SEARCH · Engineering Papers
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Rods of refractory ceramic material and glasses having relatively high fusion temperatures and tensile strengths are converted to fiber by subjecting these rods to alternate fusion and gas-jet bursts. The refractory, high tensile strength fibers produced are combined with suitable binder to produce heat-resistant fabrics and rigid structures.
Compact, cylindrical gas diffuser with radial exhaust slots and internal axial flow channels maintains the necessary pressure for the desired withdrawal rate of cryogenic liquids from tanks. The diffuser minimizes pressure loss which results from condensation of nitrogen gas in the liquid and prevents direct impingement of gas jets on liquid surface to reduce turbulence.
Computer program analyzes the motion of two rigid bodies in space, separating as a result of any one, or a combination of, the following mechanisms - springs with ball ends, springs with one end guided, pyrotechnics, rockets, cold-gas jets, air pistons, and Coulomb drag.
Electro-pneumatic transducer for conversion of electrical into fluidic signals, using temperature dependence of laminar gas jet deflection angle in flow along heated curved wall
Method for correcting orientation of spacecraft with respect to sun is discussed. System consists of two photocells on either side of sensor. When photocells are evenly illuminated, no output is made from sensor. When photocells are unevenly illuminated, sensor sends signal to gas jets to change orientation.
The development of an advanced long life rate measuring package, designed for a five year useful life as a meteorological satellite control sensor is discussed. The primary function of the rate mesuring package is to provide rate information for the reaction wheel and gas jet torquing devices that are used to damp spacecraft oscillations and to constrain the spacecraft to the required attitude with respect to the orbital plane. The specifications for the rate measuring package sensor are described. Application of the rate measuring package to the Nimbus D satellite is proposed.
Liquid viscosity was included in the Bellman-Pennington theory of the Taylor wave in a liquid vapor interface. Predictions of the most susceptible wavelength, and of the wave frequency, were made as a function of a liquid viscosity parameter and the Bond number. The stability of a gas jet in a viscous liquid was studied and the result is used to predict the peak heat flux on large horizontal heaters. Experimental measurements of the dominant Taylor wave and its growth rate were made during the film boiling of cyclohexanol on cylindrical heaters. The results bear out the predictions quite well. The thickness of the vapor blanket surrounding a cylindrical heater was measured and a correlation suggested. The effect of large fluxes of vapor volume on the dominant wavelength was also noted. Theoretical results of the peak heat flux are compared with the experimental data, and the effect of finite geometry of flat plate heaters on the peak heat flux is also discussed.
This article presents an efficient digital computer procedure, along with the complete listing of the associated computer program, which may be conveniently utilized for the accurate solution of a wide range of practical eigenvalue problems. Important applications of the present work are envisaged in the natural frequency analysis of spinning structures discretized by the finite element technique, and in the determination of transfer functions associated with the dynamic blocks of control systems of spacecraft utilizing gas jets or reaction wheels for attitude control, as well as of spin-stabilized and dual-spin-stabilized satellites. The validity of the Sturm sequence property is first established for the related matrix formulation involving Hermitian and real symmetric, positive-definite matrices, both being usually of highly banded configuration. A numerically stable algorithm based on the Sturm sequence method is then developed which fully exploits the banded form of the associated matrices.
An accelerator nominally capable of ejecting pulses of electrons up to 6 sec in length, current to 500 ma and energy to 20 keV was flown on a rocket at 1500 October 15, 1972. The Strypi rocket was launched from the Pacific Missile Range Facility at Kauai, Hawaii. The intent was to eject electron pulses of various characteristics upwards along the magnetic field so as to produce artificial auroras in the conjugate (Southern Hemisphere) atmosphere and possibly to produce weaker auroras in the nearby atmosphere as a consequence of backscattered electrons. The accelerator package included a gas jet actuated attitude control system controlled by gyros. Attitude sensing also was accomplished by a two-axis fluxgate magnetometer, and a large foil was deployed to collect ambient electrons to neutralize the accelerator when it ejected high-energy electrons. Scientific instrumentation contained on the flight package included retarding potential analyzers, energetic electron detectors, and detectors to sense very low frequency radio noise. Image orthicon television systems and other optical sensors were operated in the conjugate region aboard two NC-135 jet aircrafts based in Samoa. Similar devices were operated at Haleakala, Hawaii, to attempt detection of auroras caused by backscattered electrons.
