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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

A linear programming approach to characterizing norm bounded uncertainty from experimental data

The linear programming spectral overbounding and factorization (LPSOF) algorithm, an algorithm for finding a minimum phase transfer function of specified order whose magnitude tightly overbounds a specified nonparametric function of frequency, is introduced. This method has direct application to transforming nonparametric uncertainty bounds (available from system identification experiments) into parametric representations required for modern robust control design software (i.e., a minimum-phase transfer function multiplied by a norm-bounded perturbation).

Scheid, R. E.↗
NASA NTRS1992

Theoretical nozzle performance of a microwave electrothermal thruster using experimental data

Research aimed at developing a fundamental understanding of the plasma processes as applied to spacecraft propulsion is presented. Calorimetric, photographic, and spectrophotometric measurements based on the TM011 and TM012 modes in the resonance cavity have been performed. The efficiency of a thruster has been calculated using a theoretical model for predicting temperature, velocity, and species density within the propellant. It is concluded that the microwave electrothermal thruster is a viable alternative to electrode thrusters.

Haraburda, Scott S.↗
NASA NTRS1992

Identification of system, observer, and controller from closed-loop experimental data

This paper considers the identification problem of a system operating in closed-loop with an existing feedback controller. The closed-loop system is excited by a known excitation signal, and the resulting time histories of the closed-loop system response and the feedback signal are measured. From the time history data, the algorithm computes the Markov parameters of a closed-loop observer, from which the Markov parameters of the individual open-loop plant, observer, and controller are recovered. A state space model of the open-loop plant and the gain matrices for the controller and the observer are then realized. The results of the paper are demonstrated by an example using actual aircraft flutter test data.

Juang, Jer-Nan↗
NASA NTRS1992

ARID relative calibration experimental data and analysis

Several experiments measure the orientation error of the ARID end-frame as well as linear displacements in the Orbiter's y- and z-axes. In each experiment the position of the ARID on the trolley is fixed and the manipulator extends and retracts along the Orbiter's y-axis. A sensor platform consisting of four sonars arranged in a '+' pattern measures the platform pitch about the Orbiter's y-axis (angle b) and yaw about the Orbiter's x-axis (angle alpha). Corroborating measurements of the yaw error were performed using a carpenter's level to keep the platform perpendicular to the gravity vector at each ARID pose being measured.

Doty, Keith L↗
NASA NTRS1941

Propeller Analysis from Experimental Data

The operation of the propeller is analyzed by the use of the distribution of forces along the radius, combined with theoretical equations. The data were obtained in the NACA 20-foot wind tunnel on a 4-foot-diameter, two-blade propeller, operating in front of four body shapes, ranging from a small shaft to support the propeller to conventional NACA cowling. A method of estimating the axial and the rotational energy in the wake as a fractional part of the propeller power is given. A knowledge of the total thrust and torque is necessary for the estimation.

Stickle, George W↗
NASA NTRS1948

Theoretical and experimental data for a number of NACA 6A-series airfoil sections

The NACA 6a-series airfoil sections were designed to eliminate the trailing-edge cusp which is characteristic of the NACA 6a-series sections. Theoretical data are presented for NACA 6a-series basic thickness forms having the position of minimum pressure of 30, 40, and 50 percent chord and with thickness ratios varying from 6 percent to 15 percent. Also presented are data for a mean line designed to maintain straight sides on the cambered sections.

Loftin, Laurence K , Jr↗