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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.

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At least 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Implementation and flight tests for the Digital Integrated Automatic Landing System (DIALS). Part 2: Complete set of flight data

Five flight tests of the Digital Automated Landing System (DIALS) were conducted on the Advanced Transport Operating System (ATOPS) Transportation Research Vehicle (TSRV)--a modified Boeing 737 Aircraft for advanced controls and displays research. These flight tests were conducted at NASA's Wallops Flight Center using the Microwave Landing System (MLS) installation on Runway 22. This report is primarily a collection of data plots of all performance variables recorded for the entire five flight tests. A description and source of the performance variables is included. Performance variables include inertial data, air data, automatic control commands, control servo positions, sensor data, DIALS guidance and control parameters, and Kalman filter data. This data illustrates low overshoot captures of the localizer for intercept angles of 20 deg, 30 deg, 40 deg, and 50 deg intercept angles, and low overshoot captures of the glideslope slope for 3 deg, 4.5 deg, and 5 deg glideslopes. Flare maneuvers were successfully performed from the various glideslope angles and good decrab maneuvers were performed in crosswinds of 6 knots. In 18 to 20 knot crosswind conditions rudder limiting occurred which caused lateral drifting although heading alignment was achieved.

Hueschen, R. M.↗
NASA NTRS1985

Discovery of fast-moving oxygen filaments in Puppis A

A number of faint filaments in the Puppis A supernova remnant have been found to have spectra with strong oxygen lines, extremely weak Balmer lines, and radial velocities greater than 1500 km/s. These are very different from the bright filaments, which are nitrogen-rich and have velocities less than 300 km/s. The newly discovered filaments are spectroscopically similar to those found in young, oxygen-rich remnants, as typified by the fast-moving knots in Cas A. These Puppis A filaments are interpreted as knots of oxygen-rich supernova ejecta which remain relatively uncontaminated by interstellar material, despite the probable age of Puppis A of several thousand years. Spectra of the newly discovered filaments show, in addition to strong forbidden lines of O I, O II, and O III, permitted lines of O I: 7774, 8446 A. The permitted lines are attributed to recombination of O(+), and their strength relative to H is used to estimate that the O:H mass ratio is about 30.

Winkler, P. F.↗
NASA NTRS1986

The dynamics of Herbig-Haro objects

Radial-velocity and proper-motion information on Herbig-Haro (HH) objects is analyzed for clues to the character of the supersonic flows that produce the objects. The correlations among space velocities, excitation states, internal velocity dispersions, electron densities, and positions relative to the exciting stars for the emission knots of HH 1 and HH 2 is examined. Whereas the interstellar-bullet model may account for most of the phenomena in the HH 1-HH 2 system, HH 43 is found to show characteristics of a stellar wind shock against an obstacle cloudlet. By contrast, the HH 46-HH 47 system exhibits a continuous, well-collimated jet of emission with knots that may be due to instabilities in the confined, supersonic flow.

Schwartz, R. D.↗
NASA NTRS1986

The optical structure of the Crab Nebula's 'jet'

A deep, high-resolution forbidden O III image of the Crab Nebula's northern 'jet' is presented which reveals considerably finer details than visible on previous photographs. The jet's small-scale structure appears composed of numerous emission-line filaments and knots which collectively exhibit a strong alignment having well-defined east-west boundaries. Comparison with an earlier published image suggests a proper motion northward for one of the jet's emission knots of 0.22 + or - 0.05 arcsec/yr. The jet's optical morphology is discussed and its properties compared to predictions of several proposed models. The 'shadowed flow' model suggested by Morrison and Roberts (1985) appears to explain best the jet's known properties.

