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- FLIGHT EXPERIENCE WITH A FAIL-OPERATIONAL DIGITAL FLY-BY-WIRE CONTROLSYSTEM , Conference Paper
Authors: S. R. Brown and K. J. Szalai
Report Number: H-1002
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: The NASA Dryden Flight Research Center is flight testing a triply redundant digital fly-by-wire (DFBW) control system installed in an F-8 aircraft. The full-time, full-authority system performs three-axis flight control computations, including stability and command augmentation, autopilot functions, failure detection and isolation, and self-test functions. Advanced control law experiments include an active flap mode for ride smoothing and maneuver drag reduction. This paper discusses research being conducted on computer synchronization, fault detection, fault isolation, and recovery from transient faults. The F-8 DFBW system has demonstrated immunity from nuisance fault declarations while quickly identifying truly faulty components.
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Report Date: January 1977
No. Pages: 14
Keywords: Aircraft control; Avionics; Digital systems; Flight tests; Fly by wire control.
Notes: In: Digital Avionics Systems Conference, 2nd, Los Angeles, Calif., November 2-4, 1977, Collection of Technical Papers. New York, American Institute of Aeronautics and Astronautics, Inc., 1977, p. 186-199. AIAA Paper 77-1507.
- F-8 SUPERCRITICAL WING FLIGHT PRESSURE, BOUNDARY LAYER, AND WAKE MEASUREMENTS AND COMPARISONS WITH WIND TUNNEL DATA , Technical Memorandum
Authors: L. C. Montoya and R. D. Banner
Report Number: NASA-TM-X-3544
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: Data for speeds from Mach 0.50 to Mach 0.99 are presented for configurations with and without fuselage area-rule additions, with and without leading-edge vortex generators, and with and without boundary-layer trips on the wing. The wing pressure coefficients are tabulated. Comparisons between the airplane and model data show that higher second velocity peaks occurred on the airplane wing than on the model wing. The differences were attributed to wind tunnel wall interference effects that caused too much rear camber to be designed into the wing. Optimum flow conditions on the outboard wing section occurred at Mach 0.98 at an angle of attack near 4 deg. The measured differences in section drag with and without boundary-layer trips on the wing suggested that a region of laminar flow existed on the outboard wing without trips.
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Report Date: June 1977
No. Pages: 194
Keywords: Aircraft wakes; F-8 aircraft; Subsonic flow; Supercritical wings; Wind tunnel tests.
- FLIGHT-MEASURED LIFT AND DRAG CHARACTERISTICS OF A LARGE, FLEXIBLE, HIGH SUPERSONIC CRUISE AIRPLANE , Technical Memorandum
Authors: H. H. Arnaiz
Report Number: NASA-TM-X-3532
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: Flight measurements of lift, drag, and angle of attack were obtained for the XB-70 airplane, a large, flexible, high supersonic cruise airplane. This airplane had a length of over 57 meters, a takeoff gross mass of over 226,800 kilograms, and a design cruise speed of Mach 3 at an altitude of 21,340 meters. The performance measurements were made at Mach numbers from 0.72 to 3.07 and altitudes from approximately 7620 meters to 21,340 meters. The measurements were made to provide data for evaluating the techniques presently being used to design and predict the performance of aircraft in this category. Such performance characteristics as drag polars, lift-curve slopes, and maximum lift-to-drag ratios were derived from the flight data. The base drag of the airplane, changes in airplane drag with changes in engine power setting at transonic speeds, and the magnitude of the drag components of the propulsion system are also discussed.
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Report Date: May 1977
No. Pages: 63
Keywords: Aerodynamic drag; Angle of attack; B-70 aircraft; Flight characteristics; Lift.
