Report presenting an investigation to gain information concerning the durability of metallic coatings as affected by frit content, firing temperature, firing time, and number of coats. Four coatings of various frit content were prepared and applied to ceramals containing 80 percent chromium and 20 percent cobalt and heated at four different temperatures.

Note presenting a wind-tunnel investigation to determine the effects of jet-outlet cut-off angle on the directional and spreading characteristics of an unheated, subsonic air jet, and on the pitching moment of the body from which the jet issued. Results regarding the jet operating with the wind tunnel off, jet off with the wind tunnel operating, jet operating with the wind tunnel operating, and flow studies with the jet operating and the wind tunnel off are provided.

Report presenting practical methods for making the calculations required for the analysis of an autopilot and an autopilot-aircraft combination from frequency-response data. From Summary: "Equations are derived for determining the servo-system error voltage for both displacement input signal and displacement plus rate of displacement input signals, the autopilot frequency response for addition of rate of displacement input signal, the servo-system frequency response for a change of gain, and the relation between open-loop and closed-loop frequency responses for the servo system and the autopilot-aircraft combination."

Report presenting a method utilizing precalculated solutions graphically presented for calculating subsonic or supersonic ramjet performance parameters with the associated equations and graphs. By assuming constant values of specific-heat ratio and gas constant equal to those of standard air, the thrust-coefficient calculation has been reduced to a few simple operations.

Note presenting testing to determine whether lead compounds in the combustion products of high-octane fuel are a contributing factor in causing failures of the heat-resistant alloy parts in aircraft exhaust systems. To obtain answers for five heat-resistant alloys, a test was devised in which the alloy specimens in an uncoated condition, in a preoxidized condition, and with three different ceramic coatings were exposed for 6 hours to lead-containing vapors in an air atmosphere at 3 different temperatures.

Report presenting the results of axial-load fatigue tests on notched specimens of three sheet materials: 24S-T3 and 75S-T6 aluminum alloys and SAE 4130 steel. Fatigue tests were run at several levels of nominal mean stress, including a zero nominal mean stress. Fatigue tests for notched specimens are compared with previously reported unnotched specimens of the same materials.

From Summary: "This reports presents of axial-load fatigue tests on notched specimens of three sheet materials: 24S-T3 and 75S-T6 aluminum alloys and normalized SAE 4130 steel. Each specimen was notched by edge notches designed to have a theoretical stress-concentration factor of 5.0. Tests were run at four levels of nominal mean, stress: 0, 10,000, 20,000, and 30,000 psi. Results of these tests extend information previously reported from tests on unnotched specimens and on specimens less severely notched."

From Summary: "The hydrocarbons - 2-cyclopropyl-1-butene, cis and trans 2-cyclopropyl-2-butene, and 2-cyclopropylbutane - were obtained from methylcyclopropyl ketone by reacting the ketone with ethylmagnesium bromide, dehydrating the resultant methylethylcyclopropylcarbinol to a mixture of olefins from which 2-cyclopropyl-1-butene and cis and trans 2-cyclopropyl-2-butene were isolated, and hydrogenating the olefins to 2-cyclopropylbutane. All four hydrocarbons were obtained in high purity for the first time; their physical constants and infrared spectra are presented."

Report presenting an investigation of the significance of tensile strength and ductility in the presence of defects and the strength-reducing effects of several types of defect were investigated for some rotating disks. Some of the defects investigated included laminar-type irregularities, eutectic melting, and shrink porosity.

Note presenting calculations of the ratios of the velocity increments at test bodies to those at the tunnel walls caused by the solid blocking of these bodies within the walls of a closed rectangular wind tunnel. The bodies treated include two-dimensional airfoils, small bodies of revolution, straight, untapered, finite-span wings of varying span, and swept, untapered, finite-span wings of varying span.

Report presenting an investigation of the flutter characteristics of a uniform, unswept, cantilever wing of high aspect ratio and under conditions of high mass coupling by means of a Rayleigh type analysis based on coupled modal functions. Results are compared with an experiment and the calculated results of NACA TN 1902.

"An analytical method based on successive approximations is presented for determining the loads and deflections throughout an indeterminate structure in which one or more of the members have been stressed beyond their proportional limits. Theoretical analyses of three structures are compared with tests and found to agree very closely. For the sake of simplicity and clarity, only coplanar pin-ended structures have been analyzed and tested" (p. 1).

Report presenting the effects of cyclic and continuous immersion in heptane, toluene, and SR-6, a test fuel, on the weight, dimensions, and flexural properties of 19 samples of laminated plastics. No one sample exhibited smaller changes than all other samples in all properties for all fuels and for both cyclic and continuous immersion. Results regarding weight and dimensional changes and changes in flexural properties are provided.

Report presenting an analytic method for the design of automatic controls that has been developed and starts from arbitrary criterions on the behavior of the controlled system and gives those physically realizable equations that the control system can follow in order to realize the behavior. The criterions used are developed in the form of certain time integrals. General results are shown for systems of second order and of any number of degrees of freedom.

Report presenting studies of the effects of various aging treatments on the mechanical properties of solution-treated Inconcel X at 1200 degrees and 1500 degrees Fahrenheit for a variety of rupture times. Specimens were aged at 1200 degrees, 1400 degrees, and 1600 degrees Fahrenheit for time periods up to 1000 hours. Results regarding structural changes as a result of aging, mechanical behavior at the designated temperatures, and a comparison with work on low-carbon N-155 are provided.

The analysis of Technical Note 2250, 1950, is extended to include the effects of flow rotation. It is found that the theoretical pressure distributions over drive cylinders can be related by the hypersonic similarity rule with sufficient accuracy for most engineering purposes. The error introduced into pressure distributions and drag effective cylinders by ignoring the rotation term in the characteristic equations is investigated.

"The problem of combined bending and torsion of cantilever plates of variable thickness, such as might be considered for solid thin high-speed airplane or missile wings, is considered in this paper. The deflections of the plate are assumed to vary linearly across the chord; minimization of the potential energy by means of the calculus of variations then leads to two ordinary linear differential equations for the bending deflections and the twist of the plate. Because the cantilever is analyzed as a plate rather than as a beam, the effect of constraint against axial warping in torsion is inherently included" (p. 1).