NACA instrumentation has been installed in the X-4 airplanes to obtain stability and control data during the acceptance tests conducted by the Northrop Aircraft Corporation. This report presents data obtained on the stalling characteristics of the airplane in the clean and gear- down configurations. The center of gravity was located at approximately 18 percent of the mean aerodynamic chord during the tests. The results indicated that the airplane was not completely stalled when stall was gradually approached during nominally U accelerated flight but that it was completely stalled during a more abruptly approached stall in accelerated flight. The stall in accelerated flight was relatively mild, and this was attributed to the nature of the variation of lift with angle of attack for the 001-614 airfoil section, the plan form of the wing, and to the fact that the initial sideslip at the stall produced (as shown by wind-tunnel tests of a model of the airplane) a more symmetrical stall pattern.

Report presenting an investigation to evaluate the engine service performance of nozzle-diaphragm blades of AISI 321 and AISI 347 stainless steels. Data were obtained from three nozzle diaphragms alternately bladed with each of the two materials. Results regarding a visual inspection, a metallurgical examination, the mechanism of cracking, and the classification of failures are provided.

Models of two types of high-speed surface craft were tested in Langley tank no. 1 to obtain rough-water data for an evaluation by the David Taylor .Model Basin of the relative merits of the designs. Time-history records were obtained of trim, rise, and normal acceleration at two points in the hulls for various speeds and two sizes of waves.

Report presenting calculations of the dynamic lateral stability characteristics of a mock-up configuration of the Douglas X-3. The oscillations were found to be stable for all calculations investigated but would not meet the Air Force damping requirements for the majority of the conditions. The use of an autopilot was found to greatly improve oscillation damping.

A heat-transfer investigation was conducted with water flowing in an electrically heated Inconel tube with an inside diameter of 0.204 inch and a length-diameter ratio of 50 for ranges of Reynolds number up to 100,000 and of entrance pressure up to 200 inches of mercury gage. Correlation of average heat-transfer coefficients was obtained by use of the familiar Nusselt relation, wherein the physical properties of water were evaluated at an average bulk temperature. For conditions in which no boiling occurred, the data gave a good correlation. Runs made in the nucleate-boiling region, however, gave higher values of heat-transfer coefficient than would be predicted by the Nusselt relation.

From Summary: "The compressor from the XT-46 turbine-propeller engine was revised by removing the last two rows of stator blades and by eliminating the interstage leakage paths described in a previous report. With the revised compressor, the flow choking point shifted upstream into the last rotor-blade row but the maximum weight flow was not increased over that of the original compressor. The flow range of the revised compressor was reduced to about two-thirds that obtained with the original compressor. The later stages of the compressor did not produce the design static-pressure increase probably because of excessive boundary-layer build-up in this region. Measurements obtained in the ninth-stage stator showed that the performance up to this station was promising but that the last three stages of the compressor were limiting the useful operating range of the preceding stages. Some modifications in flow-passage geometry and blade settings are believed to be necessary, however, before any major improvements in over-all compressor performance can be obtained."

"The behavior of the Westinghouse electronic power regulator operating on a J34-WE-32 turbojet engine was investigated in the NACA Lewis altitude wind tunnel at the request of the Bureau of Aeronautics, Department of the Navy. The object of the program was to determine the, steady-state stability and transient characteristics of the engine under control at various altitudes and ram pressure ratios, without afterburning. Recordings of the response of the following parameters to step changes in power lever position throughout the available operating range of the engine were obtained; ram pressure ratio, compressor-discharge pressure, exhaust-nozzle area, engine speed, turbine-outlet temperature, fuel-valve position, jet thrust, air flow, turbine-discharge pressure, fuel flow, throttle position, and boost-pump pressure" (p. 1).

Report presenting research on the single problem of combustion efficiency of turbojet engines at high altitudes. Representative results of investigations with turbojet combustors are presented to analyze trends regarding combustor operating variables, combustor-design variables, and fuel variables.

Report discussing testing to determine the effect of sweepback on the longitudinal characteristics of a model of the Bell X-5 airplane at Mach number 1.24. Lift, drag, and pitching moments were obtained for several angles of attack. Effects on the drag coefficient and lift-curve slope are described.

Report presenting an investigation conducted to determine the minimum spark energy required for ignition in a single tubular combustor. Inlet-air pressure and flow rates limiting ignition are compared with those limiting steady-state burning in the combustor. Results regarding ignition at sea-level conditions, altitude steady-state burning limits, altitude ignition, and reproducibility are provided.

Report presenting design features for the instrumentation used in a study of the transient performance of gas-turbine engines and control systems. The dynamic characteristics of the instrumentation are discussed and examples of typical acceleration data for a controlled and an uncontrolled engine are provided.

Report presenting testing of the effects of the following variables on combustion performance are determined: inlet-air temperature, combustion-chamber-inlet Mach number and pressure, and fuel density and volatility.

