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  1. REAL-TIME IN-FLIGHT ENGINE PERFORMANCE AND HEALTH MONITORING TECHNIQUES FOR FLIGHT RESEARCH APPLICATION , Technical Memorandum
    Authors: Ronald J. Ray, John W. Hicks and Keith D. Wichman
    Report Number: NASA-TM-104239
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: Procedures for real time evaluation of the inflight health and performance of gas turbine engines and related systems were developed to enhance flight test safety and productivity. These techniques include the monitoring of the engine, the engine control system, thrust vectoring control system health, and the detection of engine stalls. Real time performance techniques were developed for the determination and display of inflight thrust and for aeroperformance drag polars. These new methods were successfully shown on various research aircraft at NASA-Dryden. The capability of NASA’s Western Aeronautical Test Range and the advanced data acquisition systems were key factors for implementation and real time display of these methods.
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    Report Date: September 1991
    No. Pages: 34
    Keywords:      Engine control; Engine failure; Engine monitoring instruments; Engine tests; In-flight monitoring; Real-time operation; Aerodynamic drag; Data acquisition; Flight tests; Gas turbine engines; Research aircraft; Test ranges; Thrust vector control


  2. DEVELOPMENT OF AN INTEGRATED AEROSERVOELASTIC ANALYSIS PROGRAM AND CORRELATION WITH TEST DATA.
    Authors: K. K. Gupta, M. J. Brenner and L. S. Voelker
    Report Number: NASA-TP-3120
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The details and results are presented of the general-purpose finite element STructural Analysis RoutineS (STARS) to perform a complete linear aeroelastic and aeroservoelastic analysis. The earlier version of the STARS computer program enabled effective finite element modeling as well as static, vibration, buckling, and dynamic response of damped and undamped systems, including those with pre-stressed and spinning structures. Additions to the STARS program include aeroelastic modeling for flutter and divergence solutions, and hybrid control system augmentation for aeroservoelastic analysis. Numerical results of the X-29A aircraft pertaining to vibration, flutter-divergence, and open- and closed-loop aeroservoelastic controls analysis are compared to ground vibration, wind-tunnel, and flight-test results. The open- and closed-loop aeroservoelastic control analyses are based on a hybrid formulation representing the interaction of structural, aerodynamic, and flight-control dynamics.
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    Subject Category: 01
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    Report Date: May 1991
    No. Pages: 105
    Keywords:      Aeroelasticity; Aeroservoelasticity; Computer programs; Dynamic response; Dynamic structural analysis.


  3. FLOW VISUALIZATION STUDY OF A 1/48-SCALE AFTI/F111 MODEL TO INVESTIGATE HORIZONTAL TAIL FLOW DISTURBANCES.
    Authors: Lisa J. Bjarke
    Report Number: NASA-TM-101698
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: During flight testing of the AFTI/F111 aircraft, horizontal tail buffet was observed. Flutter analysis ruled out any aeroelastic instability, so a water-tunnel flow visualization study was conducted to investigate possible flow disturbances on the horizontal tail which might cause buffet. For this study, a 1/48-scale model was used. Four different wing cambers and one horizontal tail setting were tested between 0 and 20 deg angle of attack. These wing cambers corresponded to the following leading training edge deflections: 0/2, 10/10, 10/2, and 0/10. Flow visualization results in the form of still photographs are presented for each of the four wing cambers between 8 and 12 deg angle of attack. In general, the horizontal tail experiences flow disturbances which become more pronounced with angle of attack or wing trailing-edge deflection.
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    Subject Category: 02
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    Report Date: June 1991
    No. Pages: 35
    Keywords:      Aeroelasticity; Buffeting; Flight tests; Flow visualization; Flutter analysis.


  4. NATIONAL AEROSPACE PLANE LONGITUDINAL LONG-PERIOD DYNAMICS.
    Authors: Donald T.Berry
    Report Number: H-1559
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
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    Subject Category: 08
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    Report Date: February 1991
    No. Pages: 2
    Keywords:      Aerospace planes; Flight mechanics; Longitudinal control; Propulsion system configuration; Trajectory analysis.
    Notes: Journal of Guidance, Control, and Dynamics (ISSN 0731-5090), Vol. 14, January–February 1991, February 1991, pp. 205–206.


  5. IN-FLIGHT FLOW VISUALIZATION CHARACTERISTICS OF THE NASA F-18 HIGH ALPHA RESEARCH VEHICLE AT HIGH ANGLES OF ATTACK.
    Authors: David F. Fisher, John H. Del Frate and David M. Richwine
    Report Number: NASA-TM-4193
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: Surface and off-surface flow visualization techniques were used to visualize the 3-D separated flows on the NASA F-18 high alpha research vehicle at high angles of attack. Results near the alpha = 25 to 26 deg and alpha = 45 to 49 deg are presented. Both the forebody and leading edge extension (LEX) vortex cores and breakdown locations were visualized using smoke. Forebody and LEX vortex separation lines on the surface were defined using an emitted fluid technique. A laminar separation bubble was also detected on the nose cone using the emitted fluid technique and was similar to that observed in the wind tunnel test, but not as extensive. Regions of attached, separated, and vortical flow were noted on the wing and the leading edge flap using tufts and flow cones, and compared well with limited wind tunnel results (includes color photos).
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    Subject Category: 02
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    Report Date: May 1991
    No. Pages: 34
    Keywords:      Boundary layer transition; Flow visualization; Separated flow; Three dimensional flow; Vortex breakdown.


  6. A SIMULATION STUDY OF TURBOFAN ENGINE DETERIORATION ESTIMATION USING KALMAN FILTERING TECHNIQUES.
    Authors: Heather H. Lambert
    Report Number: NASA-TM-104233
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: Deterioration of engine components may cause off-normal engine operation. The result is an unnecessary loss of performance, because the fixed schedules are designed to accommodate a wide range of engine health. These fixed control schedules may not be optimal for a deteriorated engine. This problem may be solved by including a measure of deterioration in determining the control variables. These engine deterioration parameters usually cannot be measured directly but can be estimated. A Kalman filter design is presented for estimating two performance parameters that account for engine deterioration: high and low pressure turbine delta efficiencies. The delta efficiency parameters model variations of the high and low pressure turbine efficiencies from nominal values. The filter has a design condition of Mach 0.90, 30,000 ft altitude, and 47 deg power level angle (PLA). It was evaluated using a nonlinear simulation of the F100 engine model derivative (EMD) engine, at the design Mach number and altitude over a PLA range of 43 to 55 deg. It was found that known high pressure turbine delta efficiencies of –2.5 percent and low pressure turbine delta efficiencies of –1.0 percent can be estimated with an accuracy of + or –0.25 percent efficiency with a Kalman filter. If both the high and low pressure turbine are deteriorated, the delta efficiencies of –2.5 percent to both turbines can be estimated with the same accuracy.
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    Subject Category: 07
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    Report Date: June 1991
    No. Pages: 47
    Keywords:      Control simulation; Dynamic models; Engine control; Kalman filters; Performance prediction.


  7. PROCEEDINGS OF THE X-15 FIRST FLIGHT 30TH ANNIVERSARY CELEBRATION.
    Authors: Author(s) Not Available.
    Report Number: NASA-CP-3105
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: A technical symposium and pilot’s panel discussion were held on June 8, 1989, to commemorate the 30th anniversary of the first free flight of the X-15 rocket-powered research aircraft. The symposium featured technical presentations by former key government and industry participants in the advocacy, design, manufacturing, and flight research program activities. The X-15’s technical contributions to the X-30 are cited. The panel discussion participants included seven of the eight surviving research pilots who flew the X-15 experimental aircraft to world altitude and speed records which still stand. Pilot’s remarks include descriptions of their most memorable X-15 flight experience. The report also includes a historical perspective of the X-15.
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    Subject Category: 05
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    Report Date: January 1991
    No. Pages: 174
    Keywords:      Aircraft design; Conferences; Histories; Hypersonic flight; NASA programs.
    Notes: Symposium, Edwards, California, June 8, 1989.


