Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “FLEX”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Mission adaptive wing soars at NASA Facility

Research pilots have flown the Mission Adaptive Wing (MAW) aircraft, a highly modified F-111 jet fighter, from subsonic speeds up to Mach 1.4 in initial flight tests. The inital test flights are clearing the envelope with the wings flexed at various curvatures. This process allows further research data to be safely gathered so that designers of future variable camber wing aircraft have the best information possible. The altitude envelope was cleared from 27,500 down to 7,500 feet where denser air can cause more stress on the aircraft. Testing with the aircraft was conducted with wing sweep angles of 26 and 58 degrees. At the conclusion of the performance tests in the manual configuration, the system will be reconfigured for automatic mode tests. The limited automatic modes include maneuver camber control where the wings are deflected automatically to the best lift versus drag combination for a particular speed; cruise camber control which can help protect the aircraft from high G stresses; and maneuver enhancement/gust alleviation which is designed to improve the aircraft's up and down movement response to pilot commands and reduce the aircraft response to turbulence.

Rahn, D.↗
NASA NTRS1986

Orbital transfer vehicle launch operations study: Manpower summary and facility requirements, volume 5

All manpower numbers, number of heads (by skill), serial time and manhours have been accumulated and compiled on a per subtask basis in spreadsheet format for both the ground based and the space based data flows. To aid in identifying the facility resources required to process the Ground Based Orbital Transfer Vehicle (GBOTV) and/or the space based orbital transfer vehicle (SBOTV) through the ground facilities at Kennedy Space Center (KSC), a software application package was developed using a general purpose data base management system known as Data Flex. The facility requirements are used as the basic input to this software application. The resources of the KSC facility that could be used by orbital transfer vehicle program were digitized in the same format used to identify facility requirements. The facility capabilities were digitized in this format for subsequent, automated comparative analyses. Composite facility requirements are compared to each of the baseline facility capabilities and the system generates a relative score that indicates how each facility weighs against the composite requirements in relation to the other facilities in the set.

Source record↗
NASA NTRS1986

Simulation and analysis of natural rain in a wind tunnel via digital image processing techniques

It is desired to simulate natural rain in a wind tunnel in order to investigate its influence on the aerodynamic characteristics of aircraft. Rain simulation nozzles have been developed and tested at JPL. Pulsed laser sheet illumination is used to photograph the droplets in the moving airstream. Digital image processing techniques are applied to these photographs for calculation of rain statistics to evaluate the performance of the nozzles. It is found that fixed hypodermic type nozzles inject too much water to simulate natural rain conditions. A modification uses two aerodynamic spinners to flex a tube in a pseudo-random fashion to distribute the water over a larger area.

Aaron, K. M.↗
NASA NTRS1986

A mirror transport mechanism for use at cryogenic temperatures

The Mirror Transport Mechanism (MTM), which supports a pair of dihedral mirrors and moves them in a very smooth and uniform scanning motion normal to a beamsplitter is described. Each scan is followed by a quick flyback and repeat. Material selection, design, and testing of all major components of the MTM are discussed. Flex pivot failures during vibration testing, excessive dihedral platform sag under one g operation, electronic and fiber optic characteristics, and tolerancing considerations are covered. Development of the mechanism has reached the final phase of thermal and vibration qualification. Environmental testing of the complete FIRAS experiment is just beginning.

Stark, Kenneth W.↗
NASA NTRS1987

Implications of lithospheric bending and faulting in lunar mare-terra tectonics

A qualitative model of lithospheric flexure and faulting is proposed which accounts for certain rille fault features around mare regions of the moon. It is suggested that the subsidence of lunar mare basins may be due to the existence of their mascons and their volcanic fills as loads that flexed the lithosphere, in addition to the effects of drying up and cooling of internal hot volumes. Differences in the internal attack against the lunar crust from above and below the mean surface are considered. The rille formation is shown to be characterized by peripheral bulging and bending, and it is suggested that asthenosphere-related effects in lunar tectonics may have been very important.

