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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 397 records · Page 22

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NASA NTRS1977

An explicit solution to the exoatmospheric powered flight guidance and trajectory optimization problem for rocket propelled vehicles

A derivation of an explicit solution to the two point boundary-value problem of exoatmospheric guidance and trajectory optimization is presented. Fixed initial conditions and continuous burn, multistage thrusting are assumed. Any number of end conditions from one to six (throttling is required in the case of six) can be satisfied in an explicit and practically optimal manner. The explicit equations converge for off nominal conditions such as engine failure, abort, target switch, etc. The self starting, predictor/corrector solution involves no Newton-Rhapson iterations, numerical integration, or first guess values, and converges rapidly if physically possible. A form of this algorithm has been chosen for onboard guidance, as well as real time and preflight ground targeting and trajectory shaping for the NASA Space Shuttle Program.

Jaggers, R. F.↗

NASA NTRS1978

Integrated guidance, navigation and control verification plan primary flight system

The verification process and requirements for the ascent guidance interfaces and the ascent integrated guidance, navigation and control system for the space shuttle orbiter are defined as well as portions of supporting systems which directly interface with the system. The ascent phase of verification covers the normal and ATO ascent through the final OMS-2 circularization burn (all of OPS-1), the AOA ascent through the OMS-1 burn, and the RTLS ascent through ET separation (all of MM 601). In addition, OPS translation verification is defined. Verification trees and roadmaps are given.

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NASA NTRS1978

Flight demonstrations of curved, descending approaches and automatic landings using time referenced scanning beam guidance

The Terminal Configured Vehicle (TCV) program operates a Boeing 737 modified to include a second cockpit and a large amount of experimental navigation, guidance and control equipment for research on advanced avionics systems. Demonstration flights to include curved approaches and automatic landings were tracked by a phototheodolite system. For 50 approaches during the demonstration flights, the following results were obtained: the navigation system, using TRSB guidance, delivered the aircraft onto the 3 nautical mile final approach leg with an average overshoot of 25 feet past centerline, subjet to a 2-sigma dispersion of 90 feet. Lateral tracking data showed a mean error of 4.6 feet left of centerline at the category 1 decision height (200 feet) and 2.7 feet left of centerline at the category 2 decision height (100 feet). These values were subject to a sigma dispersion of about 10 feet. Finally, the glidepath tracking errors were 2.5 feet and 3.0 feet high at the category 1 and 2 decision heights, respectively, with a 2 sigma value of 6 feet.

White, W. F.↗

NASA NTRS1978

Simulator evaluation of three situation and guidance displays for V/STOL aircraft zero-zero landing approaches

A simulator study was undertaken to compare and evaluate the design features of the electronic displays for possible use in V/STOL aircraft: a combined transition display (Display A), a perspective display (Display B), and a hover display (Display C). Display B presents height information via integrated elements; Displays A and C present information similarly except that Display C presents vertical and lateral guidance via conventional cross pointers. High pilot work load was attained by evaluating the displays only as situational guidance displays in a simulated vehicle without stability augmentation. Glide slopes of 6 and 15 deg were used, and steady-state and no-wind conditions were randomly presented. Six pilots participated, and fifty-five objective performance measures were taken along with pilot opinions

Murphy, M. R.↗

NASA NTRS1978

Performance evaluation of integrated guidance and navigation systems

The method of linear covariance analysis is applied to the study of an aerospace vehicle integrated guidance-and-navigation system. This requires that the rms trajectory deviations of the vehicle be computed along with the rms errors of the navigation system. The technique is used to examine the performance of the shuttle orbiter vehicle's guidance-and-navigation system during the terminal phase of the landing. Essentially the same rms trajectory deviations were obtained from a single covariance run as from a 30-sample Monte-Carlo run set. Of particular interest in the study was the result that rms trajectory deviations for the integrated-system were generally significantly larger than the rms navigation errors.

