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  • 1
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    Sensor biases effect on the estimation algorithm for performance-seeking controllers (1994)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: The performance-seeking-control algorithm (PSC) is designed to continuously optimize the performance of propulsion systems. The PSC uses a nominal model of the propulsion system and estimates, in flight, the engine deviation parameters (EDPs) characterizing engine deviations with respect to nominal conditions. In practice, the measurement biases (or model uncertainties) may prevent the estimated EDPs from reflecting the engine's actual off-nominal condition. This factor has a direct impact on the PSC scheme exacerbated by the open-loop character of the algorithm. An observability analysis shows that the biases cannot be estimated together with the EDPs. Moreover, biases and EDPs turn out to have equivalent effects on the measurements, leaving it undecided whether the estimated EDPs represent the actual engine deviation or whether they simply reflect the measurement biases. In this article, the effects produced by unknown measurement biases over the estimation algorithm are evaluated. This evaluation allows for identification of the most critical measurements for application of the PSC algorithm to an F100 engine.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Journal of Propulsion and Power (ISSN 0748-4658); 10; 4; p. 527-532
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Experimental and Analytical Investigation of the Transonic and Supersonic Divergence Characteristics of a Delta-Plan-Form All- Movable Control (1958)
    In:  CASI
    Details
    Publication Date: 2019-05-23
    Description: The static aeroelastic divergence characteristics of a delta-planform model of the canard control surface of a proposed air-to-ground missile have been studied both analytically and experimentally in the Mach number range from 0.6 to 3.0. The experiments indicated that divergence occurred at a nearly constant value of dynamic pressure at Mach numbers up to 1.2. At higher Mach numbers somewhat higher values of dynamic pressure were required to produce divergence. The analysis and the experiment indicate that the camber stiffness of the control surface and the stiffness of the control actuator are both important in divergence of surfaces of this type.
    Keywords: AERODYNAMICS
    Type: NACA-RM-L58E07
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Investigation of the divergence characteristics of delta-planform canard controls (1966)
    In:  CASI
    Details
    Publication Date: 2019-05-29
    Description: Static aeroelastic divergence characteristics of delta-planform model of canard control surfaces
    Keywords: AERODYNAMICS
    Type: NASA-TR-R-235
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    VSAERO analysis of tip planforms for the free-tip rotor (1988)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The results of a numerical analysis of two interacting lifting surfaces separated in the spanwise direction by a narrow gap are presented. The configuration consists of a semispan wing with the last 32 percent of the span structurally separated from the inboard section. The angle of attack of the outboard section is set independently from that of the inboard section. In the present study, the three-dimensional panel code VSAERO is used to perform the analysis. Computed values of tip surface lift and pitching moment coefficients are correlated with experimental data to determine the proper approach to model the gap region between the surfaces. Pitching moment data for various tip planforms are also presented to show how the variation of tip pitching moment with angle of attack may be increased easily in incompressible flow. Calculated three-dimensional characteristics in compressible flow at Mach numbers of 0.5 and 0.7 are presented for new tip planform designs. An analysis of sectional aerodynamic center shift as a function of Mach number is also included for a representative tip planform. It is also shown that the induced drag of the tip surface is reduced for negative incidence angles relative to the inboard section. The results indicate that this local drag reduction overcomes the associated increase in wing induced drag at high wing lift coefficients.
    Keywords: AERODYNAMICS
    Type: NASA-CR-177487 , NAS 1.26:177487
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 5
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    Experimental study of an independently deflected wingtip mounted on a semispan wing (1991)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The results of a subsonic wind tunnel test of a semispan wing with an independently deflected tip surface are presented and analyzed. The tip surface was deflected about the quarter chord of the rectangular wing and accounted for 17 percent of the wing semispan. The test was conducted to measure the loads on the tip surface and to investigate the nature of aerodynamic interference effects between the wing and the deflected tip. Results are presented for two swept tip surfaces of similar planform but different airfoil distributions. The report contains plots of tip lift, drag, and pitching moment for various Reynolds numbers and tip deflection angles with respect to the inboard wing. Oil flow visualization photographs for a typical Reynolds number are also included. Important aerodynamic parameters such as lift and pitching moment slopes and tip aerodynamic center location are tabulated. A discussion is presented on the relationship between tip experimental data acquired in a steady flow and the prediction of unsteady tip motion at fixed wing angles of attack.
    Keywords: AERODYNAMICS
    Type: NASA-TM-102842 , A-90210 , NAS 1.15:102842
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    On the estimation algorithm used in adaptive performance optimization of turbofan engines (1993)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The performance seeking control algorithm is designed to continuously optimize the performance of propulsion systems. The performance seeking control algorithm uses a nominal model of the propulsion system and estimates, in flight, the engine deviation parameters characterizing the engine deviations with respect to nominal conditions. In practice, because of measurement biases and/or model uncertainties, the estimated engine deviation parameters may not reflect the engine's actual off-nominal condition. This factor has a necessary impact on the overall performance seeking control scheme exacerbated by the open-loop character of the algorithm. The effects produced by unknown measurement biases over the estimation algorithm are evaluated. This evaluation allows for identification of the most critical measurements for application of the performance seeking control algorithm to an F100 engine. An equivalence relation between the biases and engine deviation parameters stems from an observability study; therefore, it is undecided whether the estimated engine deviation parameters represent the actual engine deviation or whether they simply reflect the measurement biases. A new algorithm, based on the engine's (steady-state) optimization model, is proposed and tested with flight data. When compared with previous Kalman filter schemes, based on local engine dynamic models, the new algorithm is easier to design and tune and it reduces the computational burden of the onboard computer.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-4551 , H-1908 , NAS 1.15:4551 , AIAA PAPER 93-1823 , AIAA Joint Propulsion Conference; Jun 28, 1993 - Jul 01, 1993; Monterey, CA; United States
    Format: application/pdf
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  • 7
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    On the estimation algorithm for adaptive performance optimization of turbofan engines (1993)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The performance seeking control (PSC) algorithm is designed to continuously optimize the performance of propulsion systems. The PSC algorithm uses a nominal propulsion system model and estimates, in flight, the engine deviation parameters (EDPs) characterizing the engine deviations with respect to nominal conditions. In practice, because of measurement biases and/or model uncertainties, the estimated EDPs may not reflect the engine's actual off-nominal condition. This factor has a direct impact on the PSC scheme exacerbated by the open-loop character of the algorithm. In this paper, the effects produced by unknown measurement biases over the estimation algorithm are evaluated. This evaluation allows for identification of the most critical measurements for application of the PSC algorithm to an F100 engine. An equivalence relation between the biases and EDPs stems from the analysis; therefore, it is undecided whether the estimated EDPs represent the actual engine deviation or whether they simply reflect the measurement biases. A new algorithm, based on the engine's (steady-state) optimization model, is proposed and tested with flight data. When compared with previous Kalman filter schemes, based on local engine dynamic models, the new algorithm is easier to design and tune and it reduces the computational burden of the onboard computer.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 93-1823 , AIAA, SAE, ASME, and ASEE, Joint Propulsion Conference and Exhibit; Jun 28, 1993 - Jun 30, 1993; Monterey, CA; United States|; 20 p.
    Format: text
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    NASA TECHNICAL REPORTS
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