Mechanical & Fluid Systems

Vacuum-Jacketed Cryogenic Flex-Through

John F. Kennedy Space Center, Florida A vacuum-jacketed, cryogenic flex hose was designed with an integrated flange to be able to pass through a vacuum chamber wall. This design increases the quality of the cryogenic fluid at the exit of the hose (i.e., more liquid, less vapor) by extending the hose vacuum-jacket through the chamber wall, where usually a non-insulated fluid fitting would be required.

Posted in: Briefs, Mechanical Components

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Normally-Closed Zero-Leak Valve with a Magnetostrictive Actuator

The valve can be used wherever normally closed valves are required. Goddard Space Flight Center, Greenbelt, Maryland A hermetically sealed, normally closed (NC) zero-leak valve has been developed. Prior to actuation, the valve isolates the working fluid in the upstream volume from the downstream volume with a parent metal seal. The valve utilizes the magnetostrictive alloy Terfenol-D for actuation. This alloy experiences a phenomenon known as magnetostriction, i.e., a gross elongation, when exposed to a magnetic field. This elongation fractures the seal within the wetted volume of the valve, opening the valve permanently and establishing fluid flow. The required magnetic field is generated by redundant coils concentric to the Terfenol, but isolated from the working fluid. The response time for this phenomenon to occur and subsequently for actuation is on the order of milliseconds. The wetted volume consists of entirely parent-metal 6Al-4V titanium, compatible with all storable propellants, helium, nitrogen, argon, isopropyl alcohol, and argon. When coupled with the parent metal seal, this design gives the valve internal and external leak rates of zero.

Posted in: Briefs, Mechanical Components

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Pyrotechnically Actuated Gas Generator Using Aqueous Methanol

This gas generator ensures successful inflation of a supersonic pilot ballute. NASA’s Jet Propulsion Laboratory, Pasadena, California The largest supersonic parachute ever developed is one of the test articles on the Supersonic Flight Dynamics Test (SFDT) vehicle of the Low Density Supersonic Decelerator (LDSD) project. The typical method for deploying a supersonic parachute from an entry vehicle, by firing it from a mortar, is not viable for this application due to its noncentral location on the vehicle and the associated high reaction force. Instead, the parachute is pulled off the vehicle using the Parachute Deployment Device (PDD). The PDD uses a ballute, a smaller, balloon-like, soft-good drag body that maintains positive internal pressure by ingesting air at supersonic speeds through a set of ram-air inlets. The PDD, being significantly smaller than the supersonic parachute, is deployed using a mortar.

Posted in: Briefs, Mechanical Components

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Deployable Perimeter Truss with Blade Reel Deployment Mechanism

Applications include pop-up tents, deployable deck awnings, and pop-up lawn chairs.Solar sail technology depends heavily on the total surface area of the sail. In other words, minimizing mass and volume of its support structure is the main objective, particularly when it comes to launch configuration, i.e. mass, volume constraints, etc. There is a need to develop a low-cost concept of a deployable support structure that can stow in the EELV Secondary Payload Adapter (ESPA) volume, and carries as much sail material as possible. This structure must then be able to deploy the sail material out, and provide the surface area needed.

Posted in: Briefs, TSP, Mechanical Components, Mechanics

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Cantera Integration with T-MATS

John H. Glenn Research Center, Cleveland, Ohio The Toolbox for the Modeling and Analysis of Thermodynamic Systems (TMATS) software package is a library of building blocks that can be assembled to represent any thermodynamic system in the Simulink® (MathWorks, Inc.) environment. These elements, along with a Newton Raphson solver (also provided as part of the T-MATS package), enable users to create models of a wide variety of systems. The updated version of T-MATS (v1.1.1) includes the integration of Cantera, an open source thermodynamic simulation tool. T-MATS was initially described in detail in LEW-19165-1, "Toolbox for Modeling and Analysis of Thermodynamic Systems (T-MATS)", Software Tech Briefs (September 2014), p. 11.

Posted in: Briefs, Mechanical Components

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Rocket Sled Parachute Design Verification

This test architecture helps verify parachute designs for Mars and Earth applications that are too large to fit inside existing wind tunnels. NASA’s Jet Propulsion Laboratory, Pasadena, California Historically, parachutes have been load-tested by various methods including release from an aircraft, deploying in a wind tunnel, dragging through water, and shooting out of an air cannon. Each type of testing has its own advantages and drawbacks. Due to the loading mechanics particular to parachutes deploying in a very thin atmosphere, none of the testing methods was appropriate for testing the next generation of Mars’ full-scale parachutes.

Posted in: Briefs, Mechanical Components

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NEO Hunter Seeker Micro-Spacecraft and Mission Concept

Spacecraft mass and mission cost can be drastically reduced, including the ability to not only discover, but visit near Earth objects.The area of research known as “Planetary Defense” is largely concerned with identifying and tracking asteroids that could impact Earth. The vast majority of asteroids that pose such a risk are known as “Near Earth Asteroids/Objects” or NEAs and NEOs. Some of them are unknown, un-cataloged, and untracked, but are presumed to orbit in Earth-like orbits, and periodically cross Earth’s orbit in a possibly threatening manner.

Posted in: Briefs, TSP, Mechanical Components, Mechanics

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