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  • 1
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    An electronic scanner of pressure for wind tunnel models (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: An electronic scanner of pressure (ESOP) has been developed by NASA Ames Research Center for installation in wind tunnel models. An ESOP system consists of up to 20 pressure modules (PMs), each with 48 pressure transducers and a heater, an analog-to-digital (A/D) converter module, a microprocessor, a data controller, a monitor unit, a control and processing unit, and a heater controller. The PMs and the A/D converter module are sized to be installed in the models tested in the Ames Aerodynamics Division wind tunnels. A unique feature of the pressure module is the lack of moving parts such as a pneumatic switch used in other systems for in situ calibrations. This paper describes the ESOP system and the results of the initial testing of the system. The initial results indicate the system meets the original design goal of 0.15 percent accuracy.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Format: text
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  • 2
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    Predictions of F-111 TACT aircraft buffet response (1990)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A summary is presented for the prediction method development and correlations of predicted response with flight test measurements. The prediction method was based on refinements to the method described by Cunningham. One improvement made use of direct time integration of the correlated fluctuating pressure data to obtain buffet excitation for the various modes of interest. Another improvement incorporated a hybrid technique for scaling measured wind tunnel damping data to full-scale for the modes of interest. A third improvement made use of the diagonalized form of the fully coupled equations of motion. Finally, a mechanism was described for explaining an apparent coupling between the aircraft wing torsion modes and shock induced trailing edge separation that led to very high wing motion on the aircraft that was not observed on the wind tunnel model.
    Keywords: AIRCRAFT STABILITY AND CONTROL
    Type: AGARD, Aircraft Dynamic Loads Due to Flow Separation; 16 p
    Format: text
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  • 3
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    An assessment of wind tunnel test data on flexible thermal protection materials and results of new fatigue tests of threads (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Advanced Flexible Reusable Surface Insulation (AFRSI) was developed as a replacement for the low-temperature (white) tiles on the Space Shuttle. The first use of the AFRSI for an Orbiter flight was on the OMS POD of Orbiter (OV-099) for STS-6. Post flight examination after STS-6 showed that damage had occurred to the AFRSI during flight. The failure anomaly between previous wind-tunnel tests and STS-6 prompted a series of additional wind tunnel tests to gain an insight as to the cause of the failure. An assessment of all the past STS-6 wind tunnel tests pointed out the sensitivity of the test results to scaling of dynamic loads due to the difference of boundary layer thickness, and the material properties as a result of exposure to heating. The thread component of the AFRSI was exposed to fatigue testing using an apparatus that applied pulsating aerodynamic loads on the threads similar to the loads caused by an oscillating shock. Comparison of the mean values of the number-of-cycles to failure showed that the history of the thread was the major factor in its performance. The thread and the wind tunnel data suggests a mechanism of failure for the AFRSI.
    Keywords: ACOUSTICS
    Type: NASA-CR-177466 , NAS 1.26:177466
    Format: application/pdf
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  • 4
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    The Effects of Tip-mounted Jet Nacelles on the Transonic Characteristics of Low-aspect-ratio Wings (1952)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Type: NACA-RM-A52J21
    Format: application/pdf
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  • 5
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    A Study of Local-pressure Fluctuations Relative to Static-pressure Distributions on Two-dimensional Airfoils at High Subsonic Mach Numbers (1955)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Type: NACA-RM-A55J11
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  • 6
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    Buffeting Forces on Two-dimensional Airfoils as Affected by Thickness and Thickness Distribution (1954)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Type: NACA-RM-A53K24
    Format: application/pdf
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  • 7
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    An investigation of the causes of failure of flexible thermal protection materials in an aerodynamic environment (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Tests of small panels of advanced flexible reusable surface insulation (AFRSI) were conducted using a small wind tunnel that was designed to simulate Space Shuttle Orbiter entry mean-flow and pulsating aerodynamic loads. The wind tunnel, with a 3 inch wide by 1.75 inch high by 7.5 inch long test section, proved to be capable of continuous flow at dynamic pressures q near 580 psf with fluctuating pressures over 2 psi RMS at an excitation frequency f sub E of 200 Hz. For this investigation, however, the wind tunnel was used to test entry-temperature preconditioned and heat-cleaned AFRSI at q = 280 psf, Prms was nearly equal to 1.2 psi and f sub E = 200 Hz. The objective of these tests was to determine the mechanism of failure of AFRSI at Orbiter entry conditions. Details of the test apparatus and test results are presented.