Fesen, R. A.↗
NASA NTRS1986

NASA rotor systems research aircraft: Fixed-wing configuration flight-test results

The fixed-wing, airplane configuration flight-test results of the Rotor System Research Aircraft (RSRA), NASA 740, at Ames/Dryden Flight Research Center are documented. Fourteen taxi and flight tests were performed from December 1983 to October 1984. This was the first time the RSRA was flown with the main rotor removed; the tail rotor was installed. These tests confirmed that the RSRA is operable as a fixed-wing aircraft. Data were obtained for various takeoff and landing distances, control sensitivity, trim and dynamics stability characteristics, performance rotor-hub drag, and acoustics signature. Stability data were obtained with the rotor hub both installed and removed. The speed envelope was developed to 261 knots true airspeed (KTAS), 226 knots calibrated airspeed (KCAS) at 10,000 ft density altitude. The airplane was configured at 5 deg. wing incidence with 5 deg. wing flaps as a normal configuration. Level-flight data were acquired at 167 KCAS for wing incidence from 0 to 10 deg. Step inputs and doublet inputs of various magnitudes were utilized to acquire dynamic stability and control sensitivity data. Sine-wave inputs of constantly increasing frequency were used to generate parameter identification data. The maximum load factor attained was 2.34 g at 206 KCAS.

Erickson, R. E.↗
NASA NTRS1987

Demonstration of frequency-sweep testing technique using a Bell 214-ST helicopter

A demonstration of frequency-sweep testing using a Bell-214ST single-rotor helicopter was completed in support of the Army's development of an updated MIL-H-8501A, and an LHX (ADS-33) handling-qualities specification. Hover and level-flight (V sub a = 0 knots and V sub a = 90 knots) tests were conducted in 3 flight hours by Army test pilots at the Army Aviation Engineering Flight Activity (AEFA) at Edwards AFB, Calif. Bandwidth and phase-delay parameters were determined from the flight-extracted frequency responses as required by the proposed specifications. Transfer function modeling and verification demonstrates the validity of the frequency-response concept for characterizing closed-loop flight dynamics of single-rotor helicopters -- even in hover. This report documents the frequency-sweep flight-testing technique and data-analysis procedures. Special emphasis is given to piloting and analysis considerations which are important for demonstrating frequency-domain specification compliance.

Tischler, Mark B.↗
NASA NTRS1988

Rational-Spline Subroutines

Smooth curves drawn among plotted data easily. Rational-Spline Approximation with Automatic Tension Adjustment algorithm leads to flexible, smooth representation of experimental data. "Tension" denotes mathematical analog of mechanical tension in spline or other mechanical curve-fitting tool, and "spline" as denotes mathematical generalization of tool. Program differs from usual spline under tension, allows user to specify different values of tension between adjacent pairs of knots rather than constant tension over entire range of data. Subroutines use automatic adjustment scheme that varies tension parameter for each interval until maximum deviation of spline from line joining knots less than or equal to amount specified by user. Procedure frees user from drudgery of adjusting individual tension parameters while still giving control over local behavior of spline.

Schiess, James R.↗
NASA NTRS1986

Augmentor performance of an F100 engine model derivative engine in an F-15 airplane

The transient performance of the F100 engine model derivative (EMD) augmentor was evaluated in an F-15 airplane. The augmentor was a newly designed 16-segment augmentor. It was tested with a segment-1 sprayring with 90 deg fuel injection, and later with a modified segment-1 sprayring with centerline fuel injection. With the 90 deg injection, no-lights occurred at high altitudes with airspeeds of 175 knots or less; however, the results were better than when using the standard F100-PW-100 engine. With the centerline fuel injection, all transients were successful to an altitude of 15,500 meters and an airspeed of 150 knots: no failures to light, blowouts, or stalls occurred. For a first flight evaluation, the augmentor transient performance was excellent.

Walton, James T.↗
NASA NTRS1988

Sources and levels of background noise in the NASA Ames 40- by 80-foot wind tunnel

Background noise levels are measured in the NASA Ames Research Center 40- by 80-Foot Wind Tunnel following installation of a sound-absorbent lining on the test-section walls. Results show that the fan-drive noise dominated the empty test-section background noise at airspeeds below 120 knots. Above 120 knots, the test-section broadband background noise was dominated by wind-induced dipole noise (except at lower harmonics of fan blade-passage tones) most likely generated at the microphone or microphone support strut. Third-octave band and narrow-band spectra are presented for several fan operating conditions and test-section airspeeds. The background noise levels can be reduced by making improvements to the microphone wind screen or support strut. Empirical equations are presented relating variations of fan noise with fan speed or blade-pitch angle. An empirical expression for typical fan noise spectra is also presented. Fan motor electric power consumption is related to the noise generation. Preliminary measurements of sound absorption by the test-section lining indicate that the 152 mm thick lining will adequately absorb test-section model noise at frequencies above 300 Hz.

