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The performances of the radial bearings on three 64-meter antennas are presented. Explanations for the distortion of the bearing at DSS 14 are made and the repairs are described. Recommendations for future tests and action are given.
The ion drift meter for Dynamics Explorer B is discussed. It measures two mutually perpendicular angles of arrival of thermal ions with respect to the sensor look directions. These angles lie in the vertical and horizontal planes and may be thought of as pitch and yaw in the conventional aerodynamic sense. The components of the ion drift velocity along vertical and horizontal axes through the spacecraft body are derived to first order from knowledge of the spacecraft velocity vector and more accurately with additional knowledge of the component of ion drift along the sensor look direction.
Design problems associated with the integration of flow visualization in cryogenic facilities are discussed. The possible effects from the cryogenic environment (i.e., window distortion due to thermal contraction both in the mounts and in the window material itself and turbulence in the flow due to injected LN2) are examined. The flow visualization techniques studied are schlieren, shadowgraph, moire deflectometry, and holographic interferometry. The test beds for this work are a Langley in-house cryogenic test chamber and the 0.3-Meter Transonic Cryogenic Tunnel.
Viewing problems associated with the measurement of model deformation in cryogenic wind tunnels are discussed. Tests were conducted in the Langley 0.3-Meter Transonic Cryogenic Tunnel to assess viewing capabilities thru the flow field. The effects of condensation and turbulent boundary layers are discussed and a modelling procedure for image degradation is described.
Applications of a laser velocimeter in the Langley 4 by 7 meter wind tunnel are discussed. The system configuration is described. The data acquisition, the laser velocimeter traversing, and the particle generating systems are discussed. Flow distribution and rotor wake applications are discussed.
The problems and the potential use of a nonintrusive flow velocity measuring technique in the Langley 0.3 meter transonic cryogenic tunnel (TCT) were investigated. A laser velocimeter (LV) was used. It was concluded that free-stream velocity measurements can be successfully made in the Langley 0.3-m TCT using a low-power (15-mW) LV system. The measured and calculated mean velocities typically agreed within one percent. The overall normalized standard deviation was less than one percent. Tunnel vibration and temperature had no detrimental effects on the optical system. It is recommended that the LV work should be further investigated for future use in the Langley 0.3-m TCT.
Isolated and grouped type III bursts have been observed in temporal association with impulsive hard X-ray bursts in the 26-154 keV range, down to frequencies as low as 30 MHz and out to a distance of 3.1 solar radii from the disk center. The bursts occurred in regions whose electron density may have been as much as 20 times higher than that of the Newkirk-Saito model. The present observations indicate that electron acceleration/injection occurs over a region covering a wide range of magnetic field lines. It is noted that, of the two gradual hard X-ray bursts observed in association with type IV bursts, one was accompanied by a type II event, while the other was not, although both exhibited the same characteristics. It is suggested that the gradual burst associated with a type IV only involved electrons which are trapped in the plasmoid which produces the meter-decameter emission, while another fraction of the population is trapped in the low-lying loops which produce the hard X-ray and centimeter radiation.
Mixing losses due to excessive film cooling reduced. Turbine blade or vane cooled by gas or liquid flowing through holes to exterior airfoil surface. Metering baffle inside airfoil controls flow to each row of cooling holes. Resulting surface-film flow keeps airfoil cool enough to operate in high-heat, high pressure turbines.
Numerically-controlled 5-axis machine tool uses transformer and meter to determine and indicate whether tool is in home position, but lacks built-in test mode to check them. Tester makes possible test, and repair of components at machine rather then replace them when operation seems suspect.
Hot wire anemometry was used to identify the nature of particles reportedly observed during free stream velocity measurements in the Langley 0.3-meter transonic cryogenic tunnel using a Laser Doppler Velocimeter. Since the heat-transfer process from the hot wire depends on the thermal conductivity and sticking capability of the particles, it was anticipated that the hot wire anemometer response would be affected differently upon impaction by liquid droplets and solid aerosols in the test gas stream. Based on the measured time response of the hot-wire anemometer in the cryogenic tunnel operated in the 0.3-0.8 Mach number range, it is concluded that the particles impacting the hot wire are liquid in nature rather than solid aerosols. It is further surmised that the liquid aerosols are unevaporated liquid nitrogen droplets used for cooling the tunnel test gas.
