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Pressure-Balanced, Low-Hysteresis Finger Seal

Pressure balance would be altered to reduce a hysteretic variation of leakage. A second-generation design for a finger seal has been proposed to reduce a hysteretic effect that gives rise to increased leakage in a first-generation finger seal. As explained below, the second-generation design provides for balancing of pressure drops along the flow paths within the seal in such a way as to reduce a friction force believed to cause the hysteresis.

Posted in: Mechanics, Briefs, TSP

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Instrument for Measuring Extreme Winds

This rugged instrument has no moving parts. An instrument is undergoing development for use in measuring both the horizontal direction and the horizontal speed of wind in the speed range from 60 to 300 mph (about 27 to 134 m/s) at a rate of at least 50 samples per second. The speed range of this instrument greatly exceeds that of conventional anemometers, encompassing speeds observed in hurricanes and tornadoes. Unlike conventional anemometers, this instrument has a small exposure profile and contains no rotating mechanisms and, hence, is more rugged.

Posted in: Mechanics, Briefs, TSP

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Mechanized Harvesting of Plants in a Controlled Environment

The proposed Plant Harvesting Mechanization System (PHARMS) would comprise machinery and controls for semiautomated harvesting of plants grown in a controlled environment. The PHARMS was conceived as a prototype of harvesters to be incorporated into life-support systems of spacecraft and remote planetary bases, wherein plants would provide food and contribute to recycling of air and water. On Earth, PHARMS-like systems could reduce the labor of harvesting plants from protected agricultural systems in which special fruits and vegetables, herbs, ornamental plants, and mushrooms are grown. At harvest time, the PHARMS would be moved from storage to a location near the plantgrowth chamber. There, it would be unfolded from a compact configuration, then prepared for operation by setting of control parameters and mechanical alignment with the chamber and plants. In operation, the PHARMS would pull plant trays out of the chamber and remove plants from the trays. Then it would subject the plants to a variety of other processes, depending on the crop: Examples of such processes include drying, cutting, chopping, stripping of seeds from stalks, threshing, separation of roots from stalks or vines, breaking pods to extract seeds, and pneumatic separation of seeds from chaff.

Posted in: Mechanics, Briefs

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Emergency Landing Using Thrust Control and Shift of Weight

Landing with control surfaces and engines on one side inoperative may be possible. Normally, the damage that results in a total loss of the primary flight control of a transport airplane, including all the engines on one side, would be catastrophic. Dryden Flight Research Center has conceived of a method of responding to a total loss of hydraulic pressure and failure of engines on one side: An emergency controller would utilize the engines that are still working on the other side, along with transfers of fuel among tanks to effect lateral shift of the center of gravity (CG), in order to steer the airplane to an emergency landing.

Posted in: Mechanics, Briefs

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Tests of Finger Seals

A report discusses tests of finger seals, which were described in “Pressure- Balanced, Low-Hysteresis Finger Seal” (LEW-16840), which appears on page 52 in this issue. Like a labyrinth or brush seal, a finger seal is used (typically in a gas turbine) to minimize a leakage flow along a rotating shaft. The report describes baseline (subject to considerable hysteresis) and pressure- balanced (low-hysteresis) brush seals and presents results of hysteresis, performance, and endurance tests of the seals in a seal rig at Glenn Research Center. The report concludes that a finger-seal design is ready for engine testing.

Posted in: Mechanics, Briefs, TSP

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Design Concepts for the ISS TransHab Module

Twelve reports present concepts for the design of structural and functional systems, subsystems, and components of the proposed TransHab module — an inflatable, lightweight habitation module that would be used by crewmembers of the International Space Station and would serve as a prototype of habitation modules for future spacecraft on long missions (e.g., missions to Mars). The TransHab module would be a unique hybrid structure that would combine the packaging and mass efficiencies of an inflatable structure with the advantages of a load-bearing hard structure. The governing design concept is one of a high degree of integration and multifunctionality of all parts of the Trans- Hab system. The reports include sketches (some containing estimated dimensions) and discussions of engineering requirements. There are also numerous discussions of human factors (psychological, social, and physiological) that affect many aspects of design. Although the reports address issues specific to the TransHab module, some of the concepts discussed may be applicable to the design of temporary or transportable housing for use on Earth.

Posted in: Mechanics, Briefs, TSP

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Inverted Hindle Mount Reduces Sag of a Large, Precise Mirror

The mirror is suspended from above by multiple, equally loaded supports. A mount has been devised to satisfy a requirement to suspend a highly precise, flat, circular, low-thermal-expansion glass mirror in a horizontal plane with its reflective side down while keeping the reflective mirror surface flat to within a peak-to-valley depth of less 50 nm. The difficulty of the suspension problem and the significance of the mount conceived as the solution of the problem arise from the large size and weight of the mirror (diameter 101.7 cm, thickness 18.8 cm, mass 385 kg).

Posted in: Mechanics, Briefs, TSP

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