The methods of NACA TN No. 995 have been slightly modified and extended in include flows with circulation by considering the alteration of the singularities of the incompressible solution due to the presence of the hypergeometric functions in the analytic continuation of the solution. It was found that for finite Mach numbers the only case in which the nature of the singularity can remain unchanged is for a ratio of specific heats equal to -1. From a study of two particular flows it seems that the effect of geometry cannot be neglected, and the conventional "pressure-correction" formulas are not valid, even in the subsonic region if the body is thick, especially if there is a supersonic region in the flow.

Shock-wave equations have been evaluated for a range of Mach number in front of the shock from 1.05 to 4.0. Mach number behind the shock, pressure ratio, derivation of flow, and angle of shock are presented on charts. Values are also included for density ratio and change in entropy.

"A limited number of lifting-surface-theory solutions for wings with chordwise loadings resulting from angle of attack, parabolic-arc camber, and flap deflection are now available. These solutions were studied with the purpose of determining methods of extrapolating the results in such a way that they could be used to determine lifting-surface-theory values of the aspect-ratio corrections to the lift and hinge-moment parameters for both angle-of-attack and flap-deflection-type loading that could be used to predict the characteristics of horizontal tail surfaces from section data with sufficient accuracy for engineering purposes. Such a method was devised for horizontal tail surfaces with full-span elevators" (p. 1).

Note presenting a theoretical investigation made of the hydrodynamic pitching moments experienced by V-bottom seaplanes during step-landing impacts. The entire immersion process is analyzed from the instant of initial contact until the seaplane rebounds from the water surface.

From Introduction: "The results of analyses of V-G data given in references 1 to 5 have shown that the flight loads of airplanes operated in commercial transport service are influenced by operating speeds and by forecasting and dispatching practices as reflected in differences between operations during the prewar and wartime periods. The available data are summarized and the flight results are compared with the results of analyses made in references 1 to 5."

Note presenting an experimental study of friction coefficients near the inlet of smooth, round tubes with bellmouth entrances. Four different combinations of approach section and bellmouth entry were used. Results regarding the apparent local friction coefficient, integrated friction coefficient, effect of induced turbulence, laminar inlet zone, developed friction coefficient, and application to discharge coefficients for rounded-entrance flow nozzles are provided.

Report presenting procedures for solving the equations of equilibrium of reinforced panels and isolated fuselage rings as represented by the external loads and operations table established according to Southwell's method. By using these equations, the stress distribution can be easily determined.

"A series of tests were made for the purposes of establishing the effects of several variables in welding technique on the fatigue strength of arc-welded joints in SAE 4130 seamless steel tubing. The variables included type of electrode, speed of welding, current, position, amount of preheat, and other factors which in turn controlled the weld contour, penetration, and depth of the heat-affected zone. A range of joint design was also investigated" (p. 1).

"A theoretical investigation of tail-pipe burning, water injection at the compressor inlet, combination tail-pipe burning plus water injection, bleedoff, and rocket-assist methods thrust augmentation for turbojet engines was made for an engine representative of those in current use. The effect of augmented liquid ratio on augmented thrust ratio and the effects of altitude and flight Mach number on the performance of various methods were determined. The additional take-off weight involved by the use of the different thrust augmentation methods, as well as the effect of the various thrust augmentation methods on the range of a representative aircraft was also investigated" (p. 727).

From Summary: "Axial fatigue tests at zero mean stress have been made on 0.032- and 0.064-inch 24S-T and 0.032-inch 75S-T sheet-metal specimens 1/4, 1/2, 1, and 2 inches wide without a hole and with central holes giving a range of hole diameter D to specimen width W from 0.01 to 0.95. No systematic difference was noted between the results for the 0.032-inch and the 0.064-inch specimens although the latter seemed the more consistent. In general the fatigue strength based on the minimum section dropped sharply as the ration D/W was increased from zero to about 0.25. The plain specimens showed quite a pronounced decrease in fatigue strength with increasing width. The holed specimens showed only slight and rather inconclusive evidence of this size effect. The fatigue stress-concentration factor was higher for 75S-T than for 24S-T alloy. Evidence was found that a very small hole would not cause any reduction in fatigue strength."

Report presenting a collection of available test data on lateral control with full-span flaps. Internal-control effectiveness and hinge-moment data were obtained from two-dimensional, three-dimensional, and flight tests. Results regarding slot-lip and flap-trailing-edge ailerons, spoiler-type ailerons other than slot-lip ailerons, ailerons with retractable-type flaps, and application of data to specific airplane design are provided.

