ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    facet.materialart.
    Unknown
    Effects of simulator motion and visual characteristics on rotorcraft handling qualities evaluations (1993)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The pilot's perceptions of aircraft handling qualities are influenced by a combination of the aircraft dynamics, the task, and the environment under which the evaluation is performed. When the evaluation is performed in a groundbased simulator, the characteristics of the simulation facility also come into play. Two studies were conducted on NASA Ames Research Center's Vertical Motion Simulator to determine the effects of simulator characteristics on perceived handling qualities. Most evaluations were conducted with a baseline set of rotorcraft dynamics, using a simple transfer-function model of an uncoupled helicopter, under different conditions of visual time delays and motion command washout filters. Differences in pilot opinion were found as the visual and motion parameters were changed, reflecting a change in the pilots' perceptions of handling qualities, rather than changes in the aircraft model itself. The results indicate a need for tailoring the motion washout dynamics to suit the task. Visual-delay data are inconclusive but suggest that it may be better to allow some time delay in the visual path to minimize the mismatch between visual and motion, rather than eliminate the visual delay entirely through lead compensation.
    Keywords: AIRCRAFT STABILITY AND CONTROL
    Type: NASA. Ames Research Center, Piloting Vertical Flight Aircraft: A Conference on Flying Qualities and Human Factors; p 341-359
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 2
    facet.materialart.
    Unknown
    An Intercomparison of Microphysical Retrieval Algorithms for Upper Tropospheric Ice Clouds (2006)
    In:  CASI
    Details
    Publication Date: 2018-06-11
    Description: The large horizontal extent, location in the cold upper troposphere, and ice composition make cirrus clouds important modulators of the earth's radiation budget and climate. Cirrus cloud microphysical properties are difficult to measure and model because they are inhomogeneous in nature and their ice crystal size distribution and habit are not well characterized. Accurate retrievals of cloud properties are crucial for improving the representation of cloud scale processes in large-scale models and for accurately predicting the earth's future climate. A number of passive and active remote sensing retrieval algorithms exist for estimating the microphysical properties of upper tropospheric clouds. We believe significant progress has been made in the evolution of these retrieval algorithms in the last decade, however, there is room for improvement. Members of the Atmospheric Radiation measurement program (ARM) Cloud properties Working Group are involved in an intercomparison of optical depth(tau), ice water path, and characteristic particle size in clouds retrieved using ground-based instruments. The goals of this intercomparison are to evaluate the accuracy of state-of-the-art algorithms, quantify the uncertainties, and make recommendations for improvement.
    Keywords: Meteorology and Climatology
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 3
    facet.materialart.
    Unknown
    Simulation evaluation of the effects of time delay and motion on rotorcraft handling qualities (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A study aimed at determining the effects of simulator characteristics on perceived handling qualities is discussed. Evaluations were conducted with a baseline set of rotorcraft dynamics, using a simple transfer-function model of an uncoupled helicopter, under different conditions of visual and overall time delays. As the visual and motion parameters were changed, differences in pilot opinion were found reflecting a change in the pilots' perceptions of handling qualities, rather than changes in the aircraft model itself. It is concluded that it is necessary to tailor the motion washout dynamics to suit the task, with reduced washouts for precision maneuvering as compared to aggressive maneuvering. Visual-delay data suggest that it may be better to allow some time delay in the visual path to minimize the mismatch between visual and motion, rather than eliminate the visual delay entirely through lead compensation.
    Keywords: AIRCRAFT STABILITY AND CONTROL
    Type: AIAA PAPER 91-2892
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 4
    facet.materialart.
    Unknown
    Effects of cockpit lateral stick characteristics on handling qualities and pilot dynamics (1992)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: This report presents the results of analysis of cockpit lateral control feel-system studies. Variations in feel-system natural frequency, damping, and command sensing reference (force and position) were investigated, in combination with variations in the aircraft response characteristics. The primary data for the report were obtained from a flight investigation conducted with a variable-stability airplane, with additional information taken from other flight experiments and ground-based simulations for both airplanes and helicopters . The study consisted of analysis of handling qualities ratings and extraction of open-loop, pilot-vehicle describing functions from sum-of-sines tracking data, including, for a limited subset of these data, the development of pilot models. The study confirms the findings of other investigators that the effects on pilot opinion of cockpit feel-system dynamics are not equivalent to a comparable level of added time delay, and until a more comprehensive set of criteria are developed, it is recommended that feel-system dynamics be considered a delay-inducing element in the aircraft response. The best correlation with time-delay requirements was found when the feel-system dynamics were included in the delay measurements, regardless of the command reference. This is a radical departure from past approaches.
    Keywords: AIRCRAFT STABILITY AND CONTROL
    Type: NASA-CR-4443 , H-1769 , NAS 1.26:4443
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 5
    facet.materialart.
