Note presenting an investigation in the icing research tunnel to determine the icing protection provided by external rubber-clad blade heaters at several icing, heating, and propeller operating conditions. Data are presented to show the effect of propeller speed, ambient-air temperature, liquid-water concentration, heating-power density, duration of heating, and total cycle times on the power requirements and de-icing performance of the blade heaters.

Note presenting an investigation in the icing research tunnel to determine the icing protection provided by external rubber-clad blade heaters at several icing, heating, and propeller operating conditions. Data are presented to show the effect of propeller speed, ambient-air temperature, liquid-water concentration, heating-power density, duration of heating, and total cycle times on the power requirements and de-icing performance of the blade heaters.

Note presenting a theoretical investigation made of the motions and hydrodynamic loads experienced by V-bottom seaplanes during the course of a step-landing impact. In the analysis, the primary flow about the immersed portion of a keeled float or hull is considered to occur in transverse flow planes and the virtual-mass concept is applied to calculate the reaction of the water to the motion of the seaplane. The results are presented in the form of dimensionless curves which may be used to predict the behavior of V-bottom seaplanes at all instants during an impact as well as at the particular instants of maximum acceleration, maximum draft, and rebound.

Report presenting the results of a series of fatigue testing of aluminum-alloy sheet materials and simple riveted joints. The materials tested were 24S-T Alclad, 24S-T bare, 75S-T Alclad, R303-T275 clad, and R303-T275 bare.

"Results are presented of tests of several 24S-T aluminum-alloy thin-web beams with transverse load applied at the end of an intermediate upright. A method of computing stresses and predicting failures in these directly loaded uprights is presented. A comparison between the experimental and calculated results is given" (p. 1).

Report describing pure bending testing of nine 24-ST Alclad cylinders of 20-inch diameter, 39-inch to 90-inch length, and 0.012-inch wall thickness, reinforced with 24-ST aluminum-alloy stringers and rings. All nine cylinders tested failed in general instability. Results regarding the nonlinearity of normal strain distribution, strain in sheet covering, equilibrium of forces and moments, strain variation along stringers, strain trajectories, variation of strain with applied movement, strain factors, and general instability are provided.

Note presenting compressive tests made of six different lengths of a ZK60A magnesium-alloy flat panel with skin and longitudinal T-section stiffeners extruded as one integral unit. The results indicated that the extruded panel had structural characteristics somewhere between those for 24S-T and 75S-T aluminum-alloy construction, but required far fewer rivets to assemble than those panels.

Note presenting an investigation in the icing research tunnel to determine the icing protection provided by external rubber-clad blade heaters at several icing, heating, and propeller operating conditions. Data are presented to show the effect of propeller speed, ambient-air temperature, liquid-water concentration, heating-power density, duration of heating, and total cycle times on the power requirements and de-icing performance of the blade heaters.

Report presenting results of the effects on propeller efficiency of thermal de-icing of airplane propellers by use of internal flow through hollow blades. Wind tunnel tests were made of a propeller with blades embodying tip orifices.

Note presenting a method for calculating the effect of wing flexibility on the rolling moment due to sideslip for wings of various aspect ratios and taper ratios when different shapes of the bending-deflection curve are assumed. The shape of the deflection curve is shown to be unimportant, the main factor being the amount of wing-tip deflection.

Note presenting a theoretical analysis of the hovering performance of rotors with various combinations of twist and plan-form taper in order to estimate the effects of blade twist and taper on rotor efficiency in hovering. The calculations were made with the aid of a strip-analysis procedure similar to that used in propeller analysis, the comparisons being made for rotors of equal solidity.

Results regarding the total horizontal-tail load and the root bending-moment increments calculated by use of existing rational procedures compared with the experimental values obtained in pull-up push-down maneuvers on a propeller-driven pursuit-type airplane for six combinations of power, indicated airspeed, and pressure altitude.

From Summary: "An analysis is presented of the characteristics of gas-filled bellows for sensing gas density to delineate the factors that affect the accuracy of this type of bellows."

From Introduction: "The results of varying only Reynolds number for several equivalent tip speeds are presented and probable reasons for the apparent variation of adiabatic efficiency with inlet temperature are discussed."

Report presenting an investigation of the take-off performance of light twin-float seaplanes of the personal-owner or military-observation type by means of typical take-off calculations. Generally, the take-off performance of seaplanes of this type is adversely affected by high resistance at planing speeds. Results regarding the airplane characteristics, wing and propeller characteristics, float characteristics, and float size and dimensions are provided.

Report presenting a procedure for calculating the frequencies and modes of nonuniform beams in uncoupled bending and torsional vibration. The method is quick, easy, and can be learned by anyone familiar with engineering beam theory. Nine examples are provided in order to demonstrate the effectiveness on the calculation method on a variety of beams.

Report presenting a series of tests of a 45 degree sweptback-wing model with and without fuselage and an equivalent straight-wing model in the gust tunnel to provide information on some of the problems encountered in the prediction of gust loads for airplanes incorporating swept wings.

Report presenting an application of the Falkner lifting-surface-theory method to predicting hinge-moment and lift parameters for sweptback plan forms in order to develop an analogue to the existing lifting-surface-theory procedure for prediction of these parameters on unswept plan forms. For two specific plan forms, the hinge-moment predictions based on the Falkner method were not in good agreement with experimental values.

Report presenting an investigation of the characteristics of a representative group of heat-resistant alloys in sheet form by rupture tests at 1700 and 1800 degrees Fahrenheit. The primary purpose was to provide data that could be used to determine whether the rupture-test properties of an alloy could be a criterion of service performance in combustion chambers and other applications of sheet alloys at high temperatures.

Report presenting an examination of a machine developed to study the ignition delay of fuels by means of a rapid adiabatic compression. The essential features of the machine are that the compression is completed in about 0.006 second, provision is made for obtaining simultaneous records of piston motion and cylinder pressure, and the combustion cylinder is unlubricated. An extensive explanation of the components of the machine and its applicability to different scenarios are provided.

Report presenting outdoor static testing made on two high-solidity propellers of different design, one shrouded and the other unshrouded. Three shrouds were tested to determine the effects of shroud length and exit area. Results regarding the action of shroud, results and comparison of propellers, and comparison with theory are provided.

Report presenting an investigation to correlate the engine service performance of cast Vitallium turbine buckets with standard laboratory metallurgical data. Data was obtained on four turbine wheels of Timken alloy with cast Vitallium buckets. Results regarding the engine test and metallurgical examination are provided.

Report presenting an investigation of an NACA 65A006 airfoil equipped with high-lift devices, including a 0.15-chord drooped-nose flap and a 0.20-chord plain trailing-edge flap. Airfoil section lift, pitching-moment, and drag characteristics obtained at high Reynolds numbers and low Mach numbers with the flaps deflected individually and simultaneously are presented. At Reynolds numbers up to 9.0 x 10(exp 6), the optimum combination of drooped-nose and plain trailing-edge flaps increased the maximum section lift coefficients from 0.78 to 1.89.

Report presenting high-speed wind tunnel testing of horn- and overhang-balance elevators on a full-scale, semispan, horizontal tail. The effects of unshielding the horn and unsealing the overhang were investigated. Results regarding aerodynamic characteristics, distortions of the tail, and critical Mach numbers are provided.