  8. APPLICATION AND FLIGHT TEST OF LINEARIZING TRANSFORMATIONS USING MEASUREMENT FEEDBACK TO THE NONLINEAR CONTROL PROBLEM , Technical Paper
    Authors: Robert F. Antoniewicz, Eugene L. Duke and P.K.A. Menon
    Report Number: NASA-TP-3154
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The design of nonlinear controllers has relied on the use of detailed aerodynamic and engine models that must be associated with the control law in the flight system implementation. Many of these controllers were applied to vehicle flight path control problems and have attempted to combine both inner- and outer-loop control functions in a single controller. An approach to the nonlinear trajectory control problem is presented. This approach uses linearizing transformations with measurement feedback to eliminate the need for detailed aircraft models in outer-loop control applications. By applying this approach and separating the inner-loop and outer-loop functions two things were achieved: (1) the need for incorporating detailed aerodynamic models in the controller is obviated; and (2) the controller is more easily incorporated into existing aircraft flight control systems. An implementation of the controller is discussed, and this controller is tested on a six degree-of-freedom F-15 simulation and in flight on an F-15 aircraft. Simulation data are presented which validates this approach over a large portion of the F-15 flight envelope. Proof of this concept is provided by flight-test data that closely matches simulation results. Flight-test data are also presented.
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    Subject Category: 08
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    Report Date: September 1991
    No. Pages: 55
    Keywords:      Aircraft control; Dynamic conversions; Linearizing transformations; Nonlinear control


  9. A SYSTEM FOR TESTING AIRDATA PROBES AT HIGH ANGLES OF ATTACK USING A GROUND VEHICLE.
    Authors: Robert J.Geenen, Bryan J. Moulton and Edward A.Haering, Jr
    Report Number: H-1644
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: A system to calibrate airdata probes at angles of attack between 0 and 90 deg was developed and tested at the NASA Ames Dryden Flight Research Facility. This system used a test fixture mounted to the roof of a ground vehicle and included an onboard instrumentation and data acquisition system for measuring pressures and flow angles. The data could be easily transferred to the facility mainframe computer for further analysis. The system was designed to provide convenient and inexpensive airdata probe calibrations for projects which require airdata at high angles of attack, such as the F-18 High Alpha Research Program. This type of probe was tested to 90 deg angle of attack in a wind tunnel and using the ground vehicle system. The results of both tests are in close agreement. An airdata probe with a swiveling pilot-static tube was also calibrated with the ground vehicle system. This paper presents the results of these tests and gives a detailed description of the test system.
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    Subject Category: 09
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    Report Date: January 1991
    No. Pages: 15
    Keywords:      Air data systems; Aircraft instruments; Angle of attack; Test equipment; Calibrating
    Notes: AIAA Paper 91-0088. Presented at the AIAA 29th Aerospace Sciences Meeting, Reno, Nevada, January 7–10, 1991.


  10. SINGLE-STRAIN-GAGE FORCE/STIFFNESS BUCKLING PREDICTION TECHNIQUES ON A HAT-STIFFENED PANEL.
    Authors: Larry D. Hudson and Randolph C. Thompson
    Report Number: NASA-TM-101733
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: Predicting the buckling characteristics of a test panel is necessary to ensure panel integrity developed on a hat-stiffened, monolithic titanium buckling panel. Thed was method is an adaptation of the original force/stiffness method which requires back-to-back gages. The single-gage method was developed because the test panel did not have back-to-back gages. The method was used to predict buckling loads and temperatures under various heating and loading conditions. The results correlated well with a finite element buckling analysis. The single-gage force/stiffness method was a valid real-time and post-test buckling prediction technique.
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    Report Date: February 1991
    No. Pages: 22
    Keywords:      Buckling; Hypersonic vehicles; Panels; Prediction analysis techniques; Stiffness.
    Notes: Presented at the ASME Structures and Materials Conference, Dallas, Texas, November 25–30, 1990.


  11. THERMAL BEHAVIOR OF A TITANIUM HONEYCOMB-CORE SANDWICH PANEL.
    Authors: William L. Ko and Raymond H. Jackson
    Report Number: NASA-TM-101732
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: Finite element thermal stress analysis was performed on a rectangular titanium honeycomb-core sandwich panel which is subjected to thermal load with a temperature gradient across its depth. The distributions of normal stresses in the face sheets and the face-sheet/sandwich-core interfacial shear stresses are presented. The thermal buckling of the heated face sheet was analyzed by assuming the face sheet to be resting on an elastic foundation representing the sandwich core. Thermal buckling curves and thermal buckling load surface are presented for setting the limit for temperature gradient across the panel depth.
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    Subject Category: 39
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    Report Date: January 1991
    No. Pages: 13
    Keywords:      Finite element method; Honeycomb cores; Stress analysis; Temperature effects; Thermal stresses.


  12. AEROTHERMAL TEST RESULTS FROM THE FIRST FLIGHT OF THE PEGASUS AIR-LAUNCHED SPACE BOOSTER , Technical Memorandum
    Authors: Gregory K. Noffz, Robert E. Curry, Edward A. Haering, Jr. and Paul Kolodziej
    Report Number: NASA-TM-4330
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: A survey of temperature measurements at speeds through Mach 8.0 on the first flight of the Pegasus air-launched booster system is discussed. In addition, heating rates were derived from the temperature data obtained on the fuselage in the vicinity of the wing shock interaction. Sensors were distributed on the wing surfaces, leading edge, and on the wing-body fairing or fillet. Side-by-side evaluations were obtained for a variety of sensor installations. Details of the trajectory reconstruction through first-stage separation are provided. Given here are indepth descriptions of the sensor installations, temperature measurements, and derived heating rates along with interpretations of the results.
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    Subject Category: 34
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    Report Date: October 1991
    No. Pages: 53
    Keywords:      Aerothermodynamics; Body-wing configurations; Heating; Pegasus air-launched booster; Surveys; Temperature measurement


  13. HYPERSONIC RESEARCH VEHICLE (HRV) REAL-TIME FLIGHT TEST SUPPORT FEASIBILITY AND REQUIREMENTS STUDY PART I - REAL-TIME FLIGHT EXPERIMENT SUPPORT. , Contractor Report
    Authors: Herman A. Rediess, Rudrapatna V. Ramnath, Daniel L. Vrable, David H. Hirvo, Lowell D. McMillen and Irving B. Osofsky
    Report Number: NASA-CR-179449
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: This report presents the results of a study to identify potential real time remote computational applications to support monitoring HRV flight test experiments and to define preliminary requirements. The study considered a major expansion of the support capability available at Ames-Dryden. The focus is on the use of extensive computation and data bases together with real-time flight data to generate and present high level information to those monitoring the flight. Six examples were considered: (1) boundary layer transition location; (2) shock wave position estimation; (3) performance estimation; (4) surface temperature estimation; (5) critical structural stress estimation; and (6) stability estimation.
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    Subject Category: 05
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    Report Date: May 1991
    No. Pages: 36
    Keywords:      Flight test; Flight test monitoring; Hypersonic vehicles; Real-time computation
    Notes: This contractor report was published as a companion document to NASA CR-179450 and CR-186011. NASA Technical Monitor: Kevin L. Petersen, Dryden Flight Research Facility, Edwards, CA 93523-0273.


