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 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 presenting porpoising tests of three rudimentary models composed of two V-bottom planing surfaces in tandem and fitted with a tail plane. The upper and lower branches of the upper trim limit of stability were determined for three angles of dead rise and two depths of step.

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.

Report presenting values of the lateral-stability derivative, the rate of change of yawing-moment coefficient with yawing angular velocity, contributed by the wing, the fuselage, and the vertical tail, which have been determined for a midwing airplane model by the free-oscillation method.

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 an investigation to determine the effects of wing loading and altitude on lateral stability and control in the free-flight tunnel. The results of flight tests of the model were correlated with calculated stability boundaries, and an effort was made to determine for each loading condition the airplane configuration that gave the best flight characteristics. Results regarding the lateral stability, lateral control, and general flight behavior 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.

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.

"This report presents the results of systematic model experiments on the hydrodynamic characteristics of flying boats, aimed primarily at developing a comprehensive view of the factors influencing porpoising and of their relative importance. The experiments 'radiated' from a given reference ship; they embrace changes, over reasonably wide ranges, in the value of each of a number of variables, treated independently. The experimental results are summarized in a series of 25 figures, each of which gives the complete data for all the modifications of one variable" (p. 1).

Report presenting testing made with simplified models of two types of hulls that differ considerably from conventional types. Both have a single main planing surface that is combined with after-planing surfaces placed directly below the aerodynamic tail surfaces. Results regarding an investigation of twin planing tails, a single-planing tail, and potentialities indicated by tests are provided.

Report presenting results of mechanical tests of macerated phenolic molding material. The following tests were performed: static tension, compression, torsion, and flexure tests; long-time creep tests at different stresses, tests for time to fracture under long-continued constant load; Izod and Charpy impact tests; bending fatigue tests at different ranges of stress; rotating-beam fatigue tests at different speeds of testing; rotating beam fatigue tests of notched specimens; and torsion fatigue tests.

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 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.

Report presenting a summary of published information on braking friction coefficients. Analysis indicates that the magnitude of the friction coefficient available will affect the technique required for obtaining the shortest ground run only under extreme conditions.

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.

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.

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."

"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).

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.

Report presenting tests conducted with an air-cooled cylinder on two fuels rated at approximately 100-octane number by the C.F.R. aviation method with and without a 40-percent addition of an aromatic mixture. The aromatic mixture consisted of 50 percent toluene, 37.5 percent xylene, and 12.5 percent benzene. Results regarding engine performance and engine temperature are provided.

Report presenting the results of nearly 200 tests made on the strength of shear webs of 24S-T aluminum alloy, with and without lightening holes. The tests were made in a jig of the single-specimen type, in which the specimen is free to collapse completely without developing diagonal tension. Results regarding the strength of the shear webs, stiffness of shear webs, and permanent-set tests are provided.

"The calculation of the stresses around cut-outs is discussed on the basis of a simplified application of the shear-lag theory previously published. Experimental stringer strains were measured around a systematic series of cut-outs. The test results indicate that the proposed method of calculating the stringer stresses is acceptable as a basis for stress analysis" (p. 1).

"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).