The purpose of the test was to determine the effects of cold jet gas plumes on (1) the integrated vehicle longitudinal and lateral-directional force data, (2) exposed wing hinge moment, (3) wing pressure distributions, (4) orbiter MPS external pressure distributions, and (5) model base pressure. The similarity between solid and gaseous plumes was investigated, and fluorescent oil flow visualization studies were conducted.
The purpose of the test was to determine the effects of cold jet gas plumes on (1) the integrated vehicle longitudinal and lateral-directional force data, (2) exposed wing hinge moment, (3) wing pressure distributions, (4) orbiter MPS external pressure distributions, and (5) model base pressures. An investigation was undertaken to determine the similarity between solid and gaseous plumes; fluorescent oil flow visualization studies were also conducted. Plotted wing pressure data is tabulated.
Tests were conducted to determine the effects of cold jet gas plumes on (1) the integrated vehicle longitudinal and lateral-directional force data, (2) exposed wing hinge moment, (3) wing pressure distributions, (4) orbiter MPS external pressure distributions, and (5) model base pressures. An investigation was undertaken to determine the similarity between solid and gaseous plumes; fluorescent oil flow visualization studies were also conducted. Tabulated data listings are included.
Attitude control propulsion components are described, including hydrazine thrusters, hydrazine thruster and cold gas jet valves, and pressure and temperature transducers. Component-ordered data are presented in tabular form; the manufacturer and specific space program are included.
The merits of combustion experimentation in a space environment are assessed, and the impact of such experimentation on current theoretical models is considered. It is noted that combustion theory and experimentation for less than normal gravitational conditions are incomplete, inadequate, or nonexistent. Extensive and systematic experimentation in a space environment is viewed as essential for more adequate and complete theoretical models of such processes as premixed flame propagation and extinction limits, premixed flame propagation in droplet and particle clouds, ignition and autoignition in premixed combustible media, and gas jet combustion of unpremixed reactants. Current theories and models in these areas are described, and some combustion studies that can be undertaken in the Space Shuttle Program are proposed, including crossed molecular beam, turbulence, and upper pressure limit (of gases) studies.
A test is presented which was performed to determine the effect of cold jet gas plumes generated from main propulsion system and solid rocket motor nozzles on: (1) six-component force and moment data, (2) wing static pressures, (3) wing hinge moment, (4) elevon hinge moment, (5) rudder hinge moment, and (6) orbiter MPS nozzle pressure loads. The effects of rudder deflection, nozzle gimbal angle, and plume size were also obtained.
Observations of comet Kohoutek made with a 3-mm line receiver mounted on the 11-m NRAO radio dish at Kitt Peak are presented. The detection of line transitions of hydrogen cyanide and methyl cyanide is reported and discussed along with the variability of neutral gas jets. Microwave transitions in molecules of cometary origin are also examined.
A spacecraft going within 4 solar radii of the Sun experiences an acceleration up to .00005 g from solar radiation pressure, and significant (though smaller) accelerations from the solar wind. To obtain satisfactory information about relativistic effects and the Sun's quadrupole mass coefficient, these non-gravitational accelerations are either measured or compensated out by making the spacecraft drag free. A proof mass inside the spacecraft structure is shielded from the external forces, so that it follows a nearly ideal gravitational orbit, and a control system activates gas jets (or other translational forcers) to make the vehicle follow the mass. The problems are mechanizing the control laws and minimizing extraneous effects such as the self gravitational pull of the spacecraft. The extraneous forces can be averaged in one plane by having a spinning vehicle.
Modifications and enhancements that have been made to the Recursive Estimation Attitude Program (REAP) are discussed. Continuous attitudes for OSO-8 to + or - 0.05 degree accuracy are determined from Sun and star slit sensors mounted on the spinning portion of the spacecraft. The bulk of the attitude production is performed by a Weighted Least Squares (WLS) batch processor, but REAP is used for problem passes such as those involving gas jet maneuvers, sparse star fields, or star sensor saturation by high energy particles in the South Atlantic Anomaly.