  14. THE EFFECTS OF COMPRESSOR SEVENTH-STAGE BLEED AIR EXTRACTION ON PERFORMANCE OF THE F100-PW-220 AFTERBURNING TURBOFAN ENGINE.
    Authors: Alison B. Evans
    Report Number: NASA-CR-179447
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: A study has been conducted to determine the effects of seventh-stage compressor bleed on the performance of the F100 afterburning turbofan engine. The effects of bleed on thrust, specific fuel consumption, fan turbine inlet temperature, bleed total pressure, and bleed total temperature were obtained from the engine manufacturer's status deck computer simulation for power settings of intermediate, partial afterburning, and maximum afterburning for Mach numbers between 0.6 and 2.2 and for altitudes of 30,000, 40,000, and 50,000 ft. It was found that thrust loss and specific fuel consumption increase were approximately linear functions of bleed flow and, based on a percent-thrust change basis, were approximately independent of power setting.
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    Subject Category: 07
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    Report Date: February 1991
    No. Pages: 29
    Keywords:      Engine bleed; Engine performance; F100 engine; Thrust loss
    Notes: This report was prepared during a summer intern program. NASA Technical Monitor: F. W. Burcham, NASA Ames Research Center, Dryden Flight Research Facility, Edwards, CA 93523-0273.


  15. SUMMARY OF IN-FLIGHT FLOW VISUALIZATION OBTAINED FROM THE NASA HIGH ALPHA RESEARCH VEHICLE.
    Authors: David F. Fisher, John H. Del Frate and Fanny A. Zuniga
    Report Number: NASA-TM-101734
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: A summary of the surface and off-surface flow visualization results obtained in flight on the F-18 high alpha research vehicle (HARV) is presented, highlighting the extensive 3-D vortical flow on the aircraft at angles of attack up to 50 degs. The emitted fluid technique, as well as tufts and flow cones, were used to document the surface flow. A smoke generator system injected smoke into the vortex cores generated by the forebody and leading edge extensions (LEXs). Documentation was provided by onboard still and video, by air-to-air, and by postflight photography. The surface flow visualization techniques revealed laminar separation bubbles near the forebody apex, lines of separation on the forebody and LEX, and regions of attached and separated flow on the wings and fins. The off-surface flow visualization techniques showed the path of the vortex cores on the forebody and LEX as well as the LEX vortex core breakdown location. An interaction between the forebody and LEX vortices was noted. The flow over the surfaces of the vertical tail was categorized into regions of attached, unsteady, or separated flow using flow tufts.
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    Subject Category: 02
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    Report Date: January 1991
    No. Pages: 41
    Keywords:      F-18 aircraft; Flow distribution; Flow visualization; Three Dimensional flow; Unsteady flow.
    Notes: Presented at the High Angle of Attack Technology Symposium, Hampton, Virginia, October 30–November 1, 1990.


  16. BUFFET INDUCED STRUCTURAL/FLIGHT-CONTROL SYSTEM INTERACTION OF THE X-29A AIRCRAFT.
    Authors: David F. Voracek and Robert Clarke
    Report Number: NASA-TM-101735
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: High angle-of-attack flight regime research is currently being conducted for modern fighter aircraft at the NASA Ames Research Center’s Dryden Flight Research Facility. This flight regime provides enhanced maneuverability to fighter pilots in combat situations. Flight research data are being acquired to compare and validate advanced computational fluid dynamic solutions and wind-tunnel models. High angle-of-attack flight creates unique aerodynamic phenomena including wing rock and buffet on the airframe. These phenomena increase the level of excitation of the structural modes, especially on the vertical and horizontal stabilizers. With high gain digital flight-control systems, this structural response may result in an aeroservoelastic interaction. A structural interaction on the X-29A aircraft was observed during high angle-of-attack flight testing. The roll and yaw rate gyros sensed the aircraft’s structural modes at 11, 13, and 16 Hz. The rate gyro output signals were then amplified through the flight-control laws and sent as commands to the flaperons and rudder. The flight data indicated that as the angle of attack increased, the amplitude of the buffet on the vertical stabilizer increased, which resulted in more excitation to the structural modes. The flight-control system sensors and command signals showed this increase in modal power at the structural frequencies up to a 30 degree angle-of-attack. Beyond a 30 degree angle-of-attack, the vertical stabilizer response, the feedback sensor amplitude, and control surface command signal amplitude remained relatively constant. Data are presented that show the increased modal power in the aircraft structural accelerometers, the feedback sensors, and the command signals as a function of angle of attack. This structural interaction is traced from the aerodynamic buffet to the flight-control surfaces.
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    Report Date: April 1991
    No. Pages: 15
    Keywords:      Aeroelasticity; Angle of attack; Buffeting; Fighter aircraft; Flight control.
    Notes: Presented at the 32nd AIAA Structures, Structural Dynamics, and Materials Conference, Baltimore, Maryland, April 8–10, 1991.


  17. DETERMINATION OF THE EFFECTS OF HEATING ON MODAL CHARACTERISTICS OF AN ALUMINUM PLATE WITH APPLICATION TO HYPERSONIC VEHICLES.
    Authors: H. Todd Snyder and Michael W. Kehoe
    Report Number: NASA-TM-4274
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The structural integrity of proposed high speed aircraft can be seriously affected by the extremely high surface temperatures and large temperature gradients throughout the vehicle’s structure. Variations in the structure’s elastic characteristics as a result of thermal effects can be seen by changes in vibration characteristics. Analysis codes that predict these changes must be correlated and verified with experimental data. Analytical and experimental modal test results are given from uniform, nonuniform, and transient thermoelastic vibration tests of a 12 x 50 x 0.19 aluminum plate. The data show the effect of heat on the modal characteristics of the plate. The results showed that frequencies decreased, damping increased, and mode shapes remained unchanged as the temperature of the plate increased. Analytical predictions provided good correlation with experimental results.
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    Subject Category: 05
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    Report Date: April 1991
    No. Pages: 28
    Keywords:      Aluminum; Hypersonic vehicles; Structural failure; Temperature effects; Thermoelasticity.


  18. THE EFFECTS OF PRESSURE SENSOR ACOUSTICS ON AIRDATA DERIVED FROM A HIGH-ANGLE-OF-ATTACK FLUSH AIRDATA SENSING (HI-FADS) SYSTEM.
    Authors: Stephen A. Whitmore and Timothy R. Moes
    Report Number: NASA-TM-101736
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The accuracy of a nonintrusive high angle-of-attack flush airdata sensing (Hi-FADS) system was verified for quasi-steady flight conditions up to 55 deg angle of attack during the F-18 High Alpha Research Vehicle (HARV) Program. The system is a matrix of nine pressure ports arranged in annular rings on the aircraft nose. The complete airdata set is estimated using nonlinear regression. Satisfactory frequency response was verified to the system Nyquist frequency (12.5 Hz). The effects of acoustical distortions within the individual pressure sensors of the nonintrusive pressure matrix on overall system performance are addressed. To quantify these effects, a frequency-response model describing the dynamics of acoustical distortion is developed and simple design criteria are derived. The model adjusts measured Hi-FADS pressure data for the acoustical distortion and quantifies the effects of internal sensor geometries on system performance. Analysis results indicate that sensor frequency response characteristics very greatly with altitude, thus it is difficult to select satisfactory sensor geometry for all altitudes. The solution used presample filtering to eliminate resonance effects, and short pneumatic tubing sections to reduce lag effects. Without presample signal conditioning the system designer must use the pneumatic transmission line to attenuate the resonances and accept the resulting altitude variability
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    Subject Category: 06
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    Report Date: February 1991
    No. Pages: 23
    Keywords:      Acoustics; Angle of attack; Design analysis; Flight conditions; Pressure effects.
    Notes: Presented at the AIAA 29th Aerospace Sciences Meeting, Reno, Nevada, January 7–10, 1991.


