Report presenting a scale powered model of the Douglas XSB2D-1 airplane tested with a four-blade dual-rotation propeller and a four-blade single-rotation propeller. To make the results more directly comparable, no other changes were made to the model. Results regarding longitudinal stability, directional characteristics, and lateral stability are provided.

Compression tests were conducted on 247 panels with Z-section stiffeners and 304 panels with hat-section stiffeners. Specimens were constructed from artificially aged Alclad 24S aluminum alloy with minimum guaranteed yield strengths of 64 and 57 ksi for stiffeners and sheet materials, respectively. Height, thickness, and spacing of stiffeners, sheet thickness, and length of specimens were varied systematically to show effects of changes in these dimensions on panel strength. Results show average stresses at buckling load and maximum load.

"A correlation of what are believed to be the most reliable data available on duct components of aircraft power-plant installations is presented. The information is given in a convenient form and is offered as an aid in designing duct systems and, subject to certain qualifications, as a guide in estimating their performance. The design and performance data include those for straight ducts; simple bends of square, circular, and elliptical cross sections; compound bends; diverging and converging bends; vaned bends; diffusers; branch ducts; internal inlets; and an angular placement of heat exchangers" (p. 1).

From Summary: "A method is presented for the experimental determination of the effective length of a column for which the end conditions are unknown by establishing the points of zero curvature from readings of strain gages distributed along the length of the column. Tests of four columns of different cross sections indicated that the proposed method gives satisfactory results even when there is considerable scatter in the strain-gage readings."

Report presenting the determination of the effects of static margin and rotational damping in pitch on the longitudinal stability characteristics of an airplane by flight tests of a model in the NACA free-flight tunnel. The rotational damping in pitch was varied over a wide range by using horizontal tails that varied in area from 0 to 24 percent of the wing area. Results regarding the effect of variation of static margin and effect of variation of rotational damping are provided.

Report presenting flight measurements made on a modern pursuit airplane to determine the approximate magnitude of the horizontal tail loads in accelerated flight. Pressures at a few points were used as an index of the tail loads by correlating these pressures with complete pressure-distribution data obtained in the NACA full-scale tunnel.

Report presenting the results of general tests on the hydrodynamic characteristics of four related flying-boat hull models of differing length-beam ratio. Five different characteristics were investigated in an effort to gain perspective and determine which characteristics were most important: resistance, porpoising, main forebody spray blister, bow spray in rough water, and yawing stability near hump speeds.

Report presenting an investigation which found that the absolute viscosity of exhaust gases from a gasoline engine was measured at a range of temperatures and compositions. Results regarding preliminary runs, calibration runs at room temperature, check runs at medium temperatures, and exhaust gas measurements are provided.

From Summary: "A theoretical investigation was made of the behavior of a cantilever beam in rotational motion about a transverse axis through the root determining the stresses, the deflections, and the accelerations that occur in the beam as a result of the arrest of motion. The equations for bending and shear stress reveal that, at a given percentage of the distance from root to tip and at a given trip velocity, the bending stresses for a particular mode are independent of the length of the beam and the shear stresses vary inversely with the length. When examined with respect to a given angular velocity instead of a given tip velocity, the equations reveal that the bending stress is proportional to the length of the beam whereas the shear stress is independent of the length."

From Summary: "Column and plate compressive strengths of 17S-T aluminum-alloy sheet were determined both within and beyond the elastic range from tests of thin-strip columns and from local-instability tests of formed Z- and channel-section columns. These tests are part of an extensive research investigation to provide data on the structural strengths of various aircraft materials. Results are presented in the form of curves and charts that may be used in the design and analysis of aircraft structures."

"Column and plate compressive strengths of 24S-T aluminum-alloy sheet were determined both within and beyond the elastic range from tests of thin-strip columns and from local-instability tests of formed Z-end channel-section columns. These tests are the first of a series in an extensive research investigation to provide data on the structural strength of various aircraft materials. The results, which are presented in the form of curves and charts that may be used in the design and analysis of aircraft structures, supersede preliminary results published previously" (p. 1).