Soderman, Paul T.↗
NASA NTRS1987

Imaging and spectroscopic studies of the interacting system Markarian 171

V, R, and I broadband CCD images, as well as H-alpha spectroscopic observations of Markarian 171, are presented. Two apparently interacting dust-enshrouded galaxies exhibit relatively normal V-R, V-I galactic stellar-population colors in their outer regions, and spatially extended H-alpha emission. However, the dereddened colors imply a hot stellar population. The dual characteristics of narrow H-alpha lines and spatially extended H-alpha emission clearly distinguish this type of activity from that associated with the compact central regions of active galactic nuclei and QSOs. Apparently, in the case of Mk 171 the interaction has induced star formation throughout a significant fraction of the galaxy (kiloparsecs) - not just in the immediate vicinity of the nucleus (parsecs). A peculiar stellar population of hot stars associated with a knot of weak H-alpha emission appears spatially separate from the other emission-line regions. It is possible that this stellar knot is a severed remnant attributable to the gravitational interaction between the two galaxies.

Friedman, Scott D.↗
NASA NTRS1988

Images of star-forming regions. II - The circumstellar environment of L1551 IRS 5

The circumstellar environment of L 1551 IRS 5 is investigated based on high-resolution 8000 A (i) and 9000 A (z) broadband CCD images. A small conical reflection nebula extending from a bright semistellar knot located near the cusp of the nebula is noted. It is suggested that the point-like structure at lambda of less than about 3.7 microns may represent a bright knot of dust-scattered light located on the inner surface of a flattened circumstellar disk surrounding the radio source. Evidence is found of sharp changes in the position angle of the jet emanating from IRS 5, possibly resulting from precession of the jet nozzle provided by a dense inner disk which has dynamically decoupled from the much larger flattened molecular structure.

Campbell, Bel↗
NASA NTRS1987

Fan blade angle system for the National Full-scale Aerodynamic Complex

An adjustable, fan-blade-angle-positioning system for use in a wind tunnel was designed and fabricated to control the airflow from rotating fans in the National Full-scale Aerodynamic Complex (NFAC) at Ames Research Center. The NFAC consists of two test sections, a 40- by 80-ft test section with a top airspeed rating of 300 knots and an 80- by 120-ft test section with a top airspeed rating of 110 knots.

King, Reginald F.↗
NASA NTRS1988

Differential imaging of forbidden Fe X in IC 443

This paper presents images of two areas of the supernova remnant IC 443 showing emission from the forbidden 6374 A red coronal line taken with an emission-line differential imaging camera. The areas are in the vicinity of strong soft X-ray emission as observed with the Einstein Observatory. The forbidden Fe X emission is patchy on the scale of seconds of arc. For the brightest emission regions, an electron density of approximately 60/cu cm and gas pressures of 0.l7 x 10 to the 8th/cu cm K are found. These estimates are speculative because of the large correction for interstellar dust, and the assumption of sheetlike structure. Although this region has the highest average surface brightness, no direct correlation is found between the X-ray and forbidden Fe X knots. The implied physical conditions in the region suggest that the forbidden Fe X knots are being evaporated.

Brown, Larry W.↗
NASA NTRS1989

Early shaping of asymmetrical planetary nebulae

It is suggested that the shape of a young asymmetrical planetary nebulae may be influenced by a close binary-star located at its center. This binary is a relic of the common envelope phase, presumably through which the asymmetrical planetary nebula evolved. It is assumed that, for a short period of time, shortly after the cessation of the slow wind and long before the fast wind becomes effective, the binary ejects a small amount of mass, mainly in the equatorial plane. By using two-dimensional hydrodynamics it is found that, at late times, the high-density region has a 'horsehoe' shape, as viewed in the symmetry plane. There is an instability in the maximum density region, which shows up as a high-density knot. The exact scale of the knot is determined by the numerics. The applications of the results to observations are discussed.