Tao, Y. C.↗

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 NTRS1976

OAST Space Theme Workshop. Volume 3: Working group summary. 1: Navigation, guidance, control (E-1) A. Statement. B. Technology needs (form 1). C. Priority assessment (form 2)

The six themes identified by the Workshop have many common navigation guidance and control needs. All the earth orbit themes have a strong requirement for attitude, figure and stabilization control of large space structures, a requirement not currently being supported. All but the space transportation theme have need for precision pointing of spacecraft and instruments. In addition all the themes have requirements for increasing autonomous operations for such activities as spacecraft and experiment operations, onboard mission modification, rendezvous and docking, spacecraft assembly and maintenance, navigation and guidance, and self-checkout, test and repair. Major new efforts are required to conceptualize new approaches to large space antennas and arrays that are lightweight, readily deployable, and capable of precise attitude and figure control. Conventional approaches offer little hope of meeting these requirements. Functions that can benefit from increasing automation or autonomous operations are listed.

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NASA NTRS1978

Precise terrestrial time: A means for improved ballistic missile guidance analysis

An approach developed to improve the ground instrumentation time tagging accuracy and adapted to support the Minuteman ICBM program is desired. The Timing Insertion Unit (TIU) technique produces a telemetry data time tagging resolution of one tenth of a microsecond, with a relative intersite accuracy after corrections and velocity data (range, azimuth, elevation and range rate) also used in missile guidance system analysis can be correlated to within ten microseconds of the telemetry guidance data. This requires precise timing synchronization between the metric and telemetry instrumentation sites. The timing synchronization can be achieved by using the radar automatic phasing system time correlation methods. Other time correlation techniques such as Television (TV) Line-10 and the Geostationary Operational Environmental Satellites (GEOS) terrestial timing receivers are also considered.

Ehrsam, E. E.↗

NASA NTRS1979

Capturing and tracking performance of the horizontal guidance and control systems of the terminal configured vehicle

A twin-jet commercial transport equipped with digital navigation, guidance, and control systems and advanced electronic display system was used for airborne operational research. The results of flight tests which evaluated a second-order horizontal-path guidance control law and the autopilot and airplane response are presented. This evaluation was accomplished through analysis of recorded flight data and through pilot opinion of the airplane maneuvers during automatic path-capture scenarios and path tracking. Four different path captures were flown at a ground speed of approximately 160 knots and repeated at approximately 300 knots. Path tracking tracking error was measured in terms of cross track error along two paths: one pat at cruise speeds and one at airport-terminal-area speeds. The path tracking accuracy and the smoothness of the airplane maneuvers were judged satisfactory for high speeds; however, at lower speeds the control law design should be improved so that tracking will be more accurate for operations in the airport terminal area.

Knox, C. E.↗

NASA NTRS1979

Flight performance of the TCV B-737 airplane at Kennedy Airport using TRSB/MLS guidance

The terminal configured vehicle (TCV) B 737 was flown in demonstration of the time reference scanning beam/microwave landing system (TRSB/MLS). The flight performance of the TCV airplane during the demonstration automatic approaches and landings while utilizing TRSB/MLS guidance is reported. The TRSB/MLS is shown to provide the terminal area guidance necessary for flying curved automatic approaches with short finals.

White, W. F.↗

NASA NTRS1979

Bilinear tangent yaw guidance

This paper presents a parametric yaw steering law which has been used to provide closed-loop yaw guidance for the launch of the HEAO (High Energy Astronomy Observatory) satellite mission using the Atlas/Centaur launch vehicle. This bilinear tangent steering law provides near optimal yaw steering for maneuvers requiring insertion into orbits with a specified inclination and node. Bilinear tangent steering is shown to be optimal in both the pitch and yaw planes when a uniform gravitational field is assumed. The conditions under which the general bilinear tangent laws degenerate into linear tangent and constant attitude laws are presented. The flight computer implementation of these laws in a rotating coordinate system using real-time integration of the equations of motion is detailed. Explicit solution of the parametric guidance equations requires the inflight solution of (2x2) two-point boundary value problems in the pitch and yaw planes. Excellent results are obtained even for very large (greater than 50 deg) out-of-plane steering angles.

Brusch, R. G.↗

NASA NTRS1979

Development of mining guidance and control systems

New fundamental interface sensor concepts were identified and investigated including tabulation of the physical and performance characteristics of two new interface detector concepts: - natural background radiation and magnetic spin resonance. Studies of guidance and control techniques for the longwall miner identified three basic systems for use in automated/remote controlled longwall mining. The following projects were initiated: system study which will more completely define the longwall guidance and control system design concepts; integration of the various control functions (vertical, yaw, and roll); and hardware technical requirements.