- VORTEX ATTENUATION FLIGHT EXPERIMENTS
Authors: M. R. Barber, E. C. Hastings, Jr., R. A. Champine and J. J. Tymczyszyn
Report Number: H-929
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: Flight tests evaluating the effects of altered span loading, turbulence ingestion, combinations of mass and turbulence ingestion, and combinations of altered span loading turbulance ingestion on trailed wake vortex attenuation were conducted. Span loadings were altered in flight by varying the deflections of the inboard and outboard flaps on a B-747 aircraft. Turbulence ingestion was achieved in flight by mounting splines on a C-54G aircraft. Mass and turbulence ingestion was achieved in flight by varying the thrust on the B-747 aircraft. Combinations of altered span loading and turbulence ingestion were achieved in flight by installing a spoiler on a CV-990 aircraft and by deflecting the existing spoilers on a B-747 aircraft. The characteristics of the attenuated and unattenuated vortexes were determined by probing them with smaller aircraft. Acceptable separation distances for encounters with the attenuated and unattenuated vortexes are presented.
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Subject Category: 02
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Report Date: January 1977
No. Pages: 35
Keywords: Aircraft wakes; Boeing 747 aircraft; Flight tests; Vortex breakdown; Vortices.
Notes: In its Wake Vortex Minimization p 369-403.
- EQUATIONS FOR THE DETERMINATION OF HUMIDITY FROM DEWPOINT AND PSYCHROMETRIC DATA , Technical Note
Authors: O. O. Parish and T. W. Putnam
Report Number: NASA-TN-D-8401
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: A general expression based on the Claperon-Clausius differential equation that relates saturation vapor pressure, absolute temperature, and the latent heat of transformation was derived that expresses saturation vapor pressure as a function of absolute temperature. This expression was then used to derive general expressions for vapor pressure, absolute humidity, and relative humidity as functions of either dewpoint and ambient temperature or psychrometric parameters. Constants for all general expressions were then evaluated to give specific expressions in both the international system of units and U.S. customary units for temperatures above and below freezing.
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Subject Category: 70
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Report Date: January 1977
No. Pages: 24
Keywords: Atmospheric temperature; Dew; Differential equations; Humidity; Water vapor.
- BUFFET CHARACTERISTICS OF THE F-8 SUPERCRITICAL WING AIRPLANE , Technical Memorandum
Authors: V. M. DeAngelis and R. C. Monaghan
Report Number: NASA-TM-56049
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: The buffet characteristics of the F-8 supercritical wing airplane were investigated. Wing structural response was used to determine the buffet characteristics of the wing and these characteristics are compared with wind tunnel model data and the wing flow characteristics at transonic speeds. The wingtip accelerometer was used to determine the buffet onset boundary and to measure the buffet intensity characteristics of the airplane. The effects of moderate trailing edge flap deflections on the buffet onset boundary are presented. The supercritical wing flow characteristics were determined from wind tunnel and flight static pressure measurements and from a dynamic pressure sensor mounted on the flight test airplane in the vicinity of the shock wave that formed on the upper surface of the wing at transonic speeds. The comparison of the airplane's structural response data to the supercritical flow characteristics includes the effects of a leading edge
vortex generator.
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Report Date: September 1977
No. Pages: 31
Keywords: Buffeting; F-8 aircraft; Flight tests; Flow characteristics; Supercritical wings..
- PHUGOID CHARACTERISTICS OF A YF-12 AIRPLANE WITH VARIABLE-GEOMETRY INLETS OBTAINED IN FLIGHT TESTS AT A MACH NUMBER OF 2.9 , Technical Paper
Authors: B. G. Powers
Report Number: NASA-TP-1107
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: Flight tests were conducted with the YF-12 airplane to examine the airplane's longitudinal characteristics at a Mach number of approximately 2.9. Phugoid oscillations as well as short period pulses were analyzed with the variable geometry engine inlets in the fixed and the automatic configurations. Stability and control derivatives for the velocity and altitude degrees of freedom and the standard short period derivatives were obtained. Inlet bypass door position was successfully used to represent the total inlet system, and the effect of the inlets on the velocity and altitude derivatives was determined. The phugoid mode of the basic airplane (fixed inlet configuration) had neutral damping, and the height mode was stable. With the addition of the inlets in the automatic configuration, the phugoid mode was slightly divergent and the height mode was divergent with a time to double amplitude of about 114 seconds. The results of the derivative
estimation indicated that the change in the height mode characteristics was primarily the result of the change in the longitudinal force derivative with respect to velocity.
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Report Date: November 1977
No. Pages: 45
Keywords: Flight tests; Intake systems; Longitudinal control; Oscillations; YF-12 aircraft.
