Tech Briefs

Arbitrating Control of Control and Display Units

The ARINC 739 Switch is a computer program that arbitrates control of two multi-function control and display units (MCDUs) between (1) a commercial flight-management computer (FMC) and (2) NASA software used in research on transport aircraft. (MCDUs are the primary interfaces between pilots and FMCs on many commercial aircraft.) This program was recently redesigned into a software library that can be embedded in research application programs. As part of the redesign, this software was combined with software for creating custom pages of information to be displayed on a CDU. This software commands independent switching of the left (pilot’s) and right (copilot’s) MCDUs. For example, a custom CDU page can control the left CDU while the FMC controls the right CDU. The software uses menu keys to switch control of the CDU between the FMC or a custom CDU page. The software provides an interface that enables custom CDU pages to insert keystrokes into the FMC’s CDU input interface. This feature allows the custom CDU pages to manipulate the FMC as if it were a pilot.

Posted in: Briefs, TSP, Software, Computer software and hardware, Flight management systems, Human machine interface (HMI)

Web-Based Software for Managing Research

aeroCOMPASS is a software system, originally designed to aid in the management of wind tunnels at Langley Research Center, that could be adapted to provide similar aid to other enterprises in which research is performed in common laboratory facilities by users who may be geographically dispersed. Included in aeroCOMPASS is Webinterface software that provides a single, convenient portal to a set of project- and test-related software tools and other application programs. The heart of aeroCOMPASS is a user-oriented document-management software subsystem that enables geographically dispersed users to easily share and manage a variety of documents. A principle of “write once, read many” is implemented throughout aeroCOMPASS to eliminate the need for multiple entry of the same information. The Web framework of aeroCOMPASS provides links to client-side application programs that are fully integrated with databases and server-side application programs. Other subsystems of aeroCOMPASS include ones for reserving hardware, tracking of requests and feedback from users, generating interactive notes, administration of a customer-satisfaction questionnaire, managing execution of tests, managing archives of metadata about tests, planning tests, and providing online help and instruction for users.

Posted in: Briefs, Software, Electronic control systems, Internet, Human machine interface (HMI), Wind tunnel tests

Driver Code for Adaptive Optics

A special-purpose computer code for a deformable-mirror adaptive-optics control system transmits pixel-registered control from (1) a personal computer running software that generates the control data to (2) a circuit board with 128 digital-to-analog converters (DACs) that generate voltages to drive the deformable-mirror actuators. This program reads control-voltage codes from a text file, then sends them, via the computer’s parallel port, to a circuit board with four AD5535 (or equivalent) chips. Whereas a similar prior computer program was capable of transmitting data to only one chip at a time, this program can send data to four chips simultaneously. This program is in the form of C-language code that can be compiled and linked into an adaptive-optics software system. The program as supplied includes source code for integration into the adaptive-optics software, documentation, and a component that provides a demonstration of loading DAC codes from a text file. On a standard Windows desktop computer, the software can update 128 channels in 10 ms. On Real- Time Linux with a digital I/O card, the software can update 1024 channels (8 boards in parallel) every 8 ms.

Posted in: Briefs, TSP, Software, Mirrors, Adaptive control, Architecture, Computer software and hardware, Optics

Ceramic Paste for Patching High-Temperature Insulation

Repairs can be performed by use of simple techniques.

A ceramic paste that can be applied relatively easily, either by itself or in combination with one or more layer(s) of high temperature ceramic fabrics, such as silicon carbide or zirconia, has been invented as a means of patching cracks or holes in the reinforced carbon-carbon forward surfaces of a space shuttle in orbit before returning to Earth. The paste or the paste/fabric combination could also be used to repair rocket-motor combustion chambers, and could be used on Earth to patch similar high-temperature structures.

Posted in: Briefs, Materials, Maintenance, repair, and service operations, Ceramics, Fabrics, Insulation, Reusable launch vehicles and shuttles

Protective Skins for Aerogel Monoliths

Viscous polymer precursors are applied, then polymerized before they can percolate in.

