Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Ranging”

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 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

The effects of random path fluctuations on the accuracy of laser ranging systems

The precision of satellite ranging systems, limited in part by atmospheric refraction and scattering, is examined. The effects of atmospheric turbulence on the accuracy of single color and multicolor ranging systems is discussed. The statistical characteristics of the random path length fluctuations induced by turbulence are examined. Correlation and structure functions are derived using several proposed models for the variations of the optical path length. For single color systems it is shown that the random path length fluctuations can limit the accuracy of a range measurement to a few centimeters. Two color systems can partially correct for the random path fluctuations so that in most cases their accuracy is limited to a few millimeters. However, at low elevation angles and over long horizontal paths two color systems can also have errors approaching a few centimeters.

Gardner, C. S.↗
NASA NTRS1976

Investigation of two bifurcated-duct inlet systems from Mach 0 to 2.0 over a wide range of angles of attack

A 15.354 percent/scale lightweight fighter type inlet/forebody was tested over a Mach number range of 0 to 2.0. Model configurations consisted of side mounted normal shock and fixed overhead ramp type inlets. Each configuration consisted of two inlets ducted (bifurcated) to supply a single engine face. The normal shock inlet variables included a boundary layer splitter bleed system, alternate boundary layer splitter plates, alternate upper and lower cowl lip shapes, and a blow-in-door (auxiliary inlet) in one lower lip. The only variable of the fixed overhead ramp inlet was the boundary layer bleed flow. Reynolds numbers ranged from 7.6 x 1 million to 19.5 x 1 million/m. Angle of attack ranged from -10 to 35 deg and angle of sideslip from -8 to 8 deg. Test measurements included engine face total pressure recovery, steady state distortion, dynamic distortion, and surface static pressures on the forebody and inlet surfaces.

Latham, E. A.↗
NASA NTRS1975

RTLS entry ranging analysis

Definition of the ranging capability of a mission 3A return-to-launch-site entry is reported. The limits on downrange and crossrange are established at the initiation of RTLS entry so that terminal area energy management interface conditions were achieved satisfactorily. The downrange and crossrange limits were defined for both nominal RTLS entry conditions and a composite set of dispersed RTLS entry conditions. The results indicate a wide range of acceptable downrange and crossrange positions are available at RTLS entry initiation for nominal conditions. This is greatly reduced when dispersions are considered. For dispersed RTLS entry conditions, an 18 nautical mile range of acceptable downranges is available at zero crossrange.

Crull, T. J.↗
NASA NTRS1975

Satellite laser ranging work at the Goddard Space Flight Center

The paper describes the satellite laser ranging system at the Goddard Space Flight Center, its range and accuracy capabilities, and planned improvements for future systems. Major subsystems are described, including the laser, optical/mechanical, receiver, computer/software, timing, and laser data preprocessing subsystems. Operational considerations are examined, with attention given the mobile station layout, manpower requirements, and transportability. System performance is considered, with emphasis on system accuracy (calibration, stability, clock synchronization, atmospheric propagation correction) and range capability.

Mcgunigal, T. E.↗
NASA NTRS1976

Effects of random path fluctuations on the accuracy of laser ranging systems

Effects of turbulence-induced pathlength fluctuations on the accuracy of single-color laser ranging systems are examined. Correlation and structure functions for the path deviations are derived using several proposed models for the variation of the turbulence structure parameter with altitude. For single-color systems, random pathlength fluctuations can limit the accuracy of a range measurement to a few centimeters when the turbulence is strong and the effective propagation path is long (greater than 10 km). Two-color systems can partially correct for the random path fluctuations so that in most cases their accuracy is limited to a few millimeters. However, at low elevation angles for satellite ranging (less than 20 deg) and over long horizontal paths, two-color systems can also have errors approaching a few centimeters.

Gardner, C. S.↗
NASA NTRS1977

Simplified command and range detection system

Communication system processes subcarrier that is modulated with sequential range codes and with command data. Loop locks in on range codes as they occur in sequence. When range code modulated with data-frequency arrives, loop switches to DEMOD to receive data.

