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  • 1
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    A study of transonic aerodynamic analysis methods for use with a hypersonic aircraft synthesis code (1992)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A means of performing routine transonic lift, drag, and moment analyses on hypersonic all-body and wing-body configurations were studied. The analysis method is to be used in conjunction with the Hypersonic Vehicle Optimization Code (HAVOC). A review of existing techniques is presented, after which three methods, chosen to represent a spectrum of capabilities, are tested and the results are compared with experimental data. The three methods consist of a wave drag code, a full potential code, and a Navier-Stokes code. The wave drag code, representing the empirical approach, has very fast CPU times, but very limited and sporadic results. The full potential code provides results which compare favorably to the wind tunnel data, but with a dramatic increase in computational time. Even more extreme is the Navier-Stokes code, which provides the most favorable and complete results, but with a very large turnaround time. The full potential code, TRANAIR, is used for additional analyses, because of the superior results it can provide over empirical and semi-empirical methods, and because of its automated grid generation. TRANAIR analyses include an all body hypersonic cruise configuration and an oblique flying wing supersonic transport.
    Keywords: AERODYNAMICS
    Type: NASA-CR-189854 , NAS 1.26:189854
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Comparison of theoretical and flight-measured local flow aerodynamics for a low-aspect-ratio fin (1986)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Flight test and theoretical aerodynamic data were obtained for a flight test fixture mounted on the underside of an F-104G aircraft. The theoretical data were generated using two codes: a two-dimensional transonic code called code H, and a three-dimensional subsonic and supersonic code called wing-body. Pressure distributions generated by the codes for the flight test fixture, as well as compared with the flight-measured data. The two-dimensional code pressure distributions compared well except at the minimum pressure point and the trailing edge. Shock locations compared well except at high transonic speeds. However, the two-dimensional code did not adequately predict the displacement thickness of the flight test fixture. The three-dimensional code pressure distributions compared well except at the trailing edge of the flight test fixture.
    Keywords: AERODYNAMICS
    Type: NASA-TM-86806 , H-1336 , NAS 1.15:86806
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Analysis of leading edge separation using a low order panel method (1989)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An examination of the potential flow computer code VSAERO to model leading edge separation over a delta wing is examined. Recent improvements to the code suggest that it may be capable of predicting pressure coefficients on the body. Investigation showed that although that code does predict the vortex roll-up, the pressure coefficients have significant error. The program is currently unsatisfactory, but with some additional development it may become a useful tool for this application.
    Keywords: AERODYNAMICS
    Type: NASA-CR-185892 , NAS 1.26:185892
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Takeoff predictions for powered-lift aircraft (1988)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Takeoff predictions for powered-lift short takeoff (STO) and conventional takeoff (CTO) aircraft have been added to NASA Ames Research Center's Aircraft Synthesis (ACSYNT) code. The new computer code predicts the aircraft engine and nozzle settings required to achieve the minimum takeoff roll. As a test case, the code predicted takeoff ground rolls and nozzle settings for the YAV-8B Harrier that compared well with measured values. Brief analysis of takeoff performance for an Ejector, Remote Augmented Lift, Hybrid-Tandem Fan, and Vectored Thrust STO aircraft using the new routine will be presented.
    Keywords: AERONAUTICS (GENERAL)
    Type: NASA-CR-177491 , NAS 1.26:177491
    Format: text
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    NASA TECHNICAL REPORTS
  • 5
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    A computer module used to calculate the horizontal control surface size of a conceptual aircraft design (1990)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The creation of a computer module used to calculate the size of the horizontal control surfaces of a conceptual aircraft design is discussed. The control surface size is determined by first calculating the size needed to rotate the aircraft during takeoff, and, second, by determining if the calculated size is large enough to maintain stability of the aircraft throughout any specified mission. The tail size needed to rotate during takeoff is calculated from a summation of forces about the main landing gear of the aircraft. The stability of the aircraft is determined from a summation of forces about the center of gravity during different phases of the aircraft's flight. Included in the horizontal control surface analysis are: downwash effects on an aft tail, upwash effects on a forward canard, and effects due to flight in close proximity to the ground. Comparisons of production aircraft with numerical models show good accuracy for control surface sizing. A modified canard design verified the accuracy of the module for canard configurations. Added to this stability and control module is a subroutine that determines one of the three design variables, for a stable vectored thrust aircraft. These include forward thrust nozzle position, aft thrust nozzle angle, and forward thrust split.
