From Summary :"An investigation was conducted to evaluate the possibilities of utilizing the high-performance characteristics of triptane and xylidines blended with 28-R fuel in order to increase fuel economy by the use of high compression ratios and maximum-economy spark setting. Full-scale single-cylinder knock tests were run with 20 deg B.T.C. and maximum-economy spark settings at compression ratios of 6.9, 8.0, and 10.0, and with two inlet-air temperatures. The fuels tested consisted of triptane, four triptane and one xylidines blend with 28-R, and 28-R fuel alone."

Report discussing an investigation of the DM-1 glider, which has an approximately triangular plan form, with auxiliary studies of a model of triangular wings. The pitching-moment coefficient, drag coefficient, and angle of attack with the lift coefficient are provided. Results indicated that the angles of descent without power are likely to be prohibitive and airplanes with the tested type of wings will not be able to land safely without power.

Rim cracking in turbine wheels with welded blades was evaluated. The problem is explained on the basis of the occurrence of plastic flow in the rim during transient starting conditions when thermal compressive stresses resulting from high-temperature gradients exceed the proportional elastic limit of the material.

"The results obtained from measurements of gust velocities, draft velocities, and ambient-air temperature within thunderstorms for the period from September 11, 1946 to September 16, 1946 at Orlando, Florida are presented herein. These data are summarized in.and presented" (p. 1).

Report presenting an investigation of two symmetrical circular-arc airfoils of 6 and 10 percent thickness equipped with leading-edge and trailing-edge high-lift devices. A trialing-edge flap, drooped-nose flap, and leading-edge extensible flap were all tested. Results regarding the plain airfoils, airfoils with high-lift devices, combined deflection of high-lift devices, and low-drag-control flaps are provided.

Report presenting an investigation of two 10-foot-diameter three-blade propellers to determine the effect of swept-back blade tips on propeller aerodynamic characteristics. Results regarding the effect of swept-back tips on maximum efficiency and constant-power propeller operation are provided.

Memorandum presenting high-speed wind-tunnel testing to investigate the aerodynamic characteristics at subsonic speeds of two symmetrical double-wedge airfoil sections of 4- and 6-percent-chord thickness suitable for application to supersonic aircraft. Section coefficients of lift, drag, and quarter-chord pitching moment are presented for a moderate range of angles of attack at Mach numbers up to approximately 0.93. The double-wedge airfoil exhibits no characteristics other than those common to the usual subsonic profile which would contribute to unsteady or uncontrollable flight at subsonic speeds of aircraft employing such a section for lifting surfaces.

Flight tests were conducted on a North American P-51D airplane to establish the maximum lift coefficient and the buffeting boundary line as a function of Mach number.

Investigation at transonic speeds in the high-speed 7- by 10-foot tunnel to determine the rolling-effectiveness characteristics of a spoiler on a double-wedge-type semispan wing with a sweepback angle of 42 degrees. Results regarding the variation of rolling-moment coefficient, spoiler effectiveness, and rolling effectiveness are provided.

Report discussing testing of a model of the pilotless aircraft RM-1 to measure aileron hinge moments in flight in order to determine the reason for loss of roll stabilization at supercritical speeds in flight. The aileron was found to become quickly underbalanced over the full deflection range at supercritical speeds. Information about the general flight behavior, aileron hinge moments, and roll stabilization of the model is provided.

"The performance of a 24C-4 combustor was investigated with three different combustor baskets and five modifications of these baskets at conditions simulating static (zero-ram) operation of the 24C jet engine over ranges of altitude and engine speed to determine and improve the altitude operational limits of the 24C combustor. Information was also obtained regarding combustion characteristics, the fuel-flow characteristics of the fuel manifolds, and the combustor total-pressure drop. NACA modifications, which consisted of blocking rows of holes on the baskets, increased the minimum point on the altitude-operational-limit curve, which occurs at low engine speeds, for a narrow-upstream-end basket by 8000 feet (from 23, 000 to 31,000 ft) and for a wide-upstream-end basket by 21,000 feet (from 12, 000 to 34,000 ft)" (p. 1).