The design and construction of a rocket-borne electric field meter for determining the atmosphere's electric field and the conductivity in the middle atmosphere are considered. The operating characteristics of the instrument are discussed and a proposed flight configuration is given. The testing of the prototype is described and suggestions are advanced for further improvements.
Measurements of the S-band performance of the DSS 13 26-meter antenna, equipped with the second generation S-X common aperture feed, are reported. Aperture efficiency and overall antenna gain results are compared with predicted values. The elevation dependence of the aperture efficiency is reported.
A wind tunnel investigation of an advanced technology airfoil, the CAST 10-2/DOA 2, was conducted in the Langley 0.3 meter Transonic Cryogenic Tunnel (0.3 m TCT). This was the first of a series of tests conducted in a cooperative National Aeronautics and Space Administration (NASA) and the Deutsche Forschungs- und Versuchsanstalt fur Luft- und Raumfahrt e. V. (DFVLR) airfoil research program. Test temperature was varied from 280 K to 100 K to pressures from slightly above 1 to 5.8 atmospheres. Mach number was varied from 0.60 to 0.80, and the Reynolds number (based on airfoil chord) was varied from 4 x 10 to the 8th power to 45 x 10 to the 6th power. This report presents the experimental aerodynamic data obtained for the airfoil and includes descriptions of the airfoil model, the 0.3 m TCT, the test instrumentation, and the testing procedures.
The theoretical and experimental study of a 1.5-meter offset dual shaped reflector at 31.4 GHz is detailed. An efficiency of 84.5 percent, a likely new record for reflector antennas, was ascertained through careful measurements. For larger low noise reflector systems, a 2- to 3-dB improvement in G/T performance over the state of the art ultra low noise ground stations and 90 percent or better aperture efficiency now appear feasible.
The Networks Consolidation Program (NCP) will utilize 34-meter shaped dual-reflector Cassegrain antennas. The shaping calculations, the X/S-band feedhorn to be used, and the predicted RF performance of this antenna system are discussed.
The application of a nonintrusive laser-interferometer skin-friction meter, which measures skin friction with a remotely located laser interferometer that monitors the thickness change of a thin oil film, is extended both experimentally and theoretically to several complex wind-tunnel flows. These include two-dimensional seperated and reattached subsonic flows with large pressure and shear gradients, and two and three-dimensional supersonic flows at high Reynolds number, which include variable wall temperatures and cross-flows. In addition, it is found that the instrument can provide an accurate location of the mean reattachment length for separated flows. Results show that levels up to 120 N/sq m, or 40 times higher than previous tests, can be obtained, despite encountering some limits to the method for very high skin-friction levels. It is concluded that these results establish the utility of this instrument for measuring skin friction in a wide variety of flows of interest in aerodynamic testing.
A long focal length laser velocimeter (LV) has become a production measurement tool in the Langley 4- by 7-Meter Tunnel. Two recent applications of the LV include flowfield measurements: (1) in the wake of a helicopter, and (2) around the wing of an aspect-ratio (AR) 7 wing-body model. A discussion of these two applications is provided along with a description of the flowfields in terms of the mean velocities and turbulence intensities.
An investigation of the NPL 9510 airfoil was conducted in the Langley 0.3-Meter Transonic Cryogenic Tunnel over the following ranges of test conditions: Mach number of 0.35 to 0.82, total temperature of 94 K to 300 K, total pressure of 1.20 to 5.81 atm, Reynolds number based on airfoil chord of 1.34 x 10 to the 6th power to 48.23 x 10 to the 6th power, and angle of attack of 0 deg to 6 deg. The drag creep previously reported by the British National Physics Laboratory at low Reynolds numbers was also found to be present at high Reynolds numbers; the section drag coefficient continued to decrease even at the highest Reynolds number tested. Tests made close to free-stream saturation did not produce altered aerodynamic coefficients due to condensation effects.