Note presenting the results of a survey of background and aircraft noise levels in residential communities in eight cities with major airports. The measurements were made in areas up to 12 miles away from the airports and were located in regularly used flight paths. The results indicated that there is a range of more than 20 decibels in the average background noise in the 180 areas included in the survey.

Report presenting an investigation of a 1/19-scale model of an unswept-wing trainer airplane in the 20-foot free-spinning tunnel to determine the rocket spin-recovery characteristics of the model for comparison with available full-scale-airplane results. A rocket was attached to each wing tip to fire in a direction to apply an antispin yawing moment about the Z body axis. Results regarding the full-scale spin recoveries by rockets, model spin recoveries by rudder reversal, model spin recoveries by rockets, and mass changes associated with installation of emergency device are provided.

Note presenting a method for analyzing extreme-value data which may arise in a wide variety of applications. Discussion of the method is preceded by the necessary statistical theory which also furnishes a basis for evaluating the new method in relation to existing ones. Several appendices are also included for mathematical developments not included in the text.

Note presenting an investigation of some of the possible mathematical troubles that may occur in the iterative procedure so much in use in present-day aerodynamics. The analysis indicates the general undesirability of determining the velocity potential or the stream function in the form of a series whose coefficients are analytically developed in a power series of some parameter.

From Summary: "Effects of local panel oscillations on bending and torsional vibrations of box beams with flexible covers and webs are investigated. Theoretical analyses of simplified models are made in order to shed light on the mechanism of coupling between local and overall vibrations and to derive results than can be used to estimate the coupling effects in box beams."

Report presenting an investigation of the response of wrought Stellite 21, a typical cobalt-base alloy, to heat treatment. The alloy was solution-treated and transformed by aging and isothermal transformation at temperatures of 1200 to 1950 degrees Fahrenheit for periods of 5 minutes to 72 hours. Results regarding the solution-treated structure, precipitation by isothermal transformation, precipitation by aging, grain boundary behavior, and hardness are provided.

Report presenting experiments to study the start of fretting and cause of damage during the early stages of fretting of steel-steel combinations at a frequency 5 cycles per minute, an amplitude of 0.006 inch, a load of 150 grams, in air with relative humidity of less than 10 percent. Pure iron, glass, and iron oxide powder compacts were used in supplementary experiments.

Report presenting an investigation to determine the effects of microstructure on the stress-rupture life of heat-treated wrought Stellite 21 under stress and temperature conditions comparable to those encountered during engine operation of turbine blades and to correlate with other microstructure properties. Results regarding the stress-rupture life, elongation, hardness, metallographic examination, and room-temperature tensile tests are provided.

Report presenting an investigation to determine the occurrence and nature of lamellar structures and minor phases, by use of metallographic and X-ray diffraction studies, of the following cobalt-base high-temperature alloys: rolled, cast, and high-carbon Stellite 21, 422-19, X-63, 6059, 61, X-40, S-816, I-336, and J. Results regarding the microstructure, x-ray diffraction results, and possible relations of lamellar structures are provided.

Note presenting an analysis of the temperature distributions in a fluid over an oscillating surface with heat transfer and associated heat-transfer parameters are compared with those for the case of conduction at a stationary surface with the same initial temperature potential. It was found that the heat transfer for the oscillating surface can be considerably different from that for conduction alone.

From Summary: "The presence of radomes and instruments that are sensitive to water films or ice formations in the nose section of all-weather aircraft and missiles necessitates a knowledge of the droplet impingement characteristics of bodies of revolution. Because it is possible to approximate many of these bodies with an ellipsoid of revolution, droplet trajectories about an ellipsoid of revolution with a fineness ratio of 10 were computed for incompressible axisymmetric air flow. From the computed droplet trajectories, the following impingement characteristics of the ellipsoid surface were obtained and are presented in terms of dimensionless parameters: (1) total rate of water impingement, (2) extent of droplet impingement zone, and (3) local rate of water impingement."