  19. PRELIMINARY RESULTS FROM AN AIRDATA ENHANCEMENT ALGORITHM WITH APPLICATION TO HIGH-ANGLE-OF-ATTACK FLIGHT.
    Authors: Timothy R. Moes and Stephen A. Whitmore
    Report Number: NASA-TM-101737
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: A technique was developed to improve the fidelity of airdata measurements during dynamic maneuvering. This technique is particularly useful for airdata measured during flight at high angular rates and high angles of attack. To support this research, flight tests using the F-18 high alpha research vehicle (HARV) were conducted at NASA Ames Research Center, Dryden Flight Research Facility. A Kalman filter was used to combine information from research airdata, linear accelerometers, angular rate gyros, and attitude gyros to determine better estimates of airdata quantities such as angle of attack, angle of sideslip, airspeed, and altitude. The state and observation equations used by the Kalman filter are briefly developed and it is shown how the state and measurement covariance matrices were determined from flight data. Flight data are used to show the results of the technique and these results are compared to an independent measurement source. This technique is applicable to both postflight and real-time processing of data.
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    Subject Category: 06
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    Report Date: February 1991
    No. Pages: 41
    Keywords:      Air data systems; Aircraft maneuvers; Angle of attack; F-18 aircraft; Flight tests.
    Notes: Presented at the AIAA 29th Aerospace Sciences Meeting, Reno, Nevada, January 7–10, 1990, (see A91-19405), February 1991.


  20. ANALYSIS OF STRUCTURAL RESPONSE DATA USING DISCRETE MODAL FILTERS.
    Authors: Lawrence C. Freudinger
    Report Number: NASA-CR-179448
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: This thesis describes the application of reciprocal modal vectors to the analysis of structural response data. Reciprocal modal vectors are constructed using an existing experimental modal model and an existing frequency response matrix of a structure, and can be assembled into a matrix that effectively transforms the data from the physical space to a modal space within a particular frequency range. In other words, the weighting matrix necessary for modal vector orthogonality (typically the mass matrix) is contained within the reciprocal model matrix. The ability to extract the response of a particular mode from a system due to whatever forces may be acting on it has broad appicability, from operating date analysis and force identification to vibration control. The underlying goal of this work is mostly directed toward observing the modal state responses in the presence of unknown, possibly closed loop forcing functions, thus having an impact on both operating data analysis techniques and independent modal space control techniques. This study investigates the behavior of reciprocol modal vectors as modal filters with respect to certain calculation parameters and their performance with perturbed system frequency response data.
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    Subject Category: 05
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    Report Date: May 1991
    No. Pages: 78
    Keywords:      Aeroservoelastic; Flight test; Modal filter; Modal test; Reciprocal modal vector; Spatial filter; Vibration control
    Notes: This report was prepared as a theses in partial fulfillment of the requirements of the University of Cincinnati for the degree of Master of Science.


  21. COMBINED COMPRESSIVE AND SHEAR BUCKLING ANALYSIS OF HYPERSONIC AIRCRAFT STRUCTURAL SANDWICH PANELS.
    Authors: William L. Ko and Raymond H. Jackson
    Report Number: NASA-TM-4290
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The combined-load (compression and shear) buckling equations were established for orthotropic sandwich panels by using the Rayleigh-Ritz method to minimize the panel total potential energy. The resulting combined-load buckling equations were used to generate buckling interaction curves for super-plastically-formed/diffusion-bonded titanium truss-core sandwich panels and titanium honeycomb-core sandwich panels having the same specific weight. The relative combined-load buckling strengths of these two types of sandwich panels are compared with consideration of their sandwich orientations. For square and nearly square panels of both types, the combined load always induces symmetric buckling. As the panel aspect ratios increase, antisymmetric buckling will show up when the loading is shear-dominated combined loading. The square panel (either type) has the highest combined buckling strength, but the combined load buckling strength drops sharply as the panel aspect ratio increases. For square panels, the truss-core sandwich panel has higher compression-dominated combined load buckling strength. However, for shear dominated loading, the square honeycomb-core sandwich panel has higher shear-dominated combined load buckling strength.
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    Subject Category: 39
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    Report Date: May 1991
    No. Pages: 38
    Keywords:      Aircraft structures; Aspect ratio; Buckling; Combined stress; Compressive strength.


  22. DIGITAL SIGNAL CONDITIONING FOR FLIGHT TEST INSTRUMENTATION.
    Authors: Glenn A. Bever
    Report Number: NASA-TM-101739
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: An introduction to digital measurement processes on aircraft is provided. Flight test instrumentation systems are rapidly evolving from analog-intensive to digital intensive systems, including the use of onboard digital computers. The topics include measurements that are digital in origin, as well as sampling, encoding, transmitting, and storing data. Particular emphasis is placed on modern avionic data bus architectures and what to be aware of when extracting data from them. Examples of data extraction techniques are given. Tradeoffs between digital logic families, trends in digital development, and design testing techniques are discussed. An introduction to digital filtering is also covered.
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    Report Date: March 1991
    No. Pages: 81
    Keywords:      Airborne/spaceborne computers; Data sampling; Data storage; Data transmission; Digital computers.
    Notes: AGARDOGRAPH-160, Vol. 19, March 1991.


  23. AUTOMATED FLIGHT TEST MANAGEMENT SYSTEM.
    Authors: M.D. Hewett, D.M. Tartt and A. Agarwal
    Report Number: NASA-CR-186011
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: This report describes the Phase 1 development of an automated flight test management system (ATMS) as a component of a rapid-prototyping flight research facility for AI-based flight systems concepts. The ATMS provides a flight test engineer (FTE) with a set of tools that assist in flight test planning, monitoring, and simulation. This system is also capable of controlling an aircraft during flight test by performing closed-loop guidance functions, range management, and maneuver-quality monitoring. The ATMS is being used as the prototypical system to develop a flight research facility for AI-based flight systems concepts at NASA Ames Dryden.
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    Report Date: May 1991
    No. Pages: 40
    Keywords:      Flight test; Flight test monitoring; Hypersonic vehicles; Real-time computation
    Notes: This contractor report was published as a companion document to NASA CR-179449 and CR-179450. M.D. Hewett and D.M. Tartt are affiliated with SPARTA, Inc. and A. Agarwal is affiliated with Integrated Systems, Inc., Santa Clara, CA 95054. NASA Technical Monitor: Kevin L. Petersen, Dryden Flight Research Facility, Edwards, CA 93523-0273.


  24. HYPERSONIC RESEARCH VEHICLE (HRV) REAL-TIME FLIGHT TEST SUPPORT FEASIBILITY AND REQUIREMENTS STUDY PART II - REMOTE COMPUTATION SUPPORT FOR FLIGHT SYSTEMS FUNCTIONS.
    Authors: H.A. Rediess and M.D. Hewett
    Report Number: NASA-CR-179450
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: This report assesses the requirements for the use of remote computation to support HRV flight testing. First, we develop remote computational requirements to support functions that will eventually be performed onboard operational vehicles of this type. These functions which either cannot be performed onboard in the time frame of initial HRV flight test programs because the technology of airborne computers will not be sufficiently advanced to support the computational loads required, or it is not desirable to perform the functions onboard in the flight test program for other reasons. Second, we address remote computational support either required or highly desirable to conduct flight testing itself. We propose the use of an Automated Flight Management System which is described in conceptual detail. Third, we discuss autonomous operations and finally, unmanned operations.
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    Report Date: May 1991
    No. Pages: 42
    Keywords:      Flight test; Flight test monitoring; Hypersonic vehicles; Real-time computation
    Notes: This contractor report was published as a companion document to NASA CR-179449 and CR-186011. NASA Technical Monitor: Kevin L. Petersen, Dryden Flight Research Facility, Edwards, CA 93523-0273.