Raitala, Jouko↗
NASA NTRS1987

Implementing clips on a parallel computer

The C language integrated production system (CLIPS) is a forward chaining rule based language to provide training and delivery for expert systems. Conceptually, rule based languages have great potential for benefiting from the inherent parallelism of the algorithms that they employ. During each cycle of execution, a knowledge base of information is compared against a set of rules to determine if any rules are applicable. Parallelism also can be employed for use with multiple cooperating expert systems. To investigate the potential benefits of using a parallel computer to speed up the comparison of facts to rules in expert systems, a parallel version of CLIPS was developed for the FLEX/32, a large grain parallel computer. The FLEX implementation takes a macroscopic approach in achieving parallelism by splitting whole sets of rules among several processors rather than by splitting the components of an individual rule among processors. The parallel CLIPS prototype demonstrates the potential advantages of integrating expert system tools with parallel computers.

Riley, Gary↗
NASA NTRS1989

Dynamic Torque Calibration Unit

Proposed dynamic torque calibration unit (DTCU) measures torque in rotary actuator components such as motors, bearings, gear trains, and flex couplings. Unique because designed specifically for testing components under low rates. Measures torque in device under test during controlled steady rotation or oscillation. Rotor oriented vertically, supported by upper angular-contact bearing and lower radial-contact bearing that floats axially to prevent thermal expansion from loading bearings. High-load capacity air bearing available to replace ball bearings when higher load capacity or reduction in rate noise required.

Agronin, Michael L.↗
NASA NTRS1989

Evaluation of atomic oxygen resistant protective coatings for fiberglass-epoxy composites in LEO

Fiberglass-epoxy composite masts are the prime structural members for the Space Station Freedom solar array. At the altitude where Space Station Freedom will operate, atomic oxygen atoms are the most predominant species. Atomic oxygen is highly reactive and has been shown to oxidize organic and some metallic materials. Tests with random and directed atomic oxygen exposure have shown that the epoxy is removed from the composite exposing brittle glass fibers which could be easily removed from the surface where they could contaminate Space Station Freedom Systems. Protection or fiber containment systems; inorganic based paints, aluminum braid, and a metal coating; were evaluated for resistance to atomic oxygen, vacuum ultraviolet radiation, thermal cycling, and mechanical flexing. All appeared to protect well against atomic oxygen and provide fiber containment except for the single aluminum braid covering. UV radiation resistance was acceptable and in general, thermal cycling and flexure had little to no effect on the mass loss rate for most coatings.

Rutledge, Sharon K.↗
NASA NTRS1989

Qualification Motor no. 8 (QM-8), volume 1

All inspection and instrumentation data indicate that the QM-8 static test firing conducted 20 January 1989 was successful. Ambient temperature at T-0 was 28 F. With two flights successfully accomplished, this final test in the redesigned solid rocket motor (RSRM) program certified that the design meets motor performance requirements under extreme cold conditions. This test was a prerequisite to the third flight. The entire test article was cold conditioned at 20 to 25 F for approximately 31 days to assure a maximum propellant mean bulk temperature (PMBT) of 40 F, making it the lowest PMBT in the history of the program. This extreme condition also presented the opportunity to certify critical components at low temperatures. Certification of field joint and igniter heaters, adhesive bondline integrity, flex bearing performance, flight instrumentation performance, RSRM seal performance, and LSC and nozzle plug performance was accomplished. Prior to motor ignition, the field joints were maintained between 75 to 130 F, the igniter-to-case joint was maintained between 75 to 123 F, and the case-to-nozzle joint was maintained between 75 to 120 F. QM-8 was tested with induced side loads to simulate the strut loads experienced during ignition and maximum aerodynamic loading conditions. The ability of the safe and arm device to change position from safe-to-arm and arm-to-safe was certified. Ballistics performance was certified at the lower limits. Values were within specification requirements. Nozzle performance was nominal with typical erosion. The use of Fiberite carbon-cloth phenolic was certified. The water deluge system, CO2 quench, and other test equipment performed as planned during all required test operations.

Garecht, D. M.↗
NASA NTRS1988

Two-degree-of-freedom image motion compensator for Shuttle-based pointing experiments

The mechanical design of the subarcsec-accurate, high-bandwidth two-DOF image motion compensator developed to enhance Space Shuttle-based optical telescope experiments' pointing accuracy encompasses a gimbal-type flex-pivot suspension, a novel ironless two-axis forcer, and a differential capacitive tilt-sensor system. The image motion compensator was developed to allow the UV Imaging Telescope Sensor to maintain stringent pointing accuracies over extended integration intervals while experiencing typical manned spacecraft perturbations.