A method of imparting relatively hard protective outer skins to aerogel monoliths has been developed. Even more than aerogel beads, aerogel monoliths are attractive as thermal-insulation materials, but the commercial utilization of aerogel monoliths in thermal-insulation panels has been inhibited by their fragility and the consequent difficulty of handling them. Therefore, there is a need to afford sufficient protection to aerogel monoliths to facilitate handling, without compromising the attractive bulk properties (low density, high porosity, low thermal conductivity, high surface area, and low permittivity) of aerogel materials. The present method was devised to satisfy this need.

Posted in: Briefs, TSP, Materials, Insulation, Materials properties, Protective structures

Fabrication of Polyimide-Matrix/Carbon and Boron-Fiber Tape

Production costs can be reduced and compression strengths increased.

The term “HYCARB” denotes a hybrid composite of polyimide matrices reinforced with carbon and boron fibers. HYCARB and an improved process for fabricating dry HYCARB tapes have been invented in a continuing effort to develop lightweight, strong composite materials for aerospace vehicles. Like other composite tapes in this line of development, HYCARB tapes are intended to be used to build up laminated structures having possibly complex shapes by means of automated tow placement (ATP) — a process in which a computer controlled multiaxis machine lays down prepreg tape or tows. The special significance of the present process for making dry HYCARB for ATP is that it contributes to the reduction of the overall cost of manufacturing boron-reinforced composite-material structures while making it possible to realize increased compression strengths.

Posted in: Briefs, Materials, Fabrication, Composite materials, Fibers, Polymers, Spacecraft

Asymmetric Bulkheads for Cylindrical Pressure Vessels

These bulkheads would offer advantages over prior concave, convex, and flat bulkheads.

Asymmetric bulkheads are proposed for the ends of vertically oriented cylindrical pressure vessels. These bulkheads, which would feature both convex and concave contours, would offer advantages over purely convex, purely concave, and flat bulkheads (see figure). Intended originally to be applied to large tanks that hold propellant liquids for launching spacecraft, the asymmetric-bulkhead concept may also be attractive for terrestrial pressure vessels for which there are requirements to maximize volumetric and mass efficiencies.

Posted in: Briefs, Mechanical Components, Mechanics, Bulkheads

Code Assesses Risks Posed by Meteoroids and Orbital Debris

BUMPER II version 1.92e is a computer code for assessing the risk of damage from impacts of micrometeoroids and orbital debris on the International Space Station (ISS), including those parts of the ISS covered by shielding that affords partial protection against such impacts. (Other versions of BUMPER II have been written for other spacecraft.) Bumper II quantifies the probability of penetration of shielding and the damage to spacecraft equipment as functions of the size, shape, and orientation of the spacecraft; the parameters of its orbit; failure criteria that quantify impact damage at the threshold of failure for each spacecraft surface; and the impact-damage resistance of each spacecraft surface as defined by “ballistic limit equations” that return the size of a failure causing particle as a function of target parameters (including materials, configurations, thicknesses, and gap distances) and impact conditions (impact velocity and the density and shape of the impactor). BUMPER II version 1.92e contains several dozen ballistic limit equations that are based on results from thousands of hypervelocity impact tests conducted by NASA on ISS shielding and other hardware, and on results from numerical simulations of impacts.

Posted in: Briefs, Mechanical Components, Mechanics, Computer software and hardware, Risk assessments, Spacecraft

Self-Regulating Water-Separator System for Fuel Cells

This system would not depend on hydrophobic or hydrophilic surfaces.

A proposed system would perform multiple coordinated functions in regulating the pressure of the oxidant gas (usually, pure oxygen) flowing to a fuel-cell stack and in removing excess product water that is generated in the normal fuel-cell operation. The system could function in the presence or absence of gravitation, and in any orientation in a gravitational field.

Posted in: Briefs, Mechanical Components, Mechanics, Fuel cells

Self-Advancing Step-Tap Drills

It is not necessary to apply axial drilling forces.

Self-advancing tool bits that are hybrids of drills and stepped taps make it possible to form threaded holes wider than about 1/2 in. (about 13 mm) without applying any more axial force than is necessary for forming narrower pilot holes. These self-advancing stepped-tap drills were invented for use by space-suited astronauts performing repairs on reinforced carbon/carbon space-shuttle leading edges during space walks, in which the ability to apply axial drilling forces is severely limited. Self-advancing stepped-tap drills could also be used on Earth for making wide holes without applying large axial forces.

Posted in: Briefs, TSP, Manufacturing & Prototyping, Tools and equipment, Drilling

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