    Keywords: COMPUTER OPERATIONS AND HARDWARE
    Type: NASA-CR-186872 , NAS 1.26:186872
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    Takeoff predictions for powered-lift aircraft (1986)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Takeoff predictions for powered lift short takeoff (STO) aircraft have been added to NASA Ames Research Center's aircraft synthesis (ACSYNT) code. The new computer code predicts the aircraft engine and nozzle settings required to achieve the minimum takeoff roll. As a test case, it predicted takeoff around rolls and nozzle settings for the YAV-8B Harrier that were close to the actual values. Analysis of takeoff performance for an ejector-augmentor design and a vectoring-nozzle design indicated that ground roll can be decreased, for either configuration, by horizontally moving the rear thrust vector closer to the center of gravity, by increasing the vertical position of the ram drag-vector, or by moving the rear thrust vector farther below the center of gravity.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: SAE PAPER 861630
    Format: text
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    NASA TECHNICAL REPORTS
  • 7
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    Analysis and optimization of preliminary aircraft configurations in relationship to emerging agility metrics (1993)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This paper discusses the development of a FORTRAN computer code to perform agility analysis on aircraft configurations. This code is to be part of the NASA-Ames ACSYNT (AirCraft SYNThesis) design code. This paper begins with a discussion of contemporary agility research in the aircraft industry and a survey of a few agility metrics. The methodology, techniques and models developed for the code are then presented. Finally, example trade studies using the agility module along with ACSYNT are illustrated. These trade studies were conducted using a Northrop F-20 Tigershark aircraft model. The studies show that the agility module is effective in analyzing the influence of common parameters such as thrust-to-weight ratio and wing loading on agility criteria. The module can compare the agility potential between different configurations. In addition one study illustrates the module's ability to optimize a configuration's agility performance.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-CR-195228 , NAS 1.26:195228
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    A water tunnel flow visualization study of the vortex flow structures on the F/A-18 aircraft (1991)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The vortex flow structures occurring on the F/A-18 aircraft at high angles of attack were studied. A water tunnel was used to gather flow visualization data on the forebody vortex and the wing leading edge extension vortex. The longitudinal location of breakdown of the leading edge vortex was found to be consistently dependent on the angle of attack. Other parameters such as Reynolds number, model scale, and model fidelity had little influence on the overall behavior of the flow structures studied. The lateral location of the forebody vortex system was greatly influenced by changes in the angle of sideslip. Strong interactions can occur between the leading edge extension vortex and the forebody vortex. Close attention was paid to vortex induced flows on various airframe components of the F/A-18. Reynolds number and angle of attack greatly affected the swirling intensity, and therefore the strength of the studied vortices. Water tunnel results on the F/A-18 correlated well with those obtained in similar studies at both full and sub scale levels. The water tunnel can provide, under certain conditions, good simulations of realistic flows in full scale configurations.
    Keywords: AERODYNAMICS
    Type: NASA-CR-186938 , NAS 1.26:186938
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 9
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    Aerodynamic analysis of hypersonic waverider aircraft (1993)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The purpose of this study is to validate two existing codes used by the Systems Analysis Branch at NASA ARC, and to modify the codes so they can be used to generate and analyze waverider aircraft at on-design and off-design conditions. To generate waverider configurations and perform the on-design analysis, the appropriately named Waverider code is used. The Waverider code is based on the Taylor-Maccoll equations. Validation is accomplished via a comparison with previously published results. The Waverider code is modified to incorporate a fairing to close off the base area of the waverider configuration. This creates a more realistic waverider. The Hypersonic Aircraft Vehicle Optimization Code (HAVOC) is used to perform the off-design analysis of waverider configurations generated by the Waverider code. Various approximate analysis methods are used by HAVOC to predict the aerodynamic characteristics, which are validated via a comparison with experimental results from a hypersonic test model.
    Keywords: AERODYNAMICS
    Type: NASA-CR-192981 , NAS 1.26:192981
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 10
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    The power induced effects module: A FORTRAN code which estimates lift increments due to power induced effects for V/STOL flight (1991)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A user friendly FORTRAN code that can be used for preliminary design of V/STOL aircraft is described. The program estimates lift increments, due to power induced effects, encountered by aircraft in V/STOL flight. These lift increments are calculated using empirical relations developed from wind tunnel tests and are due to suckdown, fountain, ground vortex, jet wake, and the reaction control system. The code can be used as a preliminary design tool along with NASA Ames' Aircraft Synthesis design code or as a stand-alone program for V/STOL aircraft designers. The Power Induced Effects (PIE) module was validated using experimental data and data computed from lift increment routines. Results are presented for many flat plate models along with the McDonnell Aircraft Company's MFVT (mixed flow vectored thrust) V/STOL preliminary design and a 15 percent scale model of the YAV-8B Harrier V/STOL aircraft. Trends and magnitudes of lift increments versus aircraft height above the ground were predicted well by the PIE module. The code also provided good predictions of the magnitudes of lift increments versus aircraft forward velocity. More experimental results are needed to determine how well the code predicts lift increments as they vary with jet deflection angle and angle of attack. The FORTRAN code is provided in the appendix.
    Keywords: AERODYNAMICS
    Type: NASA-CR-188081 , NAS 1.26:188081
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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