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  • AERODYNAMICS  (157)
  • 1980-1984  (157)
  • 1945-1949
  • 1935-1939
  • 1981  (74)
  • 1980  (83)
  • 1
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    PAN AIR: A computer program for predicting subsonic or supersonic linear potential flows about arbitrary configurations using a higher order panel method. Volume 4: Maintenance document (version 1.1) (1981)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The Maintenance Document is a guide to the PAN AIR software system, a system which computes the subsonic or supersonic linear potential flow about a body of nearly arbitrary shape, using a higher order panel method. The document describes the over-all system and each program module of the system. Sufficient detail is given for program maintenance, updating and modification. It is assumed that the reader is familiar with programming and CDC (Control Data Corporation) computer systems. The PAN AIR system was written in FORTRAN 4 language except for a few COMPASS language subroutines which exist in the PAN AIR library. Structured programming techniques were used to provide code documentation and maintainability. The operating systems accommodated are NOS 1.2, NOS/BE and SCOPE 2.1.3 on the CDC 6600, 7600 and Cyber 175 computing systems. The system is comprised of a data management system, a program library, an execution control module and nine separate FORTRAN technical modules. Each module calculates part of the posed PAN AIR problem. The data base manager is used to communicate between modules and within modules. The technical modules must be run in a prescribed fashion for each PAN AIR problem. In order to ease the problem of supplying the many JCL cards required to execute the modules, a separate module called MEC (Module Execution Control) was created to automatically supply most of the JCL cards. In addition to the MEC generated JCL, there is an additional set of user supplied JCL cards to initiate the JCL sequence stored on the system.
    Keywords: AERODYNAMICS
    Type: NASA-CR-3254 , NAS 1.26:3254 , D180-24910-4
    Format: application/pdf
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  • 2
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    A computational and experimental study of high Reynolds number viscous/inviscid interaction about a cone at high angle of attack (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The flow over a 5 deg semi-angle cone at incidence in supersonic flow is studied as a model problem for the flow over aircraft forebodies. A computational method utilizing the conically symmetric Navier-Stokes equations is used to obtain theoretical flow results which are compared with experimental data from the Ames Research Center 6- by 6-Foot Wind Tunnel and with results from a cone model sting mounted on an F-15 aircraft. The computed results agree well with the wind-tunnel data but less well with the flight data. Modification of the algebraic turbulence model was necessary to reflect an apparent lower turbulence level in flight than was present in the wind tunnel.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 80-1422 , Fluid and Plasma Dynamics Conference; Jul 14, 1980 - Jul 16, 1980; Snowmass, CO
    Format: text
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  • 3
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    Flight experiments with a slender cone at angle of attack (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The three-dimensional leeward separation about a 5 deg semi-angle cone at an 11 deg angle of attack was investigated in flight, in the wind tunnel, and by numerical computations. The test conditions were Mach numbers of 0.6, 1.5, and 1.8 at Reynolds numbers between 7 and 10 million based on free-stream conditions and a 30-inch wetted length or surface. The surface conditions measured included mean static and fluctuating pressures; skin friction magnitudes and separation line positions were obtained using obstacle blocks. The mean static pressures from flight and wind tunnel were in good agreement. The computed results gave the same distributions, but were slightly more positive in magnitude. The experimentally measured primary and secondary separation line locations compared closely with computed results. There were substantial differences in level and in trend between the surface root-mean-square pressure fluctuations obtained in flight and in the wind tunnel, due, it is thought, to a relatively high acoustic disturbance level in the tunnel compared with the quiescent conditions in flight.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 81-0337 , Aerospace Sciences Meeting; Jan 12, 1981 - Jan 15, 1981; St. Louis, MO
    Format: text
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  • 4
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    An analytic solution to the classical two-body problem with drag (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The two body problem was analyzed with a specific drag model. The model treats drag as a force proportional to the vector velocity and inversely proportional to the distance to the center of attraction. The solution is expressed in terms of known functions and is of a simple and compact form. The time of flight is expressed as a quadrature in the true anomaly. The results are: (1) development of a vector differential equation which allows analysis of an infinite number of gravitational and drag models; and (2) obtaining the solution of a linear differential equation using the inverse method of laplace transforms.
    Keywords: AERODYNAMICS
    Type: Houston Univ. The 1981 NASA ASEE Summer Fac. Fellowship Program, Vol. 2; 22 p
    Format: text
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  • 5
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    Unsteady transonic small disturbance theory with strong shock waves (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A theory to correct the transonic small disturbance (TSD) equation to treat strong shock waves in unsteady flow is developed. The technique involves the addition of higher order terms, which are formally of negligible magnitude, to the low frequency TSD equation. These terms are then chosen such that any shock waves in the flow have strengths approximately equal to the appropriate Rankine-Hugoniot shock strength. Two correcting approaches are investigated. The first is to derive a correction for the mean steady flow and then simply use this corrected form for oscillatory flows. The second is to derive a correction for both steady and oscillatory parts of the flow. This second development is the most satisfactory and comparisons of the present results with Euler equation results are generally favorable, particularly regarding shock location, although there are some discrepancies in the pressure distribution in the leading edge region.
