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Noncontacting gas seals investigated for performance characteristics of spiral groove and shrouded Rayleigh step profiles
A powered-lift, reduced thrust takeoff performance program utilizing quiet short-haul research aircraft has been conducted. It has been shown that the powered-lift upper surface blowing concept greatly enhances aircraft takeoff performance. The improvements include: (1) takeoff field lengths may be shortened by approximately 30%; (2) Air Force critical field lengths may be shortened by approximately 60%; (3) powered lift upper surface blowing aircraft have better handling and performance characteristics than comparable conventional aircraft; and (4) the low speeds associated with powered-lift takeoff enhance safety margins.
The Langley 16-Foot Transonic Tunnel was used to evaluate the performance characteristics of a coannular plug nozzle at static conditions (Mach number of 0) and at Mach numbers from 0.65 to 1.20. Jet total pressure ratio was varied from 1.0 (jet off) to 10.0. Thirty-seven configurations generated by the combination of three geometric variables - plug angle, shroud boattail length (fixed exit radius), and shroud extension length - were tested.
Wind tunnel and flight tests were made to determine the performance characteristics of two designs of commercially available venturi tubes used in airplanes to operate air-driven gyroscopic instruments. Data obtained at sea level may be used to make approximate predictions of performance at higher altitudes. There is some indication that this may also be done for single venturi tubes. For a given installation in which an air-driven instrument is connected through tubing with a venturi tube, the volume rate of induced air flow is approximately proportional to the product of indicated air speed and the square root of the ratio of standard to ambient air pressure. The efficiency of such a system at a given altitude is constant. Rather large variations in suction and efficiency were found for individual tubes of the same design. Cylindrical fairings on the external surface resulted in a reduction of both drag and suction but little change in efficiency.
The performance characteristics of a pre-formed elliptical parachute at altitudes between 200,000 and 100,000 feet were obtained by means of in-flight photography. The tests demonstrate that this type of parachute will open at altitudes of about 200,000 feet if conditions such as twisting of the suspension lines or draping of the suspension lines over the canopy do not occur. Drag-coefficient values between 0.6 and 0.8 were found to be reasonable for this type of parachute system in the altitude range between 200,000 and 100,000 feet.
A study of the ice accretion patterns and performance of characteristics of a multi-element airfoil was undertaken at the NASA-Lewis Icing Research Tunnel. Several configurations were examined to determine the ice shape and performance characteristics. The testing included glaze, rime, and mixed icing regimes. Tunnel cloud conditions were set to correspond to those typical of the operating environment for commercial transport aircraft. Measurements acquired included ice profile tracings and aerodynamic forces both during the accretion process and in a post-accretion evaluation over a range of angle of attack. Substantial ice accretions developed on the main wing, flaps, and slat surfaces. Force measurements indicate severe performance degradation, especially near CL max, for both light and heavy ice accretion. Frost was seen on the lower surface of the airfoil which was found to contribute significantly to the force components.
Thermic diode solar panels are a passive method of space and hot water heating using the thermosyphon principle. Simplified methods of sizing and performing economic analyses of solar heating systems had until now been limited to passive systems. A mathematical model of the thermic diode including its high level of stratification has been constructed allowing its performance characteristics to be studied. Further analysis resulted in a thermic diode design manual based on the f-chart method.
Designers have relied heavily upon aerodynamic theory and wind-tunnel testing of large and small models to obtain accurate estimates of the performance characteristics for a new configuration and to provide a realistic simulation of the vehicle’s flying characteristics before its first flight, However, the highly unusual shapes of the lifting body vehicles have raised some questions of how accurately their lift and drag characteristics could be defined with these prediction techniques. Thus it is pertinent to com- pare the lift and drag data obtained in flight for three lifting body vehicles (ref. 1 and unpublished results) with wind-tunnel measurements obtained on the actual flight vehicles (refs. 2 and 3 and unpublished results) and on small-scale models of the flight vehicles (ref. 4 and unpublished results). These comparisons, together with discussions of separated flow problems and the effects of ablated surfaces, should be useful to the designers of space shuttlecraft.