From Summary: "Pressures and temperatures throughout the X24C-4B turbojet engine are presented in both tabular and graphical forms to show the effect of altitude, flight Mach number, and engine speed on the internal operation of the engine. These data were obtained in the NACA Cleveland altitude wind tunnel at simulated altitudes from 5000 to 45,000 feet, simulated flight Mach numbers from 0.25 to 1.08, and engine speeds from 4000 to 12,500 rpm. Location and detail drawings of the instrumentation installed at seven survey stations in the engine are shown."

The performance of the 11-stage axial-flow compressor in the X24C-4B turbojet engine was analyzed on the basis of results obtained from an investigation of the complete engine in the NACA Cleveland altitude wind tunnel. The engine was operated with four, exhaust nozzles of different outlet area over a range of engine speeds from 6000 to 12,500 rpm, corrected engine speeds from approximately 6100 to 13,600 rpm, and compressor Mach numbers from 0.45 to 1.00. Data are presented for engine operation over a range of simulated altitudes from 15,000 to 45,000 feet and simulated flight Mach numbers from 0.24 to 1.08.

Memorandum presenting an investigation conducted to provide data that may be used to correlate the engine service performance of cast Vitallium turbine buckets with metallurgical properties. Data were obtained from four turbine wheels of Timken alloy with cast Vitallium buckets. Examination of 12 broken buckets indicated that 8 of the failures were probably caused by fatigue and 4 by impact with pieces of other broken buckets.

Memorandum presenting wind-tunnel tests that have been made to determine the aerodynamic characteristics of a model tail plane with modified NACA 65-010 sections and a tapered plan form. Results were obtained with the model tail plane unswept and swept back. The data show the lift, drag, pitching-moment, and hinge-moment coefficient variation with angle of attack and flap deflection at various Mach numbers.

From Introduction: "Analyses that provide a basis for comparing the centrifugal-stress distributions inherent in jet-engine turbine blades of several designs currently in use were therefore made and are presented."

Report presenting information about some of the fundamental concepts and lines of development that may be undertaken regarding helicopter stability. Some of the principles discussed include method of control, control lag, stability characteristics, control forces, and center of gravity. Some of the means for improvement discussed include use of a horizontal stabilizer, use of trim devices, use of power-operated controls, automatic controls, and choice and grouping of indicating instruments.

Combustion chamber liners for gas turbines and experimental set-ups were tested for failure. A ceramic-lined test chamber was operated at fuel/air ratios up to 0.050. Thermal-shock evaluation indicated that a ceramic lining, which expands after firing, would crack but would not fall apart during operation. Refractoriness of the lining and the resistance to mechanical shock were adequate. In general, shell temperature reductions of approximately 400 deg F were effected by the use of this lining at fuel/air ratios of 0.016 and 0.050. The mechanism of failure of the ceramic lining was induced by sudden heating and cooling during operation.

Report presenting the results of testing on a model of the D-558-1 in order to determine its pitching-moment, lift, and drag characteristics with no nose-inlet flow, and with the tail removed and at a constant setting. Only a limited analysis is provided.

"A series of calculations of the dynamic response of airplane wings to gusts were made with the purpose of showing the relative response of a reference airplane, the DC-3 airplane, and of newer types of airplanes represented by the DC-4, DC-6, and L-49 airplanes. Additional calculations were made for the DC-6 airplane to show the effects of speed and altitude. On the basis of the method of calculation used and the conditions selected for analysis, it is indicated that: 1) The newer airplanes show appreciably greater dynamic stress in gusts then does the reference airplane; 2) Increasing the forward speed or the operating altitude results in an increase of the dynamic stress ratio for the gust with a gradient distance of 10 chords" (p. 1).

Report presenting the results of a wind-tunnel investigation of aileron flutter up to 0.822 Mach number. The testing indicated the absence of flutter of significant amplitude when a considerable amount of wing-tip relief existed and the presence of flutter when the relief was minimized. Results regarding the testing without the end plate, with end plate, and comparison with theory are provided.

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.