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- AERODYNAMIC DERIVATIVES FOR AN OBLIQUE WING AIRCRAFT ESTIMATED FROM FLIGHT DATA BY USING A MAXIMUM LIKELIHOOD TECHNIQUE , Technical Paper
Authors: R. E. Maine
Report Number: NASA-TP-1336
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: There are several practical problems in using current techniques with five degree of freedom equations to estimate the stability and control derivatives of oblique wing aircraft from flight data. A technique was developed to estimate these derivatives by separating the analysis of the longitudinal and lateral directional motion without neglecting cross coupling effects. Although previously applied to symmetrical aircraft, the technique was not expected to be adequate for oblique wing vehicles. The application of the technique to flight data from a remotely piloted oblique wing aircraft is described. The aircraft instrumentation and data processing were reviewed, with particular emphasis on the digital filtering of the data. A complete set of flight determined stability and control derivative estimates is presented and compared with predictions. 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: October 1978
No. Pages: 73
Keywords: Aerodynamic characteristics; Aircraft configurations; Degrees of freedom; Stability derivatives; Wings
- FLIGHT-DETERMINED STABILITY AND CONTROL DERIVATIVES FOR THE F-111 TACT RESEARCH AIRCRAFT , Technical Paper
Authors: A. G. Sim and R. E. Curry
Report Number: NASA-TP-1350
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: A flight investigation was conducted to provide a stability and control derivative data base for the F-111 transonic aircraft technology research aircraft. Longitudinal and lateral-directional data were obtained as functions of Mach number, angle of attack, and wing sweep. For selected derivatives, the flight results were correlated with derivatives calculated based on vehicle geometry. The validity of the angle of attack measurement was independently verified at a Mach number of 0.70 for angles of attack between 3 and 10 degrees.
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Report Date: October 1978
No. Pages: 78
Keywords: Aircraft stability; F-111 aircraft; Stability derivatives; Aircraft design; Angle of attack; Flight tests; Mach number; Supercritical wings; Variable sweep wings
- FLIGHT TESTS OF A RADIO-CONTROLLED AIRPLANE MODE WITH A FREE-WING, FREE-CANARD CONFIGURATION , Technical Memorandum
Authors: S. W. Gee
Report Number: NASA-TM-72853
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: Flight characteristics, controllability, and potential operating problems were investigated in a radio-controlled airplane model in which the wing is so attached to the fuselage that it is free to pivot about a spanwise axis forward of its aerodynamic center and is subject only to aerodynamic pitching moments imposed by lift and drag forces and a control surface. A simple technique of flying the test vehicle in formation with a pickup truck was used to obtain trim data. The test vehicle was flown through a series of maneuvers designed to permit evaluation of certain characteristics by observation. The free-wing free-canard concept was determined to be workable. Stall/spin characteristics were considered to be excellent, and no effect on longitudinal stability was observed when center of gravity changes were made. Several problems were encountered during the early stages of flight testing, such as aerodynamic lockup of the free canard and excessive
control sensitivity. Lack of onboard instrumentation precluded any conclusions about gust alleviation or ride qualities.
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Report Date: January 1978
No. Pages: 13
Keywords: Aircraft models; Body-wing configurations; Canard configurations; Flight tests; Radio control; Wings
- AN EFFICIENT ALGORITHM FOR CHOOSING THE DEGREE OF A POLYNOMIAL TO APPROXIMATE DISCRETE NONOSCILLATORY DATA , Technical Memorandum
Authors: D. R. Hedgley
Report Number: NASA-TM-72854
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: An efficient algorithm for selecting the degree of a polynomial that defines a curve that best approximates a data set was presented. This algorithm was applied to both oscillatory and nonoscillatory data without loss of generality.
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Subject Category: 64
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Report Date: April 1978
No. Pages: 8
Keywords: Algorithms; Curve fitting; Polynominals; Approximation; Computer programs; Least square method
- COMPARISON OF CALCULATED AND ALTITUDE-FACILITY-MEASURED THRUST AND AIRFLOW OF TWOPROTOTYPE F100 TURBOFAN ENGINES , Technical Paper
Authors: F. J. Kurtenbach
Report Number: NASA-TP-1373
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: A comparison is made of the facility performance data for the two engines with an engine performance model, and it provides corrections that can be applied to the model so that it represents the test engines accurately over the flight envelope. Test conditions ranged from Mach numbers of 0.80 to 2.00 and altitudes from 4020 meters to 15,240 meters. Two distortion screens were used to determine the effect of distortion on airflow. Reynolds number effects were also determined. Engine hysteresis is documented, as is an attempt to determine engine degradation. The calibrated engine model had a twice standard deviation accuracy of approximately 1.24 percent for corrected airflow and 2.38 percent for gross thrust.
