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Pines, S.

Publications and source records attributed to Pines, S..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Analytical procedures for flutter model development and checkout in preparation for wind tunnel testing of the DAST ARW-1 wing

A study to develop analytical procedures to be used in the checkout and calibration of a flutter wind tunnel model of the DAST ARW-1 wing equipped with a flutter suppression device is reported. The methods used to obtain a realistic simulation of the structural inertial and aerodynamic properties of the wing, the hydro-electro-servo actuator used for flutter suppression, a prediction of the open loop flutter speed at a fixed Mach number (.897), a procedure for checkout and calibration using the method frequency response of a wing mounted accelerometer, and an analytical representation of a reduced state approximation of the overall system are described.

Pines, S.↗
NASA NTRS1982

Terminal area automatic navigation, guidance, and control research using the Microwave Landing System (MLS). Part 4: Transition path reconstruction along a straight line path containing a glideslope change waypoint

The necessary algorithms to reconstruct the glideslope change waypoint along a straight line in the event the aircraft encounters a valid MLS update and transition in the terminal approach area are presented. Results of a simulation of the Langley B737 aircraft utilizing these algorithms are presented. The method is shown to reconstruct the necessary flight path during MLS transition resulting in zero cross track error, zero track angle error, and zero altitude error, thus requiring minimal aircraft response.

Pines, S.↗
NASA NTRS1982

Application of modal control to wing-flutter suppression

A discrete modal control design approach that is applied to a single control surface, unswept aircraft wing subject to bending torsion flutter is described. The modal approach is a mathematical method to decouple the equations of motion into isolated differential equations. In this paper, a pole-placement approach is then applied to determine stability gains in the discrete plane using only the two complex-conjugate flutter-mode equations. A fixed gain Kalman filter is used to estimate the model amplitudes using three measurements. Results are presented for a full-state estimator (36 states) and two reduced state estimators using two different closed-loop pole locations. The control law is designed for a dynamic pressure that is 50 percent greater than the uncontrolled-flutter dynamic pressure. With constant control-law gains, the closed-loop system remains stable over the dynamic-pressure range from flutter onset to approximately an 80-percent increase in pressure.

Ostroff, A. J.↗
NASA NTRS1982

Terminal area automatic navigation, guidance, and control research using the Microwave Landing System (MLS). Part 3: A comparison of waypoint guidance algorithms for RNAV/MLS transition

The results of an investigation carried out for the Langley Research Center Terminal Configured Vehicle Program are presented. The investigation generated and compared three path update algorithms designed to provide smooth transition for an aircraft guidance system from DME, VORTAC, and barometric navaids to the more precise MLS by modifying the desired 3-D flight path. The first, called the Zero Cross Track, eliminates the discontinuity in cross track and altitude error by designating the first valid MLS aircraft position as the desired first waypoint, while retaining all subsequent waypoints. The discontinuity in track angle is left unaltered. The second, called the Tangent Path also eliminates the discontinuity in cross track and altitude and choose a new desired heading to be tangent to the next oncoming circular arc turn. The third, called the Continued Track eliminates the discontinuity in cross track, altitude and track angle by accepting the current MLS position and track angle as the desired ones and recomputes the location of the next waypoint. A method is presented for providing a waypoint guidance path reconstruction which treats turns of less than, and greater than, 180 degrees in a uniform manner to construct the desired path.

Pines, S.↗
NASA NTRS1982

Terminal area automatic navigation, guidance, and control research using the Microwave Landing System (MLS). Part 2: RNAV/MLS transition problems for aircraft

The problems in navigation and guidance encountered by aircraft in the initial transition period in changing from distance measuring equipment, VORTAC, and barometric instruments to the more precise microwave landing system data type navaids in the terminal area are investigated. The effects of the resulting discontinuities on the estimates of position and velocity for both optimal (Kalman type navigation schemes) and fixed gain (complementary type) navigation filters, and the effects of the errors in cross track, track angle, and altitude on the guidance equation and control commands during the critical landing phase are discussed. A method is presented to remove the discontinuities from the navigation loop and to reconstruct an RNAV path designed to land the aircraft with minimal turns and altitude changes.

Pines, S.↗
NASA NTRS1981

An influence coefficient method for the application of the modal technique to wing flutter suppression of the DAST ARW-1 wing

The methods used to compute the mass, structural stiffness, and aerodynamic forces in the form of influence coefficient matrices as applied to a flutter analysis of the Drones for Aerodynamic and Structural Testing (DAST) Aeroelastic Research Wing. The DAST wing was chosen because wind tunnel flutter test data and zero speed vibration data of the modes and frequencies exist and are available for comparison. A derivation of the equations of motion that can be used to apply the modal method for flutter suppression is included. A comparison of the open loop flutter predictions with both wind tunnel data and other analytical methods is presented.

Pines, S.↗
NASA NTRS1981

Terminal area automatic navigation, guidance, and control 1: Automatic rollout, turnoff, and taxis

A study developed for the TCV B-737, designed to apply existing navigation aids plus magnetic leader cable signals and develop breaking and reverse thrust guidance laws to provide for rapid automated rollout, turnoff, and taxi to reduce runway occupation time for a wide variety of landing conditions for conventional commercial-type aircraft, is described. Closed loop guidance laws for braking and reverse thrust are derived for rollout, turnoff, and taxi, as functions of the landing speed, the desired taxi speed and the distance to go. Brake limitations for wet runway conditions and reverse thrust limitations are taken into account to provide decision rules to avoid tire skid and to choose an alternate turnoff point, farther down the runway, to accommodate extreme landing conditions.