Butman, S. A.↗
NASA NTRS1976

Best-range flight conditions for cruise-climb flight of a jet aircraft

The Breguet range equation was developed for cruise climb flight of a jet aircraft to include the climb angle and is then maximized with respect to the no wind true airspeed. The expression for the best range airspeed is a function of the specific fuel consumption and minimum drag airspeed and indicates that an operational airspeed equal to the fourth root of three times the minimum-drag airspeed introduces range penalties of the order of one percent.

Hale, F. J.↗
NASA NTRS1976

DSS range delay calibrations: Current performance level

A means for evaluating Deep Space Station (DSS) range delay calibration performance was developed. Inconsistencies frequently noted in these data are resolved. Development of the DSS range delay data base is described. The data base is presented with comments regarding apparent discontinuities. Data regarding the exciter frequency dependence of the delay values are presented. The improvement observed in the consistency of current DSS range delay calibration data over the performance previously observed is noted.

Spradlin, G. L.↗
NASA NTRS1977

ATS-3 ranging support

The purpose of this effort was to provide NASA-Goddard Space Flight Center with ATS-3 ranging data from ground stations of the VHF network and from an additional ground station installed at the NASA-Goddard Space Flight Center. Ranging measurements to the NASA transponder enabled calculation of the transponder's line-of-position. Installation of an S-band transponder at the same site and the conduct of ranging experiments to this transponder and others via ATS-6 provided a second line-of-position. The NASA S-band transponder was specifically designed for installation aboard spacecraft. Consequently, this program provided NASA an opportunity to compare two different techniques using geostationary satellites in the tracking low orbit satellites.

Brisken, A. F.↗
NASA NTRS1976

Application of advanced technology to future long-range aircraft

The objective of this paper is to provide an overview assessment of three separate programs at Langley Research Center that have incorporated advanced technology into the design of long-range passenger and cargo aircraft. The first technology centers around the use of an span-loaded cargo aircraft with the payload distributed along the wing. This concept has the potential for reduced structural weights. The second technology is the application of laminar flow control (LFC) to the aircraft to reduce the aerodynamic drag. The use of LFC can reduce the fuel requirements during long-range cruise. The last program evaluates the production of alternate aircraft fuels from coal and the use of liquid hydrogen as an aircraft fuel. Coal-derived hydrogen as an aircraft fuel offers both the prospect for reduced dependence on petroleum fuels and improved performance for long-range aircraft.

Schrader, O. E.↗
NASA NTRS1976

On the variation and growth of wave-slope spectra in the capillary-gravity range with increasing wind

A new laser device has been used to make direct wave-slope measurements in the capillary-gravity range. Owing to the design principles, the digital nature of the system and the use of a laser beam as a probe, the earlier problems of intensity variations and meniscus effects were avoided. Using this new technique, wave-slope spectra both down and across the channel were obtained for different wind conditions, along with corresponding mean-square slope values. Comparisons are made with existing data. The results indicate that a quasi-equilibrium state may exist for each wind speed and that it increases in intensity with increasing wind, which may imply an asymptotic nature for the equilibrium-range coefficient. From the data, two significant frictional velocities, 17.5 and 31 cm/s respectively, are identified as critical values for different ranges of wave development.

Long, S. R.↗
NASA NTRS1976

A satellite-borne ion mass spectrometer for the energy range 0 to 16 keV

The Ion Composition Experiment (ICE) on GEOS represents the first comprehensive attempt to measure the positive ion composition at high altitudes in the magnetosphere. Due to the heterogeneous nature of the magnetospheric plasma a novel mass spectrometer has been developed to cover the mass per charge range from H-1(+) to beyond Ba-138(+) and the energy per charge range from 0 to 16 keV/e. The ICE consists primarily of a cylindrical electrostatic analyzer followed by a curved analyzer incorporating crossed magnetic and electric fields. This combination has limited angular and energy focusing properties, but it maintains a mass resolution of about 4 over a wide range in energy and mass, sufficient for the objectives of measuring plasmas of both solar and terrestrial origin. High sensitivity and low background should allow measurements of rarer ion constituents down to flux levels of 0.01 ions/sq cm sec ster eV. A sophisticated electronics combined with powerful ground computer and telecommand systems allow for very efficient scanning of the mass-energy space.

