Keywords:      Aircraft control; Aircraft design; Control theory; Equations of motion; Flight control; Oblique wings; Skewness
    Notes: Presented at the AIAA Conference on Guidance and Control, Williamsburg, Virginia, 18-20 Aug. 1986.


  36. TEST AND EVALUATION OF THE HIDEC ENGINE UPTRIM ALGORITHM , Technical Memorandum
    Authors: R. J. Ray and L. P. Myers
    Report Number: NASA-TM-88262
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The highly integrated digital electronic control (HIDEC) program will demonstrate and evaluate the improvements in performance and mission effectiveness that result from integrated engine-airframe control systems. Performance improvements will result from an adaptive engine stall margin mode, a highly integrated mode that uses the airplane flight conditions and the resulting inlet distortion to continuously compute engine stall margin. When there is excessive stall margin, the engine is uptrimmed for more thrust by increasing engine pressure ratio (EPR). The EPR uptrim logic has been evaluated and implemented into computer simulations. Thrust improvements over 10 percent are predicted for subsonic flight conditions. The EPR uptrim was successfully demonstrated during engine ground tests. Test results verify model predictions at the conditions tested.
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    Report Date: July 1986
    No. Pages: 13
    Keywords:      Algorithms; Digital systems; Electronic control; Engine airframe integration; Engine inlets; Evaluation; Subsonic speed
    Notes: Presented at the AIAA/ASME/SAE/ASEE 22nd Joint Propulsion Conference, Huntsville, Alabama, 16-18 Jun. 1986.


  37. AN ENGINEERING APPROACH TO THE USE OF EXPERT SYSTEMS TECHNOLOGY IN AVIONICS APPLICATIONS , Technical Memorandum
    Authors: E. L. Duke, V. A. Regenie, M. Brazee and R. W. Brumbaugh (PRC Kentron)
    Report Number: NASA-TM-88263
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The concept of using a knowledge compiler to transform the knowledge base and inference mechanism of an expert system into a conventional program is presented. The need to accommodate real-time systems requirements in applications such as embedded avionics is outlined. Expert systems and a brief comparison of expert systems and conventional programs are reviewed. Avionics applications of expert systems are discussed before the discussions of applying the proposed concept to example systems using forward and backward chaining.
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    Report Date: May 1986
    No. Pages: 12
    Keywords:      Avionics; Expert systems; Onboard data processing; Real time operation; Artificial intelligence; Computer programming; Computer systems design; Computer systems programs; Software engineering
    Notes: Presented at the IEEE National Aerospace and Electronics Conference (NAECON), Dayton, Ohio, 19-23 May 1986.


  38. APPLICATION OF PARAMETER ESTIMATION TO HIGHLY UNSTABLE AIRCRAFT , Technical Memorandum
    Authors: R. E. Maine and J. E. Murray
    Report Number: NASA-TM-88266
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The application of parameter estimation to highly unstable aircraft is discussed. Included are a discussion of the problems in applying the output error method to such aircraft and demonstrates that the filter error method eliminates these problems. The paper shows that the maximum likelihood estimator with no process noise does not reduce to the output error method when the system is unstable. It also proposes and demonstrates an ad hoc method that is similar in form to the filter error method, but applicable to nonlinear problems. Flight data from the X-29 forward-swept-wing demonstrator is used to illustrate the problems and methods discussed.
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    Report Date: August 1986
    No. Pages: 14
    Keywords:      Aircraft stability; Error analysis; Flight tests; Systems stability; Maximum likelihood estimates; Nonlinear systems; Parameter identification
    Notes: Proposed for presentation at the AIAA Atmospheric Flight Mechanics Conference, Williamsburg, Virginia, 18-20 Aug. 1986.


  39. FLIGHT CONTROL SYSTEM DEVELOPMENT AND FLIGHT TEST EXPERIENCE WITH THE F-111 MISSION ADAPTIVE WING AIRCRAFT , Technical Memorandum
    Authors: R. R. Larson
    Report Number: NASA-TM-88265
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The wing on the NASA F-111 transonic aircraft technology airplane was modified to provide flexible leading and trailing edge flaps. This wing is known as the mission adaptive wing (MAW) because aerodynamic efficiency can be maintained at all speeds. Unlike a conventional wing, the MAW has no spoilers, external flap hinges, or fairings to break the smooth contour. The leading edge flaps and three-segment trailing edge flaps are controlled by a redundant fly-by-wire control system that features a dual digital primary system architecture providing roll and symmetric commands to the MAW control surfaces. A segregated analog backup system is provided in the event of a primary system failure. This paper discusses the design, development, testing, qualification, and flight test experience of the MAW primary and backup flight control systems.
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    Report Date: August 1986
    No. Pages: 21
    Keywords:      Digital command systems; Digital navigation; Flight control; Flight tests; Fly by wire control; Leading edges; Mission adaptive wings; Supersonic aircraft; Trailing edges; Wings
    Notes: Presented at the AIAA Guidance, Navigation, and Control Conference, Williamsburg, Virginia, 18-20 Aug. 1986.


