Abstract. In investigating stability of a homogeneous pile it has been customary to assume that the production of bubbles follows the production of power instantaneously. Here we investigate the implications of introduction of an intermediate dissolved gas stage under two hypotheses on the formation of bubbles from this dissolved gas. It is seen that this additional stage tends to make the pile unstable.

A method introduced by Munk is extended to prove that the light-curve slope of thin wings in either subsonic flow or supersonic flow is the same when the direction of flight of the wing is reversed. It is also shown that the wing reversal does not change the thickness drag, damping-in-roll parameter or the damping-in-pitch parameter.

Memorandum presenting an investigation of coolant-flow rates for a turbine rotor blade with return-flow type of coolant-passage configuration formed by fins within a capped blade shell with both hydrogen and methane fuels as coolants. Results regarding spanwise blade and coolant temperature distributions, effects of coolant inlet temperature on hydrogen-coolant-flow requirements, comparison of return-flow-blade coolant requirements, effect of fin thickness and fin height, comparison of hydrogen and methane as coolants, and feasibility of fuel-cooled turbines are provided.

Memorandum presenting an investigation to determine the internal flow performance of a fixed 14 degree ramp inlet from zero to 20 degrees angle of attack conducted at three free-stream Mach numbers. The inlet was mounted in three circumferential fuselage locations and utilized inlet throat and fuselage boundary-layer removal.

Memorandum presenting an empirical cooling correlation for an experimental high-performance afterburner. The correlation relates the average combustion-chamber wall temperature at a station near the combustion-chamber outlet to the temperatures of the cooling air and combustion gas, and to the mass flows of the cooling air and combustion gas.

Report presenting flight tests of rocket-powered models at supersonic speeds to determine the effect of nose fineness ratio of winged bodies on total and component drag at high Mach numbers. Wingless models of three nose fineness ratios and winged models of two nose fineness ratios flown through a range of Mach numbers. Results regarding total drag, body drag, and wing drag are provided.

Report presenting a theoretical analysis of the air flow through the blade coolant passages in an air-cooled turbine rotor. The simultaneous effects of area change, compressibility, wall friction, heat transfer, and rotation were included.

Report presenting the application of an estimation of the derivative of yawing moment due to rolling to the dynamic lateral stability characteristics of the Bell X-2. Results regarding the airplane with flaps and gear retracted and airplane with flaps and gear lowered are provided.

Report presenting a wind-tunnel investigation of two full-span and two semispan models with 45 degrees of sweepback, an aspect ratio of 5.5, and a taper ratio of 0.53. The lift and drag data obtained from tests of the semispan agreed well with data obtained on the full-span model. Results regarding a comparison of the data for the full-span and semispan models, full-span model data, and effect of surface roughness are provided.

Report presenting tests to evaluate the usefulness of available theory for the calculation of lift-curve slope and center of pressure of low-aspect-ratio, triangular, and rectangular cruciform wings in combination with a long slender body. Tests were made over a range of Mach and Reynolds numbers based on model length.

Memorandum presenting low-speed tests of a semispan tapered wing with the leading edge swept back 63 degrees and with the NACA 0010 section cambered for a lift coefficient of 1.0 perpendicular to the leading edge to determine the extent to which stability characteristics could be improved by cambering the wing.

Report presenting an empirical cooling correlation for an experimental high-performance afterburner. The correlation equation is useful for shortening the experimental investigation of afterburner cooling characteristics inasmuch as it provides a method for interpolating the critical wall temperatures for other combinations of operating variables.

Effect of three surface finishes of roughness 4 to 5, 20 to 25, and 70 to 80 micro inches rms on fatigue properties were determined for low-carbon N-155 alloy of grain size A.S.T.M. 1 at temperatures of 80 , 1000, 1350, and 1500 F. The fatigue properties for the various finishes differed appreciably at room temperature; however, after short periods at 1000 F and for all periods investigated at temperatures above 1000 F, the specimen finishes had the same fatigue strength. It was concluded that the primary cause of the difference in room-temperature strength was due to compressive stresses set up in the surface and that at elevated temperatures these compressive stresses were relieved by annealing.