    Keywords: AERODYNAMICS
    Type: NASA-CR-166157 , NEAR-TR-230
    Format: application/pdf
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  • 6
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    Numerical lifting line theory applied to drooped leading-edge wings below and above stall (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A numerical iterative solution to the classical Prandtl lifting-line theory, suitably modified for poststall behavior, is used to study the aerodynamic characteristics of straight rectangular finite wings with and without leading-edge droop. This study is prompted by the use of such leading-edge modifications to inhibit stall/spins in light general aviation aircraft. The results indicate that lifting-line solutions at high angle of attack can be obtained that agree with experimental data to within 20%, and much closer for many cases. Therefore, such solutions give reasonable preliminary engineering results for both drooped and undrooped wings in the poststall region. However, as predicted by von Karman, the lifting-line solutions are not unique when sectional negative lift slopes are encountered. In addition, the present numerical results always yield symmetrical lift distributions along the span, in contrast to the asymmetrical solutions observed by Schairer in the late 1930's. Finally, a series of parametric tests at low angle of attack indicate that the effect of drooped leading edges on aircraft cruise performance is minimal.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft; 17; Dec. 198
    Format: text
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  • 7
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    Combined linear theory/impact theory method for analysis and design of high speed configurations (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Pressure distributions on a wing body at Mach 4.63 are calculated. The combined theory is shown to give improved predictions over either linear theory or impact theory alone. The combined theory is also applied in the inverse design mode to calculate optimum camber slopes at Mach 4.63. Comparisons with optimum camber slopes obtained from unmodified linear theory show large differences. Analysis of the results indicate that the combined theory correctly predicts the effect of thickness on the loading distributions at high Mach numbers, and that finite thickness wings optimized at high Mach numbers using unmodified linear theory will not achieve the minimum drag characteristics for which they are designed.
    Keywords: AERODYNAMICS
    Type: NASA-CR-3314
    Format: application/pdf
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  • 8
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    A flight investigation of blade section aerodynamics for a helicopter main rotor having NLR-1T airfoil sections (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A flight investigation was conducted using a teetering-rotor AH-1G helicopter to obtain data on the aerodynamic behavior of main-rotor blades with the NLR-1T blade section. The data system recorded blade-section aerodynamic pressures at 90 percent rotor radius as well as vehicle flight state, performance, and loads. The test envelope included hover, forward flight, and collective-fixed maneuvers. Data were obtained on apparent blade-vortex interactions, negative lift on the advancing blade in high-speed flight and wake interactions in hover. In many cases, good agreement was achieved between chordwise pressure distributions predicted by airfoil theory and flight data with no apparent indications of blade-vortex interactions.
    Keywords: AERODYNAMICS
    Type: NASA-TM-80166 , AVRADCOM-TR-80-B-2
    Format: application/pdf
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  • 9
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    A flight investigation of performance and loads for a helicopter with 10-64C main rotor blade sections (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A flight investigation produced data on performance and rotor loads for a teetering rotor, AH-1G helicopter flown with a main rotor that had the NLR-1T airfoil as the blade section contour. The test envelope included hover, forward flight speeds from 34 to 83 m/sec (65 to 162 knots), and collective fixed maneuvers at about 0.25 tip speed ratio. The data set for each test point describes vehicle flight state, control positions, rotor loads, power requirements, and blade motions. Rotor loads are reviewed primarily in terms of peak to peak and harmonic content. Lower frequency components predominated for most loads and generally increased with increased airspeed, but not necessarily with increased maneuver load factor. Detailed data for an advanced airfoil on an AH-1G are presented.
    Keywords: AERODYNAMICS
    Type: NASA-TM-81871 , AVRADCOM-TM-80-B-2
    Format: application/pdf
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  • 10
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    A flight investigation of performance and loads for a helicopter with RC-SC2 main-rotor blade sections (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The test envelope included hover, forward-flight speed sweeps from 33 to 74 m/sec (65 to 144 knots), and collective-fixed maneuvers at about 0.25 tip-speed ratio. The data set for each test point describes vehicle flight states, control positions, rotor loads, power requirements and blade motions. Rotor loads were reviewed primarily in terms of peak-to-peak and harmonic content. Lower frequency components predominated for most loads and generally increased with increased airspeed, but not necessarily with increased maneuver load factor.
    Keywords: AERODYNAMICS
    Type: NASA-TM-81898 , AVRADCOM-TM-81-B-1
    Format: application/pdf
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