Report presenting testing at two engine speeds on six representative fuels rated at 100-octane number by the C.F.R. aviation method. Blends of the fuels with benzene, toluene, xylene, and isopropyl comprise nine other fuels, leading to testing on 15 fuels. Results regarding the tests at 2000 rpm and 250 degrees Fahrenheit inlet-air temperature, at 3100 rpm and 250 degrees Fahrenheit inlet-air temperature, 2000 rpm and 150 degrees Fahrenheit inlet-air temperature, and 3100 rpm and 150 degrees Fahrenheit inlet-air temperature, effect of speed on knock rating, effect of inlet-air temperature on knock rating, and effect of spark advance on knock rating are provided.

Report presenting tests of 10-foot diameter, single- and dual-rotating tractor propellers with two to eight blades conducted in the 20-foot propeller-research tunnel. The blades were 50 percent wider than those used in previous investigations. Results regarding the effect of dual rotation and effect of solidity are provided.

Report presenting a propeller tested to determine the aerodynamic properties. The propeller was designed for operation on a small target airplane capable of flying at about 200 miles per hour at 1600 feet altitude with a 175-horsepower engine. Results regarding aerodynamic tests and functional tests are provided.

Two airfoil plans were used for propeller blades. One is modified Clark Y section designed for structural reliability and the second an NACA 16 airfoil section designed to produce minimum aerodynamic losses. At low air speeds, the propeller designed for aerodynamic effects showed a gain of from 1.5 to 4.0 percent in propulsive efficiency over the conventional type depending on the pitch. Because of the numerous variables involved, the effect of each one on the aerodynamic characteristics of the propellers could not be isolated.

Report presenting tests of 10-foot-diameter, single- and dual-rotating pusher propellers with three to eight blades that were conducted in the 20-foot propeller research tunnel as a continuation of previous investigations of tractor propellers. The propellers were mounted at the rear end of a streamline body in spinners that covered the hubs and part of the shanks. The effects as compared to previous testing differed only in degree of effect size.

Results are presented of tests of two specimens tested to study the effect of normal pressure on the critical compressive stress for thin curved sheets. These specimens are designated by their respective rib spacings of 10 inches and 30 inches. The relationship between compressive stress and normal pressure at which buckles disappeared is independent of whether the buckles were made to disappear by increase of normal pressure or decrease of compressive stress. (author).

Report presenting testing of dynamic models that has been helpful in the determination of the longitudinal stability characteristics on the water of a number of specific flying boats. Results regarding the constant-speed tests, accelerated runs, effect of variations in moment of inertia, effect of variations in mass moving vertically, effect of variations of depth of step, and effect of variations of gross load coefficient are provided.

Report presenting the results of comparative cooling tests run on two Wright C9GC (G-200) cylinders, one with the original steel fins and one with 1-inch spiral copper fins brazed on the barrel. Calculations were also performed using copper and aluminum fins with the same weight as the original steel fins, which showed positive results. Results regarding cylinder-temperature correlation, piston-temperature correlation, and comparative performance are also provided.