Pines, S.↗
NASA NTRS1979

Research in navigation and optimization for space trajectories

Topics covered include: (1) initial Cartesian coordinates for rapid precision orbit prediction; (2) accelerating convergence in optimization methods using search routines by applying curvilinear projection ideas; (3) perturbation-magnitude control for difference-quotient estimation of derivatives; and (4) determining the accelerometer bias for in-orbit shuttle trajectories.

Pines, S.↗
NASA NTRS1978

Requirements for Kalman filtering on the GE-701 whole word computer

The results of a study to determine scaling, storage, and word length requirements for programming the Kalman filter on the GE-701 Whole Word Computer are reported. Simulation tests are presented which indicate that the Kalman filter, using a square root formulation with process noise added, utilizing MLS, radar altimeters, and airspeed as navigation aids, may be programmed for the GE-701 computer to successfully navigate and control the Boeing B737-100 during landing approach, landing rollout, and turnoff. The report contains flow charts, equations, computer storage, scaling, and word length recommendations for the Kalman filter on the GE-701 Whole Word computer.

Pines, S.↗
NASA NTRS1978

Guidance and navigation for automatic landing, rollout, and turnoff using MLS and magnetic cable sensors

This paper describes the navigation and guidance system developed for the TCV B-737, a Langley Field NASA research aircraft, and presents the results of an evaluation during final approach, landing, rollout and turnoff obtained through a nonlinear digital simulation. A Kalman filter (implemented in square root form) and a third order complementary filter were developed and compared for navigation. The Microwave Landing Systems (MLS) is used for all phases of the flight for navigation and guidance. In addition, for rollout and turnoff, a three coil sensor which detects the magnetic field induced by a buried wire in the runway (magnetic leader cable) is used. The outputs of the sensor are processed into measurements of position and heading deviation from the wire. The results show the concept to be both feasible and practical for commercial type aircraft terminal area control.

Pines, S.↗
NASA NTRS1977

Automated landing, rollout, and turnoff using MLS and magnetic cable sensors

A description of the simulation program used to study the landing approach, rollout and turnoff of the B737-100 aircraft utilizing MLS and a buried magnetic leader cable as navigation aids is presented. Simulation results are given and show the concept to be both feasible and practical for commercial type aircraft terminal area control.

Pines, S.↗
NASA NTRS1977

A study of the optimization method used in the NAVY/NASA gas turbine engine computer code

Sources of numerical noise affecting the convergence properties of the Powell's Principal Axis Method of Optimization in the NAVY/NASA gas turbine engine computer code were investigated. The principal noise source discovered resulted from loose input tolerances used in terminating iterations performed in subroutine CALCFX to satisfy specified control functions. A minor source of noise was found to be introduced by an insufficient number of digits in stored coefficients used by subroutine THERM in polynomial expressions of thermodynamic properties. Tabular results of several computer runs are presented to show the effects on program performance of selective corrective actions taken to reduce noise.

Horsewood, J. L.↗
NASA NTRS1975

Simulation, guidance and navigation of the B-737 for rollout and turnoff using MLS measurements

A simulation program is described for the B-737 aircraft in landing approach, a touchdown, rollout and turnoff for normal and CAT III weather conditions. Preliminary results indicate that microwave landing systems can be used in place of instrument landing systems landing aids and that a single magnetic cable can be used for automated rollout and turnoff. Recommendations are made for further refinement of the model and additional testing to finalize a set of guidance laws for rollout and turnoff.

Pines, S.↗
NASA NTRS1975

Averaged initial Cartesian coordinates for long lifetime satellite studies

A set of initial Cartesian coordinates, which are free of ambiguities and resonance singularities, is developed to study satellite mission requirements and dispersions over long lifetimes. The method outlined herein possesses two distinct advantages over most other averaging procedures. First, the averaging is carried out numerically using Gaussian quadratures, thus avoiding tedious expansions and the resulting resonances for critical inclinations, etc. Secondly, by using the initial rectangular Cartesian coordinates, conventional, existing acceleration perturbation routines can be absorbed into the program without further modifications, thus making the method easily adaptable to the addition of new perturbation effects. The averaged nonlinear differential equations are integrated by means of a Runge Kutta method. A typical step size of several orbits permits rapid integration of long lifetime orbits in a short computing time.

Pines, S.↗
NASA NTRS1975

Precision orbit raising trajectories

A precision trajectory program has been developed to serve as a test bed for geocentric orbit raising steering laws. The steering laws to be evaluated have been developed using optimization methods employing averaging techniques. This program provides the capability of testing the steering laws in a precision simulation. The principal system models incorporated in the program are described, including the radiation environment, the solar array model, the thrusters and power processors, the geopotential, and the solar system. Steering and array orientation constraints are discussed, and the impact of these constraints on program design is considered.

Flanagan, P. F.↗
NASA NTRS1972

Two impulse trajectory optimization for the RAE-B orbit trim problem

The results are reported of work on an appropriate approach to the solution of the optimum two-impulse transfer problem between orbits of specified inclination. The task included a literature search to identify the current state of the art and a definition of the suggested approach for the specific application of a lunar orbit trim. The applications of the results to the problem are included. The formulation for a computer program developed under this task following a more conventional approach is also included.

Payne, M. H.↗