- THE USE OF A SIMPLIFIED STRUCTURAL MODEL AS AN AID IN THE STRAIN GAGE CALIBRATION OF A COMPLEX WING , Technical Memorandum
Authors: J. M. Jenkins, A. E. Kuhl and A. L. Carter
Report Number: NASA-TM-56046
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: The use of a relatively simple structural model to characterize the load responses of strain gages located on various spars of a delta wing is examined. Strains measured during a laboratory load calibration of a wing structure are compared with calculations obtained from a simplified structural analysis model. Calculated and measured influence coefficient plots that show the shear, bending, and torsion characteristics of typical strain gage bridges are presented. Typical influence coefficient plots are shown for several load equations to illustrate the derivation of the equations from the component strain gage bridges. A relatively simple structural model was found to be effective in predicting the general nature of strain distributions and influence coefficient plots. The analytical processes are shown to be an aid in obtaining a good load calibration. The analytical processes cannot, however, be used in lieu of an actual load calibration of an
aircraft wing.
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Subject Category: 39
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Report Date: July 1977
No. Pages: 19
Keywords: Bending; Calibrating; Shear properties; Strain gages; Structural design criteria.
- INFLUENCE OF STRUCTURAL DYNAMICS ON VEHICLE DESIGN - GOVERNMENT VIEW , Conference Paper
Authors: E. E. Kordes
Report Number: H-966
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: Dynamic design considerations for aerospace vehicles are discussed, taking into account fixed wing aircraft, rotary wing aircraft, and launch, space, and reentry vehicles. It is pointed out that space vehicles have probably had the most significant design problems from the standpoint of structural dynamics, because their large lightweight structures are highly nonlinear. Examples of problems in the case of conventional aircraft include the flutter encountered by high performance military aircraft with external stores. A description is presented of a number of examples which illustrate the direction of present efforts for improving aircraft efficiency. Attention is given to the results of studies on the structural design concepts for the arrow-wing supersonic cruise aircraft configuration and a system study on low-wing-loading, short haul transports.
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Report Date: January 1977
No. Pages: 3
Keywords: Aerospace vehicles; Aircraft design; Design analysis; Dynamic structural analysis; Spacecraft design.
Notes: In: Structures, Structural Dynamics and Materials Conference, 18th, March 21-23, 1977, and Dynamics Specialist Conference, San Diego, Calif., March 24, 25, 1977, Technical Papers. Volume B. (A77-25778 10-01) New York, American Institute of Aeronautics and Astronautics, Inc., 1977, p. 174-176.
- RESULTS OF A REMOTE MULTIPLEXER/DIGITIZER UNIT ACCURACY AND ENVIRONMENTAL STUDY , Technical Memorandum
Authors: D. O. Wilner
Report Number: NASA-TM-X-56043
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: A remote multiplexer/digitizer unit (RMDU), a part of the airborne integrated flight test data system, was subjected to an accuracy study. The study was designed to show the effects of temperature, altitude, and vibration on the RMDU. The RMDU was subjected to tests at temperatures from -54 C (-65 F) to 71 C (160 F), and the resulting data are presented here, along with a complete analysis of the effects. The methods and means used for obtaining correctable data and correcting the data are also discussed.
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Subject Category: 35
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Report Date: January 1977
No. Pages: 49
Keywords: Data acquisition; Digital systems; Environmental tests; Flight tests; Multiplexing; Pulse code modulation.
- REDUCED TRUCK FUEL CONSUMPTION THROUGH AERODYNAMIC DESIGN , Journal Article
Authors: L. L. Steers and E. J. Saltzman
Report Number: H-968
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
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Subject Category: 85
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Report Date: October 1977
No. Pages: 7
Keywords: Aerodynamic configurations; Drag reduction; Fuel consumption; Structural design; Trucks.
Notes: Journal of Energy, vol. 1, Sept.-Oct. 1977, p. 312-318.
