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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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A gimbal apparatus is disclosed, including a tubular envelope with a variable length between first and second rim structures. A rigid ring structure inside the tubular envelope is connected to diametrically opposite first and second portions of the first rim structure, and is connected to diametrically opposite first and second portions of the second rim structure. A spoke bisects the ring structure.
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In this paper we develop the coupled orbital/attitude dynamics of a multi-body solar sail spacecraft (sailcraft) under the gravitational attraction of a single central body.
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Electropneumatic linear actuator for thrust vector control on J- 2 rocket engine
Fluid amplifier, servovalve, and compensation network for use with pneumatic actuator on J- 2 rocket engine Thrust Vector Control /TVC/
Fortran IV computer program for evaluation of natural frequencies and unstable values of thrust frequency for free-free circular cylindrical shell subjected to end thrust
Fortran IV computer program to evaluate natural frequencies and unstable values of thrust frequency for circular cylindrical shell subjected to periodically varying end thrust
Hot cracking tendencies evaluation of fusion welds of Inconel 718 alloy after different heat treatments
Analysis of flow in gas feeding region of externally pressurized gas bearing
Dynamic stability of bending vibrations of uniform free-free beam under end thrust with application to rocket vehicles
Aerodynamic hinge moments for scale model boost stage nozzle of Saturn V launch vehicle during cold flow jet simulation
Effect of heat treatment on Inconel 718 nickel base alloys and on subsequent fabrication processes
Erectable truss parabolic antenna
In case two control moment gyros fail, attitude control of Skylab can be maintained with the thruster attitude control system. This results, however, in a severely increased fuel consumption, depleting the fuel in a few days. Therefore, an alternate concept was developed which does not have large fuel consumption under any circumstances. In this concept the attitude reference is commanded to oscillate in the orbital plane with twice the orbital frequency and the remaining control moment gyro controls about orbital north and about the minimum moment-of-inertia axis, while the thruster attitude control system controls rate only about the remaining axis. This rate control in conjunction with the restoring torque due to the gravity gradient will keep bounded the excursion of the minimum moment-of-inertia axis out of the orbital plane. This alternate concept has the additional advantage that it needs no information on the principal moment-of-inertia axes misalignment and is completely insensitive to star tracker failure. Proper phasing of the attitude reference oscillation even allows angular momentum desaturation, which is responsible for the insensitivity of the thruster fuel consumption to unknown disturbances, like vent torques and magnetic torques.
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This redundant strapdown INS preliminary design study demonstrates the practicality of a skewed sensor system configuration by means of: (1) devising a practical system mechanization utilizing proven strapdown instruments, (2) thoroughly analyzing the skewed sensor redundancy management concept to determine optimum geometry, data processing requirements, and realistic reliability estimates, and (3) implementing the redundant computers into a low-cost, maintainable configuration.
This paper considers the application of an Annular Momentum Control Device (AMCD) to both fine pointing and large-angle maneuvering of a large space telescope (LST). The AMCD, which consists principally of a spinning rim suspended in noncontacting electromagnetic bearings, represents a new development in momentum storage devices. A nonlinear mathematical model of the AMCD/LST system is derived. An optimal stochastic fine-pointing controller is designed via LQG theory and the minimum-energy maneuvering problem is solved via a gradient technique. Number of state variable and control variable constraints, as well as all trigonometric nonlinearities, are considered in the latter part.