Mechanical & Fluid Systems

Minimally Actuated Hopping Robot

This robot can traverse terrain that is too cluttered for wheeled vehicles. A small robot that travels by hopping has been built and tested. This is a prototype of hopping robots that would carry video cameras and possibly other sensory devices and that are under consideration for use in exploring cluttered, unpredictable terrain on distant planets. On Earth, robots like this one might have value for entertainment and civilian and military reconnoitering of hazardous areas.

Posted in: Machinery & Automation, Briefs, TSP

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User’s Guide for ENSAERO

A report summarizes the development, applications, and procedures for use of ENSAERO, a computer program for simulating aeroelastic phenomena (e.g., wing flutter) of aircraft and spacecraft. ENSAERO computes aeroelastic responses by simultaneously numerically integrating Euler and/or Navier-Stokes equations of airflow and modal finite-element equations of structural dynamics on aeroelastically adaptive dynamic grids. The numerical integrations are performed by time-accurate finitedifference schemes. The report describes the coupling of the governing equations of flow with the governing equations of structural dynamics and with equations that describe active controls and thermal loads. The criteria and procedures for generation of zonal adaptive grids are discussed. Results of simulations performed by use of ENSAERO are presented for examples that involve, variously, steady or unsteady flow about rigid full aircraft or elastic wing/body assemblies. This work was done by Guru P. Guruswamy of Ames Research Center. This invention is owned by NASA, and a patent application has been filed. Inquiries concerning nonexclusive or exclusive license for its commercial development should be addressed to the Patent Counsel, Ames Research Center, (650) 604-5104. Refer to ARC-14239.

Posted in: Mechanics, Briefs, TSP

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Precise Air Bearings Redesigned

A simplified design affords low friction at minimum airflow. Highly precise air bearings for suspending objects over an epoxy flat floor in a laboratory have been developed. These bearings float on airgaps 3 to 5 mil (about 0.08 to 0.13 mm) thick. They are modern versions of precise air bearings, developed during the 1960s, that offer a working coefficient of friction of only 1/16,000. The basic design of these bearings can be scaled easily for different loads and airflows.

Posted in: Mechanics, Briefs, TSP

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Variable Submillimeter-Wave Delay Line for Cryogenic Use

Stiffness, size, vacuum adhesion, range, and number of parts were considered in designing this device. A variable delay line is being developed as part of a far-infrared or submillimeter- wavelength interferometer that would operate in a vacuum in the cryogenic temperature range. No such delay line for spatial interferometry has previously been built for operation under these conditions.

Posted in: Mechanics, Briefs, TSP

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Emergency Tether-Deployment-and-Recoil-Mitigating Systems

A report describes an emergency tether-deployment (ETD) system designed to minimize the harm caused by two events that can occur during deployment of tethered payloads from a space shuttle in orbit. One such event is snagging of the tether during payout while the payload is near the shuttle, causing rebound of the shuttle and payload toward each, thus possibly causing a collision. The other event is recoil of a tether that must be cut while it is under tension. If not suppressed, the recoil can cause the tether to become tangled around the shuttle. The ETD system includes a tether wound on a spool in a standard pattern that minimizes friction during payout, plus a rotating-arm mechanism that prevents snagging. The ETD system can be either (1) used as a primary deployment system or (2) activated automatically through breakage of a tether tiedown in the event of a snag or when the payload is at a safe distance from the shuttle. To suppress recoil, a core of solder is inserted along part of the length of the tether. When a wave of recoil reaches this part, the solder absorbs most of the recoil energy.

Posted in: Machinery & Automation, Briefs, TSP

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Mechanism for Docking a Miniature Spacecraft

This report discusses a proposed docking mechanism to be located in a small hangar on the outside of the International Space Station (ISS). The mechanism would enable docking of a miniature robotic spacecraft (or free flyer) that would carry a video camera and would operate in the vicinity of the ISS. The docking mechanism would include, among other things, (1) an electromagnet for actuation, (2) electrical connectors for transferring data to and from the free flyer and recharging the freeflyer power system, and (3) a quick-disconnect (QD) coupling for recharging a supply of gaseous N2. Once the free flyer had maneuvered into approximate docking alignment, an electromagnet in the mechanism would attract a ferromagnetic plate on the free flyer strongly enough to pull the free flyer in from a distance of as much as several inches (≈10 cm). The mechanism would include surfaces that would mate with surfaces on the free flyer to correct any misalignment as the free flyer was pulled in. Once docked, the free flyer would be held in place by either spring-loaded cam locks or the QD coupling itself. Data, power, and N2 can then be transferred to the vehicle.

Posted in: Machinery & Automation, Briefs, TSP

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Flexure Rings for Centering Lenses

The rings accommodate fabrication tolerances and thermal-expansion mismatches. Specially shaped mounting rings keep lenses precisely centered, regardless of temperature, in the lens housings of cameras and other optical systems. These rings feature (1) well-defined contact spots for alignment, plus (2) relieved surfaces that form flexures to accommodate small manufacturing tolerances and differences among the thermal expansions of lenses, lens housings, and the rings themselves. These rings are made by numerically controlled machining of recently developed clean, strong, machinable plastics.

Posted in: Mechanics, Briefs, TSP

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