- UNSTEADY AERODYNAMIC MODELING FOR ARBITRARY MOTIONS , Journal Article
Authors: J. W. Edwards
Report Number: H-969
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: Results indicating that unsteady aerodynamic loads derived under the assumption of simple harmonic motions executed by airfoil or wing can be extended to arbitrary motions are summarized. The generalized Theodorsen (1953) function referable to loads due to simple harmonic oscillations of a wing section in incompressible flow, the Laplace inversion integral for unsteady aerodynamic loads, calculations of root loci of aeroelastic loads, and analysis of generalized compressible transient airloads are discussed.
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Report Date: April 1977
No. Pages: 3
Keywords: Aerodynamic loads; Aeroelasticity; Dynamic models; Unsteady aerodynamics; Wing Loading.
Notes: AIAA Journal, vol. 15, Apr. 1977, p. 593-595.
- PROBLEMS ASSOCIATED WITH ATTACHING STRAIN GAGES TO TITANIUM ALLOY TI-6AL-4V , Technical Memorandum
Authors: Jerald M. Jenkins
Report Number: NASA-TM-X-56044
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: Weldable strain gages have shown excellent high temperature characteristics for supersonic cruise aircraft application. The spotwelding attachment method, however, has resulted in serious reductions in the fatigue life of titanium alloy (Ti-6Al-4V) fatigue specimens. The reduction is so severe that the use of weldable strain gages on operational aircraft must be prohibited. The cause of the fatigue problem is thought to be a combination of the microstructure changes in the material caused by spotwelding and the presence of the flange of the stain gage. Brazing, plating, and plasma spraying were investigated as substitutes for spotwelding. The attachment of a flangeless gage by plasma spraying provided the most improvement in the fatigue life of the titanium.
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Report Date: February 1977
No. Pages: 19
Keywords: Fatigue (materials); Spot welds; Strain gages; Temperature effects; Titanium alloys.
- MAXIMUM LIKELIHOOD ESTIMATION OF AERODYNAMIC DERIVATIVES FOR AN OBLIQUE WING AIRCRAFT FROM FLIGHT DATA , Conference Paper
Authors: R. E. Maine
Report Number: H-979
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: There are several practical problems in using current techniques on 5-degree-of-freedom equations to estimate the stability and control derivatives of oblique wing aircraft from flight data. A technique has been developed to estimate these derivatives by separating the analysis of the longitudinal and lateral-directional motion without neglecting cross-coupling effects. This technique was used on flight data from a remotely piloted oblique wing aircraft. The results demonstrated that the relatively simple approach developed was adequate to obtain high quality estimates of the aerodynamic derivatives of such aircraft.
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Report Date: January 1977
No. Pages: 10
Keywords: Aerodynamic characteristics; Aircraft configurations; Coupled modes; Maximum likelihood estimates; Oblique wings.
Notes: In: Atmospheric Flight Mechanics Conference, Hollywood, Fla., August 8-10, 1977, Technical Papers. New York, American Institute of Aeronautics and Astronautics, Inc., 1977, p. 124-133. AIAA Paper 77-1135.
- FURTHER OBSERVATIONS ON MAXIMUM LIKELIHOOD ESTIMATES OF STABILITY AND CONTROL CHARACTERISTICS OBTAINED FROM FLIGHT DATA , Conference Paper
Authors: K. W. Iliff and R. E. Maine
Report Number: H-982
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: A maximum likelihood estimation method for flight test data is described. Flight results based on 3000 maneuvers from 30 aircraft on the effect of resolution and sampling rate on the estimates, on understanding the discrepancies previously observed in the magnitude of the Cramer-Rao bounds, on the scale effects on the derivative estimates obtained from dynamic aircraft flight maneuvers, and on the analysis of lateral-directional maneuvers obtained in turbulence, are presented.
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Report Date: January 1977
No. Pages: 13
Keywords: Aircraft control; Aircraft maneuvers; Flight stability tests; Maximum likelihood estimates; Stability derivatives.
Notes: In: Atmospheric Flight Mechanics Conference, Hollywood, Fla., August 8-10, 1977, Technical Papers. New York, American Institute of Aeronautics and Astronautics, Inc., 1977, p. 100-112. AIAA Paper 77-1133.
- ACTIVE FLUTTER CONTROL USING GENERALIZED UNSTEADY AERODYNAMIC THEORY , Conference Paper
Authors: J. W. Edwards, J. V. Breakwell and A. E. Bryson, Jr.