Report discusses a procedure for estimating the wing lift coefficient for and spanwise location of the first occurrence of section stall on a swept wing. It has been modified from a method used to calculate the same information for unswept wings. The effects of split flaps, leading-edge modifications, and fences are described.

"An investigation of two semispan wings swept back 50 degrees 38 minutes was conducted in the Langley high-speed 7- by 10-foot tunnel over a Mach number range of 0.68 to 1.15 by use of the transonic-bump technique. This paper presents the results of the investigation of wing-alone and wing-fuselage configurations of the two wings; one was an untwisted uncambered wing and the other was the same wing but incorporated twist and camber designed to give uniform load at a lift coefficient of 0.25 at a Mach number of 1.10. The semispan wings had their quarter-chord lines swept back 50 degrees 38 minutes, aspect ratios 2.98, taper ratios 0.45, and modified NACA 64A-series airfoil sections tapered in thickness" (p. 1).

"A rocket-propelled model of the X-3 configuration equipped with an all-movable tail of aspect ratio 3.0 has been flown to determine the longitudinal characteristics of this configuration at high lift coefficients. An analysis of the response of the model to rapid deflections of the horizontal tail gave information on lift, drag, longitudinal stability, and longitudinal trim change. The primary result of the tests was that the configuration was indicated to have very unstable tendencies at lift coefficients above the stall and at Mach number near 0.7" (p. 1).

Results of experimental measurements of low-frequency combustion instability of a 300-pound thrust acid-heptane rocket engine were compared to the trends predicted by an analysis of combustion instability in a rocket engine with a pressurized-gas propellant pumping system. The simplified analysis, which assumes a monopropellant model, was based on the concept of a combustion the delay occurring from the moment of propellant injection to the moment of propellant combustion. This combustion time delay was experimentally measured; the experimental values were of approximately half the magnitude predicted by the analysis.

The two techniques for conducting annealing experiments for the purpose of determining the distribution of atoms of a solid among non equilibrium states are considered. Related definitions for resolving power for annealing with steadily rising temperature and for annealing at a series of fixed temperatures are given. The necessary separation of activation energies for the resolution of two different non equilibrium states is found to be greater in the case of a steadily rising temperature, but of the order of 10 percent of the activation energy for both techniques. The resolving power in the case of a steadily rising temperature is independent of the rate of temperature rise.

Report presenting free-fall tests of a wing-body configuration with a 45 degree sweptback cambered and twisted wing of aspect ratio 6 on a fuselage of fineness ratio 12.4. Results regarding the load and pitching moments and load-coefficient distribution are provided.

Report presenting a low-speed investigation in the stability tunnel to determine the lateral control characteristics of a 60 degree triangular wing model equipped with half-delta tip controls with areas of 5, 10, and 15 percent of the wing area. Results regarding lateral control effectiveness, rolling effectiveness, and a comparison of control and effectiveness with theory are provided.

The performance of MIL-F-5624A fuels, grades JP-3 and JP-4, was investigated in an axial-flow turbojet engine over a range of altitude conditions of 10,000 to 55,000 feet. Examination of the fuel flow, combustion efficiency, and net thrust specific fuel consumption showed the grade JP-4 fuel to be slightly inferior to the grade JP-3 fuel, although the altitude ignition limits were essentially equal for the two fuels over a range of flight Mach numbers and fuel-inlet temperatures.

A study of two 20 degrees half-angle, low mass-flow ratio conical supersonic inlets with cone boundary-layer bleed was made on a 16-inch ram-jet engine in the Lewis 8- by 6-foot supersonic wind tunnel. A greater stable subcritical range of operation was obtained with the bleed inlets than with the corresponding inlet without boundary-layer bleed. The drag added by the bleed system was small.

A study of a 20 degree and a 25 degree half-angle high mass-flow ratio conical supersonic inlet was made on a 16-inch ram jet in the 8- by 6-foot supersonic tunnel. A greater range of stable subcritical operation was obtained with the low mass-flow ratio inlets; a greater range was obtained with the 25 degree than with the 20 degree half-angle low mass-flow ratio inlet. The high mass-flow ratio inlet had the least drag.

From Introduction: "The intermediate subsonic speed range is considered and the liquid-metal turbine-propeller cycle discussed in this report. In this report, compressor pressure ratio, heat-exchanger air-inlet Mach number, and turbine-inlet temperature were optimized for maximum engine net thrust per engine-plus-heat exchanger weight (minimum airplane gross weight) for a range of heat-exchanger effective wall temperature."

From Introduction: "The intermediate subsonic speed range is considered and the liquid-metal turbine-propeller cycle discussed in this report. In this report, compressor pressure ratio, heat-exchanger air-inlet Mach number, and turbine-inlet temperature were optimized for maximum engine net thrust per engine-plus-heat-exchanger weight (minimum airplane gross weight) for a range of heat-exchanger effective wall temperature."