Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “achieved”

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 757 records · Page 42
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

A new design approach to achieve a minimum impulse limit cycle in the presence of significant measurement uncertainties

A new design was developed for the Space Shuttle Transition Phase Digital Autopilot to reduce the impact of large measurement uncertainties in the rate signal during attitude control. The signal source, which was dictated by early computer constraints, is characterized by large quantization, noise, bias, and transport lag which produce a measurement uncertainty larger than the minimum impulse rate change. To ensure convergence to a minimum impulse limit cycle, the design employed bias and transport lag compensation and a switching logic with hysteresis, rate deadzone, and 'walking' switching line. The design background, the rate measurement uncertainties, and the design solution are documented.

Martin, M. W.↗
NASA NTRS1983

A method of predicting flow rates required to achieve anti-icing performance with a porous leading edge ice protection system

A proposed method of analytically predicting the minimum fluid flow rate required to provide anti-ice protection with a porous leading edge system on a wing under a given set of flight conditions is presented. Results of the proposed method are compared with the actual results of an icing test of a real wing section in the NASA Lewis Icing Research Tunnel.

Kohlman, D. L.↗
NASA NTRS1983

A method of predicting flow rates required to achieve anti-icing performance with a porous leading edge ice protection system

An analytical method was developed for predicting minimum flow rates required to provide anti-ice protection with a porous leading edge fluid ice protection system. The predicted flow rates compare with an average error of less than 10 percent to six experimentally determined flow rates from tests in the NASA Icing Research Tunnel on a general aviation wing section.

Kohlman, D. L.↗
NASA NTRS1983

Our First Quarter Century of Achievement... Just the Beginning

Space flight, space science, space applications, aeronautics, tracking and data acquisition, international programs, technology utilization, NASA installations, the NASA launch record, astronauts, and the fine arts program are reviewed in light of NASA's 25th anniversary.

Source record↗
NASA NTRS1981

AgRISTARS - Plans and first-year achievements

The results of the agriculture and resources inventory surveys through aerospace remote sensing (AgRISTARS) program managed by the USDA for exploring the use of satellite data for domestic and global commodity information needs are discussed. The program was intended to gather early warning of changes affecting production and quality of commodities and renewable resources, for predicting commodity production, land use classification and quantification, for inventories and assessments of renewable resources, land productivity measurements, assessment of conservation practices, and for pollution detection and impact evaluation. Up to 20 crop/region combinations in 7 countries were covered by the experiments, which comprised NOAA 6 and Landsat data analyses. Attempts to reduce variances through improved machine classification techniques are reported, together with soil moisture profiling, and the use of airborne sensors for providing comparative data.

Hall, F. G.↗
NASA NTRS1982

Enhanced erythrocyte suspension layer stability achieved by surface tension lowering additives

In connection with a fractionation procedure involving the separation of particles, a dilute suspension of these particles in a liquid is carefully layered on a dense liquid. Under ideal conditions, the suspension forms a zone of finite thickness with a 'sharp' interface between the suspension layer and the supporting liquid. Under an applied field, e.g., gravitational or electrical, the particles in the suspension layer migrate to form different layers according to their size and/or density or according to their electrophoretic mobilities. However, in many cases the ideal conditions necessary for the fractionation process are not obtained. Many studies have been conducted to explore the reasons for suspension layer 'instability'. The present investigation represents an extension of a study conducted by Omenyi et al. (1981). An electrostatic repulsion-van der Waals mechanism was used to study the stability of fixed erythrocyte suspensions layered on a D2O cushion.

Omenyi, S. N.↗
NASA NTRS1984

Significant achievements in the planetary geology program

Recent developments in planetology research are summarized. Important developments are summarized in topics ranging from solar system evolution, comparative planetology, and geologic processes active on other planetary bodies, to techniques and instrument development for exploration.

Head, J. W.↗
NASA NTRS1984

Fan noise reduction achieved by removing tip flow irregularities behind the rotor - forward arc test configurations

The noise source caused by the interaction of the rotor tip flow irregularities (vortices and velocity defects) with the downstream stator vanes was studied. Fan flow was removed behind a 0.508 meter (20 in.) diameter model turbofan through an outer wall slot between the rotor and stator. Noise measurements were made with far-field microphones positioned in an arc about the fan inlet and with a pressure transducer in the duct behind the stator. Little tone noise reduction was observed in the forward arc during flow removal; possibly because the rotor-stator interaction noise did not propagate upstream through the rotor. Noise reductions were maded in the duct behind the stator and the largest decrease occurred with the first increment of flow removal. This result indicates that the rotor tip flow irregularity-stator interaction is as important a noise producing mechanism as the normally considered rotor wake-stator interaction.

Dittmar, J. H.↗
NASA NTRS1984

The importance of thermal-vacuum testing in achieving high reliability of spacecraft mechanisms

The work performed on thermal vacuum testing of complex mechanisms is described. The objective of these tests is to assess the mechanism reliability by monitoring performance in an environment that closely resembles the environment that will occur during flight. To be both valid and cost effective, these tests are performed in a detailed, formally controlled manner. A review of the major test observations is given, during which time some failure modes are detected. Full confidence now exists in many mechanism and component designs, and much valuable data obtained.