Report Number: H-983
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: This paper describes the application of generalized unsteady aerodynamic theory to the problem of active flutter control. The controllability of flutter modes is investigated. It is shown that the response of aeroelastic systems is composed of a portion due to a rational transform and a portion due to a nonrational transform. The oscillatory response characteristic of flutter is due to the rational portion, and a theorem is given concerning the construction of a linear, finite-dimensional model of this portion of the system. The resulting rational model is unique and does not require state augmentation. Active flutter control designs using optimal regulator synthesis are presented.
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Report Date: January 1977
No. Pages: 14
Keywords: Aerodynamic forces; Aircraft structures; Flutter analysis; Optimal control; Structural vibration.
Notes: In: Guidance and Control Conference, Hollywood, Fla., August 8-10, 1977, Technical Papers. New York, American Institute of Aeronautics and Astronautics, Inc., 1977, p. 172-185.
- A STUDY OF THE EFFECT OF RADICAL LOAD DISTRIBUTIONS ON CALIBRATED STRAIN GAGE LOAD EQUATIONS , Technical Memorandum
Authors: J. M. Jenkins and A. E. Kuhl
Report Number: NASA-TM-56047
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: For several decades, calibrated strain gages have been used to measure loads on airplanes. The accuracy of the equations used to relate the strain gage measurements to the applied loads has been based primarily on the results of the load calibration. An approach is presented for studying the effect of widely varying load distributions on strain gage load equations. The computational procedure provides a link between the load calibration and the load to be measured in flight. A matrix approach to equation selection is presented, which is based on equation standard error, load distribution, and influence coefficient plots of the strain gage equations, and is applied to a complex, delta-wing structure.
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Report Date: July 1977
No. Pages: 36
Keywords: Delta wings; Flight load recorders; Load distribution (forces); Matrices (mathematics); Strain gages.
- RECENT LOADS CALIBRATION EXPERIENCE WITH A DELTA WING AIRPLANE , Conference Paper
Authors: Jerald M. Jenkins and Albert E. Kuhl
Report Number: H-986
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
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Report Date: September 1977
Notes: Presented at Fall Meeting, Western Regional Strain Gage Committee, Society for Experimental Stress Analysis, September 28, 1977.
- SPACE SHUTTLE ORBITER APPROACH AND LANDING PROGRAM STATUS , Conference Paper
Authors: W. H. Andrews
Report Number: H-987
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: The space shuttle approach and landing test (ALT) program is being conducted in four phases. The first phase, completed in March of 1977, consisted of verifying the airworthiness of the mated B-747 shuttle carrier aircraft and orbiter. The second phase consists of checking the orbiter systems in captive flight. The third phase is to be confined to launching the orbiter with and without the tail cone installed to evaluate the final landing phase of the shuttle operations through the verification of the automatic landing system. The fourth and final phase of the program is to document the mated configuration's performance relative to the ferry operations to be conducted between the return from the orbiter's landing sites and launch sites. This paper presents the results of the SCA inert orbiter flight testing and the program plans up to the completion of the ALT program.
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Report Date: August 1977
No. Pages: 15
Keywords: Aircraft reliability; Captive tests; Flight tests; Space shuttle orbiters; Spacecraft recovery.
Notes: American Institute of Aeronautics and Astronautics, Aircraft Systems and Technology Meeting, Seattle, Wash., Aug. 22-24, 1977, 15 p. AIAA Paper 77-1204.
- LOADS CALIBRATION EXPERIENCE WITH A REENTRY WING STRUCTURE , Conference Paper
Authors: Walter J. Sefic and Alan L. Carter
Report Number: H-989
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
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Report Date: September 1977
Notes: Presented at Fall Meeting, Western Regional Strain Gage Committee, Society for Experimental Stress Analysis, September 28, 1977.
- ANALYSIS OF A LOADS CALIBRATION OF A HYPERSONIC CRUISE WING TEST STRUCTURE , Conference Paper
Authors: Ming H. Tang and Roger A. Fields
Report Number: H-994
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
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Report Date: September 1977
Notes: Presented at Fall Meeting, Western Regional Strain Gage Copmmittee, Society for Experimental Stress Analysis, September 28, 1977.
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