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  • 1
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    The effects of strain heating in lithospheric stretching models (1985)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The deformation by stretching of a continental type lithosphere has been formulated so that the problem can be solved by a continuum mechanical approach. The deformation, stress state, and temperature distribution are constrained to satisfy the physical laws of conservation of mass, energy, momentum, and an experimentally defined rheological response. The conservation of energy equation including a term of strain energy dissipation is given. The continental lithosphere is assumed to have the rheology of an isotropic, incompressible, nonlinear viscous, two layered solid.
    Keywords: GEOPHYSICS
    Type: Lunar and Planetary Inst. Papers Presented to the Conference on Heat and Detachment in Crustal Extension on Continents and Planets; p 145 - 146
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    NASA rotor systems research aircraft: Fixed-wing configuration flight-test results (1986)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The fixed-wing, airplane configuration flight-test results of the Rotor System Research Aircraft (RSRA), NASA 740, at Ames/Dryden Flight Research Center are documented. Fourteen taxi and flight tests were performed from December 1983 to October 1984. This was the first time the RSRA was flown with the main rotor removed; the tail rotor was installed. These tests confirmed that the RSRA is operable as a fixed-wing aircraft. Data were obtained for various takeoff and landing distances, control sensitivity, trim and dynamics stability characteristics, performance rotor-hub drag, and acoustics signature. Stability data were obtained with the rotor hub both installed and removed. The speed envelope was developed to 261 knots true airspeed (KTAS), 226 knots calibrated airspeed (KCAS) at 10,000 ft density altitude. The airplane was configured at 5 deg. wing incidence with 5 deg. wing flaps as a normal configuration. Level-flight data were acquired at 167 KCAS for wing incidence from 0 to 10 deg. Step inputs and doublet inputs of various magnitudes were utilized to acquire dynamic stability and control sensitivity data. Sine-wave inputs of constantly increasing frequency were used to generate parameter identification data. The maximum load factor attained was 2.34 g at 206 KCAS.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-TM-86789 , A-85363 , NAS 1.15:86789
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Airborne gravity and other geophysical techniques for understanding the lithosphere beneath the West Antarctic Ice Sheet (1993)
    In:  Other Sources
    Details
    Publication Date: 2019-01-25
    Description: As part of a program entitled Corridor Aerogeophysics of the Southeastern Ross Transect Zone (CASERTZ), an aerogeophysical platform was developed to study the interaction of geological and glaciological processes in West Antarctica. A de Havilland Twin Otter was equipped with an ice-penetrating radar, a proton precession magnetometer, an airborne gravity system, and a laser altimeter. The 60-MHz ice-penetrating radar can recover sub-ice topography with an accuracy of about 10 m through 3 km of comparatively warm West Antarctic ice, while the laser altimeter profiling of the ice surface is accurate to approximately 1 m. The magnetic field observations are accurate to several nT, and the gravity measurements are accurate to better than 3 mGal. The aircraft is navigated by a local radio transponder network, while differential positioning techniques based on the Global Positioning System (GPS) satellites are used for recovering high-resolution horizontal and vertical positions. Attitude information from an inertial navigation system is used to correct the laser altimetry and a digital pressure transducer is used to recover vertical positions and accelerations in the absence of satellite positioning. Continuous base-station observations are made for the differential GPS positioning and the removal of ionospheric noise from the airborne magnetometer measurements.
    Keywords: GEOPHYSICS
    Type: NASA. Goddard Space Flight Center, The First Annual West Antarctic Ice Sheet (WAIS) Science Workshop; p 26
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    Aerogeophysical evidence for active volcanism beneath the West Antarctic Ice Sheet (1993)
    In:  Other Sources
    Details
    Publication Date: 2019-01-25
    Description: Although it is widely understood that the collapse of the West Antarctic Ice Sheet (WAIS) would cause a global sea-level rise of 6 m, there continues to be considerable debate about the response of this ice sheet to climate change. The stability of the WAIS, which is characterized by a bed grounded well below sea level, may depend on geologically controlled conditions at the base, which are independent of climate. Ice streams moving up to 750 m/yr disperse material from the interior through to the oceans. As these ice streams tend to buffer the reservoir of slow-moving inland ice from exposure to oceanic degradation, understanding the ice-streaming process is important for evaluating WAIS stability. There is strong evidence that ice streams slide on a lubricating layer of water-saturated till. Development of this basal layer requires both water and easily eroded sediments. Active lithospheric extension may elevate regional heat flux, increase basal melting, and trigger ice streaming. If a geologically defined boundary with a sharp contrast in geothermal flux exists beneath the WAIS, ice streams may only be capable of operating as a buffer over a restricted region. Should ocean waters penetrate beyond this boundary, the ice-stream buffer would disappear, possibly triggering a collapse of the inland ice reservoir. Aerogeophysical evidence for active volcanism and elevated heat flux beneath the WAIS near the critical region where ice streaming begins is presented.
