Mechanical & Fluid Systems

In-Situ Load System for Calibrating and Validating Aerodynamic Properties of Scaled Aircraft in Ground-Based Aerospace Testing Applications

This portfolio of technologies can be used in wind-tunnel force balance applications, and robotics applications such as rovers or prosthetic shoulder joints. Langley Research Center, Hampton, Virginia NASA’s Langley Research Center has developed three techniques and systems to calibrate and validate wind-tunnel force balances and other multi-component force transducers. The first is the Single Vector Calibration System (SVS), which uses a single deadweight for calibration and has been in active use at NASA for over 15 years. The second system is the In-Situ Load System (ILS). The ILS is based on the same fundamental concept as the SVS, but is designed for in-situ verification just prior to testing. Building off of the SVS and ILS, the third system is the Variable Acceleration Force Calibration System (VACS), which shares the single-vector force application concept, but generates those forces differently by keeping the mass constant and varying the acceleration. These techniques and systems provide for less complex and less labor-intensive calibration and verification of multi-component force transducers.

Posted in: Briefs, Mechanical Components, Machinery & Automation, Calibration, Scale models, Wind tunnel tests, Aerodynamics


Release of a Stuck Solar Array or Antenna

Several options are examined that may also be useful in remotely controlled terrestrial environments. Goddard Space Flight Center, Greenbelt, Maryland Satellite launches experience approximately one deployment failure every two years. These failures include a solar array or antenna that fails to deploy because it is stuck due to a mechanism failure, or is snagged by a cable or thermal blanket. Knowledge of the exact circumstances of the deployable failure is limited. Ground commanding of the spacecraft is conducted in an attempt to free the stuck deployable.

Posted in: Briefs, Mechanical Components, Machinery & Automation, Failure analysis, Antennas, Robotics, Satellites


High-Heat-Flux-Capable Boundary Layer Vortex Generator and Boundary Layer Transition Device

Lyndon B. Johnson Space Center, Houston, Texas Afixed geometry device has been developed to promote boundary layer transition and generation of streamwise vorticity, and is capable of withstanding entry heating environments for the Space Shuttle Orbiter. Designed to have a total height above the surface of the same order as the local boundary layer thickness, this device is approximately 0.25 in. (≈0.6 cm) tall and 4 in. (≈10 cm) long for the Orbiter entry application. Because temperature exposure is a key design factor for entry systems, the geometry has been optimized to establish peak heating rates and peak surface temperatures that are close to being spatially consistent on the protuberance. A relatively thin cross-section of 0.4 in. (≈1 cm) provides significant thermal radiation relief via conduction through the aft surface of the geometry. Sufficient mechanical strength to satisfy launch, ascent, entry, and landing conditions has been maintained in the design.

Posted in: Briefs, Mechanical Components, Machinery & Automation, Thermal management, Aerodynamics, Entry, descent, and landing


GEMINI Stability Control for Reducing Pointing Jitter in CubeSats and Smallsats

Pointing jitter is significantly reduced by using two reaction wheels per axis, passive vibration isolators, and differential speed control. NASA’s Jet Propulsion Laboratory, Pasadena, California Because of the cost-effectiveness of flying smallsats compared to large flagship spacecraft, there is increasing interest in boosting their capabilities for supporting precision science payloads and sophisticated instrumentation. Unfortunately, a major current drawback with using smallsats is their inability to hold the pointing line-of-sight steady without jittering. Line-of-sight jitter degrades observations made by cameras and other imaging-type instruments, and fundamentally limits the quality of science that can be obtained.

Posted in: Briefs, Mechanical Components, Machinery & Automation, Stability control, Imaging and visualization, Vibration, Test equipment and instrumentation, Satellites


Piezoelectric-Actuated Rotary Ultrasonic Motor

This motor can be used where rotary actuation is required, particularly in cryogenic and high-temperature applications. NASA’s Jet Propulsion Laboratory, Pasadena, California This actuator was developed out of a need for a cryogenic actuator that can operate effectively in spite of the thermal mismatch involved with construction materials that have different expansion coefficients. Also, there is a need for a cryogenic motor that can drive infrared systems and produce minimal thermal energy that can interfere with their operation.

Posted in: Briefs, Mechanical Components, Mechanics, Machinery & Automation, Sensors and actuators, Thermal management, Materials properties


Launch Tie-Down and Release Mechanism for CubeSat Spacecraft

This hardware configuration takes up an extremely small volume inside the CubeSat bus. NASA’s Jet Propulsion Laboratory, Pasadena, California As CubeSats take on increased functionality, including larger solar arrays for increased power demands and large antennas for science and communications needs, the requirements for launch tie-down and release mechanisms are evolving. In the past, some large CubeSat-deployable structures (solar arrays) relied on the confining walls of the CubeSat canister to act as the restraint mechanism. However, this practice is largely eliminated now, with most CubeSat specifications requiring a minimum amount of dwell time (after the CubeSat has been ejected from its parent canister) before the deployable structure can be released and deployed on orbit. Thus, a reliable restraint and release mechanism that does not depend on the geometry of the canister walls must be implemented.

Posted in: Briefs, Mechanical Components, Antennas, Packaging, Launch vehicles, Satellites


Ratcheting Threaded Tapered Collet for use in Planetary Sample Caching Systems

The desired sample tube preload can be tailored to specific applications, and allows each sample to be individually secured. NASA’s Jet Propulsion Laboratory, Pasadena, California Aridged retention interface is necessary to secure planetary sample tubes within a caching system for use in future sample return missions. The assumed retention interface requirements are as follows: the interface shall maintain sample integrity at large deceleration landing loads; the interface shall minimize weight and complexity; and any required actuation for sample tube retention shall be performed by an external source (such as a robotic end-effector).

Posted in: Briefs, Mechanical Components, Containers, Mountings, Entry, descent, and landing


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