Investigation of a panel code for airframe/propeller integration analyses

The Hess panel code was investigated as a procedure to predict the aerodynamic loading associated with propeller slipstream interference on the airframe. The slipstream was modeled as a variable onset flow to the lifting and nonlifting bodies treated by the code. Four sets of experimental data were used for comparisons with the code. The results indicate that the Hess code, in its present form, will give valid solutions for nonuniform onset flows which vary in direction only. The code presently gives incorrect solutions for flows with variations in velocity. Modifications to the code to correct this are discussed

A catalogue of devices applicable to the measurement of boundary layers and wakes on flight vehicles

A literature search was conducted to assemble a catalog of devices and techniques which have possible application to boundary layer and wake measurements on flight vehicles. The indices used in the search were NACA, NASA STAR, IAA, USGRDR and Applied Science and Technology Index. The period covered was 1950 through 1970. The devices contained in the catalog were restricted to those that provided essentially direct measurement of velocities, pressures and shear stresses. Pertinent material was included in the catalog if it contained either an adequate description of a device and associated performance data or a presentation of applicable information on a particular measurement theory and/or technique. When available, illustrations showing the configuration of the device and test condition data were also included

Propeller propulsion integration, phase 1

A bibliography was compiled of all readily available sources of propeller analytical and experimental studies conducted during the 1930 through 1960 period. A propeller test stand was developed for the measurement of thrust and torque characteristics of full scale general aviation propellers and installed in the LaRC 30 x 60 foot full scale wind tunnel. A tunnel entry was made during the January through February 1980 period. Several propellers were tested, but unforseen difficulties with the shaft thrust torque balance severely degraded the data quality

An experimental investigation of the aerodynamics and cooling of a horizontally-opposed air-cooled aircraft engine installation

A flight-test based research program was performed to investigate the aerodynamics and cooling of a horizontally-opposed engine installation. Specific areas investigated were the internal aerodynamics and cooling mechanics of the installation, inlet aerodynamics, and exit aerodynamics. The applicable theory and current state of the art are discussed for each area. Flight-test and ground-test techniques for the development of the cooling installation and the solution of cooling problems are presented. The results show that much of the internal aerodynamics and cooling technology developed for radial engines are applicable to horizontally opposed engines. Correlation is established between engine manufacturer's cooling design data and flight measurements of the particular installation. Also, a flight-test method for the development of cooling requirements in terms of easily measurable parameters is presented. The impact of inlet and exit design on cooling and cooling drag is shown to be of major significance

Propeller propulsion system integration: State of technology survey

A literature survey was performed to identify and review technical material applicable to the problem area of propeller propulsion system integration. The survey covered only aerodynamic interference aspects of the problem, and was restricted primarily to propeller effects on the airframe. The subject of airframe aerodynamic interference on the propeller was limited to the problem of vibration due to nonuniform inflow. The problem of airframe effects on propeller performance was not included. A total of 1121 references are given. The references are grouped into the subject areas of Aircraft Stability, Propulsive Efficiency, Aerodynamic Interference, Aerodynamic Interference-Propeller Vibration, and Miscellaneous

Extreme laser pulses for possible development of boron fusion power reactors for clean and lasting energy

Extreme laser pulses driving non-equilibrium processes in high density plasmas permit an increase of the fusion of hydrogen with the boron isotope 11 by nine orders of magnitude of the energy gains above the classical values. This is the result of initiating the reaction by non-thermal ultrahigh acceleration of plasma blocks by the nonlinear (ponderomotive) force of the laser field, in addition to the avalanche reaction that has now been experimentally and theoretically manifested. The design of a very compact fusion power reactor is scheduled to produce then environmentally fully clean and inexhaustible generation of energy at profitably low costs. The reaction within a volume of cubic millimetres during a nanosecond can only be used for controlled power generation.Comment: 10 pages, 5 fugure