Note presenting the operating characteristics of an acceleration restrictor which limits the normal acceleration of an airplane in maneuvers determined from tests on a simulator. The simulator consisted of a control stick geared to a magnetic brake unit and an analog computer which simulated the dynamic characteristics of the airplane.

Note presenting tests performed on 21 sheet-stringer panels of 75S-T6 aluminum alloy with alclad sheets nominally 0.051 inch thick and stringers nominally 3.5 inches apart. Three panels of different types, with five stringers each and overall dimensions of approximate 18 by 15 inches, were tested in axial flat-end compression. Results regarding the flat-end compression, protruding-stringer compression, and bending are provided.

From Summary: "Free-flight tests have been made to investigate the total drag and base drag at different Reynolds numbers of full-scale and half-scale models of an NACA research model designated the RM-10. The general shape of the body was a parabola of revolution of fineness ratio 12.2 with a blunt base to provide space for the rocket jet. The models were stabilized by four 60 degree sweptback fins mounted at the base of the bodies."

From Introduction: "These aerodynamic data were used previously in an analytical investigation of a spin recovery by rudder reversal, the results of which have been published in reference 2. Because of certain discrepancies in the rotary-balance data similar to those discussed in reference 3, some modifications were made to the aerodynamic data used in calculating the results in reference 2 and also the results in this paper; these discrepancies and modifications are discussed in detail herein."

Report presenting an approximate, theoretical analysis of the inlet or induction losses due to subsonic flow into a high-solidity cascade of finite thickness blades at incidence angle. Results indicated that the losses can become considerable for large deviations from the design incidence such as compressor off-design operating conditions. Results regarding the computational results, significance of assumptions and limitations, comparison of theoretical approximation with actual compressor results, and applicability of the results are provided.

Note presenting data obtained for the viscosity corrections to cone probes in supersonic rarefied air flow at a nominal Mach number of 4. The test models consisted of a set of seven geometrically similar 5 degree semivertex-angle cones. Results regarding cone surface pressure distributions, calibration data for geometrically similar cones, orifices size effect, and tests at other Mach numbers are provided.

Report presenting an investigation to study the influence of size, particularly notch-size effect, on extruded 75S-T6 aluminum-alloy test specimens under rotating bending. Results regarding fatigue strength and fatigue-notch factor are provided.

Report presenting a theoretical and experimental investigation of heat transfer involving laminar natural convection of fluids enclosed between parallel walls oriented in the direction of body force. The results are presented in the form of equations for the velocity and temperature profiles and ratio of actual temperature drop across the fluid to the temperature drop for pure conduction.

From Summary: "The present report presents the chordwise distributions of pressure measured concurrently with the force and moment data of NACA TN 3007."

The problem of the finite displacement and buckling, of a shallow spherical dome is investigated both theoretically and experimentally. Experimental results seem to indicate that the classical criterion of buckling is applicable to very shallow spherical domes for which the theoretical calculation was made. A transition to energy criterion for higher domes is also indicated.

Report presenting the results of tensile and compressive stress-strain tests at temperatures up to 1200 degrees Fahrenheit for SAE 4340, Hy-Tuf, Stainless W, and Inconel X sheet materials which were heat treated to provide ultimate tensile strengths at room temperatures. Tensile and compressive stress-strain curves are given for each material at test temperatures.

Note presenting experimental results for transonic flow past cone-cylinder, axially symmetric bodies. The drag coefficient and surface Mach number are studied as the free-stream Mach number is varied and, wherever possible, the experimental results are compared with theoretical predictions. The theoretical problem of transonic flow past finite cones is discussed briefly and an approximate solution of the axially symmetric transonic equations, valid for a semi-infinite cone, is presented.

Report presenting a systematic investigation of the sound field of a 1,000-pound-thrust solid-fuel rocket and data on two other rockets of 900 and 5500 pounds of thrust, which were obtained at a few isolated field points. Each of the three rockets was found to produce spectra somewhat similar to those of subsonic jets, which were random and with an envelope which peaks in the lower part of the audible range.