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NASA NTRS1980

Flight performance of the TCV B-737 airplane at Jorge Newberry Airport, Buenos Aires, Argentina using TRSB/MLS guidance

The flight performance of the Terminal Configured Vehicle airplane is summarized. Demonstration automatic approaches and landings utilizing time reference scanning beam microwave landing system (TRSB/MLS) guidance are presented. The TRSB/MLS was shown to provide the terminal area guidance necessary for flying curved automatic approaches with final legs as short as 2 km.

White, W. F.↗

NASA NTRS1980

MCC level C formulation requirements. Shuttle TAEM guidance and flight control, STS-1 baseline

The TAEM guidance and body rotational dynamics models required for the MCC simulation of the TAEM mission phase are defined. This simulation begins at the end of the entry phase and terminates at TAEM autoland interface. The logic presented is the required configuration for the first shuttle orbital flight (STS-1). The TAEM guidance is simulated in detail. The rotational dynamics simulation is a simplified model that assumes that the commanded rotational rates can be achieved in the integration interval. Thus, the rotational dynamics simulation is essentially a simulation of the autopilot commanded rates and integration of these rates to determine orbiter attitude. The rotational dynamics simulation also includes a simulation of the speedbrake deflection. The body flap and elevon deflections are computed in the orbiter aerodynamic simulation.

Carman, G. L.↗

NASA NTRS1980

Entry guidance and entry autopilot (STS-1 baseline)

Preliminary entry guidance and autopilot software formulations, for use in the Mission Control Center (MCC) entry processor, are presented. The MCC requirements are met by a definition of coordinate systems, a list of parameter definitions for the software formulations, a description of the entry guidance detailed formulation requirements, a description of the detailed autopilot formualtion requirements, a description of the targeting routine, and a set of formulation flow charts.

Harpold, J. C.↗

NASA NTRS1980

Flight performance of the TCV B-737 airplane at Montreal/Dorval International Airport, Montreal, Canada, using TRSB/MLS guidance

The NASA terminal configured vehicle B-737 was flown in support of the world wide FAA demonstration of the time reference scanning beam microwave landing system. A summary of the flight performance of the TCV airplane during demonstration automatic approaches and landings while utilizing TRSB/MLS guidance is presented. The TRSB/MLS provided the terminal area guidance necessary for automatically flying curved, noise abatement type approaches and landings with short finals.

White, W. F.↗

NASA NTRS1979

Charge-coupled device /CCD/ trackers for high accuracy guidance applications

Recent advances in large area charge coupled device (CCD) imaging detectors and high speed microprocessors have prompted the development of a new class of electro-optical tracking instruments at the Jet Propulsion Laboratory (JPL). These instruments are designed for standardized NASA-wide usage and are characterized by their extremely high pointing accuracy and stability and performance capabilities which are largely software defined and thus easily adapted to a variety of mission requirements. This paper presents an examination of the methods by which CCD detectors are being incorporated in star tracker instruments and the performance capabilities that can be expected from currently available devices. The multi-function sensor concept, in which a single sensor can function in a variety of guidance applications, is described. Software algorithms designed to provide efficient extraction of guidance information from both point and extended images are also presented. CCD star tracker implementations currently underway at JPL are described, and performance data obtained during laboratory testing is presented and discussed.

Salomon, P. M.↗

NASA NTRS1980

A model for helicopter guidance on spiral trajectories

A point mass model is developed for helicopter guidance on spiral trajectories. A fully coupled set of state equations is developed and perturbation equations suitable for 3-D and 4-D guidance are derived and shown to be amenable to conventional state variable feedback methods. Control variables are chosen to be the magnitude and orientation of the net rotor thrust. Using these variables reference controls for nonlevel accelerating trajectories are easily determined. The effects of constant wind are shown to require significant feedforward correction to some of the reference controls and to the time. Although not easily measured themselves, the controls variables chosen are shown to be easily related to the physical variables available in the cockpit.

Mendenhall, S.↗