"This report presents results of a research and engineering program performed during the first half of 1950 that resulted in an acoustical treatment for the 8- by 6-foot supersonic wind tunnel at the Lewis Flight Propulsion Laboratory" (p. 1).

From Introduction: "The results of one phase of this investigation, presented in reference 1, have indicated that hull drag can be reduced without causing large changes in aerodynamic stability and hydrodynamic performance by the use of high length-beam ratios. Another phase of the investigation, reference 2, indicated that hulls of the deep-step planning-tail type have much lower air drag than the conventional type of hull and about the same aerodynamic stability; tank tests, reference 3, have indicated that this type of hull also has hydrodynamic performance equal to and in some respects superior to the conventional type of hull. Unpublished tank tests have indicated that the hull models presented in the present paper (with the possible exception of the forebody alone for which data are not available) will have acceptable hydrodynamic performance."

From Introduction: "A method for the design of three-dimensional nozzles based on axi-symmetric flow is presented in this paper. The design method presented in this paper is general; however, as an illustrative example of the design of a Mach number 10 nozzle with square test section is included."

Report presenting an investigation of the aerodynamic characteristics of a four-blade rigid model propeller in the full-scale tunnel for a range of angles of attack, blade angles, and advance ratio. It included a preliminary explanation of vertical descent and a comparison with theory. Results regarding the static thrust and forward flight are provided.

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

From Introduction: "The servo system considered in this report is in the latter category, due mainly to the fact its amplifier tends to saturate. An investigation of the longitudinal dynamic response of the stabilized airplane was made and the results were reported in reference 1. In this investigation it was found that when restricted to linear methods of analysis the performance of the autopilot-aircraft combination could be predicted for only the small range of operation where the elements of the autopilot operated within their linear range."

Note presenting an investigation of the inviscid flow in the region of the leading edge of curved airfoils with attached shock waves. Tables and charts are presented for determining the surface-pressure gradient and the shock-wave curvature in supersonic flow of an ideal diatomic gas. An approximate procedure for determining the flow field a short distance downstream of the leading edge is also presented.

From Introduction: "Many investigations have been made in the Langley 20-foot free-spinning tunnel in which the natures of airplane spins and recoveries have been determined experimentally with dynamically scaled-down models. The results of some of these investigations are presented in references 1 to 5."

Report presenting a theoretical treatment of absorption problems that considers the following cases: radiation is normal to an absorber with plane parallel surfaces, radiations are of several polyenergetic types, induced radioactive isotopes decay to stable atoms in multistep decay processes, and radiations from the absorber affect the time-dependency of the source activity. Radiation from intermediate isotopes can become more dangerous than the original activity, so the entire range of radiations must be accounted for.

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.

"An analysis shows that the scattering of unpolarized plane light waves which penetrate turbulent, transparent gases provides a measure of the average integral scale and intensity of the turbulent density fluctuations. The analysis is based upon the scattering coefficient deduced by Booker and Gordon and, thus, assumes isotropic fluctuations having an exponentially decaying (Markoffian) correlation function. Photometric data taken through turbulent boundary layers in air are found to conform functionally with the analytical prediction" (p. 1).

Report presenting a study of the application of Newton's modification of the Wiener filter theory to optimize a beam-rider guidance system operating in the presence of glint noise.

Report presenting a method to obtain a relatively quick approximate determination of the detailed subsonic flow of a nonviscous fluid past arbitrary turbomachine blades. The method is illustrated with examples of compressible flow in a turbine cascade and in a centrifugal compressor.

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.

Note presenting a solution obtained for the complete tunnel-interference flow for a lifting vortex in a two-dimensional slotted tunnel. Curves are presented for the longitudinal distribution of tunnel-induced downwash angle for various values of boundary openness parameter and various heights of the vortex above the tunnel center line.

Report presenting a derivation for a series of thin sweptback tapered wings with streamwise tips and supersonic leading and trailing edges. The results of the analysis are presented as a series of design charts. Results regarding formulas and computations for several derivatives, chordwise center-of-pressure location, and extensions of the results by the use of reversibility theorems are provided.

Report presenting the use of the shock-expansion method for the calculation of the pressure distribution on cylindrical wings in supersonic flow as extended to tapered wings made up of single-curved surfaces. The method applies in regions of the wing where the component of velocity normal to the surface rulings is supersonic and the flow is not influenced by the presence of the root or tip.

Report presenting charts for estimating the effects of variations in short-period stability characteristics of a rigid airplane on its root-mean-square vertical-acceleration and pitch-angle response to continuous atmospheric turbulence. A comparison of the root-mean-square vertical-acceleration response of an airplane free to be disturbed in vertical and pitching motion with that of an airplane free to be disturbed only in vertical motion indicates that the responses are similar for a nearly critically damped airplane.

A simple and practical method for evaluating the onset of permanent buckling in plates in the presence of combined thermal and compressive load stresses is outlined. A particular application of the method shows reasonable agreement with tests of 17-7 PH stainless-steel square tubes. The results indicate that the compressive load stress which the plate can support at the onset of permanent buckling is substantially reduced as the temperature difference of the plate and adjoining members increases.

Report presenting a critical comparison between experimental and theoretical results for the aerodynamic characteristics of wings at supersonic flight speeds. The lift, pitching moment, and drag characteristics of several families of wings of varying plan form and section in the wind tunnel and compared with values predicted by the three-dimensional linear theory.

"Three multicylinder cloud meters, fundamentally similar but differing in important details, were compared in use at the Mount Washington Observatory. Determinations of liquid water content were found to agree within the limits of the probable error, but the two instruments designed by the National Advisory Committee for Aeronautics indicated larger drop sizes than did the Observatory's instrument, apparently because of spurious ice catch on the rather rough surface of the larger cylinders. Comparisons of drop-size distribution were largely indeterminate" (p. 1).

Note presenting the equations for development of the compressible laminar boundary layer over a yawed infinite cylinder. The results indicate that the effect of yaw on the heat-transfer coefficient at the stagnation line depends markedly on the free-stream Mach number.

"The condensation pressure of air was determined over the range of temperature from 60 to 85 K. The experimental results were slightly higher than the calculated values based on the ideal solution law. Heat of vaporization of oxygen was determined at four temperatures ranging from about 68 to 91 K and of nitrogen similarly at four temperatures ranging from 62 to 78 K" (p. 1).

Note presenting an evaluation of the existing theories of linearized tire motion and wheel shimmy. A series of systematic approximations to the summary theory is developed for the treatment of problems too simple to merit the use of the complete summary theory. Procedures are discussed for applying the summary theory and its systematic approximations to the shimmy of more complex landing-gear structures than have previously been considered.