"Finally the work of the report is applied exclusively to consideration of the turbine-propeller power plant because previous performance analyses of the various gas-turbine propulsion systems combine with recent improvements in propeller design indicate that it is this combination which, will give the best over-all performance in the speed ranges considered" (p. 5).

Flow-metering devices used by the NACA and by the manufacturer of the J33 turbojet engine were calibrated together to determine whether an observed discrepancy in weight flow of approximately 4 percent for the two separate investigations might be due to the different devices used to meter air flow. A commercial adjustable orifice and a square-edge flat-plate orifice used by the NACA and a flow nozzle used by the manufacturer were calibrated against surveys across the throat of the nozzle. It was determined that over a range of weight flows from 18 to 45 pounds per second the average weight flows measured by the metering device used for the compressor test would be 0.70 percent lower than those measured by the metering device used in the engine tests and the probable variation about this mean would be +/- 0.39 percent. The very close agreement of the metering devices shows that the greater part of the discrepancy in weight flow is attributable to the effect of inlet pressure.

Contains theoretical and experimental analysis of circular inlets having a central body at Mach numbers of 3.30, 2.75, and 2.45. The inlets have been designed in order to have low drag and high pressure recovery. The pressure recoveries obtained are of the same order of magnitude as those previously obtained by inlets having very large external drag.

Memorandum presenting a description of an axial-discharge mixed-flow compressor, which is especially adapted for jet engines because of the large mass flow per unit frontal area. The best impeller was selected on the basis of the maximum air-flow capacity, which was 19.6 pounds per second for a 14-inch-diameter impeller with a tip speed of 1480 feet per second and a pressure ratio of 3.5.

Report presenting an analysis of an axial-discharge mixed-flow compressor designed to combine the compactness, reliability, and wide operating range of a mixed-flow compressor with the high flow capacity per unit of frontal area that characterizes the axial-flow compressor. The primary objective of this design was to maximize the flow capacity for a predetermined pressure ratio. Results regarding the flow distribution at the impeller inlet, flow distribution at the impeller outlet, and impeller performance are provided.

Memorandum presenting an investigation in natural icing conditions to determine the effect of ice formations on the performance of an axial-flow turbojet engine. A description of the change over time in tail-pipe temperature, engine jet thrust, fuel flow, ice collection, and acceleration qualities are provided.

"A two-dimensional wedge diffuser, designed to be used with a ducted-airfoil ram jet, was tested on a rocket-powered test vehicle up to a Mach number of 1.45. Orifice plates and a choking section behind the diffuser exit simulated burning in a combustion chamber by providing the proper pressure drop. Results obtained from these tests showed there was no abrupt changes in mass flow and pressure recovery as the model velocity increased through the transonic region" (p. 1).

From Introduction: "In this report, altitude, airplane velocity, exhaust-nozzle area, and turbine-inlet temperature were chosen and corresponding engine speed, fuel flow, and throttle pressure ratio were found. A detailed discussion of the engine analysis and the calculations used are presented in Appendix A. The derivations of the principal equations used are presented in appendix B."

"As part of an investigation of the performance and operational characteristics of the axial-flow gas turbine-propeller engine, conducted in the Cleveland altitude wind tunnel, the performance characteristics of the compressor and the turbine were obtained. The data presented were obtained at a compressor-inlet ram-pressure ratio of 1.00 for altitudes from 5000 to 35,000 feet, engine speeds from 8000 to 13,000 rpm, and turbine-inlet temperatures from 1400 to 2100 R. The highest compressor pressure ratio obtained was 6.15 at a corrected air flow of 23.7 pounds per second and a corrected turbine-inlet temperature of 2475 degrees R" (p. 1).

Memorandum presenting low-speed wind-tunnel tests made of flat-plate wings with an aspect ratio of 2.0 and their leading edges swept back 63.4 degrees. Both plain and split flaps of several plan forms were investigated to provide qualitative information as to the relative merits of these flaps. The constant-chord flap was found to be the most effective and a skewed wing-tip flap the least effective.

Memorandum presenting an investigation of a model with a ramp that produced an oblique shock wave in front of an annular duct inlet, which was tested at Mach numbers between 1.36 and 2.01 to determine the effect of reducing the entrance Mach number on the total-pressure recovery after diffusion. The results showed that the maximum total-pressure recovery of the model investigated was considerably improved through the addition of a ramp.

From Summary: "An investigation was conducted in the Cleveland altitude wind tunnel to determine the operational characteristics of an axial flow-type turbojet engine with a 4000-pound-thrust rating over a range of pressure altitudes from 5,000 to 50,000 feet, ram pressure ratios from 1.00 to 1.86, and temperatures from 60 deg to -50 deg F. The low-flow (standard) compressor with which the engine was originally equipped was replaced by a high-flow compressor for part of the investigation. The effects of altitude and airspeed on such operating characteristics as operating range, stability of combustion, acceleration, starting, operation of fuel-control systems, and bearing cooling were investigated."