Review of Liquid-Cooled Aircraft Engine Installation Aerodynamics

The aerodynamic behavior of liquid-cooled aircraft engine cooling installations is reviewed. Design considerations for inlets, diffusers, and exists are discussed. It is shown that the design of an efficient liquid-cooled installation is a techically sophisticated problem. This problem should not be underestimated in the development program of liquid-cooled aircraft engines. Questions are raised concerning the availability of suitable radiators for aircraft installations. INTRODUCTION To many, liquid-cooled aircraft engines seem to have an aura, a fascination that has not been given to air-cooled engines. Some of this is certainly due to aesthetics. Liquid-cooled engines are synonymous with streamlining and aerodynamically clean profiles. The connection is readily made to the legendary Spitfire, M 1 ustang, and Messerschmitt. The unappealing radial-air cooled engine does not enjoy this subjective attribute. Today's horizontally-opposed air-cooled engines fare no better. The mention of liquid-cooling immediately stimulates designers to visualizing low-drag shapes and improved performance, and stimulates marketing to thinking in terms of lightning-bolt and shark-mouth paint schemes. However, if more objective criteria are applied, the air-cooled engine compares more favorably with the liquid-cooled engine. It is apparent from literature during the 1930s period that each had strong proponents and that it was relatively easy to start an argument over the relative merits of each. Most of the same technical points apply today. The author, though, will separate these points into propulsion concerns and aerodynamic design concerns. From the standpoint of propulsion, the liquid-cooled engine offers better fuel efficiency and longer engine life. Better control of cooling paths and subsequently of component cooling is realizable. On the other hand, the air-cooled engine offers system simplicity and is less vulnerable to system component failure. The weight of the cooling system is less. From the standpoint of external aerodynamic design, the liquid-cooled engine offers reduced frontal area and the potential for reduced drag, particularly compressibility drag. The internal combustion engine aircraft speed record was held by a liquid-cooled engine; however, it is now held by a radial air-cooled engine. Engine power must be factored into the comparison. Ground cooling is more of a problem for liquid-cooled engines. From the standpoint of internal aerodynamic design, the liquid-cooled engine has a definite advantage. Aerodynamically, each component of the system is in theory well behaved, i.e., no separated flows. The liquid-cooling system is more tractable to analytical aerodynamic modeling and design. The horizontally-opposed air-cooled engine configuration leads to large separated flows, because the relatively large internal volumes and ducting necessary to do otherwise are not practical. This is inherent in the geometry of the engine. The radial air-cooled engine configuration is aerodynamically much easier to deal with. Liquid-cooled aircraft engines are presently available up to approximately 400 hp. There are developmental programs under way that could extend this range. In some cases, these are derivatives of automobile 1 Presented as Paper 86-2587 at the AIAA General Aviation Technology Conference, Anaheim, CA., Sept. 29-Oct. 1, 1986; received Nov. 12, 1986; revision received Aug. 22, 1987. Copyright (c) engines; in other cases, these are unique designs, such as the rotary type. The author's recent experience with one of these programs has brought forward an appreciation for the level of technology required to design an effective and efficient liquid-cooled installation. The technical problem of achieving the required cooling for minimum drag penalty should not be underestimated. It is the purpose of this paper to identify and discuss the various design problems of a liquid-cooled installation, indicating, where possible, what is known and what is unknown. Much of the information in this paper is taken from literature, particularly the works of Kuchemann and Weber

An application of wake survey rakes to the experimental determination of thrust for a propeller driven aircraft

The lack of slipstream static pressure distribution seriously affected the results but recommendations for removing the deficiency are discussed. The wake survey rake is shown to be a valuable tool in aircraft flight testing. Flow characteristics in the wake of the propeller were examined

Investigation of helicopter rotor blade/wake interactive impulsive noise

An analysis of the Tip Aerodynamic/Aeroacoustic Test (TAAT) data was performed to identify possible aerodynamic sources of blade/vortex interaction (BVI) impulsive noise. The identification is based on correlation of measured blade pressure time histories with predicted blade/vortex intersections for the flight condition(s) where impulsive noise was detected. Due to the location of the recording microphones, only noise signatures associated with the advancing blade were available, and the analysis was accordingly restricted to the first and second azimuthal quadrants. The results show that the blade tip region is operating transonically in the azimuthal range where previous BVI experiments indicated the impulsive noise to be. No individual blade/vortex encounter is identifiable in the pressure data; however, there is indication of multiple intersections in the roll-up region which could be the origin of the noise. Discrete blade/vortex encounters are indicated in the second quadrant; however, if impulsive noise were produced here, the directivity pattern would be such that it was not recorded by the microphones. It is demonstrated that the TAAT data base is a valuable resource in the investigation of rotor aerodynamic/aeroacoustic behavior

Radio Galaxy Zoo: Cosmological Alignment of Radio Sources

We study the mutual alignment of radio sources within two surveys, FIRST and TGSS. This is done by producing two position angle catalogues containing the preferential directions of respectively $30\,059$ and $11\,674$ extended sources distributed over more than $7\,000$ and $17\,000$ square degrees. The identification of the sources in the FIRST sample was performed in advance by volunteers of the Radio Galaxy Zoo project, while for the TGSS sample it is the result of an automated process presented here. After taking into account systematic effects, marginal evidence of a local alignment on scales smaller than $2.5\deg$ is found in the FIRST sample. The probability of this happening by chance is found to be less than $2$ per cent. Further study suggests that on scales up to $1.5\deg$ the alignment is maximal. For one third of the sources, the Radio Galaxy Zoo volunteers identified an optical counterpart. Assuming a flat $\Lambda$CDM cosmology with $\Omega_m = 0.31, \Omega_\Lambda = 0.69$, we convert the maximum angular scale on which alignment is seen into a physical scale in the range $[19, 38]$ Mpc $h_{70}^{-1}$. This result supports recent evidence reported by Taylor and Jagannathan of radio jet alignment in the $1.4$ deg$^2$ ELAIS N1 field observed with the Giant Metrewave Radio Telescope. The TGSS sample is found to be too sparsely populated to manifest a similar signal