Report presenting an investigation regarding the strengths of bonds between different chemical types of adhesives and adherends. Some of the topics explored include the theoretical aspects of adhesion and properties of adhesively bonded structures.

Report discussing an open box joined to a closed box subjected to torsional loading. A stiff bulkhead and a flexible bulkhead were tested at the discontinuity and the results were compared to a previously published theory. Stress distribution was found to not be sensitive to bulkhead stiffness when the stiffness is large, but the calculations became sensitive to errors in estimating when the stiffness was small.

Report presenting wind-tunnel testing in two-dimensional and three-dimensional flow to investigate the aerodynamic characteristics of spoilers on tail surfaces for low-speed flight. Test results indicated that spoilers on tail surfaces showed little possibility of replacing conventional control surfaces. Results regarding a flap alone, rear spoiler alone, forward spoiler alone, forward spoiler and flap, and a combination of forward and rear spoilers on upper and lower surfaces in both types of flow are provided.

Report discusses the results of testing on a linked differential flap system upon the effective-dihedral characteristics of an airplane scale model. The negative dihedral changes caused by power can be materially reduced or eliminated by use of a differential flap system. The static directional stability also increased with differential flap action.

Report presenting tests in a seal test chamber to determine the hinge moments contributed by the fabric seal in an internal-balance arrangement employing a thin-plate overhang. The tests were performed with various widths of fabric sealing various widths of flap-nose gap, with a horizontal, a vertical, and a circular type of wing structure forward of the balance, and with various heights of balance chamber. Results regarding seal-profile photographs, desired seal-moment characteristics, experimental seal-moment characteristics, effect of the balance configuration on the seal-moment characteristics, comparison of analytical and experimental seal-moment characteristics, computation of seal-moment characteristics by the approximate method, and application of the data are provided.

Report presenting the results of a theoretical analysis of the hinge-moment characteristics of various sealed-internal-balance arrangements for control surfaces. The results of the investigation indicated that the most nearly linear control-surface hinge-moment characteristics can probably be obtained from a flexible seal over a narrow gap, which is so installed that the motion of the seal is restricted to a region behind the point of attachment of the seal to the wing structure.

An experimental investigation is being conducted to determine the effect of varying the rivet diameter and pitch on the compressive strength of 24S-T aluminum-alloy panels with longitudinal Z-section stiffeners. The average stress at failing load for each rivet diameter, depth of countersink, and pitch of rivet is provided

Report presenting power-off tests made in the 6- by 6-foot test section of the stability tunnel to determine the variation of the static lateral stability characteristics with vertical-tail area, fuselage length, and wing dihedral. The results are presented as curves showing the variation of the static-lateral-stability slopes with angle of attack, and the rolling-moment, yawing-moment, and lateral-force coefficients with angle of yaw.

Report discuss the results of force tests, yaw-trim tests, and power-off tests to compare the stability and control characteristics of a powered airplane model in the erect and inverted flight attitudes. Due to the violent and uncontrollable maneuvers that sometimes occur after flight in the inverted attitude, more information was requested about stability and control characteristics in this position. Testing found that with the power on, a serious reduction in longitudinal and directional stability occurred in inverted flight.

Report presenting design charts for 24S-T aluminum-alloy flat compression panels with longitudinal Z-section stiffeners. It was found that maximum possible structural efficiency with these panels requires closer stiffener spacings than those now in common use.

Report discusses data obtained from measuring sideslip characteristics via the continuous-record method and the steady-record method. The situations in which each recording method is preferred are presented.

From Summary: "Directly comparable drag measurements have been made of an airfoil with a conventional rectangular plan form and an airfoil with a sweptback plan form mounted on freely falling bodies. Both airfoils had NACA 65-009 sections and were identical in span, frontal area, and chord perpendicular to the leading edge. The sweptback plan form incorporated a sweepback angle of 45 degrees. The data obtained have been used to establish the relation between the airfoil drag coefficients and the free-stream Mach number over a range of Mach numbers from 0.90 to 1.27. The results of the measurements indicate that the drag of the sweptback plan form is less than 0.3 that of the rectangular plan form at a Mach number of 1.00 and is less than 0.4 that at a Mach number of 1.20."

