Report discusses an investigation into the tensile strength of cast-iron piston rings, NACA microtensile specimens, and bar specimens. Photographs showing the relation between graphite-flake size and tensile strength and radiographs showing the shrinkage cavities in the piston rings are provided. Piston rings tend to be one of the first parts of an aircraft engine to fail, so discovering the ideal material composition and foundry treatment is very important.

Report presenting tests to verify and extend ultraviolet spectroscopic techniques for applications to the analysis of aviation fuels for their aromatic constituents. Results regarding photographic absorption spectra, spectrophotometric absorption spectra, and spectrophotometric analyses are provided.

Report presenting an electric torquemeter that was used to measure the power of an Allison V-1710-93 engine installed in a Bell P-63A-1 airplane. Results of maximum-available-power tests in flight at a range of density altitudes showed good agreement between the measured maximum power output and the maximum power shown on the engine manufacturer's calibration chart.

Report discusses the results of an investigation to determine the effect of extreme changes in mass distribution along each of the three body axes. The effects of individual inertia moment parameters upon spin and recovery characteristics were examined.

Report explores the periodic forces that helicopter rotors are subjected to, both horizontal and vertical, and several configurations and material combinations of blades are described. The vibrations and exciting forces are demonstrated through calculations and explored with combinations of one, two, three, and four blades.

From Introduction: "In the present paper a numerical procedure for the stress analysis of flat-sheet and stringer combinations of arbitrary construction and loading is presented and applied to axially loaded panels and to the reinforced covers of box beams."

Report presenting flight tests of an all-movable horizontal tail installed on a Curtiss XP-42 airplane due to its possible advantages as a longitudinal control at high Mach numbers. The elevator control was found to be unsatisfactory with the control arrangements tested.

"Strength tests and strain measurements were made of 19 long shear panels with rectangular inspection cut-outs; that is, cut-outs obtained by removing the sheet between two adjacent stringers without cutting any stringer. The test results indicated that the stress concentration existing at low stresses tends to disappear at very high stresses and that the assumption of uniform stress distribution leads to a satisfactory correlation of the test results. Stiffening of the sheet bay containing the cut-out was found to have practically no effect on the panel strength" (p. 1).

Results are presented of tests of two sets of 20 curved-sheet specimens to determine the effect of normal pressure on the critical compressive and shear stress of curved sheets. It was found that normal pressure raised the critical compressive and shear stress of curved sheets except when outward bulging occurred in compression, in which case the critical stress was lowered by normal pressure. (author).

Report presenting statistical gust-frequency data used to determine the effect of overloading an airplane on the frequency of occurrence of gust loads that stress the airplane to or above its design applied bending moment. The analysis was made for three transport-type airplanes operating at cruising power with overloads varying from 0 to 50 percent of the design gross weight. The probability of structural failure was found to increase rapidly with overload.

Report discusses the results of an investigation of an NACA 0009 airfoil with a 40-percent-chord flap with medium and large aerodynamic balances of elliptical and blunt nose shapes and a plain overhang. The results are presented as aerodynamic section characteristics for several flap deflections with the gap at the flap nose sealed and unsealed.

Report presenting tests made on an XCG-7 all-wood glider on a PT-19A training airplane with a tubular metal fuselage and wooden wings by passing electrical surges simulating lightning discharges through the aircraft and measuring the voltage induced between various points which might be touched by an occupant. While certain recommendations for electrical protection are provided, the personnel in a metal fuselage aircraft are reasonably well protected from induced voltage shock without other protection.