Mechanical & Fluid Systems

How to Prevent Step Losses with Stepper Motors

While stepper motors are an excellent solution for many applications, a key concern is step losses. However, in most instances step losses can be prevented or corrected. It is important to remember that a stepper motor does not operate like a DC motor. This white paper from MICROMO engineers provides guidance to determine step losses or non-operation across a variety of applications.

Posted in: White Papers, White Papers, Motors & Drives

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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

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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

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Planetary Ice Mining by Down-Hole Energy Injection

This lightweight technology operates in low gravity with energy efficiency. John F. Kennedy Space Center, Florida Ice has been discovered on Mars and is present in the permanently shadowed craters on the Moon and on many asteroids. The ice is usually buried beneath an overburden of regolith. Evidence indicates this overburden may be a meter deep in some locations for the Moon; for Mars, it varies with latitude and may be as deep as or deeper than two meters in many locations. To obtain this ice as a resource in usable quantities, existing technology will require that it be strip-mined.

Posted in: Briefs

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Integrated Epoxy Feedthroughs Improve Fuel Pump Reliability

Of all the design decisions that affect the operation of an in-tank fuel pump, the way you seal the pump housing may top the list. A bad seal will allow liquid fuel to work its way into the housing, which will eventually corrode the electronics and potentially cause a risk of fire.

Posted in: White Papers

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The Best Springs You Haven't Tried Yet

Flat wire wave springs offer the best balance of size and spring force. Here’s what you need to know to design with these high-performance alternatives to traditional springs. Discussed in this paper are the different styles of wave springs and the design advantages offered to the engineer, such as axial space savings, no torsional loads, consistent spring force, dimensional tolerances improvements, increased travel, etc. Additionally it shows some application examples and includes a formulas page for spring calculations.

Posted in: White Papers

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Wire Wound Springs versus Machined Springs; A Comparison

This white paper addresses the high points of choosing between Machined Springs and Wire Wound Springs, and goes into further detail regarding the unique differences that can significantly affect design considerations. Complete with charts detailing technical benefits between the two methods of producing springs. This educational white paper is an essential reference document for any engineer working with mechanical components.

Posted in: White Papers

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