"The method of recording the direction of flows on the basis of the hydrodynamic zero-point measurement has now reached a certain limit, in spite of the good results achieved. While the available flow-direction devices are accurate enough for many purposes, they are all insufficient for perfectly exact prediction of the flow direction. The next problem will be to achieve a point-by point flow-direction record, whereby the test procedure must be simplified, accelerated, and the degree of accuracy of the test data improved" (p. 1).

This report deals with the flow past an infinite screen of thin airfoil (two-dimensional problem). The vortex distribution across the profile is established with appropriate expansion in series and the velocity distribution lift, moment, and profile shape deduced. Inversely, the distribution is deduced from the vorticity. The method is the extension of the Birnbaum-Glauert method for the isolated wing.

"The present report deals with the development of a thermometer for recording stagnation temperature in compressible mediums in turbulent flow within 1 to 2 percent error of the adiabatic temperature in the stagnation point, depending upon the speed. This was achieved by placing the junction of a thermocouple near the stagnation point of an aerodynamically beneficial body, special care being taken to assure an uninterrupted supply of fresh compressed air on the junction together with the use of metals of low thermal conductivity, thus keeping heat-transfer and heat-dissipation losses to a minimum. In other experiments the use of the plate thermometer was proved unsuitable for practical measurements by reason of its profound influence in the reading by the Reynolds number and by the direction of flow" (p. 1).

This report deals with a reciprocal comparison of an automatic pressure control, an automatic rpm control, an automatic temperature control, and an automatic directional control. It shows the difference between the "faultproof" regulator and the actual regulator which is subject to faults, and develops this difference as far as possible in a parallel manner with regard to the control systems under consideration. Such as analysis affords, particularly in its extension to the faults of the actual regulator, a deep insight into the mechanism of the regulator process.

From Summary: "The present report deals with temperature measurements on cylinders of 0.2 to 3 millimeters diameter in longitudinal and transverse air flow at speeds of 100 to 300 meters per second. Within the explored test range, that is, the probable laminar boundary layer region, the temperature of the cylinders in axial flow is practically independent of the speed and in good agreement with Pohlhausen's theoretical values; Whereas, in transverse flow, cylinders of certain diameter manifest a close relationship with speed, the ratio of the temperature above the air of the body to the adiabatic stagnation temperature decreases with rising speed and then rises again from a Mach number of 0.6. The importance of this "specific temperature" of the body for heat-transfer studies at high speed is discussed."

"The stresses in circular frames of constant bending stiffnesses, as encountered in thin-wall shells, are investigated from the point of view of finite depth of sectional area of frame. The solution is carried out for four fundamental load conditions. The method is illustrated on a worked out example" (p. 1).

From earlier measurements and the mathematical examples, it can be gathered that the inertia of dynamic pressure arrays can be computed with sufficient accuracy and the proper size of tubing established, provided that certain requirements are made on the inertia. A new mathematical term, the pneumatic time constant, depends only on the dimensions of the tubing and of the indicator and enables the comparison of different dynamic pressure arrays.

"The present report describes a device for ascertaining the bending and buckling effect in stress measurements on shell structures accessible from one side only. Beginning with a discussion of the relationship between flexural strain and certain parameters, the respective errors of the test method for great or variable skin curvature within the test range are analyzed and illustrated by specimen example" (p. 1).

The speed of a two-dimensional flow potential flow past a smooth wall, which evinces a finite curvature jump at a certain point and approximates to two arcs in the surrounding area, has a vertical tangent of inflection in the critical point as a function of the arc length of the boundary curve. This report looks at a general theorem of the local character of the conformal function at the critical point as well as the case of the finite curvature jump.

"The long-time loading strength of a number of laminated synthetic resin plastics was ascertained and the effect of molding pressure and resin content determined. The best value was observed with a 30 to 40 percent resin content. The long-time loading strength also increases with increasing molding pressure up to 250 kg/cm(exp 2); a further rise in pressure affords no further substantial improvement" (p. 1)..

"The investigation was made for the purpose of ascertaining the notch sensitivity of flat strips of light alloy with cylindrical holes under initial tension stress, with special attention to the change in notch-effect factors with the number of load cycles. Then the studies were extended to similar flat strips with pin-loaded holes (tension lugs). This report deals with fatigue tests under initial tension load on flat test specimens of 3116.5 duralumin and AZM 3510.1 electron with plain unloaded and pin-loaded holes (tension lugs) of different forms" (p. 1).