Compressor operation at low air flows for a given speed is limited by unstable flow conditions, commonly called surge. An investigation of surge in centrifugal compressors (reference 1) showed that the pulsation of pressures and velocities occurred when the slope of the compressor characteristic curve was positive and that the magnitude and frequency, as well as the incidence of surge, depended on the capacity and resistance of the total system. Although the theory presented in reference 1 is applicable to axial-floe compressors, little experimental information is available on the surge characteristics of the individual stages of axial-flow compressors, or on the variation of the surge characteristics with operating conditions.

"An investigation to determine the performance and operational characteristics of an axial-flow gas turbine-propeller engine was conducted in the Cleveland altitude wind tunnel. As part of this investigation, the combustion-chamber performance was determined at pressure altitudes from 5000 to 35,000 feet, compressor-inlet ram-pressure ratios of 1.00 and 1.09, and engine speeds from 8000 to 13,000 rpm. Combustion-chamber performance is presented as a function of corrected engine speed and corrected horsepower" (p. 1).

Memorandum presenting a flight investigation in natural icing conditions to determine the effect of ice formations on the performance of an axial-flow turbojet engine. Tail-pipe temperature increased from 761 to 1065 degrees Fahrenheit and the jet thrust decreased from 1234 to 910 pounds during a period of 45 minutes in icing. No general conclusions can be reached from the data because the icing condition was relatively light.

Report presenting a flight investigation in natural icing conditions to determine the effect of ice formations on the performance of an axial-flow turbojet engine. Results regarding the tail-pipe temperature, engine jet thrust, and characteristics of ice formation are provided. No general conclusions can be reached from the data because the icing condition was relatively light.

"An investigation is being conducted to determine the altitude performance characteristics of the Nene II engine and its components. The present paper presents the preliminary results obtained using jet nozzle 18.00 inches in diameter, with an area equal to 92.2 percent of the area of the standard jet nozzle for this engine. The experimental results presented are for conditions simulating altitudes from 20,000 to 60,000 feet and ram-pressure ratios from 1.1 to 3.5" (p. 1).

A wind tunnel investigation was conducted to determine the performance of a 4000-pound-thrust axial-flow turbojet engine with a high flow compressor. Pressure altitudes included 5000 to 40000 feet with ram pressure ratios from 1.00 to 1.82. Altitudes included 20000 to 40000 feet and ram pressure ratios from 1.09 to 1.75. A comparison is made between engine performance with high flow and low flow compressors.

Operating characteristics of the 11-stage 4000-pound-thrust axial-flow turbojet engine were determined. A standard compressor and a compressor with the blade angles of the rotor and stator blades increased 5 degrees to obtain greater air flow, were investigated.

"Performance characteristics of the turbine of a 4000-pound-thrust axial-flow turbojet engine was determined in investigations of the complete engine in the NACA Cleveland altitude wind tunnel. Characteristics are presented as functions of the total-pressure ratio across the turbine and of turbine speed and gas flow corrected to sea-level conditions. Three turbine nozzles of different areas were used to determine the area that gave optimum performance" (p. 1).

"An analysis of the performance of the types A, B, and C combustion chambers of the 4000-pound-thrust axial-flow turbojet engine is presented. The data were obtained from investigations of the complete engine over a range of pressure altitudes from 5000 to 40,000 feet and ram pressure ratios from 1.00 to 1.86. The combustion-chamber pressure losses, the effect of the losses on cycle efficiency, and the combustion efficiency are discussed" (p. 1).

"The effect of rotor-blade length, inlet angle, and shrouding was investigated with four different nozzles in a single-stage modification of the Mark 25 aerial-torpedo power plant. The results obtained with the five special rotor configurations are compared with those of the standard first-stage rotor with each nozzle. Each nozzle-rotor combination was operated at nominal pressure ratios of 8, 15 (design), and 20 over a range of speeds from 6000 rpm to the design speed of 18,000 rpm" (p. 1).

"An investigation of the EX-3 pine-cone-head pellet was made in the Langley high-speed 7-by 10-foot wind tunnel to determine the static force and moment characteristics at high Mach numbers with the reference center of gravity located at 37.5 percent of the over-all length aft of the nose. For this center-of-gravity location there were no secondary trim positions, and the center-of-pressure position was not appreciably affected by Mach number" (p. 1).

Report presenting measurements of the chordwise pressure distributions over the 8-percent-thick wing of the XS-1 research airplane at a section near the midspan of the left wing. Data are presented for a Mach number range and a normal-force coefficient of about 0.33. Results regarding the upper-surface pressure distribution, lower-surface pressure distributions, and total section loads are provided.