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Report Date: December 1978
No. Pages: 29
Keywords: Air flow; Jet thrust; Thrust measurement; Turbofan engines; Comparison; Flow distortion; Hyteresis; Performance tests; Prototypes
- MEASUREMENTS AND PREDICTIONS OF FLYOVER AND STATIC NOISE OF A TF30 AFTERBURNING TURBOFAN ENGINE , Technical Paper
Authors: F. W. Burcham, Jr., P. L. Lasagna and S. C. Oas (Boeing Com. Airplance Co.)
Report Number: NASA-TP-1372
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: The noise of the TF30 afterburning turbofan engine in an F-111 airplane was determined from static (ground) and flyover tests. A survey was made to measure the exhaust temperature and velocity profiles for a range of power settings. Comparisons were made between predicted and measured jet mixing, internal, and shock noise. It was found that the noise produced at static conditions was dominated by jet mixing noise, and was adequately predicted by current methods. The noise produced during flyovers exhibited large contributions from internally generated noise in the forward arc. For flyovers with the engine at nonafterburning power, the internal noise, shock noise, and jet mixing noise were accurately predicted. During flyovers with afterburning power settings, however, additional internal noise believed to be due to the afterburning process was evident; its level was as much as 8 decibels above the nonafterburning internal noise. Power settings that
produced exhausts with inverted velocity profiles appeared to be slightly less noisy than power settings of equal thrust that produced uniform exhaust velocity profiles both in flight and in static testing.
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Report Date: December 1978
No. Pages: 94
Keywords: Afterburning; Engine noise; F-111 aircraft; Noise measurement; Turbofan engines
- COMPARISON OF CONCURRENT STRAIN GAGE- AND PRESSURE TRANSDUCER-MEASURED FLIGHT LOADS ON A LIFTINGREENTRY VEHICLE AND CORRELATION WITH WIND TUNNELPREDICTIONS , Technical Paper
Authors: M. H. Tang, W. J. Sefic and R. G. Sheldon
Report Number: NASA-TP-1331
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: Concurrent strain gage and pressure transducer measured flight loads on a lifting reentry vehicle are compared and correlated with wind tunnel-predicted loads. Subsonic, transonic, and supersonic aerodynamic loads are presented for the left fin and control surfaces of the X-24B lifting reentry vehicle. Typical left fin pressure distributions are shown. The effects of variations in angle of attack, angle of sideslip, and Mach number on the left fin loads and rudder hinge moments are presented in coefficient form. Also presented are the effects of variations in angle of attack and Mach number on the upper flap, lower flap, and aileron hinge-moment coefficients. The effects of variations in lower flap hinge moments due to changes in lower flap deflection and Mach number are presented in terms of coefficient slopes.
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Subject Category: 02
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Report Date: October 1978
No. Pages: 42
Keywords: Aerodynamic loads; Flight load recorders; Lifting reentry vehicles; Pressure sensors; Strain gages
- UTILIZATION OF THE WING-BODY AERODYNAMIC ANALYSIS PROGRAM , Technical Memorandum
Authors: R. E. Curry
Report Number: NASA-TM-72856
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: The analysis program was used to investigate several aircraft characteristics. The studies performed included vehicle stability analysis, determination of upwash angle, identification of nonpotential flow, launch dynamics, and wake vortex upset loads. The techniques and are discussed. When possible, computed results are compared with experimental data.
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Report Date: October 1978
No. Pages: 29
Keywords: Aerodynamic characteristics; Aircraft stability; Computer programs; Aircraft wakes; Body-wing configurations; F-111 aircraft; Vortices
- CORRELATION OF PREDICTED AND MEASURED THERMAL STRESSES ON A TRUSS-TYPE AIRCRAFT STRUCTURE , Technical Memorandum
Authors: J. M. Jenkins, L. S. Schuster and A. L. Carter
Report Number: NASA-TM-72857
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: A test structure representing a portion of a hypersonic vehicle was instrumented with strain gages and thermocouples. This test structure was then subjected to laboratory heating representative of supersonic and hypersonic flight conditions. A finite element computer model of this structure was developed using several types of elements with the NASA structural analysis (NASTRAN) computer program. Temperature inputs from the test were used to generate predicted model thermal stresses and these were correlated with the test measurements.