Parker, K.↗
NASA NTRS1985

Debris control design achievements of the booster separation motors

The stringent debris control requirements imposed on the design of the Space Shuttle booster separation motor are described along with the verification program implemented to ensure compliance with debris control objectives. The principal areas emphasized in the design and development of the Booster Separation Motor (BSM) relative to debris control were the propellant formulation and nozzle closures which protect the motors from aerodynamic heating and moisture. A description of the motor design requirements, the propellant formulation and verification program, and the nozzle closures design and verification are presented.

Smith, G. W.↗
NASA NTRS1985

The space shuttle program from challenge to achievement: Space exploration rolling on tires

The Space Shuttle Transportation System is the first space program to employ the pneumatic tire as a part of space exploration. For aircraft tires, this program establishes new expectations as to what constitutes acceptable performance within a set of tough environmental and operational conditions. Tire design, stresses the usual low weight, high load, high speed, and excellent air retention features but at extremes well outside industry standards. Tires will continue to be an integral part of the Shuttle's landing phase in the immediate future since they afford a unique combination of directional control, braking traction, flotation and shock absorption not available by other systems.

Felder, G. L.↗
NASA NTRS1984

Achievements of the plasma composition experiment on ISEE-1 during the IMS

The ISEE-1 spacecraft measured energetic ion composition over a wide radial range in the near-equatorial magnetosphere, from close to the Earth to a distance of 23 RE. The Plasma Composition Experiment covers energies from 0 eV/e to 17 keV/e. Results for energetic O+ ions of terrestrial origin show that these ions are found in every region of the magnetosphere reached by the spacecraft and can have energy and pitch-angle distributions very similar to those of H+ ions. The O+ ions are the most numerous ions in the 0.1 to 17 keV/e energy range at L 5 and are often a substantial part of the ion population at larger distances as well, especially during geomagnetically disturbed conditions.

Lennartsson, W.↗
NASA NTRS1985

Historical perspective of barriers to achieving high-efficiency silicon solar cells

Early silicon solar cells were made of metallurgical-grade silicon with very low efficiency. The single-crystal silicon introduced in the mid-50's increased the efficiency to the 5% to 10% region. Throughout the 1960s the technology of the 2 x 2 cm or 2 x 4 cm space solar cell with 10% efficiency was established. In the early 1970s work related to the violet cell upset the status quo and space solar cells and cells in general became more efficient. The rest of the decade became characterized by establishing a terrestrial photovoltaic technology to support the development of a new industry. Costs per watt became the dominant consideration and frequently the efficiency was compromised. The introduction of materials and other forms of silicon dropped the efficiency and it is now a state of mine that accomplishing 10% efficiency with some alternative combination is regarded as success. Silicon solar cells are capable of delivering efficiences much greater than 10%.

Lindmayer, J.↗
NASA NTRS1985

Initial results of SEPAC scientific achievement

Electron beam injection of 5 keV, 300 mA (1.5 kW) and MPD arcjet plasma injection of 2 kJ/shot were successfully performed together with various kinds of diagnostic instruments including a high sensitivity TV camera observation in the Spacelab 1. Major scientific results obtained are studies of: (1) vehicle charge-up due to the electron beam emission and its neutralization by the MPD arcjet plasma; (2) beam-plasma interaction including the plasma wave excitation; (3) beam-atmosphere interaction such as the verification of critical velocity ionization effect; and (4) anomalous enhancement of ionization associated with a neutral gas injection into space.

Obayashi, T.↗
NASA NTRS1985

The construction of airfoil pressure models by the plate method: Achievements, current research, technology development and potential applications

A method of constructing airfoils by inscribing pressure channels on the face of opposing plates, bonding them together to form one plate with integral channels, and contour machining this plate to form an airfoil model is described. The research and development program to develop the bonding technology is described as well as the construction and testing of an airfoil model. Sample aerodynamic data sets are presented and discussed. Also, work currently under way to produce thin airfoils with camber is presented. Samples of the aft section of a 6 percent airfoil with complete pressure instrumentation including the trailing edge are pictured and described. This technique is particularly useful in fabricating models for transonic cryogenic testing, but it should find application in a wide ange of model construction projects, as well as the fabrication of fuel injectors, space hardware, and other applications requiring advanced bonding technology and intricate fluid passages.

Lawing, P. L.↗
NASA NTRS1986

Technology achievements and projections for communication satellites of the future

Multibeam systems of the future using monolithic microwave integrated circuits to provide phase control and power gain are contrasted with discrete microwave power amplifiers from 10 to 75 W and their associated waveguide feeds, phase shifters and power splitters. Challenging new enabling technology areas include advanced electrooptical control and signal feeds. Large scale MMIC's will be used incorporating on chip control interfaces, latching, and phase and amplitude control with power levels of a few watts each. Beam forming algorithms for 80 to 90 deg. wide angle scanning and precise beam forming under wide ranging environments will be required. Satelllite systems using these dynamically reconfigured multibeam antenna systems will demand greater degrees of beam interconnectivity. Multiband and multiservice users will be interconnected through the same space platform. Monolithic switching arrays operating over a wide range of RF and IF frequencies are contrasted with current IF switch technology implemented discretely. Size, weight, and performance improvements by an order of magnitude are projected.

Bagwell, J. W.↗