  25. THERMAL MODELING AND ANALYSIS OF A CRYOGENIC TANK DESIGN EXPOSED TO EXTREME HEATING PROFILES.
    Authors: Craig A.Stephens and Gregory J. Hanna
    Report Number: H-1702
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: A cryogenic test article, the Generic Research Cryogenic Tank, was designed to qualitatively simulate the thermal response of transatmospheric vehicle fuel tanks exposed to the environment of hypersonic flight. One-dimensional and two-dimensional finite-difference thermal models were developed to simulate the thermal response and assist in the design of the Generic Research Cryogenic Tank. The one-dimensional thermal analysis determined the required insulation thickness to meet the thermal design criteria and located the purge jacket to eliminate the liquefaction of air. The two-dimensional thermal analysis predicted the temperature gradients developed within the pressure-vessel wall, estimated the cryogen boiloff, and showed the effects the ullage condition has on pressure-vessel temperatures. The degree of ullage mixing, location of the applied high-temperature profile, and the purge gas influence on insulation thermal conductivity had significant effects on the thermal behavior of the Generic Research Cryogenic Tank. In addition to analysis results, a description of the Generic Research Cryogenic Tank and the role it will play in future thermal structures and transatmospheric vehicle research at the NASA Dryden Flight Research Facility is presented.
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    Report Date: June 1991
    No. Pages: 19
    Keywords:      Cryogenic fluid storage; Fuel tanks; Hypersonic flight; Thermal Analysis; Transatmospheric vehicles.
    Notes: AIAA Paper 91-1383. Presented at the AIAA 26th Thermophysics Conference, Honolulu, Hawaii, June 24–26, 1991.


  26. MULTIAXIS THRUST VECTORING USING AXISYMMETRIC NOZZLES AND POSTEXIT VANES ON AN F/A-18 CONFIGURATION VEHICLE.
    Authors: Albion H. Bowers, Gregory K. Noffz, Sue B. Grafton, Mary L. Mason and Lee R. Peron
    Report Number: NASA-TM-101741
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: A ground-based investigation was conducted on an operational system of multiaxis thrust vectoring using postexit vanes around an axisymmetric nozzle. This thrust vectoring system will be tested on the NASA F/A-18 High Alpha Research Vehicle (HARV) aircraft. The system provides thrust vectoring capability in both pitch and yaw. Ground based data were gathered from two separate tests at NASA Langley Research Center. The first was a static test in the 16-foot Transonic Tunnel Cold-Jet Facility with a 14.25 percent scale model of the axisymmetric nozzle and the postexit vanes. The second test was conducted in the 30 by 60 foot wind tunnel with a 16 percent F/A-18 complete configuration model. Data from the two sets are being used to develop models of jet plume deflection and thrust loss as a function of vane deflection. In addition, an aerodynamic interaction model based on plume deflection angles will be developed. Results from the scale model nozzle test showed that increased vane deflection caused exhaust plume turning. Aerodynamic interaction effects consisted primarily of favorable interaction of moments and unfavorable interaction of forces caused by the vectored jet plume.
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    Report Date: April 1991
    No. Pages: 36
    Keywords:      Aerodynamic characteristics; Aerodynamics; Deflection; Exhaust gases; Exhaust nozzles.


  27. A KNOWLEDGE BASED APPLICATION OF THE EXTENDED AIRCRAFT INTERROGATION AND DISPLAY SYSTEM , Technical Memorandum
    Authors: Richard D. Glover and Richard R. Larson
    Report Number: NASA-TM-4327
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: A family of multiple-processor ground support test equipment was used to test digital flight-control systems on high-performance research aircraft. A unit recently built for the F-18 high alpha research vehicle project is the latest model in a series called the extended aircraft interrogation and display system. The primary feature emphasized monitors the aircraft MIL-STD-1553B data buses and provides real-time engineering units displays of flight-control parameters. A customized software package was developed to provide real-time data interpretation based on rules embodied in a highly structured knowledge database. The configuration of this extended aircraft of the rule based package and its application to failure modes and effects testing on the F-18 high alpha research vehicle is discussed.
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    Report Date: October 1991
    No. Pages: 40
    Keywords:      Aircraft performance; Applications programs (computers); Display devices; F-18 aircraft; Ground support equipment; Knowledge bases (artificial intelligence); Multiprocessing (computers); Research aircraft; Test equipment


  28. THERMOELASTIC VIBRATION TEST TECHNIQUES.
    Authors: Michael W. Kehoe and H. Todd Snyder
    Report Number: NASA-TM-101742
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The structural integrity of proposed high speed aircraft can be seriously affected by the extremely high surface temperatures and large temperature gradients throughout the vehicle’s structure. Variations in the structure’s elastic characteristics as a result of thermal effects can be observed by changes in vibration frequency, damping, and mode shape. Analysis codes that predict these changes must be correlated and verified with experimental data. The experimental modal test techniques and procedures used to conduct uniform, nonuniform, and transient thermoelastic vibration tests are presented. Experimental setup and elevated temperature instrumentation considerations are also discussed. Modal data for a 12 by 50 inch aluminum plate heated to a temperature of 475 F are presented. These data show the effect of heat on the plate’s modal characteristics. The results indicated that frequency decreased, damping increased, and mode shape remained unchanged as the temperature of the plate was increased.
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    Report Date: April 1991
    No. Pages: 21
    Keywords:      Aircraft structures; Aluminum; Modal response; Structural vibration; Temperature effects.
    Notes: Presented at the 9th International Modal Analysis Conference, Florence, Italy, April 14–18, 1991.


  29. COMBINED-LOAD BUCKLING BEHAVIOR OF METAL-MATRIX COMPOSITE SANDWICH PANELS UNDER DIFFERENT THERMAL ENVIRONMENTS , Technical Memorandum
    Authors: William L. Ko and Raymond H. Jackson
    Report Number: NASA-TM-4321
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: Combined compressive and shear buckling analysis was conducted on flat rectangular sandwich panels with the consideration of transverse shear effects of the core. The sandwich panel is fabricated with titanium honeycomb core and laminated metal matrix composite face sheets. The results show that the square panel has the highest combined load buckling strength, and that the buckling strength decreases sharply with the increases of both temperature and panel aspect ratio. The effect of layup (fiber orientation) on the buckling strength of the panels was studied in detail. The metal matrix composite sandwich panel was much more efficient than the sandwich panel with nonreinforced face sheets and had the same specific weight.
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    Subject Category: 39
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    Report Date: September 1991
    No. Pages: 27
    Keywords:      Buckling; Honeycomb cores; Load tests; Metal matrix composites; Sandwich structures; Thermal stresses; Aspect ratio; Compression loads; Shear strength; Temperature effects; Thermal environments


  30. RESEARCH FLIGHT-CONTROL SYSTEM DEVELOPMENT FOR THE F-18 HIGH ALPHA RESEARCH VEHICLE.
    Authors: Joseph W. Pahle, Bruce Powers, Victoria Regenie, Vince Chacon, Steve Degroote and Steven Murnyak
    Report Number: NASA-TM-104232
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The F-18 high alpha research vehicle was recently modified by adding a thrust vectoring control system. A key element in the modification was the development of a research flight control system integrated with the basic F-18 flight control system. Discussed here are design requirements, system development, and research utility of the resulting configuration as an embedded system for flight research in the high angle of attack regime. Particular emphasis is given to control system modifications and control law features required for high angle of attack flight. Simulation results are used to illustrate some of the thrust vectoring control system capabilities and predicted maneuvering improvements.
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    Report Date: April 1991
    No. Pages: 25
    Keywords:      Control theory; F-18 aircraft; Systems engineering; Thrust vector control.
    Notes: Presented at the High-Angle-of-Attack Technology Conference, Hampton, Virginia, October 30–November 1, 1990.


  31. PROPULSION MODELING TECHNIQUES AND APPLICATIONS FOR THE NASA DRYDEN X-30 REAL-TIME SIMULATOR , Conference Paper
    Authors: John W. Hicks
    Report Number: H-1722
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: An overview is given of the flight planning activities to date in the current National Aero-Space Plane (NASP) program. The government flight-envelope expansion concept and other design flight operational assessments are discussed. The NASA Dryden NASP real-time simulator configuration is examined and hypersonic flight planning simulation propulsion modeling requirements are described. The major propulsion modeling techniques developed by the Edwards flight test team are outlined, and the application value of techniques for developmental hypersonic vehicles are discussed.
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    Report Date: August 1991
    No. Pages: 14
    Notes: Presented at the AIAA Flight Simulation Technologies Conference, AIAA 91-2937, New Orleans, Louisiana, August 12-14, 1991.


