From Summary: "Despite the development of relatively ice-free fuel-metering systems, the widespread use of alternate and heated-air intakes, and the use of alcohol for emergency de-icing, icing of aircraft-engine induction systems is a serious problem. Investigations have been made to study and to combat all phases of this icing problem. From these investigations, criterions for safe operation and for design of new induction systems have been established. The results were obtained from laboratory investigations of carburetor-supercharger combinations, wind-tunnel investigations of air scoops, multicylinder-engine studies, and flight investigations. Characteristics of three forms of ice, impact, throttling, and fuel evaporation were studied."

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.

Report presenting an analysis of the measurements of drag-angle oscillation of a helicopter rotor made with the helicopter apparatus to determine both the natural frequencies and the damping required to prevent excessive drag-angle-oscillation response to various throttle and control movements. Results regarding symmetrical oscillations, unsymmetrical oscillations, blade damping, and general discussion are provided.

"Results are presented of calculations for the elastic buckling load of a simply supported flat rectangular plate of uniform thickness subjected to unequal compressive stresses at two opposite edges, with a linear variation of stress between the two edges. The difference between the compressive stresses at the two loaded edges is equilibrated by shear stresses along the other two edges. The results show that a plate with a linear stress gradient will buckle at an average stress that is lower, but at a maximum stress that may be appreciably higher, than the uniform compressive buckling stress of the same plate" (p. 1).

Report presenting a wind-tunnel investigation to determine the boundary-layer and stalling characteristics of the NACA 63-009 airfoil section. Pressure distributions, tuft studies, and boundary-layer measurements were obtained. A localized region of flow separation was found to develop on the upper surface of the airfoil near the leading edge.

"This report is the result of the first part of a broad program to analyze the transient motions of a helicopter, which occur in the various phases of flight following power failure" (p. 1).

"This report is the second phase of a broad program of study of the transient motions of helicopters in autorotative flight. The first phase (reference 1) dealt with the steady-state condition of autorotative vertical descent. This report is concerned with the the transition from the steady condition of hovering to the steady autorotative descent" (p. 1).

Note presenting an investigation of the use of measured static pressures in a vaneless-diffuser passage for determining centrifugal-compressor performance. The general effects of diffuser-wall-surface friction were studied to locate the regions in the vaneless-diffuser passage where the most valid evaluation can be made by the static-pressure method.

From Introduction: "Although the aerodynamic characteristics of the components of such configurations may be well known, the mutual interference resulting from combining the wings, as well as the wings and body, may be so great that is desirable to study the aerodynamic properties of the complete configurations. Two methods of handling this problem are presented in this report. The first method is essentially an extension of the theory for slender wing-body combinations of reference 1 to determine the load distribution, forces, and moments exerted on slender cruciform-wing and body combinations inclined simultaneously at small angles in pitch and yaw. "

Note presenting meteorological data from flight observations in icing conditions during the first 5 months of 1948. A total of 335 measurements of liquid-water content and mean-effective drop diameter were obtained by the multicylinder method in the course of 40 flights in icing conditions covering most of the northern United States. Information regarding the discontinuous character of icing clouds, variation of average liquid-water content with extent of icing conditions, and variation of drop diameter from year to year and with geographic location are provided.

Report presenting the results of a preliminary investigation of a scale model of a convertible-type airplane in the full-scale tunnel. The maximum lift and stalling characteristics of several configurations, the longitudinal stability characteristics, and the effectiveness of the control surfaces with the propellers removed are provided. Results regarding the propulsive characteristics, and effect of propeller operation on the lift and static thrust of the model propellers are also provided.

Report presenting an investigation using a 4600 pound-thrust turbojet engine as part of a program to determine the comparative performance of fuels conforming to specifications AN-F-58 and AN-F-32. Results regarding the altitude performance, altitude low-speed blow-out limits, idling limits of fuel-metering control, altitude windmilling starts, carbon-deposition rates, and iron oxide contamination are provided.

"Abrupt, rudder-fixed aileron rolls have been made with the Bell X-1 airplane having a 10-percent-thick wing in glides to a Mach number of 0.82 at about 30,000 feet pressure altitude. Aileron movements were between one-fourth and one-half of full deflection. These aileron rolls indicate that Mach number has little effect on the aileron effectiveness up to a Mach number of 0.82" (p. 1).

Report presenting a partial-span wing tested to determine the cause of a flutter which had occurred in high-speed flight. Changes were made to the wing stiffness, location of the center of gravity of the wing, and the mass balance of the aileron. Results regarding the effect of wing changes on flutter, effect of aileron changes on flutter, shock-wave study, and static aerodynamic coefficients are provided.

Report presenting an analysis of the estimated flying qualities of a tailless airplane with the wing quarter-chord line swept back 35 degrees in a range of Mach numbers based on tests of a model of the airplane in the 7- by 10-foot tunnel. Results regarding performance, longitudinal stability and control, and lateral stability and control are provided.

Report discussing testing using two rocket-propelled models to test the jettisonable-nose method of pilot escape. The nose was jettisoned successfully on the second attempt and the accelerations produced were found to be within human tolerance. The first test ended with a collision of the nose and wing, indicating that this is a possible risk during power-on flight.

Report presenting an investigation using a single combustor from a 4600-pound-thrust turbojet engine to determine the amount of carbon deposition of AN-F-58 fuels and the effect of carbon formations in the combustor on the altitude operational limits. Three fuel blends conforming to AN-F-58 specification were prepared in order to determine the influence of boiling temperature and of aromatic content on carbon deposition. Results regarding carbon deposition and effect of carbon formations on altitude operational limits are provided.

Report presenting a wind-tunnel investigation through a speed range from Mach number 0.30 to 0.90 to determine the lateral-control characteristics of a 20-percent-chord by 39-percent-semispan aileron and a 60-percent-semispan stepped spoilers on a semispan-wing model with aspect ratio of 3.06 with 51.3 degrees sweepback of the wing leading edge. The aileron rolling effectiveness decreased as the Mach number increased, while the spoiler rolling-moment effectiveness decreased with Mach number.

Report presenting an investigation to determine the effects of several leading-edge modifications on the maximum lift and pitching-moment characteristics on a large-scale 45 degree swept-forward wing. A full-span leading-edge flap deflected 30 degrees down tended to give the largest gain of maximum lift. Results regarding the plain leading-edge flaps and cambered nose are explored.

Report discussing an investigation of two full-scale NACA propellers at a range of blade angles and at speeds of up to 500 miles per hour. The results are compared to previous investigations of five NACA propellers to evaluate the effects of blade-section thickness ratios on propeller characteristics.

Report presenting the performance of a ramjet unit consisting of an intake diffuser, an exhaust nozzle, and a cluster of thin-plate burners contained in a semicircular combustion chamber as investigated in the induction aerodynamics laboratory.

An investigation of the damping-in-roll characteristics of three wings with an aspect ratio of 4, a taper ratio of 0.6, three sweep angles at the quarter chord line, and the NACA 65A006 section as determined through a range of Mach numbers and angles of attack.

Report presenting an investigation to determine the effect of the primary-jet temperature on the performance of several ejector configurations. The performance of ejectors expressed in terms of the ratio of weight of secondary air flow to primary air flow was found to be affected by temperature in two ways.

Report presenting the results of an experimental investigation of the downwash and wake characteristics behind a triangular plan-form wing in a supersonic stream. Measurements were made of the variation of downwash angle with angle of attack at several positions within the induced flow field. Results regarding the spanwise variation of the induced stream angle, rate of change of downwash at zero lift, variation of downwash with angle of attack, and wake are provided.