From Introduction: "During previous investigations of afterburning conducted at the NACA Lewis laboratory (references 1 to 4, for example), the objective of obtaining high exhaust-gas temperatures and, consequently, maximum thrust augmentation was compromised to some extent in order to alleviate the problem of afterburner shell cooling. The primary objective of the investigation reported herein was therefore the attainment of maximum exhaust-gas temperature imposed by the cooling techniques previously used, a secondary flow of cooling air was provided around the afterburner shell."

Report presenting a study of the flow phenomena within the rotating passages of a 48-inch radial-inlet impeller at low tip speeds. Total and static pressures were measured within the impeller passages at two different tip speeds by using a suitable pressure-transfer device to transmit the pressures from the rotating passages to the stationary measuring station. Results regarding the overall compressor performance, static-pressure distribution along blades, total-pressure distribution across the passage, static-pressure distribution across the passage, pressure distribution from hub to shroud, and power input to impeller are provided.

Report presenting an investigation to determine the effect of rate of flap deflection on flap hinge moment and wing lift at a range of Mach and Reynolds numbers. For the rate of flap-deflection range investigated, the hinge-moment coefficient was practically independent of rate of flap deflection.

Report discussing the importance of designing aircraft turbines so that the entire range of operating conditions has been considered. In this particular investigation, the compressor performance was used to determine the turbine design requirements for a turbine-propeller engine to be operated up to altitudes of 40,000 feet and flight velocities up to 600 miles per hour. The two modes of engine operation considered were constant exhaust-nozzle area and variable exhaust-nozzle area.

From Summary: "An experimental investigation of high-frequency combustion oscillations (screaming) was conducted with a 100-pound-thrust acid-hydrocarbon rocket engine and a 500-pound-thrust oxygen-fuel rocket engine. The oscillation frequencies could be correlated as a linear function of the parameter C/L, where C is the experimentally measured characteristic velocity and L is the combustion-chamber length. The tendency of the engines to scream increased as chamber length was increased. With engine configurations that normally had a low efficiency, screaming resulted in increased performance; at the same time, a five to tenfold increase in heat-transfer rate occurred. It was possible, however, to achieve good performance without screaming."

Report presenting a study of the effects of high reactor and cycle temperatures and the effect of thickness of high-temperature fuel element materials on the feasibility of the nuclear-powered direct-air-cycle aircraft for flight at Mach number 1.5 and an altitude of 35,000 feet. Testing occurred over a range of reactor fuel temperatures, turbine-inlet temperatures, and reactor fuel plate thicknesses.

Report presenting an investigation studying the effects of compressibility on the internal-flow characteristics of an NACA 1-series cowling-spinner combination equipped with a dual-rotation propeller at Mach numbers up to 0.8. Two propellers were examined, one with a sealed propeller-spinner juncture and one with a raised-platform-airfoil shaped juncture. The propeller was not found to have appreciable compressibility effects on the impact pressures when operating at design cruise blade angle.

From Introduction: "In response to the ever-increasing need for high thrust augmentation, an investigation was conducted that had as its primary objective the attainment of maximum exhaust-gas temperature and thrust (ref. 1). The investigation reported herein was therefore conducted to ascertain the operational limits of the most promising high-temperature afterburner design of reference 1 and to determine its performance over a wind range of flight conditions."

Report discussing tests to determine the performance of an aircraft engine cylinder using nitrous oxide to provide additional supercharging. The test results of injecting it as a gas and calculated results of injecting it as a liquid are described.

"A compilation of theoretical values of the lateral-stability derivatives for wings at supersonic speeds is presented in the form of design charts. The wing plan forms for which this compilation has been prepared include a rectangular, two trapezoidal, two triangular, a fully-tapered swept-back, a sweptback hexagonal, an unswept hexagonal, and a notched triangular plan form. A full set of results, that is, values for all nine of the lateral-stability derivatives for wings, was available for the first six of these plan forms only. The reasons for the incompleteness of the results available for other plan forms are discussed" (p. 1211).

Report presenting an investigation in the 8- by 6-foot supersonic tunnel to determine the external-stream effects on the gross thrust and pumping characteristics of ejectors operating at off-design Mach numbers. Results regarding the pumping, thrust, and base characteristics, boattail drag characteristics, and stream effects on jet thrust for typical ejector installations are provided.