Report presenting an investigation of a full-scale horizontal tail surface to determine the elevator-fabric deflection at high speeds and the aerodynamic effects of the fabric deflection. Two fabric-covered elevators differing only in rib spacing and a solid wooden elevator were tested. Results regarding fabric deflection and aerodynamic characteristics are provided.

Report presenting an investigation to determine the effect of varying the carburetor throttle settings on the flow characteristics at the outlet of the supercharger inlet elbow. Air flow tests were made at several carburetor throttle settings ranging from open to closed. Results regarding distortion and turbulence are provided.

Report presenting an investigation of the use of ethylene dibromide to leaded fuel in order to prevent lead deposits within the cylinder. It is meant to react with lead to form volatile compounds that will be scavenged with exhaust gases. Results regarding the lead deposits, knock-limited effective pressures, performance, and temperatures are provided.

Report presenting a concept of a simplified vortex system of a rotor wake in order to obtain a formula for the normal component of induced velocity along the fore-and-aft diameter of the rotor disk of a helicopter rotors.

From Summary: "A general representation of fan and turbine arrangements on a single classification chart is presented which is made possible by a particular definition of the stage of an axial-flow fan or turbine. Several unconventional fan and turbine arrangements are indicated and the applications of these arrangements are discussed."

Report presenting an investigation to determine the nature and extent of the reversal of flow, which occurs at the inlet of centrifugal superchargers over a considerable portion of the operating range. Results regarding lampback patterns, tuft studies, backflow surveys, and effect of impeller tip speed on backflow are provided.

Report discusses graphs of constants meant to be used with a knowledge of maximum total head loss, static-pressure decrement, and integral of total-head loss across the wake of an airfoil to determine the section profile-drag coefficient. Computations of free-stream Mach numbers for certain assumed types of total-pressure distribution in the wake are provided to compare theoretical drag coefficients as determined by other equations based on the momentum method. While some disagreements are found, the more rapid technique is usable for wide variations in wake shapes for a Mach number range of 0.5 to 1.0.

"Blunt-nose and elliptical-nose overhangs of 0.35 and 0.50 flap chord and a plain overhang on a flap having a chord of 0.20 airfoil chord have been tested in two-dimensional flow on an NACA 0009 airfoil. The results of the tests are presented as aerodynamic section characteristics for several flap deflections with the gap at the flap nose sealed or unsealed. Tests were made also to determine the effectiveness of a tab of 0.20 flap chord on the plain sealed flap and on a sealed flap having an elliptical overhang of 0.35 flap chord" (p. 1).

"The gross weight, beam, and afterbody length of 12 contemporary flying boats and amphibians with pointed afterbodies are tabulated and correlated. For most of the hulls considered, the afterbody length-beam ratios are shown to be directly proportion to the gross-load coefficients" (p. 1).

Report presenting the knock-limited performance of nine fuels comprising isolated members of four classes of hydrocarbons in the form of three-dimensional plots of fuel-air ratio, compression temperature, and compression-air density.

Report presenting an investigation for the determination of the behavior of ceramic bodies in tension at elevated temperatures for the purpose of determining data for the design of ceramic blades for gas turbines. Observations were made of six special ceramic bodies in order to determine their tensile strength and creep during prolonged loading under a range of stresses and temperatures.

"Convenient charts are presented for computing the thrust, fuel consumption, and other performance values of a turbojet system. These charts take into account the effects of ram pressure, compressor pressure ratio, ratio of combustion-chamber-outlet temperature to atmospheric temperature, compressor efficiency, turbine efficiency, combustion efficiency, discharge-nozzle coefficient, losses in total pressure in the inlet to the jet-propulsion unit and in the combustion chamber, and variation in specific heats with temperature. The principal performance charts show clearly the effects of the primary variables and correction charts provide the effects of the secondary variables" (p. 1).