  32. COMPRESSIVE BUCKLING ANALYSIS OF HAT-STIFFENED PANEL , Technical Memorandum
    Authors: William L. Ko and Raymond H. Jackson
    Report Number: NASA-TM-4310
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: Buckling analysis was performed on a hat-stiffened panel subjected to uniaxial compression. Both local buckling and global buckling were analyzed. It was found that the global buckling load was several times higher than the buckling load. The predicted local buckling loads compared favorably with both experimental data and finite-element analysis.
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    Subject Category: 39
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    Report Date: August 1991
    No. Pages: 16
    Keywords:      Buckling Compressibility; Finite element method; Panels; Stiffening; Structural analysis; Loads (forces); Titanium


  33. A NASA/RAE COOPERATION IN THE DEVELOPMENT OF A REAL-TIME KNOWLEDGE-BASED AUTOPILOT , Technical Memorandum
    Authors: Colin Daysh, Malcolm Corbin, Geoff Butler, Eugene L. Duke, Steven D. Belle and Randal W. Brumbaugh
    Report Number: NASA-TM-104234
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: As part of a US/UK cooperative aeronautical research program, a joint activity between the NASA Dryden Flight Research Facility and the Royal Aerospace Establishment on knowledge-based systems was established. This joint activity is concerned with tools and techniques for the implementation and validation of real-time knowledge-based systems. The proposed next stage of this research is described, in which some of the problems of implementing and validating a knowledge-based autopilot for a generic high-performance aircraft are investigated.
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    Subject Category: 62
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    Report Date: August 1991
    No. Pages: 15
    Keywords:      Automatic pilots; Expert systems; Knowledge bases (artificial intelligence); Project planning; Real-time operation; Research projects
    Notes: Presented at the Avionics Panel Symposium, Lisbon, Portugal, May 1991.


  34. THE ROLE OF THE REMOTELY AUGMENTED VEHICLE (RAV) LABORATORY IN FLIGHT RESEARCH , Technical Memorandum
    Authors: Dorothea Cohen and Jeanette H. Le
    Report Number: NASA-TM-104235
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: An overview is presented of the unique capabilities and historical significance of the Remotely Augmented Vehicle (RAV) Lab at NASA-Dryden. The role is reviewed of the RAV Lab in enhancing flight test programs and efficient testing of new aircraft control laws. The history of the RAV Lab is discussed with a sample of its application using the X-29 aircraft. The RAV Lab allows for closed or open loop augmentation of the research aircraft while in flight using ground based, high performance real time computers. Telemetry systems transfer sensor and control data between the ground and the aircraft. The RAV capability provides for enhanced computational power, improved flight data quality, and alternate methods for the testing of control system concepts. The Lab is easily reconfigured to reflect changes within a flight program and can be adapted to new flight programs.
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    Report Date: September 1991
    No. Pages: 16
    Keywords:      Aircraft control; Control systems design; Control theory; Expert systems; Flight tests; Remotely piloted vehicles
    Notes: Presented at the AIAA Flight Simulation Technologies Conference and Exhibit, New Orleans, LA, August 12-14, 1991.


  35. HIGH TEMPERATURE GROUND VIBRATION TEST TECHNIQUES , Conference Paper
    Authors: Michael W. Kehoe and H. T. Snyder
    Report Number: H-1730
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: This paper describes the experimental modal test techniques and procedures used to conduct uniform, nonuniform, and transient thermoelastic vibration tests. Experimental setup and elevated temperature instrumentation considerations are also discussed. Modal data for a 30.48- by 127-cm aluminum plate heated to a temperature of 371.1 C are presented. These data show the effect of heat on the plate’s modal characteristics.
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    Subject Category: 09
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    Report Date: November 1991
    No. Pages: 10
    Keywords:      Ground tests; High temperature tests; Hypersonic vehicles; Surface temperature; Thermoelasticity; Vibration tests
    Notes: Proceedings, Structural Testing Technology at High Temperature Conference, Dayton, Ohio, November 4-6, 1991.


  36. MODELING, SIMULATION, AND FLIGHT CHARACTERISTICS OF AN AIRCRAFT DESIGNED TO FLY AT100,000 FEET , Technical Memorandum
    Authors: Alex G. Sim
    Report Number: NASA-TM-104236
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: A manned real time simulation of a conceptual vehicle, the stratoplane, was developed to study the problems associated with the flight characteristics of a large, lightweight vehicle. Mathematical models of the aerodynamics, mass properties, and propulsion system were developed in support of the simulation and are presented. The simulation was at first conducted without control augmentation to determine the needs for a control system. The unaugmented flying qualities were dominated by lightly damped dutch roll oscillations. Constant pilot workloads were needed at high altitudes. Control augmentation was studied using basic feedbacks. For the longitudinal axis, flight path angle, and pitch rate feedback were sufficient to damp the phugoid mode and to provide good flying qualities. In the lateral directional axis, bank angle, roll rate, and yaw rate feedbacks were sufficient to provide a safe vehicle with acceptable handling qualities. Intentionally stalling the stratoplane to very high angles of attack (deep stall) was studied as a means of enable safe and rapid descent. It was concluded that the deep stall maneuver is viable for this class of vehicle.
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    Report Date: September 1991
    No. Pages: 44
    Keywords:      Deep stall; High-altitude flight; High angle of attack


  37. UPDATE OF THE X-29 HIGH-ANGLE-OF-ATTACK PROGRAM , Conference Paper
    Authors: Gary Trippensee
    Report Number: H-1733
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The X-29A forward-swept wing flight research aircraft flight envelope was expanded to 66 deg angle-of-attack during 1990. Following this flight envelope expansion, a military utility evaluation was performed to investigate the tactical utility of the X-29 configurations at high-angle-of-attack, slow-speed flight conditions. An overall management view and perspective of the expansion process, the technical problems encountered, and the results obtained when compared to the predictions are presented.
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    Report Date: January 1991
    No. Pages: 8
    Keywords:      Aircraft configurations; Angle of attack; Flight envelopes; Flight tests; X-29 aircraft; Aerodynamics; Controllability; Wind tunnel tests
    Notes: SAE Paper 912006. Proceedings of the 29th International Pacific Air and Space Technology Conference and Aircraft Symposium, Gifu, Japan, October 7-11, 1991.


  38. A PRELIMINARY INVESTIGATION OF THE USE OF THROTTLES FOR EMERGENCY FLIGHT CONTROL , Technical Memorandum
    Authors: F. W. Burcham, Jr., Gordon C. Fullerton, Glenn B. Gilyard, Thomas D. Wolf and James F. Stewart
    Report Number: NASA-TM-4320
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: A preliminary investigation was conducted regarding the use of throttles for emergency flight control of a multiengine aircraft. Several airplanes including a light twin-engine piston-powered airplane, jet transports, and a high performance fighter were studied during flight and piloted simulations. Simulation studies used the B-720, B-727, MD-11, and F-15 aircraft. Flight studies used the Lear 24, Piper PA-30, and F-15 airplanes. Based on simulator and flight results, all the airplanes exhibited some control capability with throttles. With piloted simulators, landings using manual throttles-only control were extremely difficult. An augmented control system was developed that converts conventional pilot stick inputs into appropriate throttle commands. With the augmented system, the B-720 and F-15 simulations were evaluated and could be landed successfully. Flight and simulation data were compared for the F-15 airplane.
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    Report Date: September 1991
    No. Pages: 24
    Keywords:      Engine control; Engine failure; Engine monitoring instruments; Engine tests; In-flight monitoring; Real-time operation; Aerodynamic drag; Data acquisition; Flight tests; Gas turbine engines; Research aircraft; Test ranges; Thrust vector control


