Memorandum presenting an investigation conducted to reduce the pressure drop in an experimental combustor designed to operate with high efficiencies at high altitude. The combustor utilized a previously designed prevaporizing fuel system that supplied vapor fuel to the injectors for high-altitude operation. Results regarding combustor development and performance of final combustor model 47L are provided.

Report presenting analytical estimates of the thrust, efficiency, drag, and weight of the air-turborocket engine. The effects of changes in the engine components on design and off-design performance are emphasized. Results regarding the performance, effect of design parameters, effect of subsonic cruising Mach number, geometry variations, engine weight estimates, and comparison with turbojet engines are provided.

Report presenting an investigation of the hydrodynamic characteristics of a powered dynamic model of the Martin PBM-5 seaplane equipped with a single Edo hydro-ski. Various hydro-ski positions were investigated. Results regarding aerodynamic and hydrodynamic characteristics, including excess thrust, smooth-water landings, smooth-water take-offs, rough-water take-offs, and spray are provided.

Report presenting a determination of the combustion efficiency of gaseous hydrogen fuel in a ramjet engine in a connected-pipe test facility. Operating conditions simulated a range of Mach numbers and altitudes. Results regarding the effect of inlet parameters and design variables on combustion efficiencies, comparison between methods of determining efficiency, and ignition characteristics are provided.

Report presenting an evaluation of data obtained with an automatic constant inlet-pressure control valve designed to facilitate the study of transient engine performance characteristics in the altitude wind tunnel. The engine characteristics obtained by use of the pressure valve were compared with those obtained with a bellmouth inlet operating in simulated free-stream conditions.

Report presenting an investigation of an exhaust jet and elementary contoured surface at Mach number 1.6 over a range of nozzle pressure ratios from jet-off to a pressure ratio of 9. The effect of the presence of streamline fairings between the surfaces and parabolic afterbody housing the exhaust nozzle on the interaction was also investigated.

Report presenting a determination of the relative reactivities of six fuels with red fuming nitric acid in a 40-pound-thrust rocket engine with rapid liquid-phase mixing. Hydrazine, trimethyl-trithiophosphite, furfuryl alcohol, unsymmetrical dimethylhydrazine, allylamine, and o-toluidine were studied. Results regarding the combustion characteristics of the fuels, fuel ratings, pressure in the mixing cup, effect of chamber diameter, and overall combustion efficiency are provided.

Memorandum presenting a study of several typical air induction systems for modern aircraft, which indicates that flow distortions of about-pipe-flow magnitudes can be expected at near-optimum inlet-engine matched air-flow conditions and at small angles of attacks. The distortions may be seriously increased by operation at large angles of attack or yaw, or by supercritical operation of the inlets. Boundary-layer bleed, duct overexpansion and contraction, and freely rotating fans appear promising as devices for reducing distortions with little cost in propulsive thrust.

An annular prevaporizing turbojet combustor having pressure losses lower than those obtained in current turbojet combustors was developed, Pressure losses of 2 to 4 percent, satisfactory temperature profiles, and combustion efficiencies of 98, 88, and 81 percent were obtained at 56,000, 70,000, and 80,000 feet respectively, for a simulated 5.2- pressure-ratio engine at rated speed and 0.6 flight Mach number with JP-4 fuel. Use of JP-5 fuel resulted in a small penalty in efficiency due, at least in part, to insufficient prevaporizer capacity.

Report presenting a method to provide a simple means of comparing engine components on the basis of either range or the margin of thrust over drag. The equations include the variation in thrust coefficient and specific impulse and the change in engine weight and drag. Four general cases are considered: fixed-size airplanes with constant gross weight, fixed-size airplanes with variable gross weight, variable-size airplanes with constant payload weight, and variable-size airplanes with constant ratio of payload to gross weight.

From Summary: "During the course of an aerodynamic loads investigation of a model of the Martin XP6M-1 flying boat in the Langley 16-foot transonic tunnel, longitudinal-aerodynamic-performance information was obtained. Data were obtained at speeds up to and exceeding those anticipated for the seaplane in level flight and included the Mach number range from 0.84. to 1.09. The angle of attack was varied from -2deg to 6deg and the average Reynolds number, based on wing mean aerodynamic chord, was about 3.7 x 10(exp 6)."

Turbine centrifugal stress is a limiting factor for all flight conditions studied. This stress is more severe for sea-level operations than for subsonic flight at the tropopause. Turbines designed for a stress of 30,000 psi are capable of driving a light, compact, high-spedd compressor but only at high values of specific fuel consumption. An increase in turbine-inlet temperature is accompanied by an increase in turbine centrifugal stress.