Report presenting an investigation to determine which of two ceramic coatings, L-7C and A-417, developed by the National Bureau of Standards is more suitable as a protective coating for turbine blades in a turbojet engine. Four cast Vitallium turbine blades, two coated with each of the ceramics, were installed in a turbine wheel of a turbojet engine and subjected to accelerated cyclic life tests.

Report presenting an experimental investigation on a ramjet in the 20-inch supersonic tunnel at a Mach number of 1.92 to determine the effects of combustion on the performance of a basic normal-shock diffuser. Total-pressure recovery with and without combustion was evaluated as a function of outlet-inlet area ratio and fuel flow. A rapid decrease in peak total-pressure recovery was obtained with increasing outlet-inlet area ratio.

From Summary: "An investigation was conducted in the NACA Cleveland altitude wind tunnel to determine the operational characteristics of the Westinghouse 19B-2, 19B-8, and 19XB-l jet-propulsion engines. The 19B engine is one of the earliest experimental Westinghouse axial flow engines. The 19XB-1 engine is an experimental prototype of the Westinghouse 15 series, having a rated thrust of 1400 pounds. Improvements in performance and operational characteristics have resulted in the 19XB-2B engine with a rated thrust of 1600 pounds. The operational characteristics were determined over a range of simulated altitudes from 5000 to 30,000 feet for the 19B engines and from 5000 to 35000 feet for the 19XB-l engine at airspeed from 20 to 380 miles per hour."

"Gust-velocity measurements and air-borne-radar observations obtained during a transcontinental flight in July 1947 have been analyzed as part of a general investigation of the uses of air-borne radar. The analysis indicates that some reduction in turbulence and a consequent reduction in the risk of encountering the larger gust velocities may be obtained by avoiding portions of clouds giving a radar echo" (p. 1).

Memorandum describing a way in which the data of three previous reports can be used to compute the incompressible flow fields for cowling-spinner combinations and open-nose inlets for use in the design of propeller shanks and cuffs. The method consists of regarding the cowling surface as replaced by a ring vortex sheet whose strength at any point is equal to the local tangential velocity.

Pressure measurements were made during wind-tunnel tests of the McDonnell XP-85 parasite fighter. Static-pressure orifices were located over the fuselage nose, over the canopy, along the wing root, and along the upper and lower stabilizer roots. A total-pressure and static-pressure rake was located in the turbojet engine air-intake duct. It was installed at the station where the compressor face would be located. Pressure data were obtained for two airplane conditions, clean and with skyhook extended, through a range of angle of attack and a range of yaw.

From Summary: "The pressure drops through electrically heated Inconel tubes with length-diameter ratios of 29.25, 58.50, 87.75, and 117.00 have been measured at entrance Mach numbers from approximately 0.12 to the value at which choking occurred. The heat-input rate was varied from zero to the highest values allowable without damaging the tubes. Experimental data and a number of computed variables are presented in tabular form."

Report presenting a discussion of a number of the problems that most frequently arise with airfoils on helicopters. A reference list of published reports on airfoil section characteristics which are useful in regards to these helicopter problems is also included.

Report presenting an investigation with a ram-jet combustion chamber to determine the effect of fuel-air ratio and the inlet-air parameters of pressure, temperature, and velocity on combustion limit, combustion efficiency, and flame length.

Report presenting testing of a twin-scoop duct inlet that enclosed 37.2 percent of the forebody circumference at Mach numbers between 1.36 and 2.01. The approach to each scoop consisted of a ramp that deflected the flow to create an oblique shock wave in front of the duct entrance. Results regarding the inlet proportions, ramp angle, slots, and angle of incidence are provided.

Report presenting an investigation of turbine operating temperatures as affected by liquid cooling, especially if materials of high conductivity are used, at gas temperatures up to 1925 degrees Fahrenheit. Results regarding the statio heat-transfer rig and turbine rig are provided. The investigation showed that nonstrategic material such as aluminum alloy can be used in liquid-cooled turbine wheels at high gas temperatures.

Results of a wind-tunnel investigation at a Reynolds number of 6.8 x 10(exp 6) to determine the static longitudinal stability characteristics of a 42 degree sweptback wing and fuselage combination with a sweptback horizontal tail are provided. Included are the effects of vertical position of fuselage and tail with respect to wing for several combinations of high-lift and staff-control devices. Also included is the effect of a simulated ground.

Report presenting tank results for take-off tests with a powered dynamic model of a hypothetical jet-propelled high-speed airplane fitted with NACA hydro-skis and with flush turbojet intakes on the upper part of the fuselage near the nose. Some of the investigations included were the possibility of making take-offs without spray entering the intakes, the effect of turbojet air inflow on the tendency of spray to enter the intakes, and the effect of jet power on trim.

Report presenting an experimental investigation to determine the vibration phenomena that occur in turbine blades of a typical jet-propulsion engine during service operation; high-temperature strain gages were used to measure the turbine-blade vibrations. Results regarding modes of vibration, centrifugal stresses, and vibration of turbine blades during operation are provided.

Memorandum presenting the results of a wind-tunnel investigation of the low-speed characteristics of horizontal tails of aspect ratio 3 with unswept and swept-back plan forms. Two models were tested which had identical areas, aspect ratio, taper ratio, and airfoil section, differing only in the angle of sweepback and elevator area ratios. The major effect of sweepback was to increase the rate of change of hinge-moment coefficient with angle of attack, to reduce the rate of change with elevator deflection, and to reduce the elevator effectiveness.

Memorandum presenting measurements of gust and draft velocities within cumulus clouds at a certain army air field using an AT-6 airplane. The measurements were made to supplement the at a obtained with P-61C airplanes. The data are summarized in tables.

"An investigation of the XJ-41-V turbojet-engine compressor was conducted to determine the performance of the compressor and to obtain fundamental information on the aerodynamic problems associated with large centrifugal-type compressors. The results of the research conducted on the original compressor indicated the compressor would not meet the desired engine-design air-flow requirements because of an air-flow restriction in the vaned collector. The compressor air-flow choking point occurred near the entrance to the vaned-collector passage and was instigated by a poor mass-flow distribution at the vane entrance and from relatively large negative angles of attack of the air stream along the entrance edges of the vanes at the outer passage wall and large positive angles of attack at the inner passage wall" (p. 1).

Report presenting testing of a semispan model of a wing of triangular plan form and aspect ratio 2 in the 12-foot pressure tunnel to determine the aerodynamic characteristics of the wing as influenced by the independent effects of Reynolds number and Mach number up to Mach numbers approaching unity. Results regarding the effect of body and effect of wing-profile modification are also provided.