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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Development of a silicone ablator for high-heat-flux and high-shear-rate condition

A silicone material was developed which gives suitable ablative protection in the high heat flux, high shear environments encountered in severe reentry applications, such as nose cones for ballistic vehicles and protection of leading edges or other critical areas of a vehicle. In addition, the ease of handling, low application cost, and room temperature cure make such a silicon material suitable nozzles for the large rockets necessary for vehicle launching. The development of this product is traced from the selection of suitable polymers through the choice of fillers and the finalization of filler loadings.

Campbell, R. A.↗
NASA NTRS1973

Study of porous surface microphones for acoustic measurements in wind tunnels

Porous surface sensors acting as directional microphones in subsonic airflow were investigated. The first part of the report deals with the design of a porous strip sensor set in an aerofoil. The second part presents the experimental results of frequency response, directivity, and flow noise of a porous pipe sensor and a porous strip sensor. For flow noise, these sensors were compared with the Bruel and Kjaer half-inch condenser microphone with a nose cone. The flow noise was examined under two conditions of flow: in a very quiet flow where the turbulence was approximately 0.3% and in a spoiled flow where the turbulence was approximately 5%.

Noiseux, D. U.↗
NASA NTRS1973

Overall fluctuating pressure levels on prospective space shuttle launch configurations at Mach numbers from 0.8 to 2.2

Overall fluctuating pressure levels of seven space shuttle launch configurations are presented. The model was a 4-percent-scale space shuttle vehicle, tested in both a 11- by 11-foot transonic wind tunnel and a 9- by 7-foot supersonic wind tunnel. Mach numbers varied from 0.8 to 2.2, and the angle of attack range was from -8 deg to 8 deg at angles of sideslip of -5 deg, and 5 deg. The model configurations included both series-burn and parallel-burn configurations, two canopy configurations, two positions of the orbiter nose relative to the HO tank nose and two HO tank nose-cone angles (15 deg and 20 deg). The fluctuating pressure levels are presented in three forms.

Dods, J. B., Jr.↗
NASA NTRS1974

Use of cross-correlation measurements to investigate noise generating regions of a real jet engine and a model jet

Cross-correlations are reported of the jet static pressure fluctuations (as measured with a B and K microphone fitted with a nose cone), with the far-field radiated sound pressure. These measurements were made for various probe positions and a large number of far-field positions (at various angles). In addition, the tests were run for a number of different jet exit velocities. The measured, normalized cross-correlation functions vary between 0.004 and 0.155. These values depend upon the angular position of the far-field microphone, the jet exit Mach number, and the position of the probe. In addition, the cross-correlation technique was employed to study the symmetry of the far-field radiated sound about the jet axis. Third-octave analyses of both the probe signal and the far-field radiated sound were made. This is the first time correlation measurements have been made on a jet engine. In addition, a report is given on an extensive noise survey of a model jet. The correlations are related to sound source functions and jet source regions are discussed.

Meecham, W. C.↗
NASA NTRS1974

Observations of radiation from an electron beam artificially injected into the ionosphere

This paper reports the observations of waves generated by a controlled beam of particles artificially injected into the ionosphere and magnetosphere. The measurements were made during the Electron Echo 1 experiment, in which an electron accelerator was carried to a height of 350 km in the ionosphere from Wallops Island, Virginia, on an Aerobee 350 sounding rocket. It injected into the earth's magnetic field over 3000 16-ms pulses of electrons with 40-keV energy and a current of 70 mA at pitch angles between 70 and 110 deg. The ejected fiber glass nose cone carried antennas and receivers to measure the electric field of waves generated by the beam. Associated with the electron beam was radiation detected at frequencies near the electron plasma frequency of the background ionosphere, near twice the electron cyclotron frequency in the whistler mode, and near zero frequency. Associated with the operation of an argon plasma generator used to keep the accelerator neutralized were continuous emissions detected at frequencies near the lower-hybrid resonance (LHR).

Cartwright, D. G.↗
NASA NTRS1974

A directional microphone array for acoustic studies of wind tunnel models

An end-fire microphone array that utilizes a digital time delay system has been designed and evaluated for measuring noise in wind tunnels. The directional response of both a four- and eight-element linear array of microphones has enabled substantial rejection of background noise and reverberations in the NASA Ames 40- by 80-foot wind tunnel. In addition, it is estimated that four- and eight-element arrays reject 6 and 9 dB, respectively, of microphone wind noise, as compared with a conventional omnidirectional microphone with nose cone. Array response to two types of jet engine models in the wind tunnel is presented. Comparisons of array response to loudspeakers in the wind tunnel and in free field are made.