Balsiger, H.↗
NASA NTRS1977

Geodetic applications of laser ranging

The paper describes the use of dynamic methods of laser ranging of a low altitude satellite along with proposed experiments involving both dynamic and geodetic methods of laser ranging of the Lageos satellite. Particular attention is given to the testing of laser ranging techniques across the San Andreas Fault in California where it is hoped that plate motion will be observable after several years of measurements.

Smith, D. E.↗
NASA NTRS1977

High-accuracy range measurements to the moon

The lunar ranging station at the University of Texas McDonald Observatory has made more than 1800 range measurements to the four lunar retroreflectors during the first six years of its operation. Each range consists of a normal point constructed of from 5 to 20 single photoelectron returns. Normal point accuracies to about four parts in 10 to the tenth plus or minus 10 cm have become routine. The availability of excellent commercial timing equipment means that the error for such a measurement is primarily dependent on the width of the transmitted laser pulse. Second generation systems using mode-locked subnanosecond lasers can probably achieve routine normal point accuracies approaching one part in 10 to the tenth plus or minus 2 cm. High speed pockel cells may permit such accuracies to be realized with conventional Q-switched lasers.

Silverberg, E. C.↗
NASA NTRS1977

Remote sensing in operational range management programs in Western Canada

A pilot program carried out in Western Canada to test remote sensing under semi-operational conditions and display its applicability to operational range management programs was described. Four agencies were involved in the program, two in Alberta and two in Manitoba. Each had different objectives and needs for remote sensing within its range management programs, and each was generally unfamiliar with remote sensing techniques and their applications. Personnel with experience and expertise in the remote sensing and range management fields worked with the agency personnel through every phase of the pilot program. Results indicate that these agencies have found remote sensing to be a cost effective tool and will begin to utilize remote sensing in their operational work during ensuing seasons.

Thompson, M. D.↗
NASA NTRS1977

Synthesis and analysis of precise spaceborne laser ranging systems, volume 1

Measurement accuracy goals of 2 cm rms range estimation error and 0.003 cm/sec rms range rate estimation error, with no more than 1 cm (range) static bias error are requirements for laser measurement systems to be used in planned space-based earth physics investigations. Constraints and parameters were defined for links between a high altitude, transmit/receive satellite (HATRS), and one of three targets: a low altitude target satellite, passive (LATS), and active low altitude target, and a ground-based target, as well as with operations with a primary transmit/receive terminal intended to be carried as a shuttle payload, in conjunction with the Spacelab program.

Paddon, E. A.↗
NASA NTRS1977

Usefulness of LANDSAT data for monitoring plant development and range conditions in California's annual grassland

A network of sampling sites throughout the annual grassland region was established to correlate plant growth in stages and forage production to climatic and other environmental factors. Plant growth and range conditions were further related to geographic location and seasonal variations. A sequence of LANDSAT data was obtained covering critical periods in the growth cycle. Data were analyzed by both photointerpretation and computer aided techniques. Image characteristics and spectral reflectance data were then related to forage production, range condition, range site, and changing growth conditions.

Carneggie, D. M.↗
NASA NTRS1978

Determining crustal strain rates with spaceborne geodynamics ranging system data. 1: Baseline analysis

A satellite-borne laser ranging system is proposed that is capable of making highly precise geodetic measurements over baselines ranging from a few tens of kilometers to several hundred kilometers. The precision with which crustal strain rates are derived from measurements made with this system is analyzed by using simple site configurations, intersite distances of about 25-70 kilometers, and measurement programs ranging from a few years to fifteen years. It is concluded that precisions of several parts in 10 to the 9th power per year are achievable. Compared to the expected shear strain rates of about 7 x 10 to the minus 7th power yr/1, this produces very favorable signal-to-noise ratios.

Cohen, S. C.↗