    Keywords: THERMODYNAMICS AND STATISTICAL PHYSICS
    Type: NASA-CR-166624 , H-1389 , NAS 1.26:166624
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  • 8
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    Predictions of F-111 TACT aircraft buffet response and correlations of fluctuating pressures measured on aluminum and steel models and the aircraft (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Results of buffet research that was conducted as part of the joint USAF/NASA F-111 TACT Research Program are presented. The correlation of wind tunnel and flight measurements of buffet excitation showed that there generally was good agreement between measurements of pressure fluctuations on the models and aircraft in regions of separated flow. At shock-wave boundaries of the separated flow, correlations of pressure fluctuations were not so good, due to Reynolds number and static elastic effects. The buffet prediction method, which applies a forcing function that is obtained by real-time integration of pressure time histories with the natural modes, is described. The generalized forces, including the effects of wing and tail, correlations of predicted and measured damping, and correlations of predicted and measured buffet response are presented. All presented data are for a Mach number of 0.8 with wing-sweep angles of 26 and 35 deg for a range of angles-of-attack that include buffet onset to high intensity buffeting. Generally, the buffet predictions were considered to be quite good particularly in light of past buffet-prediction experience.
    Keywords: AERODYNAMICS
    Type: NASA-CR-4069 , NAS 1.26:4069
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  • 9
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    An Investigation of the Aerodynamic Characteristics in Pitch of an XB-52 Airplane Model in a High-Speed Wind Tunnel (1951)
    In:  CASI
    Details
    Publication Date: 2019-07-11
    Description: A wind-tunnel investigation of a 0.049-scale model of the Boeing XB-52 airplane was made at Mach numbers from 0.30 to 0.925 and at corresponding Reynolds numbers from about 2.3 x 10(exp 6) to 4.3 x 10(exp 6). The results of the investigation indicate satisfactory static longitudinal stability throughout the test Mach-number range and some loss in tail effectiveness beginning at about 0.80 Mach number. A comparison of the results of these tests with those of the same model in the Boeing Airplane Company's wind tunnel showed close agreement of lift- and drag-divergence Mach numbers. Slight differences were observed in tail effectiveness and the position of the stick-fixed neutral point.
    Keywords: Aerodynamics
    Type: NACA-RM-SA51C16
    Format: application/pdf
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  • 10
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    Integration Time Required to Extract Accurate Data from Transonic Wind-Tunnel Tests (1979)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Because the forces and pressures on wind-tunnel models tested at transonic speeds are not steady, even for static aerodynamic tests, integration time is required to obtain data of acceptable accuracy. The integration time required for both static and dynamic tests is evaluated analytically and confirmed by experimental measurements. It is shown that, for static and dynamic tests, the accuracy obtained is a function of integration time, frequency of the signal, and the ratio of the dynamic amplitude to the full signal of interest. In addition, for the dynamic case, the frequency bandwidth used in analysis is important. Results of this study indicate that, for typical data accuracy desired from models in a large transonic wind tunnel (11- by 11-ft), up to the following integration times are required: static force and moment tests, 0.5 s; static pressure tests, 1 s; flutter tests, 30 to 60 s; and random-dynamic tests, 10 s.
    Keywords: Research and Support Facilities (Air)
    Type: AIAA Paper 78-142R , Aerospace Sciences; Jan 20, 1975 - Jan 22, 1975; Pasadena, CA; United States|Journal of Aircraft; 16; 9; 620-625
    Format: text
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