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  • 1985-1989  (4)
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  • 1
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    Demonstration of frequency-sweep testing technique using a Bell 214-ST helicopter (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A demonstration of frequency-sweep testing using a Bell-214ST single-rotor helicopter was completed in support of the Army's development of an updated MIL-H-8501A, and an LHX (ADS-33) handling-qualities specification. Hover and level-flight (V sub a = 0 knots and V sub a = 90 knots) tests were conducted in 3 flight hours by Army test pilots at the Army Aviation Engineering Flight Activity (AEFA) at Edwards AFB, Calif. Bandwidth and phase-delay parameters were determined from the flight-extracted frequency responses as required by the proposed specifications. Transfer function modeling and verification demonstrates the validity of the frequency-response concept for characterizing closed-loop flight dynamics of single-rotor helicopters -- even in hover. This report documents the frequency-sweep flight-testing technique and data-analysis procedures. Special emphasis is given to piloting and analysis considerations which are important for demonstrating frequency-domain specification compliance.
    Keywords: AIRCRAFT STABILITY AND CONTROL
    Type: NASA-TM-89422 , A-87073 , AVSCOM-TM-87-A-1 , NAS 1.15:89422 , AD-A182361
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Time and frequency-domain identification and verification of BO-105 dynamic models (1989)
    In:  Other Sources
    Details
    Publication Date: 2018-12-01
    Description: Mathematical models for the dynamics of the DLR BO 105 helicopter are extracted from flight test data using two different approaches: frequency-domain and time-domain identification. Both approaches are reviewed. Results from an extensive data consistency analysis are given. Identifications for 6 degrees of freedom (DOF) rigid body models are presented and compared in detail. The extracted models compare favorably and their prediction capability is demonstrated in verification results. Approaches to extend the 6 DOF models are addressed and first results are presented. System identification is broadly defined as the deduction of system characteristics from measured data. It provides the only possibility to extract both non-parametric (e.g., frequency responses) and parametric (e.g., state space matrices) aircraft models from flight test data and therefore gives a reliable characterization of the dynamics of the actually existing aircraft. Main applications of system identification are seen in areas where higher accuracies of the mathematical models are required: Simulation validation, control system design (in particular model-following control system design for in-flight simulation), and handling qualities.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    Time and frequency-domain identification and verification of BO-105 dynamic models (1989)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Mathematical models for the dynamics of the DLR BO 105 helicopter are extracted from flight test data using two different approaches: frequency-domain and time-domain identification. Both approaches are reviewed. Results from an extensive data consistency analysis are given. Identifications for 6 degrees of freedom (DOF) rigid body models are presented and compared in detail. The extracted models compare favorably and their prediction capability is demonstrated in verification results. Approaches to extend the 6 DOF models are addressed and first results are presented. System identification is broadly defined as the deduction of system characteristics from measured data. It provides the only possibility to extract both non-parametric (e.g., frequency responses) and parametric (e.g., state space matrices) aircraft models from flight test data and therefore gives a reliable characterization of the dynamics of the actually existing aircraft. Main applications of system identification are seen in areas where higher accuracies of the mathematical models are required: Simulation validation, control system design (in particular model-following control system design for in-flight simulation), and handling qualities.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: AD-A216828 , European Rotorcraft Forum; Sep 12, 1989 - Sep 15, 1989; Amsterdam; Netherlands
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    Applications of flight control system methods to an advanced combat rotorcraft (1989)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Advanced flight control system design, analysis, and testing methodologies developed at the Ames Research Center are applied in an analytical and flight test evaluation of the Advanced Digital Optical Control System (ADOCS) demonstrator. The primary objectives are to describe the knowledge gained about the implications of digital flight control system design for rotorcraft, and to illustrate the analysis of the resulting handling-qualities in the context of the proposed new handling-qualities specification for rotorcraft. Topics covered in-depth are digital flight control design and analysis methods, flight testing techniques, ADOCS handling-qualities evaluation results, and correlation of flight test results with analytical models and the proposed handling-qualities specification. The evaluation of the ADOCS demonstrator indicates desirable response characteristics based on equivalent damping and frequency, but undersirably large effective time-delays (exceeding 240 m sec in all axes). Piloted handling-qualities are found to be desirable or adequate for all low, medium, and high pilot gain tasks; but handling-qualities are inadequate for ultra-high gain tasks such as slope and running landings.
    Keywords: AIRCRAFT STABILITY AND CONTROL
    Type: NASA-TM-101054 , A-89006 , USAAVSCOM-CP-89-A-002 , NAS 1.15:101054 , AD-A211906 , Royal Aeronautical Society International Conference on Helicopter Handling Qualities and Control; Nov 15, 1988 - Nov 17, 1988; London
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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