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
Filter
  • Aircraft Design, Testing and Performance  (9)
  • Astrodynamics  (7)
  • 2010-2014  (16)
  • 11
    facet.materialart.
    Unknown
    Orbit Determination Accuracy Analysis of the Magnetospheric Multiscale Mission During Perigee Raise (2014)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The Goddard Space Flight Center (GSFC) Flight Dynamics Facility (FDF) will provide orbit determination and prediction support for the Magnetospheric Multiscale (MMS) mission during the mission's commissioning period. The spacecraft will launch into a highly elliptical Earth orbit in 2015. Starting approximately four days after launch, a series of five large perigee-raising maneuvers will be executed near apogee on a nearly every-other-orbit cadence. This perigee-raise operations concept requires a high-accuracy estimate of the orbital state within one orbit following the maneuver for performance evaluation and a high-accuracy orbit prediction to correctly plan and execute the next maneuver in the sequence. During early mission design, a linear covariance analysis method was used to study orbit determination and prediction accuracy for this perigee-raising campaign. This paper provides a higher fidelity Monte Carlo analysis using the operational COTS extended Kalman filter implementation that was performed to validate the linear covariance analysis estimates and to better characterize orbit determination performance for actively maneuvering spacecraft in a highly elliptical orbit. The study finds that the COTS extended Kalman filter tool converges on accurate definitive orbit solutions quickly, but prediction accuracy through orbits with very low altitude perigees is degraded by the unpredictability of atmospheric density variation.
    Keywords: Astrodynamics
    Type: GSFC-E-DAA-TN16122 , AIAA Space 2014; Aug 04, 2014 - Aug 07, 2014; San Diego, CA; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 12
    facet.materialart.
    Unknown
    Partial Derivatives of the Lambert Problem (2014)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A procedure for deriving analytic partial derivatives of the Lambert problem is presented. Using the universal, cosine based Lambert formulation; first order partial derivatives of the velocities with respect to the positions and times are developed. Taking advantage of inherent symmetries and intermediate variables, the derivatives are expressed in a computationally efficient form. The added cost of computing these partials is found to be approximately 10% to approximately 60% of the Lambert compute cost. The availability of analytic partial derivatives increases optimization speed, efficiency and allows for trajectory optimization formulations that implicitly enforce continuity constraints via embedded Lambert problems.
    Keywords: Astrodynamics
    Type: AIAA SPACE 2014 Conference and Exposition; Aug 05, 2014 - Aug 07, 2014; San Diego, CA; United States
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 13
    facet.materialart.
    Unknown
    Shake Test Results and Dynamic Calibration Efforts for the Large Rotor Test Apparatus (2014)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Prior to the full-scale wind tunnel test of the UH-60A Airloads rotor, a shake test was completed on the Large Rotor Test Apparatus. The goal of the shake test was to characterize the oscillatory response of the test rig and provide a dynamic calibration of the balance to accurately measure vibratory hub loads. This paper provides a summary of the shake test results, including balance, shaft bending gauge, and accelerometer measurements. Sensitivity to hub mass and angle of attack were investigated during the shake test. Hub mass was found to have an important impact on the vibratory forces and moments measured at the balance, especially near the UH-60A 4/rev frequency. Comparisons were made between the accelerometer data and an existing finite-element model, showing agreement on mode shapes, but not on natural frequencies. Finally, the results of a simple dynamic calibration are presented, showing the effects of changes in hub mass. The results show that the shake test data can be used to correct in-plane loads measurements up to 10 Hz and normal loads up to 30 Hz.
    Keywords: Aircraft Design, Testing and Performance
    Type: ARC-E-DAA-TN12524 , Decennial AHS Aeromechanics Specialists'' Conference; Jan 22, 2014 - Jan 24, 2014; San Francisco, CA; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 14
    facet.materialart.
    Unknown
    Improving FermiI Orbit Determination and Prediction in an Uncertain Atmospheric Drag Environment (2014)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Orbit determination and prediction of the Fermi Gamma-ray Space Telescope trajectory is strongly impacted by the unpredictability and variability of atmospheric density and the spacecrafts ballistic coefficient. Operationally, Global Positioning System point solutions are processed with an extended Kalman filter for orbit determination, and predictions are generated for conjunction assessment with secondary objects. When these predictions are compared to Joint Space Operations Center radar-based solutions, the close approach distance between the two predictions can greatly differ ahead of the conjunction. This work explores strategies for improving prediction accuracy and helps to explain the prediction disparities. Namely, a tuning analysis is performed to determine atmospheric drag modeling and filter parameters that can improve orbit determination as well as prediction accuracy. A 45 improvement in three-day prediction accuracy is realized by tuning the ballistic coefficient and atmospheric density stochastic models, measurement frequency, and other modeling and filter parameters.
    Keywords: Astrodynamics
    Type: GSFC-E-DAA-TN14296 , International Symposium on Space Flight Dynamics (ISSFD); May 05, 2014 - May 09, 2014; Laurel, MD; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 15
    facet.materialart.
    Unknown
    Improving Fermi Orbit Determination and Prediction in an Uncertain Atmospheric Drag Environment (2014)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Orbit determination and prediction of the Fermi Gamma-ray Space Telescope trajectory is strongly impacted by the unpredictability and variability of atmospheric density and the spacecraft's ballistic coefficient. Operationally, Global Positioning System point solutions are processed with an extended Kalman filter for orbit determination, and predictions are generated for conjunction assessment with secondary objects. When these predictions are compared to Joint Space Operations Center radar-based solutions, the close approach distance between the two predictions can greatly differ ahead of the conjunction. This work explores strategies for improving prediction accuracy and helps to explain the prediction disparities. Namely, a tuning analysis is performed to determine atmospheric drag modeling and filter parameters that can improve orbit determination as well as prediction accuracy. A 45% improvement in three-day prediction accuracy is realized by tuning the ballistic coefficient and atmospheric density stochastic models, measurement frequency, and other modeling and filter parameters.
    Keywords: Astrodynamics
    Type: GSFC-E-DAA-TN14297 , International Symposium on Space Flight Dynamics (ISSFD); May 05, 2014 - May 09, 2014; Laurel, MD; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 16
    facet.materialart.
    Unknown
    Environmentally Friendly Rotorcraft Concepts: 2011-2014 (2013)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Motivation: Greenhouse gas concentrations have increased well beyond their pre-industrial levels due to human activities; Aircraft emissions are becoming regulated in industrialized nations, so future rotorcraft will need to be designed for minimal environmental impact. Objectives: Determine suitable metrics to measure environmental impact of rotorcraft, focusing first on air pollution; Integrate performance metrics with rotorcraft design codes; Generate rotorcraft designs with minimal environmental impact. Outcomes: Obtain an understanding of how targeting reduced emissions affects the rotorcraft design process; Advance the capability of existing rotorcraft design tools to include environmental performance metrics. Tools: Evaluation and predesign - NDARC (NASA Design and Analysis of Rotorcraft) and CREATION (Concepts of Rotorcraft Enhanced Assessment Through Integrated Optimization Network); Flight simulation - CAMRAD II (Comprehensive Analytical Model of Rotorcraft Aerodynamics and Dynamics) and HOST (Helicopter Overall Simulation Tool).
    Keywords: Aircraft Design, Testing and Performance
    Type: ARC-E-DAA-TN9508 , US/France MoA Helicopter Aeromechanics Semiannual Meeting; May 28, 2013 - May 29, 2013; Moffet Field, CA; United States
    Format: application/pdf
    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...