Schuster, Ludwig E.↗
NASA NTRS1988

Oxidation and protection of fiberglass-epoxy composite masts for photovoltaic arrays in the low earth orbital environment

The extent of degradation of fiberglass-epoxy composite masts of the Space Station solar array panel, when these are exposed to atomic oxygen environment of the low-earth orbit, was investigated in ground testing of fiberglass-epoxy composites in an RF plasma asher. In addition, several methods of protecting the composite structures were evaluated, including an aluminum braid covering, an In-Sn eutectic, and a silicone based paint. It was found that, during exposure, the epoxy at the surface of the composite was oxidized, exposing individual glass fibers which could easily be removed. The results of mass measurements and SEM examination carried out after thermal cycling and flexing of exposed composite samples indicated that coatings such as In-Sn eutectic may provide adequate protection by containing the glass fibers, even though mass loss still occurs.

Rutledge, Sharon K.↗
NASA NTRS1988

Three-meter balloon-borne telescope

The Three-Meter Balloon-Borne Telescope is planned as a general purpose facility for making far-infrared and submillimeter astronomical observations from the stratosphere. It will operate throughout the spectral range 30 microns to 1 millimeter which is largely obscurred from the ground. The design is an f/13.5 Cassegrain telescope with an f/1.33 3-meter primary mirror supported with a 3-axis gimbal and stabilization system. The overall structure is 8.0 m high by 5.5 m in width by 4.0 m in depth and weighs 2000 kg. This low weight is achieved through the use of an ultra lightweight primary mirror of composite construction. Pointing and stabilization are achieved with television monitoring of the star field, flex-pivot bearing supports, gyroscopes, and magnetically levitated reaction wheels. Two instruments will be carried on each flight; generally a photometric camera and a spectrometer. A 64-element bolometer array photometric camera operating from 30 to 300 microns is planned as part of the facility. Additional instruments will be derived from KAO and other development programs.

Hoffmann, William F.↗
NASA NTRS1990

Composite superconducting wires obtained by high-rate tinning in molten Bi-Pb-Sr-Ca-Cu-O system

The preparation of high-T(sub c) superconducting long composite wires by short-time tinning of the metal wires in a molten Bi-Pb-Sr-Ca-Cu-O compound is discussed. The application of this method to the high-T(sub c) materials is tested, possibly for the first time. The initial materials used for this experiment were ceramic samples with nominal composition Bi(1.5)Pb(0.5)Sr2Ca2Cu3O(x) and T(sub c) = 80 K prepared by the ordinary solid-state reaction, and industrial copper wires from 100 to 400 microns in diameter and from 0.5 to 1 m long. The continuously moving wires were let through a small molten zone (approximately 100 cubic mm). The Bi-based high-T(sub c) ceramics in a molten state is a viscous liquid and it has a strongly pronounced ability to spread on metal wire surfaces. The maximum draw rate of the Cu-wire, at which a dense covering is still possible, corresponds to the time of direct contact of wire surfaces and liquid ceramics for less than 0.1 s. A high-rate draw of the wire permits a decrease in the reaction of the oxide melt and Cu-wire. This method of manufacture led to the fabrication of wire with a copper core in a dense covering with uniform thickness of about h approximately equal to 5 to 50 microns. Composite wires with h approximately equal to 10 microns (h/d approximately equal to 0.1) sustained bending on a 15 mm radius frame without cracking during flexing.