Soderman, P. T.↗
NASA NTRS1975

The Effect of a Planetary Surface Penetrator on the Soil Column Surrounding the Impacting Body

A prototype penetrator instrument was impacted into a dry lake bed. Laboratory studies of the soil surrounding the penetrator revealed that the soil was contaminated by paint and metal from the penetrator's casing. Paint pigment rich in titanium and sulfur was found in the adjacent soil. The highly mobile paint pigment migrated onto viewing ports in the penetrator's exterior. Bulk analysis of the soil adjacent to the impactor showed a significant increase in both elements, as well as the presence of metal chips from the casing and nose cone. It is recommended that great care be taken in the use of coating materials and the metal alloys selected for the penetrator's exterior, or the accuracy of any experiment requiring an uncontaminated in situ sample may be adversely affected.

Blanchard, Maxwell B.↗
NASA NTRS1975

Cross-correlation of noise produced inside a hot turbojet exhaust with and without suppression using a new, hot probe

The noise producing region of a hot turbojet exhaust is studied by cross-correlating hydrodynamic pressure fluctuations within the exhaust with far field sound for Mach numbers up to 0.99. Measurements are made on unsuppressed engine and on a suppressed engine fitted with a 31-tube multijet nozzle. Hydrodynamic pressure fluctuations inside the hot exhaust are measured using a special 1/4 inch diameter probe tube (acoustically damped and air cooled), fitted with a ported nose cone. Maximum, normalized cross-correlations of 0.2 are found for Ma = 0.99 at an angle of 30 deg.

Meecham, W. C.↗
NASA NTRS1975

Designing for solid rocket booster reusability

The Solid Rocket Booster (SRB) of the Space Shuttle Program has been designed to be recovered, refurbished, and reused up to 19 times on subsequent launches. The design modifications to the SRB to incorporate this capability include the addition of a parachute recovery system and minor structural modifications to the nose cone, forward skirt, aft skirt, and solid rocket motor structures for withstanding the water impact loading. In addition, the detail design of subsystem hardware requires careful attention to corrosion prevention and facility of refurbishment operations. A cost analysis comparing the reusable SRB with an expendable version shows a substantial reduction in Space Shuttle cost per flight is achieved with the reusable design approach.

Nevins, C. D.↗
NASA NTRS1975

Shadowgraphs of air flow over prospective space shuttle configurations at Mach numbers from 0.8 to 1.4

Shadowgraphs of five space shuttle launch configurations are presented. The model was a 4 percent-scale space shuttle vehicle, tested in the 11- by 11-foot Transonic Wind Tunnel at Ames Research Center. The Mach number was varied from 0.8 to 1.4 with three angles of sideslip (0 deg, 5 deg and -5 deg) that were used in conjunction with three angles of attack (4 deg, -4 deg, and 0 deg). The model configurations included both series-burn and parallel-burn configurations, two canopy configurations, two positions of the orbiter nose relative to the HO tank nose, and two HO tank nose-cones angles (15 deg and 20 deg). The data consist entirely of shadowgraph photographs.

Dods, J. B., Jr.↗
NASA NTRS1976

An investigation to determine the pressure distribution on the 0.0137 scale solid rocket booster forebody (MSFC model 467) at angles of attack at or near 90 deg and high Reynolds numbers in the MSFC High Reynolds Number Wind Tunnel (SA29F)

An aerodynamic investigation was conducted in the MSFC High Reynolds Number Wind Tunnel to determine the pressure distribution over the foresection of the current 146 inch diameter shuttle SRB. The test model consisted of a 0.0137 scale version of the SRB nose cone and a forward portion of the cylindrical body which was approximately 2.7 calibers in length. The pressure distributions are plotted as a function of longitudinal station ratioed to body diameter and circumferential location for each angle of attack and Mach number. A Reynolds number variation study was made for Mach numbers of 0.4 and 0.6 at an angle of attack of 270 deg and roll angle of 180 deg.

Ramsey, P. E.↗
NASA NTRS1976

Whistler mode plasma waves observed on Electron Echo 2

Observations of whistler-mode waves associated with beams of electrons injected into the ionosphere are reported. The measurements are from the plasma-wave experiments carried on the Electron Echo 2 sounding rocket launched on September 24, 1972. Over 2000 electron injections were made with durations of 8 ms and 64 ms and pitch angles from 0 to 180 deg. The electric field receivers carried on the ejected nose cone observed strong whistler waves in the range from less than 100 kHz up to the electron cyclotron frequency of 1400 kHz. The whistler characteristics fall into four distinct types depending on pitch angle and gun energy. Both frequency and amplitude showed strong dependence on time from the start of the pulse and pitch angle. Cases of enhancement at the leading edge of a gun pulse, growth during a pulse, and echoes after the end of a pulse were all observed.