  40. RAPID PROTOTYPING FACILITY FOR FLIGHT RESEARCH IN ARTIFICIAL-INTELLIGENCE-BASED FLIGHT SYSTEMSCONCEPTS , Technical Memorandum
    Authors: E. L. Duke, V. A. Regenie and D. A. Deets
    Report Number: NASA-TM-88268
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The Dryden Flight Research Facility of the NASA Ames Research Facility of the NASA Ames Research Center is developing a rapid prototyping facility for flight research in flight systems concepts that are based on artificial intelligence (AI). The facility will include real-time high-fidelity aircraft simulators, conventional and symbolic processors, and a high-performance research aircraft specially modified to accept commands from the ground-based AI computers. This facility is being developed as part of the NASA-DARPA automated wingman program. This document discusses the need for flight research and for a national flight research facility for the rapid prototyping of AI-based avionics systems and the NASA response to those needs.
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    Report Date: October 1986
    No. Pages: 19
    Keywords:      Artificial intelligence; Flight management systems; Prototypes; Research facilities


  41. DETERMINATION OF LIFT AND DRAG CHARACTERISTICS OF SPACE SHUTTLE ORBITER USING MAXIMUM LIKELIHOODESTIMATION TECHNIQUE , Conference Paper
    Authors: B. M. Trujillo
    Report Number: H-1369
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: This paper presents the technique and results of maximum likelihood estimation used to determine lift and drag characteristics of the Space Shuttle Orbiter. Maximum likelihood estimation uses measurable parameters to estimate nonmeasurable parameters. The nonmeasurable parameters for this case are elements of a nonlinear, dynamic model of the orbiter. The estimated parameters are used to evaluate a cost function that computes the differences between the measured and estimated longitudinal parameters. The case presented is a dynamic analysis. This places less restriction on pitching motion and can provide additional information about the orbiter such as lift and drag characteristics at conditions other than trim, instrument biases, and pitching moment characteristics. In addition, an output of the analysis is an estimate of the values for the individual components of lift and drag that contribute to the total lift and drag. The results show that maximum likelihood estimation is a useful tool for analysis of Space Shuttle Orbiter performance and is also applicable to parameter analysis of other types of aircraft.
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    Report Date: January 1986
    No. Pages: 12
    Keywords:      Aerodynamic coefficients; Aerodynamic drag; Lift; Maximum Likelihood estimates; Space shuttle orbiters
    Notes: Atmospheric Flight Mechanics Conference, Williamsburg, VA, August 18-20, 1986, Technical Papers (A86-47651 23-08). New York, American Institute of Aeronautics and Astronautics, 1986. AIAA 86-2225.


  42. WRIGHT BROTHERS LECTURESHIP IN AERONAUTICS: EXPERIENCE WITH HIMAT REMOTELY PILOTED RESEARCHVEHICLE - AN ALTERNATE FLIGHT TEST APPROACH , Conference Paper
    Authors: D. A. Deets and L. E. Brown
    Report Number: H-1370
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The highly maneuverable aircraft technology (HiMAT) program explored the various and complex interactions of advanced technologies, such as aeroelastic tailoring, close-coupled canard, and relaxed static stability. A 0.44-subscale remotely piloted research vehicle (RPRV) of a hypothetical fighter airplane was designed and flight-tested to determine the effects of these interactions and to define the design techniques appropriate for advanced fighter technologies. Flexibility and high maneuverability were provided by flight control laws implemented in ground-based computers and telemetered to the vehicle control system during flight tests. The high quality of the flight-measured data and their close correlation with the analytical design modeling proved that the RPRV is a viable and cost-effective tool for developing aerodynamic, structure, and control law requirements for highly maneuverable fighter airplanes of the future.
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    Report Date: October 1986
    No. Pages: 19
    Keywords:      Flight tests; Highly maneuverable aircraft; Remotely piloted vehicles; Research aircraft
    Notes: AIAA, AHS, and ASEE, Aircraft Systems, Design and Technology Meeting, Dayton, Ohio, Oct. 20-22, 1986. AIAA 86-2754.