Grozav, A. D.↗
NASA NTRS1990

In-flight investigation of shuttle tile pressure orifice installations

To determine shuttle orbiter wing loads during ascent, wing load instrumentation was added to Columbia (OV-102). This instrumentation included strain gages and pressure orifices on the wing. The loads derived from wing pressure measurements taken during STS 61-C did not agree with those derived from strain gage measurements or with the loads predicted from the aerodynamic database. Anomalies in the surface immediately surrounding the pressure orifices in the thermal protection system (TPS) tiles were one possible cause of errors in the loads derived from wing pressure measurements. These surface anomalies were caused by a ceramic filler material which was installed around the pressure tubing. The filler material allowed slight movement of the TPS tile and pressure tube as the airframe flexed and bent under aerodynamic loads during ascent and descent. Postflight inspection revealed that this filler material had protruded from or receeded beneath the surface, causing the orifice to lose its flushness. Flight tests were conducted at NASA Ames Research Center Dryden Flight Research Facility to determine the effects of any anomaly in surface flushness of the orifice installation on the measured pressures at Mach numbers between 0.6 and 1.4. An F-104 aircraft with a flight test fixture mounted beneath the fuselage was used for these flights. Surface flushness anomalies typical of those on the orbiter after flight (STA 61-C) were tested. Also, cases with excessive protrusion and recession of the filler material were tested. This report shows that the anomalies in STS 61-C orifice installations adversely affected the pressure measurements. But the magnitude of the affect was not great enough to account for the discrepancies with the strain gage measurements and the aerodynamic predictions.

Moes, Timothy R.↗
NASA NTRS1989

Constraints on the deep structure and dynamic processes beneath the Alps and adjacent regions from an analysis of gravity anomalies

Gravity anomalies over the Alps and the Molasse Basin are examined, focusing on the relationship between the anomalies and the tectonic processes beneath the region. Bouguer gravity anomalies measured in France, Germany, Italy, and Switzerland are analyzed. No large isostatic anomalies are observed over the Alps and an elastic model is unable to account for gravity anomalies over the Molasse Basin. These results suggest that the dynamic processes that flexed the European plate down, forming the Molasse Basin and building the Alpine chain, have waned. It is proposed that the late Cenozoic uplift of the region may be due to a diminution or termination of downwelling of mantle material.

Lyon-Caen, Helene↗
NASA NTRS1989

Evaluation of atomic oxygen resistant protective coatings for fiberglass-epoxy composites in LEO

Fiberglass-epoxy composite masts are the prime structural members for the Space Station Freedom solar array. At the altitude where Space Station Freedom will operate, atomic oxygen atoms are the most predominant species. Atomic oxygen is highly reactive and has been shown to oxidize organic and some metallic materials. Tests with random and directed atomic oxygen exposure have shown that the epoxy is removed from the composite exposing brittle glass fibers which could be easily removed from the surface where they could contaminate space Station Freedom Systems. Protection or fiber containment systems, inorganic based paints, aluminum braid, and a metal coatinsg, were evaluated for resistance to atomic oxygen, vacuum ultraviolet radiation, thermal cycling, and mechanical flexing. All appeared to protect well against atomic oxygen and provide fiber containment except for the single aluminum braid covering. UV radiation resistance was acceptable and in general, thermal cycling and flexure had little to no effect on the mass loss rate for most coatings.

Rutledge, Sharon K.↗
NASA NTRS1991

Localized corrosion of high performance metal alloys in an acid/salt environment

Various vacuum jacketed cryogenic supply lines at the Space Shuttle launch site at Kennedy Space Center use convoluted flexible expansion joints. The atmosphere at the launch site has a very high salt content, and during a launch, fuel combustion products include hydrochloric acid. This extremely corrosive environment has caused pitting corrosion failure in the thin walled 304L stainless steel flex hoses. A search was done to find a more corrosion resistant replacement material. The study focussed on 19 metal alloys. Tests which were performed include electrochemical corrosion testing, accelerated corrosion testing in a salt fog chamber, and long term exposure at a beach corrosion testing site. Based on the results of these tests, several nickel based alloys were found to have very high resistance to this corrosive environment. Also, there was excellent agreement between the electrochemical tests and the actual beach exposure tests. This suggests that electrochemical testing may be useful for narrowing the field of potential candidate alloys before subjecting samples to long term beach exposure.

Macdowell, L. G.↗
NASA NTRS1991

Manufacturing processes

The following issues are covered: process development frequently lags behind material development, high fabrication costs, flex joints (bellows) - a continuing program, SRM fabrication-induced defects, and in-space assembly will require simplified design.

Bennet, Jay↗