Mechanical & Fluid Systems

Rapid-Chill Cryogenic Coaxial Direct- Acting Solenoid Valve

A commercially available cryogenic direct-acting solenoid valve has been modified to incorporate a rapid-chill feature. In the original application for which this feature was devised, there is a requirement to ensure that at all times, the valve outlet flow consists entirely or mostly of liquid; that is, there is a requirement to minimize vaporization of cryogenic liquid flowing through the valve. This translates to a requirement to chill interior valve surfaces in contact with the flowing liquid.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Cooling, Valves
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Variable-Tension-Cord Suspension/Vibration-Isolation System

Cord tensions are adjusted to optimize vibration-isolation properties.

A system for mechanical suspension and vibration isolation of a machine or instrument is based on the use of Kevlar (or equivalent aromatic polyamide) cord held in variable tension between the machine or instrument and a surrounding frame. The basic concept of such a tensioned-cord suspension system (including one in which the cords are made of aromatic polyamide fibers) is not new by itself; what is new here is the additional provision for adjusting the tension during operation to optimize vibration-isolation properties.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Suspension systems, Performance upgrades, Vibration, Vibration
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System for Continuous Deaeration of Hydraulic Oil

The proportion of dissolved air is reliably maintained below 1 volume percent.

A system for continuous, rapid deaeration of hydraulic oil has been built to replace a prior system that effected deaeration more slowly in a cyclic pressure/vacuum process. Such systems are needed because (1) hydraulic oil has an affinity for air, typically containing between 10 and 15 volume percent of air and (2) in the original application for which these systems were built, there is a requirement to keep the proportion of dissolved air below 1 volume percent because a greater proportion can lead to pump cavitation and excessive softness in hydraulic-actuator force-versus-displacement characteristics. In addition to overcoming several deficiencies of the prior deaeration system, the present system removes water from the oil.
Posted in: Briefs, TSP, Mechanical Components, Mechanics, Water, Gases, Hydraulic fluids
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Spacecraft Escape Capsule

A report discusses the Gumdrop capsule — a conceptual spacecraft that would enable the crew to escape safely in the event of a major equipment failure at any time from launch through atmospheric re-entry. The scaleable Gumdrop capsule would comprise a command module (CM), a service module (SM), and a crew escape system (CES). The CM would contain a pressurized crew environment that would include avionic, life-support, thermal control, propulsive attitude control, and recovery systems. The SM would provide the primary propulsion and would also supply electrical power, life-support resources, and active thermal control to the CM. The CES would include a solid rocket motor, embedded within the SM, for pushing the CM away from the SM in the event of a critical thermal-protection system failure or loss of control. The CM and SM would normally remain integrated with each other from launch through recovery, but could be separated using the CES, if necessary, to enable the safe recovery of the crew in the CM. The crew escape motor could be used, alternatively, as a redundant means of de-orbit propulsion for the CM in the event of a major system failure in the SM.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Avionics, Electronic control systems, Avionics, Electronic control systems, Life support systems, Evacuation and escape, Entry, descent, and landing, Spacecraft
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Tool for Torquing Circular Electrical-Connector Collars

A simple tool exerts a strong grip.

An improved tool has been devised for applying torque to lock and unlock knurled collars on circular electrical connectors. The tool was originally designed for, and used by, astronauts working in outer space on the Hubble Space Telescope (HST). The tool is readily adaptable to terrestrial use in installing and removing the same or similar circular electrical connectors as well as a wide variety of other cylindrical objects, the tightening and loosening of which entail considerable amounts of torque.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Connectors and terminals, Connectors and terminals, Tools and equipment, Fasteners
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Retaining Device for the Interior Structure of a Spacecraft Payload

Device protects without penalizing interior space.

A device denoted as a bumper assembly for a spacecraft payload container comprises an interior structure surrounded by skin or some other protective enclosure (see figure). When arranged with three or more like assemblies, this bumper assembly is designed to secure the interior structure within a payload’s protective enclosure during the stresses endured in flight and, if required, recovery of the payload. Furthermore, proper use of this innovation facilitates the ability of designers and engineers to maximize the total placement area for components, thus increasing utilization of very valuable and limited space.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Containers, Protective structures, Spacecraft
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On Release of Microbe-Laden Particles From Mars Landers

A paper presents a study in which rates of release of small particles from Mars lander spacecraft into the Martian atmosphere were estimated from first principles. Because such particles can consist of, or be laden with, terrestrial microbes, the study was undertaken to understand their potential for biological contamination of Mars. The study included taking account of forces and energies involved in adhesion of particles and of three mechanisms of dislodgement of particles from the surface of a Mars lander: wind shear, wind-driven impingement of suspended dust, and impingement of winddriven local saltating sand particles. Wind shear was determined to be effective in dislodging only particles larger than about 10 microns and would probably be of limited interest because such large particles could be removed by pre-flight cleaning of the spacecraft, and their number on the launched spacecraft would thus be relatively small. Dislodgement by wind-driven dust was found to be characterized by an adhesion half-life of the order of 10,000 years — judged to be too long to be of concern. Dislodgement by saltating sand particles, including skirts of dust devils, was found to be of potential importance, depending on the sizes of the spacecraft-attached particlesand characteristics of both Mars sand-particle and spacecraft surfaces.

Posted in: Briefs, Mechanical Components, Mechanics, Particulate matter (PM), Bacteria, Entry, descent, and landing, Spacecraft
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Measurement of Model Noise in a Hard-Wall Wind Tunnel

Spurious noise is suppressed in processing of digitized microphone outputs.

Identification, analysis, and control of fluid mechanically generated sound from models of aircraft and automobiles in special low-noise, semi-anechoic wind tunnels are an important research endeavor. Such studies can also be done in aerodynamic wind tunnels that have hard walls if phased microphone arrays are used to focus on the noise source regions and reject unwanted reflections or background noise. Although it may be difficult to simulate the total flyover or drive-by noise in a closed wind tunnel, individual noise sources can be isolated and analyzed.

Posted in: Briefs, Mechanical Components, Mechanics, Scale models, Noise, Sound quality, Noise, Sound quality, Wind tunnel tests, Aerodynamics
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Tilt/Tip/Piston Manipulator With Base-Mounted Actuators

The geometry and kinematics of this manipulator would afford advantages for some applications.

A proposed three degree of freedom (tilt/tip/piston) manipulator, suitable for aligning an optical or mechanical component, would offer several advantages over prior such manipulators:

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Sensors and actuators, Sensors and actuators, Mountings, Pistons
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Multifunctional Tanks for Spacecraft

A document discusses multifunctional tanks as means to integrate additional structural and functional efficiencies into designs of spacecraft. Whereas spacecraft tanks are traditionally designed primarily to store fluids and only secondarily to provide other benefits, multifunctional tanks are designed to simultaneously provide multiple primary benefits. In addition to one or more chamber(s) for storage of fluids, a multifunctional tank could provide any or all of the following:

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Containers, Storage, Spacecraft
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