  43. EXPERIENCE WITH SYNCHRONOUS AND ASYNCHRONOUS DIGITAL CONTROL SYSTEMS , Technical Memorandum
    Authors: V. A. Regenie, C. V. Chacon and W. P. Lock
    Report Number: NASA-TM-88271
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: Flight control systems have undergone a revolution since the days of simple mechanical linkages; presently the most advanced systems are full-authority, full-time digital systems controlling unstable aircraft. With the use of advanced control systems, the aerodynamic design can incorporate features that allow greater performance and fuel savings, as can be seen on the new Airbus design and advanced tactical fighter concepts. These advanced aircraft will be and are relying on the flight control system to provide the stability and handling qualities required for safe flight and to allow the pilot to control the aircraft. Various design philosophies have been proposed and followed to investigate system architectures for these advanced flight control systems. One major area of discussion is whether a multichannel digital control system should be synchronous or asynchronous. This paper addressed the flight experience at the Dryden Flight Research Facility of NASA's Ames Research Center with both synchronous and asynchronous digital flight control systems. Four different flight control systems are evaluated against criteria such as software reliability, cost increases, and schedule delays.
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    Report Date: August 1986
    No. Pages: 19
    Keywords:      Aerodynmaic characteristics; Digital command systems; Flight control; Flight safety; Stability; Synchronism; Systems analysis
    Notes: Presented at the AIAA Guidance, Navigation and Control Conference, Williamsburg, Virginia, 18-20 Aug. 1986.


  44. EXHAUST-GAS PRESSURE AND TEMPERATURE SURVEY OF F404-GE-400 TURBOFAN ENGINE , Technical Memorandum
    Authors: James T. Walton and Frank W. Burcham, Jr.
    Report Number: NASA-TM-88273
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: An exhaust-gas pressure and temperature survey of the General Electric F404-GE-400 turbofan engine was conducted in the altitude test facility of the NASA Lewis Propulsion System Laboratory. Traversals by a survey rake were made across the exhaust-nozzle exit to measure the pitot pressure and total temperature. Tests were performed at Mach 0.87 and a 24,000-ft altitude and at Mach 0.30 and a 30,000-ft altitude with various power settings from intermediate to maximum afterburning. Data yielded smooth pressure and temperature profiles with maximum jet temperatures approximately 1.4 in. inside the nozzle edge and maximum jet temperatures from 1 to 3 in. inside the edge. A low-pressure region located exactly at engine center was noted. The maximum temperature encountered was 3800 R.
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    Report Date: December 1986
    No. Pages: 32
    Keywords:      Exhaust gases; Exhaust nozzles; Pressure measurement; Temperature measurement; Turbofan engines


  45. A RADAR DATA PROCESSING AND ENHANCEMENT SYSTEM , Technical Memorandum
    Authors: K. F. Anderson (NASA Hugh L. Dryden Flight Research Center), J. W. Wrin (NASA Hugh L. Dryden Flight Research Center) and R. James (GMD Systems)
    Report Number: NASA-TM-88274
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: This report describes the space position data processing system of the NASA Western Aeronautical Test Range. The system is installed at the Dryden Flight Research Facility of NASA Ames Research Center. This operational radar data system (RADATS) provides simultaneous data processing for multiple data inputs and tracking and antenna pointing outputs while performing real-time monitoring, control, and data enhancement functions. Experience in support of the space shuttle and aeronautical flight research missions is described, as well as the automated calibration and configuration functions of the system.
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    Subject Category: 17
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    Report Date: August 1986
    No. Pages: 19
    Keywords:      Data processing; Flight tests; Geodetic surveys; Space shuttles; Tracking radar; Trajectory measurement
    Notes: Presented at the IRIG Electronic Trajectory Measurements Group Meeting, El Paso, Texas, 6 Aug. 1986.


  46. EFFECTS OF FORCED AND FREE CONVECTIONS ON STRUCTURAL TEMPERATURES OF SPACE SHUTTLE ORBITER DURINGREENTRY FLIGHT , Technical Memorandum
    Authors: William L. Ko, Robert D. Quinn and Leslie Gong
    Report Number: NASA-TM-86800
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: Structural performance and resizing (SPAR) finite element thermal analysis computer programs was used in the heat transfer analysis of the space shuttle orbiter wing subjected to reentry aerodynamic heating. With sufficient external forced convective cooling near the end of the heating cycle, the calculated surface temperatures of the thermal protection system (TPS) agree favorable with the flight data for the entire flight profile. However, the effects of this external forced convective cooling on the structural temperatures were found to be negligible. Both free and forced convection elements were introduced to model the internal convection effect of the cool air entering the shuttle interior. The introduction of the internal free convection effect decreased the calculated wing lower skin temperatures by 20 degrees F, 1200 sec after touchdown. If the internal convection is treated as forced convection, the calculated wing lower skin temperatures after touchdown can be reduced to match the flight measured data. By reducing the TPS thicknesses to certain thicknesses to account for the TPS gap heating, the calculated wing lower skin temperatures prior to touchdown can be raised to agree with the flight data perfectly.
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    Report Date: October 1986
    No. Pages: 14
    Keywords:      Forced convection; Free convection; Heating transfer; Space shuttle orbiters; Spacecraft reentry; Spacecraft temperature; Thermal analysis
    Notes: Presented at the AIAA 22nd Thermophysics Conference, Honolulu, Hawaii, 8-10 Jun. 1987.
 
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