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Report Date: November 1978
No. Pages: 57
Keywords: Computerized simulation; Hypersonic vehicles; NASTRAN; Thermal stresses; Data correlation; Heat transfer; Prediction analysis techniques; Temperature measurement
- EFFECT OF SAMPLING RATE AND RECORD LENGTH ON THE DETERMINATION OF STABILITY AND CONTROL DERIVATIVES , Technical Memorandum
Authors: M. J. Brenner, K. W. Iliff and R. K. Whitman
Report Number: NASA-TM-72858
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: Flight data from five aircraft were used to assess the effects of sampling rate and record length reductions on estimates of stability and control derivatives produced by a maximum likelihood estimation method. Derivatives could be extracted from flight data with the maximum likelihood estimation method even if there were considerable reductions in sampling rate and/or record length. Small amplitude pulse maneuvers showed greater degradation of the derivative maneuvers than large amplitude pulse maneuvers when these reductions were made. Reducing the sampling rate was found to be more desirable than reducing the record length as a method of lessening the total computation time required without greatly degrading the quantity of the estimates.
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Subject Category: 08
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Report Date: December 1978
No. Pages: 140
Keywords: Controllability; Estimating; Sampling; Stability derivatives; Aircraft maneuvers; Flight control; Graphics (charts); Maximum likelihood estimates
- DIGITAL FLY-BY-WIRE FLIGHT CONTROL VALIDATION EXPERIENCE , Technical Memorandum
Authors: K. J. Szalai, C. R. Jarvis, G. E. Krier, V. A. Megna, L. D. Brock and R. N. O'Donnell
Report Number: NASA-TM-72860
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: The experience gained in digital fly-by-wire technology through a flight test program being conducted by the NASA Dryden Flight Research Center in an F-8C aircraft is described. The system requirements are outlined, along with the requirements for flight qualification. The system is described, including the hardware components, the aircraft installation, and the system operation. The flight qualification experience is emphasized. The qualification process included the theoretical validation of the basic design, laboratory testing of the hardware and software elements, systems level testing, and flight testing. The most productive testing was performed on an iron bird aircraft, which used the actual electronic and hydraulic hardware and a simulation of the F-8 characteristics to provide the flight environment. The iron bird was used for sensor and system redundancy management testing, failure modes and effects testing, and stress testing in many
cases with the pilot in the loop. The flight test program confirmed the quality of the validation process by achieving 50 flights without a known undetected failure and with no false alarms.
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Report Date: December 1978
No. Pages: 241
Keywords: Digital systems; F-8 aircraft; Flight tests; Fly by wire control; Aircraft hydraulic systems; Computer programs; Electronic equipment; Failure modes; Flight simulation; Hardware; Loops; Stress analysis; Systems analysis
- FLIGHT EVALUATION OF THE TRANSONIC STABILITY AND CONTROL CHARACTERISTICS OF AN AIRPLANE INCORPORATING A SUPERCRITICAL WING , Technical Paper
Authors: N. W. Matheny and D. H. Gatlin
Report Number: NASA-TP-1167
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: A TF-8A airplane was equipped with a transport type supercritical wing and fuselage fairings to evaluate predicted performance improvements for cruise at transonic speeds. A comparison of aerodynamic derivatives extracted from flight and wind tunnel data showed that static longitudinal stability, effective dihedral, and aileron effectiveness, were higher than predicted. The static directional stability derivative was slower than predicted. The airplane's handling qualities were acceptable with the stability augmentation system on. The unaugmented airplane exhibited some adverse lateral directional characteristics that involved low Dutch roll damping and low roll control power at high angles of attack and roll control power that was greater than satisfactory for transport aircraft at cruise conditions. Longitudinally, the aircraft exhibited a mild pitchup tendency. Leading edge vortex generators delayed the onset of flow separation, moving the
pitchup point to a higher lift coefficient and reducing its severity.
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Report Date: February 1978
No. Pages: 61
Keywords: Aerodynamic stability; Aircraft control; Flight tests; Supercritical wings; Transonic Speed
- ANALYTICAL STUDY OF RIDE SMOOTHING BENEFITS OF CONTROL SYSTEM CONFIGURATIONS OPTIMIZED FOR PILOT HANDLING QUALITIES , Technical Paper
Authors: B. G. Powers
Report Number: NASA-TP-1148
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: An analytical study was conducted to evaluate the relative improvements in aircraft ride qualities that resulted from utilizing several control law configurations that were optimized for pilot handling qualities only. The airplane configuration used was an executive jet transport in the approach configuration. The control law configurations included the basic system, a rate feedback system, three command augmentation systems (rate command, attitude command, and rate command/attitude hold), and a control wheel steering system. Both the longitudinal and lateral directional axes were evaluated. A representative example of each control law configuration was optimized for pilot handling qualities on a fixed base simulator. The root mean square airplane responses to turbulence were calculated, and predictions of ride quality ratings were computed by using three models available in the literature.
