Mechanical & Fluid Systems

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, Sensors and actuators, Methanol, Entry, descent, and landing

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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, Solar energy, Packaging, Lightweighting, Spacecraft

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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, Computer simulation, Computer software and hardware, Thermodynamics

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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, Landing gear, Test equipment and instrumentation, Test procedures, Spacecraft

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How To Make Pressure Switches That Last

Simple design principles for harsh operating conditions Fluid control systems for many aerospace, industrial and heavy equipment applications require accurate, reliable pressure switching under harsh operating conditions. In these applications, the wrong pressure switch can cause catastrophic damage or even endanger human life.

Posted in: White Papers, Mechanical Components, Fluid Handling, Motion Control

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Controlling the EMI Effects of Avionic Equipment

Devices that can cause interference in aircraft include laptops, tablets, and cell phones, and all have been suspected of causing events such as autopilot disconnects, erratic flight deck indications, and airplanes turning off course. Board level shielding has never been more important in maintaining the functionality and safety of avionic equipment.

Posted in: White Papers, White Papers, Aerospace, Mechanical Components

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Force Transfer Machines

There has been ongoing debate as to whether or not a hydraulic force machine that applies the force simultaneously to both the reference standard and the unit under test is more repeatable and reproducible when the force is applied and transferred with 3 bars versus 2 bars. The debate centers around alignment of the reference standard and the unit under test. There is no disagreement about the benefits of using a triangular configuration when using multiple load cells to weigh an object; however, there is a debate over any advantages that might be offered by using a 3 bar Universal Calibrating Machine (UCM) instead of a traditional 2 bar system. This paper provides test results for repeatability and reproducibility for a 2 bar UCM and a 3 bar UCM, showing the null hypothesis to be correct and proving that there is not a difference between either type of UCM.

Posted in: White Papers, Instrumentation, Mechanical Components, Test & Measurement

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