    Unknown
    Simulation investigation of the effects of helicopter hovering dynamics on pilot performance (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A fixed base simulation has been performed to investigate the handling qualities requirements for the mid-term pitch response of a helicopter at hover and in low-speed flight. Pilot rating results from this simulation were compared with those from previous experiments to develop handling qualities limits on the frequency and damping of the oscillatory mode in the hovering cubic. Pilot performance data obtained during the experiment were used to confirm the pilot rating results. These data show the pilot performance to closely match that predicted by the theory of piloted control. A means of predicting pilot ratings from the open-loop aircraft dynamics is presented.
    Keywords: AIRCRAFT STABILITY AND CONTROL
    Type: AIAA PAPER 87-2533
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 6
    facet.materialart.
    Unknown
    A flight investigation of helicopter low-speed response requirements (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A flight experiment has been conducted using the Canadian National Aeronautical Establishment's variable-stability airborne simulator to define the dynamic response requirements for operations at hover and low speeds. Fourteen Attitude Command/Attitude Hold, Rate, and Rate Command/Attitude Hold configurations were evaluated by six pilots using both conventional controls and a four-axis integrated sidestick over a low-speed course consisting of precision hover, landing, sidestep, and dash/quickstop tasks. The results indicate that with conventional controls all three response-types were acceptable as long as their response bandwidth was sufficiently high, and higher bandwidths were required in roll than in pitch. With the four-axis sidestick, there was a preference for the Rate systems. The range of acceptable bandwidths was lower, and the spread in pilot ratings smaller, than were found in a similar ground-based simulation.
    Keywords: AIRCRAFT STABILITY AND CONTROL
    Type: AIAA PAPER 87-2285
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 7
    facet.materialart.
    Unknown
    Contributions of the ARM Program to Radiative Transfer Modeling for Climate and Weather Applications (2016)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: Accurate climate and weather simulations must account for all relevant physical processes and their complex interactions. Each of these atmospheric, ocean, and land processes must be considered on an appropriate spatial and temporal scale, which leads these simulations to require a substantial computational burden. One especially critical physical process is the flow of solar and thermal radiant energy through the atmosphere, which controls planetary heating and cooling and drives the large-scale dynamics that moves energy from the tropics toward the poles. Radiation calculations are therefore essential for climate and weather simulations, but are themselves quite complex even without considering the effects of variable and inhomogeneous clouds. Clear-sky radiative transfer calculations have to account for thousands of absorption lines due to water vapor, carbon dioxide, and other gases, which are irregularly distributed across the spectrum and have shapes dependent on pressure and temperature. The line-by-line (LBL) codes that treat these details have a far greater computational cost than can be afforded by global models. Therefore, the crucial requirement for accurate radiation calculations in climate and weather prediction models must be satisfied by fast solar and thermal radiation parameterizations with a high level of accuracy that has been demonstrated through extensive comparisons with LBL codes. See attachment for continuation.
    Keywords: Meteorology and Climatology
    Type: GSFC-E-DAA-TN35638
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 8
    facet.materialart.
    Unknown
    Flight investigation of helicopter low-speed response requirements (1989)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Keywords: AIRCRAFT STABILITY AND CONTROL
    Type: Journal of Guidance, Control, and Dynamics (ISSN 0731-5090); 12; 623-630
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 9
    facet.materialart.
    Unknown
    Radar aperture synthesis observations of asteroids (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-08-28
    Description: We report of Goldstone-VLA, radar aperture-synthesis observations of the mainbelt asteroids 324 Bamberga and 7 Iris and the near-Earth asteroids 1991 EE and 4179 Toutatis. Simultaneous resolution of echoes in both angle and Doppler frequency provide new constraints on the mainbelt asteroids' pole directions: Bamberga's spin vector is within 40 deg of the south ecliptic pole, and the twofold ambiguity in Iris' pole direction (P. Magnusson, 1989) is resolved in favor of the ecliptic coordinates lambda = 15 deg, beta = +25 deg. For Bamberga, monostatic and bistatic radar echoes and VLA thermal-emission measurements, also reported here, are consistent with radiometric estimates of Bamberga's size and with the hypothesis that the asteroid is overlain by a regolith having a porosity of approximately 50%. Our near-Earth asteroid measurements required the development of new on-line VLA software that allows imaging of objects that are in the telescope's `near field.' This software has been successfully tested on Toutatis at a distance of 0.06 AU and will be essential for VLA observations of Earth-approaching comets.
    Keywords: ASTRONOMY
    Type: Icarus (ISSN 0019-1035); 111; 2; p. 489-502
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 10
    facet.materialart.
    Unknown
    Simulation investigation of the effects of helicopter hovering dynamics on pilot performance (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Keywords: AIRCRAFT STABILITY AND CONTROL
    Type: Journal of Guidance, Control, and Dynamics (ISSN 0731-5090); 13; 8-15
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...