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Harpold, J. C.

Publications and source records attributed to Harpold, J. C..

8 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Atmospheric guidance techniques and performance

The Orbiter entry guidance system controls the Space Shuttle Orbiter from the initial atmospheric penetration point to the point at which an earth relative velocity of 2500 feet/second is reached. At the latter point, control of the Orbiter is transferred to the terminal area energy management system. The entry guidance system is based on the concept that the range to be flown during entry is a unique function of the drag deceleration profile flown throughout the entry. The range prediction during entry is based on analytic equations which are simple drag deceleration functions of earth relative velocity above Mach 10.5 and energy with respect to the earth below Mach 10.5. Flight through the entry corridor is accomplished by linking these simple drag deceleration functions together in series in order to define a drag deceleration reference profile. The results of the first three Space Shuttle missions have not only verified the entry guidance concept but have also demonstrated the stability of the guidance system.

Harpold, J. C.↗
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

MCC level C formulation requirements. Entry guidance and entry autopilot, optional TAEM targeting

The level C software formulations requirements for the entry guidance and the simplified autopilot to be used by the Mission Control Center (MCC) entry processor are presented. The modifications required to functionally simulate optional Terminal Area Energy Management (TAEM) targeting capability (OTT) are incorporated. Implementation of this logic in the MCC must be coordinated with flight software OTT implementation and MCC TAEM guidance OTT. The entry guidance logic is based on the orbiter avionics entry guidance software. Descriptions of the entry guidance detailed formulation requirements, the detailed autopilot formulation requirements, and the targeting routine are given. Also included are a definition of coordinate systems, a list of parameter definitions for the software formulations, and a set of formulation flow charts.

Harpold, J. C.↗
NASA NTRS1980

Shuttle program. MCC Level C formulation requirements: Entry guidance and entry autopilot

A set of preliminary entry guidance and autopilot software formulations is presented for use in the Mission Control Center (MCC) entry processor. These software formulations meet all level B requirements. Revision 2 incorporates the modifications required to functionally simulate optimal TAEM targeting capability (OTT). Implementation of this logic in the MCC must be coordinated with flight software OTT implementation and MCC TAEM guidance OTT. The entry guidance logic is based on the Orbiter avionics entry guidance software. This MCC requirements document contains 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 formulation requirements, a description of the targeting routine, and a set of formulation flow charts.

Harpold, J. C.↗
NASA NTRS1978

Shuttle entry guidance

This paper describes the design of the entry guidance for the Space Shuttle Orbiter. This guidance provides the steering commands for trajectory control from initial penetration of the earth's atmosphere until the terminal area guidance is activated at an earth-relative speed of 2500 fps. At this point, the Orbiter is at a distance of about 50 nmi from the runway threshold, and at an altitude of about 80,000 ft. The entry guidance design is based on an analytic solution of the equations of motion defining the drag acceleration profile that meets the terminal criteria of the entry flight while maintaining the flight within systems and operational constraints. Guidance commands, which are based on a control law that ensures damping of oscillatory type trajectory motion, are computed to steer the Orbiter to this drag acceleration profile.

Harpold, J. C.↗
NASA NTRS1972

Apollo experience report: Mission planning for Apollo entry

The problems encountered and the experience gained in the entry mission plans, flight software, trajectory-monitoring procedures, and backup trajectory-control techniques of the Apollo Program should provide a foundation upon which future spacecraft programs can be developed. Descriptions of these entry activities are presented. Also, to provide additional background information needed for discussion of the Apollo entry experience, descriptions of the entry targeting for the Apollo 11 mission and the postflight analysis of the Apollo 10 mission are presented.

Graves, C. A.↗