Report presenting a solution for reducing the fatigue of the Diesel engine by permitting the preservation of its components and, at the same time, raising its specific horsepower to a par with that of carburetor engines, while maintaining for the Diesel engine its perogative of burning heavy fuel under optimum economical conditions. The feeding of Diesel engines by injection pumps actuated by engine compression achieves the required high speeds of injection readily and permits rigorous control of the combustible charge introduced into each cylinder and of the peak pressure in the resultant cycle.

The results from stress measurements in flight operation afford data for analyzing the frequency of appearance of certain parts of the static breaking strength during a specified number of operating hours. Appropriate frequency evaluations furnish data for the prediction of the required strength under repeated stress in the wing structures of aircraft of the different stress categories for the specified number of operating hours demanded during the life of a component.

"The interrelations established in an earlier report (NACA-TM-921) are used to study the best assumptions for hovering and horizontal flight. The effect of the twisted and tapered blade on the rotor efficiency is analyzed and the gliding coefficient at different stages (from autogyro to helicopter) of horizontal flight compared. To the extent that model or full-scale test data are available, they are included in the comparison" (p. 1).

"Formulas are obtained for computing the buckling load of rods eccentrically loaded at each end, the computation being extended in particular to the inelastic range. The test results are graphically presented on three sets of curves. Two of these, at least for the elastic range, are independent of the material tested. The third set, which is independent of the material, possesses greater clearness and is therefore used for comparing the test results with the theoretical" (p. 1).

"The spread of the separation of flow on three tapered wings insymmetrical and unsymmetrical flow was observed with silk tufts. By equal thickness and chord distribution the wings manifested a different form of lifting line. The principal result of the study was that the wings alone first disclosed complete breakdown of the flow at the tips, even the one with twist, but that after adding fuselage and engine nacelles, the twisted wing broke down completely first in the wing center" (p. 1).

"A number of factors are considered which influence the static and fatigue strength of materials under practical operating conditions as contrasted with the relations obtaining under conditions of the usual testing procedure. Such factors are interruptions in operation, periodically fluctuating stress limits and mean stresses with periodic succession of several groups and stress states, statistical changes and succession of stress limits and mean stresses, frictional corrosion at junctures, and notch effects" (p. 1).

From measurements in the free boundary layer of a plate the laws governing the velocity distribution and a new resistance law are derived which, by increasing Reynolds number Re(sub x) afford lower resistance values than the logarithmic law. The transverse velocities, the shearing stress, and the mixing path profiles were also defined.

Report presenting tables for computing various cases of beam columns in regards to their buckling properties. An explanation of the methods and modulus of buckling under column effect are provided.

Systematic experiments were undertaken with special reference to the effect of gross specific weight (specific weight inclusive of pores) and the moisture content of wood. It was found that the modules of elasticity of wood at room temperature and frozen at -8 degrees is practically the same. The effect of moisture on the compression strength of frozen wood was explored as well as the flexural and impact strength of frozen wood and frozen laminated wood.

The development of suitable thermometer shapes giving the amount of temperature rise if possible without calibration and affording ready repetition is predicated upon a fundamental elucidation of this heating on a number of elementary body forms. This report provides results of tests at subsonic and supersonic velocities.

This report shows that by applying both energy and impulse theorems the optimum throat dimension of the mixing nozzle and the best shape of intake can be predicted approximately in a relatively simple manner. The necessary length of the mixing nozzle follows from Prandtl's turbulent mixing theory. The calculations are carried out for the mixing of similar and dissimilar fluids.

"The present article deals with what is considered to be a simpler and more accurate method of determining, from the results of bench tests under approved rating conditions, the power at altitude of a supercharged aircraft engine, without application of correction formulas. The method of calculating the characteristics at altitude, of supercharged engines, based on the consumption of air, is a more satisfactory and accurate procedure, especially at low boost pressures" (p. 1).

This short analysis may be useful in determining the real tactical possibilities of "glider trains" and in adopting the course to be followed in possible studies of these questions. In this analysis most prominent are: (a) the power required for the train in level flight; (b) its speed; (c) climb; and (d) the type of airplane best suited for towing as well as design requirements for transport gliders.