  39. PREDICTED THERMAL RESPONSE OF A CRYOGENIC FUEL TANK EXPOSED TO SIMULATED AERODYNAMIC HEATING PROFILES WITH DIFFERENT CRYOGENS AND FILL LEVELS
    Authors: Gregory J. Hanna (Hanna Technology Resources, Boulder, CO) and Craig A. Stephens (PRC Inc., Edwards, CA)
    Report Number: NASA-CR-4395
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: A two-dimensional finite-difference thermal model was developed for the Generic Research Cryogenic Tank (GRCT). The model was used to predict the effects of heating profile, fill level, and cryogen type prior to experimental testing. These numerical predictions will assist in defining test scenarios, sensor locations, and venting requirements for the GRCT experimental tests. Boiloff rates, tank-wall and fluid temperatures, and wall heat fluxes were determined for 20 computational test cases. The test cases spanned three discrete fill levels and three heating profiles for hydrogen and nitrogen. Large temperature gradients developed in the vapor region of the tank when the vapor was allowed to stratify, but vapor mixing greatly reduced the top-to-bottom temperature gradient. The thermal response of the GRCT was qualitatively similar to anticipated transatmospheric vehicle (TAV) behavior. Nitrogen simulations deviated from hydrogen simulations in several key areas, particularly where the vapor heat capacity contributed to the system thermal response. The internal radiation and wall-to-vapor heat transfer effects were small compared with the effect of vapor mixing.
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    Report Date: September 1991
    No. Pages: 19
    Keywords:      Aerodynamic heating; Cryogenics; Fuel tanks; Heat transfer; Liquid hydrogen; Liquid nitrogen; MASP; Numerical analysis; Thermal insulation
    Notes: Prepared as AIAA-91-4007 for presentation at the AIAA Session of the ASME/AICHE National Heat Transfer Conference, Minneapolis, Minnesota, July 28–31, 1991. NASA Technical Monitor was Dwain Deets, NASA Dryden Flight Research Facility, Edwards, California.


  40. A SIMULATION EVALUATION OF A FOUR-ENGINE JET TRANSPORT USING ENGINE THRUST MODULATION FOR FLIGHTPATH CONTROL , Technical Memorandum
    Authors: Glenn B. Gilyard, Joseph L. Conley, Jeanette Le and Frank W. Burcham, Jr.
    Report Number: NASA-TM-4324
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The use of throttle control laws to provide adequate flying qualities for flight path control in the event of a total loss of conventional flight control surface use was evaluated. The results are based on a simulation evaluation by transport research pilots of a B-720 transport with visual display. Throttle augmentation control laws can provide flight path control capable of landing a transport-type aircraft with up to moderate levels of turbulence. The throttle augmentation mode dramatically improves the pilots’ ability to control flight path for the approach and landing flight condition using only throttle modulation. For light turbulence, the average Cooper-Harper pilot rating improved from unacceptable to acceptable (a pilot rating improvement of 4.5) in going from manual to augmented control. The low frequency response characteristics of the engines require a considerably different piloting technique. The various techniques used by the pilot resulted in considerable scatter in data. Many pilots readily adapted to a good piloting technique while some had difficulty. A new viable approach is shown to provide independent means of redundancy of transport aircraft flight path control.
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    Report Date: September 1991
    No. Pages: 24
    Keywords:      Atmospheric turbulence; Control simulation; Control theory; Flight control; Flight paths; Thrust control
    Notes: Presented at the AIAA/ASME/SAE/ASEE 27t Joint Propulsion Conference, Sacramento, CA June 24-26, 1991


  41. PRELIMINARY FLIGHT EVALUATION OF AN ENGINE PERFORMANCE OPTIMIZATION ALGORITHM , Technical Memorandum
    Authors: H. H. Lambert, G. B. Gilyard, J. D. Chisholm and L. J. Kerr
    Report Number: NASA-TM-4328
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: A performance seeking control (PSC) algorithm has undergone initial flight test evaluation in subsonic operation of a PW 1128 engine F-15. This algorithm is designed to optimize the quasi-steady performance of an engine for three primary modes: (1) minimum fuel consumption; (2) minimum fan turbine inlet temperature (FTIT); and (3) maximum thrust. The flight test results have verified a thrust specific fuel consumption reduction of 1 pct., up to 100 R decreases in FTIT, and increases of as much as 12 pct. in maximum thrust. PSC technology promises to be of value in next generation tactical and transport aircraft.
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    Report Date: October 1991
    No. Pages: 19
    Keywords:      Engine control; F-15 aircraft; Flight tests; Inlet temperature; Propulsion system performance; Turbofan engines; Algorithms; Fuel consumption; Kalman filters; Optimal control; Optimization; Thrust control
    Notes: Presented at the AIAA/ASME/SAE/ASEE 27th Joint Propulsion Conference, Sacramento, California, June 24-26, 1991.


  42. CONTROLLING CRIPPLED AIRCRAFT-WITH THROTTLES , Technical Memorandum
    Authors: Frank W. Burcham, Jr. and Gordon C. Fullerton
    Report Number: NASA-TM-104238
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: A multiengine crippled aircraft, with most or all of the flight control system inoperative, may use engine thrust for control. A study was conducted of the capability and techniques for emergency flight control. Included were light twin engine piston powered airplanes, an executive jet transport, commercial jet transports, and a high performance fighter. Piloted simulations of the B-720, B-747, B-727, MD-11, C-402, and F-15 airplanes were studied, and the Lear 24, PA-30, and F-15 airplanes were flight tested. All aircraft showed some control capability with throttles and could be kept under control in up-and-away flight for an extended period of time. Using piloted simulators, landings with manual throttles-only control were extremely difficult. However, there are techniques that improve the chances of making a survivable landing. In addition, augmented control systems provide major improvements in control capability and make repeatable landings possible. Control capabilities and techniques are discussed.
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    Report Date: September 1991
    No. Pages: 30
    Keywords:      Control theory; Engine control; Flight control; Flight simulation; Throttling; Thrust control
    Notes: Presented at the AIAA/ASME/SAE/ASEE 27th Joint Propulsion Conference, Sacramento, California, June 24-26, 1991.


  43. REAL-TIME IN-FLIGHT ENGINE PERFORMANCE AND HEALTH MONITORING TECHNIQUES FOR FLIGHT RESEARCH APPLICATION , Technical Memorandum
    Authors: Ronald J. Ray, John W. Hicks and Keith D. Wichman
    Report Number: NASA-TM-104239
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: Procedures for real time evaluation of the inflight health and performance of gas turbine engines and related systems were developed to enhance flight test safety and productivity. These techniques include the monitoring of the engine, the engine control system, thrust vectoring control system health, and the detection of engine stalls. Real time performance techniques were developed for the determination and display of inflight thrust and for aeroperformance drag polars. These new methods were successfully shown on various research aircraft at NASA-Dryden. The capability of NASA’s Western Aeronautical Test Range and the advanced data acquisition systems were key factors for implementation and real time display of these methods.
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    Report Date: September 1991
    No. Pages: 34
    Keywords:      Engine control; Engine failure; Engine monitoring instruments; Engine tests; In-flight monitoring; Real-time operation; Aerodynamic drag; Data acquisition; Flight tests; Gas turbine engines; Research aircraft; Test ranges; Thrust vector control


  44. A HISTORICAL OVERVIEW OF HIGH-TEMPERATURE STRUCTURAL TESTING AT THE NASA DRYDEN FLIGHT RESEARCH FACILITY , Conference Paper
    Authors: V. M. DeAngelis
    Report Number: H-1754
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: Major hot structure test programs conducted at NASA Dryden Flight Research Facility from 1960s to the present are reviewed with emphasis placed on the YF-12A flight load program, which included extensive experimental and analytical tasks. Analytical models of the YF-12A aircraft were generated using NASTRAN and FLEXTAB codes. Experimental data were generated from wind tunnel model tests, laboratory tests performed on the flight vehicle (including Mach-3 thermal simulation that involved heating the entire aircraft’s surface after which the aircraft was returned to flight status), and flight tests.
    Distribution/Availability: Unclassified - Unlimited
    Subject Category: 09
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    Report Date: November 1991
    No. Pages: 3
    Keywords:      High temperature tests; Research facilities; Structural engineering; X-15 aircraft; YF-12 aircraft
    Notes: Proceedings, Structural Testing Technology at High Temperature Conference, Dayton, Ohio, November 4-6, 1991.