From Introduction: "In references 1, 2, and 3, flight measurements of the performance of a conventional, single-rotor helicopter equipped with its production fabric-covered main rotor blades are presented."

Report presenting a theoretical analysis of the characteristics of constant-chord partial-span control surfaces on thin triangular wings at supersonic speeds by use of methods based on the linearized theory for supersonic flow. Two cases were treated with the analysis. Results regarding lift coefficient, rolling-moment coefficient, and hinge-moment coefficient due to flap deflection, hinge-moment coefficient due to angle of attack, and the pitching-moment coefficient due to flap lift.

From Introduction: "In an incomprehensible medium, the mutual interference of a fuselage and wing of high-aspect ratio (to which lifting-line theory is applicable) has been treated by Lennertz, Wiselsberger, Pepper, and Multhopp in reference 1, 2, 3, and 4. It is the purpose of this note to treat the effect of on the aerodynamic loading of the mutual interference between a low-aspect-ratio pointed wing and a fuselage consisting of a slender body of revolution."

Report presenting an investigation to determine the effects of forward movements of transition on the section characteristics of a 12-percent-thick low-drag airfoil section with a 0.24-chord sealed plain aileron. Section lift and aileron section hinge-moment and seal-pressure characteristics were determined at a specific Reynolds number for aerodynamically smooth surfaces and with fixed transition at two different points.

Report presenting a new apparatus for varying the effective dihedral in flight by means of servo actuation of the ailerons in response to sideslip angle. Results regarding the characteristics of the effective-dihedral control in steady sideslips, in abrupt rudder kicks, and in lateral oscillations are provided.

Note presenting a theoretical investigation made of the motions and hydrodynamic loads experienced by V-bottom seaplanes during the course of a step-landing impact. In the analysis, the primary flow about the immersed portion of a keeled float or hull is considered to occur in transverse flow planes and the virtual-mass concept is applied to calculate the reaction of the water to the motion of the seaplane. The results are presented in the form of dimensionless curves which may be used to predict the behavior of V-bottom seaplanes at all instants during an impact as well as at the particular instants of maximum acceleration, maximum draft, and rebound.

Report presenting an examination of a machine developed to study the ignition delay of fuels by means of a rapid adiabatic compression. The essential features of the machine are that the compression is completed in about 0.006 second, provision is made for obtaining simultaneous records of piston motion and cylinder pressure, and the combustion cylinder is unlubricated. An extensive explanation of the components of the machine and its applicability to different scenarios are provided.

Report presenting theoretical results for the surface-velocity-potential functions, surface-pressure distributions, and stability derivatives for various motions at supersonic speeds of thin flat rectangular wings without dihedral. The investigation included steady and accelerating vertical and longitudinal motions and steady rolling, yawing, sideslipping, and pitching for Mach numbers are provided.

Note presenting an analysis based on simple geometry of the effect of thrust-axis inclination on propeller disk loading. Calculations are in excellent agreement with available flight measurements, so that the analysis is indicated to be adequate for predicting the primary effects of inclination. Because of the possible large effects of wing and fuselage interference, flow angles at the propeller should be determined by survey for most accurate results.

Report presenting simplified expressions for the neutral-oscillatory-stability boundary in order to obtain the boundary in the analysis essential for each airplane.

Report presenting a general method of analysis developed for the two-dimensional, steady, compressible flow through mixed-flow compressors in which the center line of the passage generates a right circular cone about the axis of the compressor. The two-dimensional, radial-discharge compressor is a special case in which the cone angle is equal to 180 degrees. The general analysis also applies to inward-flow turbines.

Note presenting an improved photoelastic method that has been developed for determining stress concentrations which occur in nonisotropic materials under load. Drucker's method has been extended by means of an additional oblique photograph, and simpler equations for relating fringe order to principal stresses were obtained. The conclusion indicates that the improved oblique method of photoelastic analysis yields reasonably accurate results over regions of the photoelastic model which are not subjected to excessive stress concentrations.

"The effects of outdoor weathering for 2 years and of an accelerated weathering test on the weight, dimensional stability, and flexural properties of selected reinforced plastics were investigated. The results of all tests, both in this report and the previous report (NACA TN No. 1240), indicate that none of the laboratory aging tests correlated with outdoor weathering with respect to all properties and all materials" (p. 1).