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 discusses the results of a study "of the requirements for the attainment of a straight-line trajectory for a preset guided missile in the presence of wind or target motion" (from Summary). Information about the straight-line trajectory, position of the launching airplane, straight-line collision course, and arrangement of the autopilot in the missile is provided. Recommendations are also made about the creation of a bombsight mounting for the pilot of the launching airplane in order to attain the desired straight-line collision course.

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.

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 testing performed to determine the fatigue strength of various types of riveted and spot-welded joints in the following aluminum alloys: Alclad 24S-T, 24S-RT, 758-T, 24S-T81, and 24S-T86. Details of the experiment, tensile properties, and information about failure are provided.

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.

Report presenting several methods of computing bending moments in helicopter rotor blades in the plane of flapping, and the results of a numerical example analyzed by four different methods are compared. The effect of computed bending moments of the tip-loss correction introduced by Wheatley is also considered.

Report discusses the differences between the mean tangential velocity of the air leaving the blade tips of a centrifugal supercharger calculated by the conventional turbine equation and by an equation that uses the isentropic increase in total enthalpy. The velocities are compared to experimental values observed with three diffusers.

"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).

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 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.

"A comparison has been made in flight of the antiknock characteristics of 33-R fuel with that of 28-R and a triptane blend. The knock-limited performance of the three fuels - 33-R, a blend of 80 percent 28-R plus 20 percent triptane (leaded to 4.5 ml TEL/gal), and 28-R - was investigated in two modified 14-cylinder double-row radial air-cooled engines. Tests were conducted on the engines as installed in the left inboard nacelle of an airplane. A carburetor-air temperature of approximately 85 deg F was maintained" (p. 1).

"As part of an investigation of the cooling characteristics of liquid-cooled engines, tests were conducted with an electrically heated single-tube heat exchanger to determine the heat-transfer characteristics of AN-E-2 ethylene glycol and other ethylene glycol-water mixtures. Similar tests were conducted with water and commercial butanol (n-butyl alcohol) for check purposes. The results of tests conducted at an approximately constant liquid-flow rate of 0.67 pound per second (Reynolds number, 14,500 to 112,500) indicate that at an average liquid temperature 200 degrees f, the heat-transfer coefficients obtained using water, nominal (by volume) 30 percent-70 percent and 70 percent-30 percent glycol-water mixtures are approximately 3.8, 2.8, and 1.4 times higher, respectively, than the heat-transfer coefficients obtained using an-e-2 ethylene glycol.

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.

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 an investigation to determine the suitability and precision of a modified, routine-model, infrared spectrophotometer for analyzing binary and ternary mixtures of aircraft-fuel components. Analyses by means of infrared measurements are described for the following hydrocarbon mixtures: 12 known mixtures of 2,2,3-trimethylbutane (triptane) and cyclohexane, 4 known mixtures of triptane and benzene, and 4 known mixtures of triptane, cyclohexane, and benzene.

Report presenting a summary of a series of reports regarding heat exchangers, and in particular, the design of exhaust gas and air heat exchangers. The four parts included are a summary of heat transfer equations, single pass heat exchangers, heater performance in flight, and appendicies with additional aerodynamic information.

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 presenting an investigation by lifting-surface theory of a thin elliptic wing of aspect ratio 6 in a steady roll by means of the electromagnetic-analogy method. The results obtained by lifting-surface theory indicate that the damping in roll for a wing of aspect ratio of 6 is 13 percent less than that give by lifting-line theory and 5 percent less than that given by lifting-line theory with the edge-velocity correction derived by Robert T. Jones applied. Simple practical methods of applying the results of the investigation to wings of other plan forms are given.

Report discussing tests of a model of the XP-55 to determine which modifications would prevent trim at large positive and negative angles of attack. The model was found to not trim at flat attitudes if the large wing tips with an extension of the wing-tip trimmers and a large elevator are installed on the airplane.

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 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 presenting a generalized drag curve providing an estimate for the drag rise due to compressibility as obtained from an analysis of wind-tunnel data of several airfoils, fuselages, nacelles, and windshields at speeds up to and above the wing critical speed. Results regarding drag characteristics and terminal-velocity calculation are provided.

Report discussing spin tests performed on a scale model of the Curtiss-Wright XP-55 airplane. A large elevator with increased deflections and large wing tips with extensions were installed to improve the longitudinal-trim characteristics. Information about the spins, attitude after rotation, and recommended technique for spin recovery is provided.