  45. FROM AN AUTOMATED FLIGHT-TEST MANAGEMENT SYSTEM TO A FLIGHT-TEST ENGINEER'S WORKSTATION , Technical Memorandum
    Authors: E. L. Duke, Randal W. Brumbaugh, M. D. Hewett and D. M. Tartt
    Report Number: NASA-TM-104242
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The capabilities and evolution is described of a flight engineer’s workstation (called TEST-PLAN) from an automated flight test management system. The concept and capabilities of the automated flight test management systems are explored and discussed to illustrate the value of advanced system prototyping and evolutionary software development.
    Distribution/Availability: Unclassified - Unlimited
    Subject Category: 62
    Availability:
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    Report Date: October 1991
    No. Pages: 16
    Keywords:      Automatic control; Computer programming; Expert systems; Flight tests; Computerized simulation; Man machine systems; Management systems; Prototypes; Systems management; Trajectory control; Workstations
    Notes: Presented at the Guidance and Control Panel's 53rd Symposium: Air Vehicle Mission Control and Management, Amsterdam, Netherlands, Octover 22-26, 1991.


  46. SUMMARY OF AEROTHERMAL TEST RESULTS FROM THE FIRST FLIGHT OF THE PEGASUS AIR-LAUNCHED SPACE BOOSTER , Conference Paper
    Authors: Gregory K. Noffz and Robert E. Curry
    Report Number: H-1763
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: Temperature measurements were obtained on the Pegasus booster from launch through Mach 8.0. The majority of sensors were thin-foil temperature gages installed near the surface within the vehicle’s ablating thermal protection system. These gages were distributed on the wing surfaces and on the wing-body fairing or fillet. Temperature time histories from these installations are presented. In addition, thermocouples were installed on the surface of nonablating plugs located on the fairing. These sensors were more responsive to changes in flight conditions than the foil gages and allowed a derivation of convective heat flux. A heating rate magnification of 2 was found in the vicinity of the wing shock interaction.
    Distribution/Availability: Unclassified - Unlimited
    Subject Category: 15
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    Report Date: December 1991
    No. Pages: 28
    Keywords:      Aerothermodynamics; Flight tests; Pegasus air-launched booster; Temperature measurement; Hypersonic speed; Mach number; Thermal protection
    Notes: AIAA Paper 91-5046. Presented at the AIAA 3rd International Aerospace Planes Conference, Orlando, Florida, December 3-5, 1991.


  47. DEVELOPMENT OF A PNEUMATIC HIGH-ANGLE-OF-ATTACK FLUSH AIRDATA SENSING (HI-FADS) SYSTEM , Technical Memorandum
    Authors: Stephen A. Whitmore
    Report Number: NASA-TM-104241
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: A nonintrusive high-angle-of-attack flush airdata sensing system was installed and flight tested in the F-18 High Alpha Research Vehicle. This system consists of a matrix of 25 pressure orifices arranged in concentric circles on the nose of the vehicle to determine angles of attack and sideslip, Mach number, and pressure altitude. During the course of the flight tests, it was determined that satisfactory results could be achieved using a subset of just nine ports.
    Distribution/Availability: Unclassified - Unlimited
    Subject Category: 06
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    Report Date: November 1991
    No. Pages: 28
    Keywords:      Air data systems; Angle of attack; Flight tests; Pneumatics; Pressure sensors; Sideslip; F-18 aircraft; Fault tolerance; Mach numbers; Research aircraft
    Notes: Presented at the SAE Aerotech 1991 Conference, Long Beach, California, September 23-26, 1991.


  48. AN AIRCRAFT MODEL FOR THE AIAA CONTROLS DESIGN CHALLENGE.
    Authors: Randal W. Brumbaugh
    Report Number: NASA-CR-186019
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: This paper describes a generic, state-of-the-art, high-performance aircraft model, including detailed, full-envelope, nonlinear aerodynamics, and full-envelope thrust and first-order engine response data. While this model was primarily developed for the AIAA Controls Design Challenge, the availability of such a model provides a common focus for research in aeronautical control theory and methodology. This paper also describes an implementation of this model using the FORTRAN computer language, associated routines furnished with the aircraft model, and techniques for interfacing these routines to external procedures. Figures showing vehicle geometry, surfaces, and sign conventions are included.
    Distribution/Availability: Unclassified - Unlimited
    Subject Category: 05
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    Report Date: December 1991
    No. Pages: 19
    Keywords:      Simulation; Controls; Design challenge; Model; Numerical simulation
    Notes: Prepared as AIAA 91-2631. Presented at the AIAA GNC Conference, New Orleans, Louisiana, August 12, 1991. Technical Monitor: Vince Chacon


  49. THERMAL-STRUCTURAL PANEL BUCKLING TESTS , Technical Memorandum
    Authors: Randolph C. Thompson and W. Lance Richards
    Report Number: NASA-TM-104243
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: The buckling characteristics of a titanium matrix composite hat-stiffened panel were experimentally examined for various combinations of thermal and mechanical loads. Panel failure was prevented by maintaining the applied loads below real-time critical buckling predictions. The test techniques used to apply the loads, minimize boundary were shown to compare well with a finite-element buckling analysis for previous panels. Comparisons between test predictions and analysis for this panel are ongoing.
    Distribution/Availability: Unclassified - Unlimited
    Subject Category: 39
    Availability:
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          PDF (1,581 KBytes)
    Report Date: December 1991
    No. Pages: 22
    Keywords:      Buckling; Composite structures; Finite element method; Load tests; Metal matrix compsites; Panels; Prediction analysis techniques; Spacecraft construction materials; Titanium
    Notes: Presented at the Structural Testing Technology at High Temperature Conference, Dayton, Ohio, November 4-6, 1991.


  50. FLOW OF SUPERCRITICAL HYDROGEN IN RECTANGULAR DUCTS , UCLA Ph.D. dissertation
    Authors: Baek Youn
    Report Number: H-2288
    Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
    Abstract: Turbulent flow of supercritical hydrogen through rectangular ducts has been investigated using numerical methods, in order to expand the database available for the design of active cooling systems for hypersonic aircraft. The 'PHOENICS' computer code system was used for the computations, which required special provision for: evaluation of supercritical hydrogen thermophysical properties, a low Reynolds number form of the k-e turbulence model, wall functions for smooth and rough walls, and coupling of wall conduction to convective heat transport. The turbulence modeling and computational method were evaluated by computing circular tube flows for both constant properties and for supercritical hydrogen. Good agreement with experiment was demonstrated. A simple model of coupled conduction and convection in cooling panels was developed and used for preliminary optimization indicated appropriate parameter values for 'exact' numerical simulation, and corresponding computations were made. These results were used to assess the validity of the preliminary optimization, with special attention given to the effect of conduction in channel side-walls, and augmentation of heat transfer by transverse ribs.
    Distribution/Availability: Unclassified - Unlimited
    Subject Category: n.a.
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    Report Date: June 1991
    No. Pages: 254
    Funding Organization: NASA Grant number NCC-2-374
    Keywords:      n.a.
    Notes: This document is the result of work sponsored by NASA Dryden Flight Research Center and performed through the UCLA, Flight Systems Research Center. Contract monitor was Robert Quinn, and funding was facilitated by Dr. Kenneth Iliff.
 
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