Report discussing testing on 22 inch-diameter pulse-jet engines to determine the effect on performance of a change in combustion-air temperature from approximately 80 degrees to 130 degrees. The effects on jet thrust, combustion-air flow, and engine thrust are described.

Report presenting flight tests of a three-blade thin Clark Y propeller operating at a fixed blade angle of approximately 46.8 degrees at 0.75 radius, at an advance-diameter ratio of 2.37, and at true airplane speeds of approximately 300 and 450 miles per hour. Comparisons of the results at the two different speeds indicated losses in propeller efficiency from 11 to 18 percent at high speed. Report is incomplete.

Report describes the installation of six-cylinder blocks from two in-line aircraft engines on CUE crankcases, which permits the separate operation of any cylinder as part of a single-cylinder test engine. Using multicylinder-engine blocks for single-cylinder tests is advantageous because there is greater availability of standard engine parts and there is less temperature gradient. Modifications of the crankcase, camshaft-drive mechanism, and operation of the cylinder are described.

Report presenting an analysis of records of more than 134,000 flying hours, which have been received and evaluated in order to bring the V-G recorder data up to date. The analysis of the records is contained in the report. Results indicate that the maximum effective gust velocities for both the land transport airplanes and the flying boats have approached values of 40 feet per second.

Availability data obtained on SNB-1 trainer-class airplanes were analyzed and results presented as flight envelopes which predict occurrences of large values of air speed and acceleration. Comparison is made with SNJ-4 trainer-class airplane data analyzed by the same method. It is concluded that flight envelopes are satisfactory; that the two types show large differences in flight loads and speeds experience; and that SNB-1 will seldom, if ever, exceed design limit load factor and restricted speed, which SNJ-4 can be expected to exceed design-limit load factor and restricted speed in a very small number of flight hours.

Report presenting a discussion of some of the parameters that enter into the equation of the path of a missile which is pursuing its target. The missile is assumed to be guided by a target seeker that might be employed in any one of several ways. Results regarding the normal-pursuit navigation, constant navigation, proportional navigation, line-of-sight navigation, and effect of angle of attack and sideslip are provided.

Report discussing the cooling characteristics of a modified 14-cylinder double-row radial air-cooled engine installed in a four-engine airplane at a pressure altitude of 7000 feet. Testing of the variable charge-air flow, variable cooling-air pressure drop, and variable fuel-air ratio was conducted. The cooling equation, temperature-limited performance, maximum engine temperatures, and other information predicted by calculations is described.

Report presenting a survey of aircraft heat exchangers in three parts: design, selection, and installation. Appendices give the physical properties of air, properties of standard atmosphere as defined by the Navy, Army, and NACA, and an impact-pressure chart.

From Summary: "An investigation was carried out in the NACA low-turbulence tunnel to develop low-drag airfoil sections suitable for admitting air at the leading edge. A thickness distribution having the desired type of pressure distribution was found from tests of a flexible model. Other airfoil shapes were derived from this original shape by varying the thickness, the camper, the leading-edge radius, and the size of the leading-edge opening. Data are presented giving the characteristics of the airfoil shapes in the range of lift coefficients for high-speed and cruising flight."

Report presenting an analysis of data for turbulent boundary layers along wings and bodies of various shapes in order to determine the fundamental variables that control the development of turbulent boundary layers. Results indicate that the type of velocity distribution in the boundary layer could be expressed in terms of a single parameter.