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Subject Category: 08
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Report Date: February 1978
No. Pages: 60
Keywords: Aircraft control; Control configured vehicles; Pilot performance; Riding quality; Aircraft configurations; Approach control; Command and control; Flight simulators; Performance prediction
- RESULTS FROM FLIGHT AND SIMULATOR STUDIES OF A MACH 3 CRUISE LONGITUDINAL AUTOPILOT , Technical Paper
Authors: G. B. Gilyard and J. W. Smith
Report Number: NASA-TP-1180
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: At Mach numbers of approximately 3.0 and altitudes greater than 21,300 meters, the original altitude and Mach hold modes of the YF-12 autopilot produced aircraft excursions that were erratic or divergent, or both. Flight data analysis and simulator studies showed that the sensitivity of the static pressure port to angle of attack had a detrimental effect on the performance of the altitude and Mach hold modes. Good altitude hold performance was obtained when a high passed pitch rate feedback was added to compensate for angle of attack sensitivity and the altitude error and integral altitude gains were reduced. Good Mach hold performance was obtained when the angle of attack sensitivity was removed; however, the ride qualities remained poor.
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Report Date: April 1978
No. Pages: 85
Keywords: Control simulation; Flight tests; Longitudinal control; Mach number; Angle of attack; Attitude control; Automatic pilots; YF-12 aircraft
- FLIGHT-MEASURED PRESSURE CHARACTERISTICS OF AFT-FACING STEPS IN HIGH REYNOLDS NUMBER FLOW ATMACH NUMBERS OF 2.20, 2.50, AND 2.80 ANDCOMPARISON WITH OTHER DATA , Technical Memorandum
Authors: S. G. Powers
Report Number: NASA-TM-72855
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: The YF-12 airplane was studied to determine the pressure characteristics associated with an aft-facing step in high Reynolds number flow for nominal Mach numbers of 2.20, 2.50, and 2.80. Base pressure coefficients were obtained for three step heights. The surface static pressures ahead of and behind the step were measured for the no-step condition and for each of the step heights. A boundary layer rake was used to determine the local boundary layer conditions. The Reynolds number based on the length of flow ahead of the step was approximately 10 to the 8th power and the ratios of momentum thickness to step height ranged from 0.2 to 1.0. Base pressure coefficients were compared with other available data at similar Mach numbers and at ratios of momentum thickness to step height near 1.0. In addition, the data were compared with base pressure coefficients calculated by a semiempirical prediction method. The base pressure ratios are shown to be a
function of Reynolds number based on momentum thickness. Profiles of the surface pressures ahead of and behind the step and the local boundary layer conditions are also presented.
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Subject Category: 02
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Report Date: May 1978
No. Pages: 38
Keywords: Base pressure; Momentum transfer; Reynolds number; Separated flow; YF-12 aircraft
- DEVELOPMENT OF SYSTEMS AND TECHNIQUES FOR LANDING AN AIRCRAFT USING ONBOARD TELEVISION , Technical Paper
Authors: S. W. Gee, P. C. Carr, W. R. Winter and J. A. Manke
Report Number: NASA-TP-1171
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: A flight program was conducted to develop a landing technique with which a pilot could consistently and safely land a remotely piloted research vehicle (RPRV) without outside visual reference except through television. Otherwise, instrumentation was standard. Such factors as the selection of video parameters, the pilot's understanding of the television presentation, the pilot's ground cockpit environment, and the operational procedures for landing were considered. About 30 landings were necessary for a pilot to become sufficiently familiar and competent with the test aircraft to make powered approaches and landings with outside visual references only through television. When steep approaches and landings were made by remote control, the pilot's workload was extremely high. The test aircraft was used as a simulator for the F-15 RPRV, and as such was considered to be essential to the success of landing the F-15 RPRV.
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Subject Category: 05
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Report Date: February 1978
No. Pages: 24
Keywords: Aircraft landing; F-15 aircraft; Instrument landing systems; Remotely piloted vehicles; Television systems
- DESIGN AND PHYSICAL CHARACTERISTICS OF THE TRANSONIC AIRCRAFT TECHNOLOGY (TACT) RESEARCHAIRCRAFT , Technical Memorandum
Authors: W. D. Painter and L. J. Caw
Report Number: NASA-TM-56048
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: The Transonic Aircraft Technology (TACT) research program provided data necessary to verify aerodynamic concepts, such as the supercritical wing, and to gain the confidence required for the application of such technology to advanced high performance aircraft. An F-111A aircraft was employed as the flight test bed to provide full scale data. The data were correlated extensively with predictions based on data obtained from wind tunnel tests. An assessment of the improvement afforded at transonic speeds in drag divergence, maneuvering performance, and airplane handling qualities by the use of the supercritical wing was included in the program. Transonic flight and wind tunnel testing techniques were investigated, and specific research technologies evaluated were also summarized.