From Introduction: "The tests reported herein, conducted during the early part of 1945, were made to determine the inherent charge-air distribution characteristics of the engine-stage supercharger of the double-row radial engine."

Report on the NACA test-rig installation, measurements, instrumentation, test procedure, methods of calculation, and presentation of data for rating and testing centrifugal superchargers. Special precautions for certain portions of testing are also provided.

Report presenting testing to determine the stresses and bending moments required to break pieces 1 inch or less in length from the ends of cast-iron, keystone, compression piston rings. Strain gages were used to determine the stress pattern for various modes of vibration. The maximum-stress points of vibrating piston rings were at the antinodes or points of maximum deflection.

Report on the NACA recommended method for comparing the performance of centrifugal compressors. The most important indices of compressor performance are the adiabatic temperature rise ratio or adiabatic efficiency, the adiabatic shaft efficiency, and the pressure ratio, which incorporate many other parameters. Recommendations for reporting on compressor effectiveness and characteristics are provided.

A method has been developed for interpreting v-g records taken during the course of commercial transport operation. This method involves the utilization of fairly simple statistical procedures to obtain "flight envelopes," which predict that, on the average, in a stated number of flight hours, one value of airspeed will exceed the envelope, and one positive and one negative acceleration increment will exceed the envelope with equal probability of being experienced at any airspeed. Comparison with the actual data obtained from various airplanes and from various airlines indicates that these envelopes predict the occurrences of large values of acceleration and airspeed with a high degree of accuracy.

From Summary: "An analysis of available theory on seaplane impact and a proposed modification thereto are presented. In previous methods the overall momentum of the float and virtual mass has been assumed to remain constant during the impact but the present analysis shows that this assumption is rigorously correct only when the resultant velocity of the float is normal to the keel."

From Summary: "A V-type engine provided with a glass cylinder was used to study visually the lubrication characteristics of an aircraft-type piston. Photographs and data were obtained with the engine motored at engine speeds up to 1000 r.p.m. and constant cylinder-head pressures of 0 and 50 pounds per square inch. A study was made of the orientation of the piston under various operating conditions, which indicated that the piston was inclined with the crown nearest the major-thrust cylinder face throughout the greater part of the cycle. The piston moved laterally in the cylinder under the influence of piston side thrust."

"The laws of conservation of mass, momentum, and energy are applied to the compressible flow through a two-dimensional cascade of airfoils. A fundamental relation between the ultimate upstream and downstream flow angles, the inlet Mach number, and the pressure ratio across the cascade is derived. Comparison with the corresponding relation for incompressible flow shows large differences. The fundamental relation reveals two ranges of flow angles and inlet Mach numbers, for which no ideal pressure ratio exists" (p. 123).

Report presenting an investigation to develop methods and equipment for the measurement of operating stresses in aircraft-engine crankshafts and connecting rods. The results indicate that the measurement of stresses in connecting rods is feasible. Results regarding stresses in the crankshaft and stresses in the master connecting rod are provided.

Report presenting an analysis of the contact stresses in a damper installation of an aircraft engine that indicated that galling could be eliminated by increasing the diameters of damper pins and holes. Torsional-vibration pendulum dampers have been successful in minimizing vibrations at critical speeds in aircraft engines, but serious wearing problems are often encountered when using them. The damper used in this experiment did not suffer any type of damage after many hours of use.

"Air-consumption data from calibrations of two radial aircraft engines were analyzed to show the relation of engine air consumption to its primary influencing factors: intake-manifold pressure, exhaust back pressure, intake-manifold temperature, and engine speed. The analysis of the test data from these two engines led to the establishment of a relation of variables upon which the design of automatic metering controls can be based. The data obtained from one engine indicate that the air-consumption correlation obtained for this engine is accurate within 2 percent except under certain conditions that are well outside current engine-operation limits" (p. 1).

Report presenting charts relating helicopter aerodynamic design variables to performance in steady powered flight. The flight conditions covered are hovering, climb, and horizontal flight. The use of the charts is illustrated by numerical examples in order that computations can be made for particular problems.