Ti-Ag contact N-P and P-N single crystal Si solar cells electrical and mechanical performance characteristics
Performance characteristics of liquid and solid lubricants for contacts of miniature slip-ring capsules
Investigations were conducted of a 12 degree 21-inch conical diffuser of 2:l area ratio to determine the interrelation of boundary layer growth and performance characteristics. surveys were made of inlet and exit from, longitudinal static pressures were recorded, and velocity profiles were obtained through an inlet Reynolds number range, determined From mass flows and based on inlet diameter of 1.45 x 10(exp 6) to 7.45 x 10(exp 6) and a Mach number range of 0.11 to approximately choking. These investigations were made to two thicknesses of inlet boundary layer. The mean value, over the entire range of inlet velocities, of the displacement thickness of the thinner inlet boundary layer was approximately 0.035 inch and that of the thicker inlet boundary layer was approximately six times this value. The loss coefficient in the case of the thinner inlet boundary layer had a value between 2 to 3 percent of the inlet impact pressure over most of the air-flow range. The loss coefficient with the thicker inlet boundary layer was of the order of twice that of the thinner inlet boundary layer at low speeds and approximately three times at high speeds. In both cases the values were substantially less than those given in the literature for fully developed pipe flow. The static-pressure rise for the thinner inlet boundary layer was of the order of 95 percent of that theoretically possible over the entire speed range. For the thicker inlet boundary layer the static pressure rise, as a percentage of that theoretically possible, ranged from 82 percent at low speeds to 68 percent at high speeds.
The Ensign-Bickford Company has been actively involved in the design and development of a laser equivalent to the electrically initiated NASA Standard Initiator (NSI). The purpose of this paper is to describe the present design and its performance characteristics. Recommendations for advancement of this program are also presented.
Experimental aerodynamic investigations were made in transonic and supersonic wind tunnels on a .008899 scale model of the Boeing model 979-145 Ballistic Recoverable Booster. The purpose of the tests was to define the stability and performance characteristics of the BRB at re-entry attitudes in the transonic and supersonic flight regimes. Data were obtained over a Mach number range from 0.6 to 4.0 at angles of attack between 50 deg and 85 deg at zero sideslip and at angles of sideslip between -17.5 deg and +15 deg at angles of attack between 50 deg and 85 deg.
A semispan wing/body model with a powered propeller was tested to provide data on a total powerplant installation drag penalty of advanced propfan-powered aircraft. The test objectives were to determine the total power plant installation drag penalty on a representative propfan aircraft; to study the effect of configuration modifications on the installed powerplant drag; and to determine performance characteristics of an advanced design propeller which was mounted on a representative nacelle in the presence of a wing.
The Lightning Imaging Sensor (LIS) on board the Tropical Rainfall Measuring Mission (TRMM) effectively reached its end of life on April 15, 2015 after 17+ years of observation. Given the wealth of information in the archived LIS lightning data, and growing use of optical observations of lightning from space throughout the world, it is still of importance to better understand LIS calibration and performance characteristics. In this work, we continue our efforts to quantify the optical characteristics of the LIS pixel array, and to further characterize the detection efficiency and location accuracy of LIS. The LIS pixel array was partitioned into four quadrants, each having its own signal amplifier and digital conversion hardware. In addition, the sensor optics resulted in a decreasing sensitivity with increasing displacement from the center of the array. These engineering limitations resulted in differences in the optical emissions detected across the pixel array. Our work to date has shown a 20% increase in the count of the lightning events detected in one of the LIS quadrants, because of a lower detection threshold. In this study, we will discuss our work in progress on these limitations, and their potential impact on the group- and flash-level parameters.
The Core Driven Fan Stage (CDFS) Variable Cycle Engine (VCE) has been identified as a leading candidate for advanced supersonic cruise aircraft. A scale demonstrator version of this engine has been designed and tested. This testbed engine features a split fan with double bypass capability, variable forward and aft mixers, and a variable area low pressure turbine nozzle to permit exploration and optimization of the cycle in both single and double bypass modes. This paper presents the aerodynamic performance characteristics and experimental results obtained from both the core engine and full engine tests.
The Orbiter Camera Payload System, the OCPS, is an integrated photographic system which is carried into earth orbit as a payload in the Shuttle Orbiter vehicle's cargo bay. The major component of the OCPS is a Large Format Camera (LFC) which is a precision wide-angle cartographic instrument that is capable of producing high resolution stereophotography of great geometric fidelity in multiple base to height ratios. The primary design objective for the LFC was to maximize all system performance characteristics while maintaining a high level of reliability compatible with rocket launch conditions and the on-orbit environment.
Enhanced radio frequency carrier margin improvement for arrayed receiving systems for coherent reception of phase modulated signals with residual carrier provides a significant reduction in carrier loop phase noise and an increase in the signal to noise ratio in the RF carrier tracking loop with an attendant in telemetry radio loss. A significant increase in doppler frequency rate capability is also realized relative to operating at a narrower tracking loop bandwidth to obtain the same carrier sensitivity improvement. These performance characteristics are examined for an array of two receiving sysems with equal apertures and statistically independent prediction noise.