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Subject Category: 02
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Report Date: January 1978
No. Pages: 32
Keywords: Aircraft design; F-111 aircraft; Supercritical wings; TACT program; Transonic flight
- DRAG REDUCTION OBTAINED BY MODIFYING A STANDARD TRUCK , Technical Memorandum
Authors: A. E. Sheridan and S. J. Grier
Report Number: NASA-TM-72846
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: A standard two-axle truck with a box-shaped cargo compartment was tested to determine whether significant reductions in aerodynamic drag could be obtained by modifying the front of the cargo compartment. The coastdown method was used to determine the total drag of the baseline vehicle, which had a square-cornered cargo box, and of several modified configurations. Test velocities ranged from 56.3 to 94.6 kilometers per hour (35 to 60 miles per hour). At 88.5 kilometers per hour (55 miles per hour), the aerodynamic drag reductions obtained with the modified configurations ranged from 8 to 30 percent.
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Subject Category: 34
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Report Date: February 1978
No. Pages: 28
Keywords: Aerodynamic drag; Drag reduction; Structural design; Trucks
- A STATISTICAL PACKAGE FOR COMPUTING TIME AND FREQUENCY DOMAIN ANALYSIS , Technical Memorandum
Authors: J. Brownlow
Report Number: NASA-TM-56045
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: The spectrum analysis (SPA) program is a general purpose digital computer program designed to aid in data analysis. The program does time and frequency domain statistical analyses as well as some preanalysis data preparation. The capabilities of the SPA program include linear trend removal and/or digital filtering of data, plotting and/or listing of both filtered and unfiltered data, time domain statistical characterization of data, and frequency domain statistical characterization of data.
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Subject Category: 65
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Report Date: August 1978
No. Pages: 80
Keywords: Digital filters; Fourier analysis; Frequency analyzers; Spectrum analysis; Time series analysis
- FLIGHT COMPARISON OF THE TRANSONIC AGILITY OF THE F-111A AIRPLANE AND THE F-111 SUPERCRITICAL WING AIRPLANE , Technical Paper
Authors: E. L. Friend and G. M. Sakamoto
Report Number: NASA-TP-1368
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: A flight research program was conducted to investigate the improvements in maneuverability of an F-111A airplane equipped with a supercritical wing. In this configuration the aircraft is known as the F-111 TACT (transonic aircraft technology) airplane. The variable-wing-sweep feature permitted an evaluation of the supercritical wing in many configurations. The primary emphasis was placed on the transonic Mach number region, which is considered to be the principal air combat arena for fighter aircraft. An agility study was undertaken to assess the maneuverability of the F-111A aircraft with a supercritical wing at both design and off-design conditions. The evaluation included an assessment of aerodynamic and maneuver performance in conjunction with an evaluation of precision controllability during tailchase gunsight tracking tasks.
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Report Date: December 1978
No. Pages: 79
Keywords: Buffeting; handling qualities; energy maneuverability; gunsight tracking; supercritical wing; F-111 TACT airplane
- FLIGHT-MEASURED BUFFET CHARACTERISTICS OF A SUPERCRITICAL WING AND A CONVENTIONAL WING ON A VARIABLE-SWEEP AIRPLANE , Technical Paper
Authors: R. C. Monaghan
Report Number: NASA-TP-1244
Performing Organization: NASA Dryden Flight Research Center, Edwards, CA
Abstract: Windup-turn maneuvers were performed to assess the buffet characteristics of the F-111A aircraft and the same aircraft with a supercritical wing, which is referred to as the F-111 transonic aircraft technology (TACT) aircraft. Data were gathered at wing sweep angles of 26, 35, and 58 deg for Mach numbers from 0.60 to 0.95. Wingtip accelerometer data were the primary source of buffet information. The analysis was supported by wing strain-gage and pressure data taken in flight, and by oil-flow photographs taken during tests of a wind tunnel model. In the transonic speed range, the overall buffet characteristics of the aircraft having a supercritical wing are significantly improved over those of the aircraft having a conventional wing.
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Subject Category: 02
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Report Date: May 1978
No. Pages: 40
Keywords: Buffeting; F-111 aircraft; Supercritical wings; Variable sweep wings; Pressure measurement; Schilieren photography; Wind tunnel models
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