Monson, S. J.↗
NASA NTRS1977

The total hemispherical emittance of silicon-carbide coated reinforced carbon composites in the temperature range 100 K to 450 K

This paper deals with the measurement of the total hemispherical emittance of a silicon carbide coated carbon composite which is the thermal control material of the nose cone and leading edges of the Space Shuttle. In order to effect the thermal design of the spacecraft, it is desirable to have emittance data available for the temperature range 100 K to 2000 K to encompass the thermal extremes associated with orbiting and reentry conditions. Since the multiple thermal cycling associated with fifty to one hundred missions might result in substantial property changes, the data to be presented are for the low temperature regime 100 K to 450 K for both virgin material and material which was thermally treated to simulate multiple reentries. The discussion emphasizes the identification of possible sources of error in the measurement of equilibrium temperatures and the extent to which these measurement errors or uncertainties would alter the derived emittance values.

Mcgrath, J. J.↗
NASA NTRS1977

Design and fabrication of nosecone for WB-57F aircraft fitted with APQ-102A side looking radar

The design, fabrication, and testing of a nose cone which included a radome for a NASA WB-57F high altitude natural resources mapping aircraft was reviewed. The plane was fitted with a APQ-102A side looking radar operating at 9.6 GHz. The radar is directed normally to the direction of the flight and downward by a changeable angle, and it is assumed that the axis of the plane will not deviate from this direction by more than + or - 6 deg. The radome is required to subtend an angle of 160 deg centered 30 deg below the left horizon.

Source record↗
NASA NTRS1977

An investigation of rotor noise generation by aerodynamic disturbance

An open rotor was considered as a process for converting an unsteady velocity inflow into sound radiation. With the aid of crude assumptions, aero-acoustic transfer functions were defined theoretically for both discrete frequency and broad band noise. A study of the validity of these transfer functions yielded results which show good agreement at discrete frequencies though slightly less good for broad band noise. Agreement in both cases holds over three or more decades of the relevant parameters. A rotating hot wire anemometry system consisting of a single hot wire probe mounted in the nose cone of the rotor was used to quantify fluctuations in the airflow onto a single rotor blade for the transfer function results. Further theoretical analysis revealed that the sound field can be expressed in terms of blade-to-blade correlations in the airflow, and results from two probes rotating simultaneously were modelled mathematically and inserted in the theory. Preliminary results snow encouraging agreement with experimental data.

Whitfield, C. E.↗
NASA NTRS1978

The qualification of the shuttle booster separation motors

Four booster separation motors (BSM) located at each end of every solid rocket booster (SRB) provide the needed side force to separate the boosters from the external tank at booster burnout. Four BSMs at the top of the SRB are located in a box pattern in the nose cone frustum. The four BSMs at the aft end of the SRB are arranged side-by-side on the SRB aft skirt. Aspects of BSM design and performance are considered, taking into account a motor design/performance summary, the case design, the insulation, the grain design, the nozzle/aft closure design, the ignition system, the propellant, and the motor assembly. Details of motor testing are also discussed, giving attention to development testing, qualification testing, and flight testing.

Chase, C. A.↗
NASA NTRS1980

Transonic pressure and load distributions for a group of simulated launch vehicles

Pressure and load distributions for a related group of simulated launch vehicle configurations are presented. The configurations were selected so that the nose cone and interstage transition flare components were relatively close to one another and subject to mutual interference effects. Tests extended over a Mach number range from 0.40 to 1.20 at angles of attack from 0 deg to about 10 deg. The test Reynolds numbers, based on main stage diameter, were of the order of 0.00000098.

Kelly, T. C.↗
NASA NTRS1982

Space Shuttle External Tank Gaseous Oxygen Vent System

Two problems had to be solved to assure successful elimination of ice on the External Tank (ET). First, an access/support structure was provided from the Launch Complex 39A Fixed Service Structure to the vicinity of the nose cone on the ET approximately 82.3 meters (270 feet) above the surface of the pad and 22.9 meters (75 feet) from the face of the FSS. Second, an umbilical was designed and tested that would seal around the ET gaseous oxygen (GOX) vent louvers and not allow ice to form on the tank or the umbilical. A modified Apollo service arm was chosen. An inflatable vent seal subsystem was chosen, providing a cloth seal around each vent louver with an internal annulus to provide a path for the gaseous oxygen from the ET to a hard duct on the swing arm.

Franklin, W. G.↗