Soker, Noam↗
NASA NTRS1989

The high-resolution structure of the Centaurus A nucleus at 2.3 and 8.4 GHz

VLBI observations of the nucleus of Centaurus A have been made at two frequencies with an array of five Australian radio telescopes as part of the Southern Hemisphere VLBI Experiment. Observations were made at 2.3 GHz with all five antennas, while only two were employed at 8.4 GHz. At 2.3 GHz seven tracks in the (u,v) plane with coverage of 6-8 hr each were obtained, yielding significant information on the structure of the nuclear jet. At 8.4 GHz a compact unresolved core was detected as well. It is found that the source consists of the compact self-absorbed core, a jet containing a set of three knots extending from 100 to 160 mas from the core, and a very long, narrow component elongated along the same position angle as the knots. The allowable range for the position angle of the jet is 51 + or - 3 deg, in agreement with that of the radio and X-ray structure on arcsecond and arcminute scales. The jet has brightened at 2.3 GHz by about 4 Jy, a factor of nearly 3, since the early 1970s, 1.8 Jy of which has occurred in the last 2 yr with no discernable changes in structure.

Meier, David L.↗
NASA NTRS1989

The discovery of a highly polarized bipolar nebula

During a search for the optical counterparts of IRAS sources whose flux peaks at 25 microns, a small faint bipolar nebula was discovered in Monoceros at the position of IRAS 07131-0147. The CCD images display the object's considerable structure. The central star seems relatively free of closeby nebulosity: the two lobes have a bow-tie structure with those parts nearest to the star consisting of series of small knots. The outer parts of the lobes seem to be made up of filaments streaming away from knots. On the basis of its optical spectrum, the central star was classified as a M5-6 giant. In the IRAS color classification scheme of Van der Veen and Habing (1988), the central star is VIb which indicates that there are distinct hot and cold components of circumstellar dust and that the mass loss process may have temporarily abated. Therefore, it is proposed that the object is in the post main sequence stage of evolution and is a protoplanetary nebulae. Young protoplanetary nebulae have totally obscured central stars illuminating reflective lobes whereas older ones such as M2-9 have lobes seen in emission from gas ionized by the central hot star which is clearly visible. Since the central object of IRAS07131-0147 is a relatively unobscured late type star and the lobes are seen only by reflection, it is suggested that this nebula is a protoplanetary nebula in an evolutionary stage intermediate between that of CRL2688 and M2-9.

Wolstencroft, Ramon D.↗
NASA NTRS1991

Technology needs for high speed rotorcraft (2)

An analytical study was conducted to identify rotorcraft concepts best capable of combining a cruise speed of 350 to 450 knots with helicopter-like low speed attributes, and to define the technology advancements needed to make them viable by the year 2000. A systematic approach was used to compare the relative attributes and mission gross weights for a wide range of concepts, resulting in a downselect to the most promising concept/mission pairs. For transport missions, tilt-wing and variable diameter tilt-rotor (VDTR) concepts were found to be superior. For a military scout/attack role, the VDTR was best, although a shrouded rotor concept could provide a highly agile, low observable alternative if its weight empty fraction could be reduced. A design speed of 375 to 425 knots was found to be the maximum desirable for transport missions, with higher speed producing rapidly diminishing benefits in productivity. The key technologies that require advancement to make the tilt-wing and VDTR concepts viable are in the areas of wing and proprotor aerodynamics, efficient structural design, flight controls, refinement of the geared flap pitch control system, expansion of the speed/descent envelope, and the structural and aerodynamic tradeoffs of wing thickness and forward sweep. For the shrouded rotor, weight reduction is essential, particularly with respect to the mechanism for covering the rotor in cruise.

Scott, Mark W.↗
NASA NTRS1990

A kinematic determination of the structure of the double ring planetary nebula NGC 2392, the Eskimo

Slit spectra and existing 'velocity cube' data have been used to determine the structure of the double ring PN NGC 2392. The inner shell is a stellar wind-sculpted prolate spheroid with a ratio of axes of 2:1 and the approaching end of the long axis pointed 20 deg from the line of sight in P.A. = 200 deg. The outer ring is caused by an outer disk with density dropping off with distance from the central star and with distance from its plane, which is the same as the equatorial band of high density in the inner shell. The outer disk contains a ring of higher density knots at a distance of 16 arcsec and is losing material through free expansion, forming an outer envelope of increasing velocity. Forbidden S II spectra are used to determine the densities in all of the major regions of the nebula. It is argued that the filamentary cores at the centers of the knots seen in the outer ring originate in the sublimation of bodies formed at the same time as the parent star.

O'Dell, C. R.↗