    Keywords: GEOPHYSICS
    Type: NASA. Goddard Space Flight Center, The First Annual West Antarctic Ice Sheet (WAIS) Science Workshop; p 27
    Format: text
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    NASA TECHNICAL REPORTS
  • 5
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    NASA rotor system research aircraft flight-test data report: Helicopter and compound configuration (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The flight test activities of the Rotor System Research Aircraft (RSRA), NASA 740, from June 30, 1981 to August 5, 1982 are reported. Tests were conducted in both the helicopter and compound configurations. Compound tests reconfirmed the Sikorsky flight envelope except that main rotor blade bending loads reached endurance at a speed about 10 knots lower than previously. Wing incidence changes were made from 0 to 10 deg.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-TM-85843 , NAS 1.15:85843
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    Comparison of analytical and flight test identified aerodynamic derivatives for a tandem-rotor transport helicopter (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Flight tests for verifying an analytical aerodynamic derivative model of a CH-47 helicopter were conducted for low cruise speeds and transition to hover portions of curved, decelerating landing approach trajectories. All testing was performed on a closed loop basis with the stability augmentation system of the helicopter operating, and response data were obtained using both manual and computer generated input maneuvers. The results indicate some differences between the measured response time histories and those predicted by both analytical and flight test identified derivatives. With some exceptions the discrepancies are not severe, and the overall agreement between the measured and computed time histories is reasonably good. No adverse effects attributable to closed loop testing were noted, and the use of computer generated inputs proved to be superior to manual ones.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-TP-1581 , L-13228
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 7
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    The CTS 11.7 GHz angle of arrival experiment (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The objective of the experiment was to determine the statistical behavior of attenuation and angle of arrival on an Earth-space propagation path using the CTS 11.7 GHz beacon. Measurements performed from 1976 to 1978 form the data base for analysis. The statistics of the signal attenuation and phase variations due to atmospheric disturbances are presented. Rainfall rate distributions are also included to provide a link between the above effects on wave propagation and meteorological conditions.
    Keywords: GEOPHYSICS
    Type: NASA-CR-164338 , ESL-712759-2
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    Atmospheric microwave refractivity and refraction (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The atmospheric refractivity can be expressed as a function of temperature, pressure, water vapor content, and operating frequency. Based on twenty-year meteorological data, statistics of the atmospheric refractivity were obtained. These statistics were used to estimate the variation of dispersion, attenuation, and refraction effects on microwave and millimeter wave signals propagating along atmospheric paths. Bending angle, elevation angle error, and range error were also developed for an exponentially tapered, spherical atmosphere.
    Keywords: GEOPHYSICS
    Type: NASA-CR-164339 , TR-712759-1
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 9
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    Thermal control of low-pressure fractionation processes (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Thermal models detailing the solidification paths for shallow basaltic magma chambers (both open and closed systems) were calculated using finite-difference techniques. The total solidification time for closed chambers are comparable to previously published calculations; however, the temperature-time paths are not. These paths are dependent on the phase relations and the crystallinity of the system, because both affect the manner in which the latent heat of crystallization is distributed. In open systems, where a chamber would be periodically replenished with additional parental liquid, calculations indicate that the possibility is strong that a steady-state temperature interval is achieved near a major phase boundary. In these cases it is straightforward to analyze fractionation models of the basaltic liquid evolution and their corresponding cumulate sequences. This steady thermal fractionating state can be invoked to explain large amounts of erupted basalts of similar composition over long time periods from the same volcanic center and some rhythmically layered basic cumulate sequences.
    Keywords: GEOPHYSICS
    Type: Journal of Volcanology and Geothermal Research; 4; 1978
    Format: text
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    NASA TECHNICAL REPORTS
  • 10
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    Gain degradation and amplitude scintillation due to tropospheric turbulence (1978)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: It is shown that a simple physical model is adequate for the prediction of the long term statistics of both the reduced signal levels and increased peak-to-peak fluctuations. The model is based on conventional atmospheric turbulence theory and incorporates both amplitude and angle of arrival fluctuations. This model predicts the average variance of signals observed under clear air conditions at low elevation angles on earth-space paths at 2, 7.3, 20 and 30 GHz. Design curves based on this model for gain degradation, realizable gain, amplitude fluctuation as a function of antenna aperture size, frequency, and either terrestrial path length or earth-space path elevation angle are presented.
    Keywords: GEOPHYSICS
    Type: NASA-CR-156796 , ESL-784299-6
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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