Report presenting an investigation to determine the properties of diffuser-resistance combinations. The work applies to the design of airplane cooling ducts in which air is expanded in front of resistances, such as radiators, oil coolers, intercoolers, or the cylinders of an air-cooled engine.

"A discussion of the general principles involved in the rating and testing of centrifugal superchargers, a statement and discussion of present standard methods in rating and testing, and reasons for the adoption of these standards are given" (p. 1).

Report presenting data on the rolling accelerations of airplanes of different types and sizes in abrupt aileron rolls in connection with a number of maneuverability and flying qualities investigations. An analysis was made to determine the relation between the torque applied to the aileron system by the pilot, the motion of the system, and the subsequent rolling motion of the airplane in abrupt aileron roll.

Report presenting an investigation in the 7- by 10-foot wind tunnel of an NACA 23012 airfoil equipped with a Handley Page slat and a slotted and a split flap. The purpose of the investigation was to determine the aerodynamic section characteristics of the airfoil with and without flaps as affected by the location of the Handley Page slat. A range of slat-nose locations was investigated both with and without flaps at a constant slat gap.

Report presenting an investigation of the internal and external airflow characteristics of carburetor-air inlets for liquid-cooled engine installations in the full-scale wind tunnel. Full-scale models of two representative pursuit airplanes were used in the investigation of nine carburetor-air inlets differing in shape, size, and location. Results regarding air flow and ram, drag, and compressibility are provided.

Report presenting tests of 10-foot-diameter, single- and dual-rotating pusher propellers with three to eight blades that were conducted in the 20-foot propeller research tunnel as a continuation of previous investigations of tractor propellers. The propellers were mounted at the rear end of a streamline body in spinners that covered the hubs and part of the shanks. The effects as compared to previous testing differed only in degree of effect size.

Report presenting a series of models of flying-boat hulls tested to determine the effects of the angle of dead rise and the angle of afterbody keel on resistance and spray characteristics. Three angles of dead rise and three angles of afterbody keel were investigated. The results are expressed in nondimensional coefficients.

Report presenting general formulas for determining the jet-boundary corrections to the angle of attack, the drag coefficient, the downwash, the pitching, rolling, and yawing-moment coefficients of complete powered yawed models, and to the increments of rolling and yawing-moment coefficients due to the ailerons on yawed models.

From Summary: "Results are presented of measurement of the pressure drop in ducts produced by two equal 90 degree elbows arranged at three different angular positions to each other, placed adjacent to each other, or separated by straight ducts of various lengths. The measured pressure drops have been analyzed and correlated, and the results are summarized in the form of curves adapted for design computations of pressure drop in compound-duct bends."

Report presenting a detailed account of approximately half of the work planned for a specified contract. The work called for fatigue tests on three simple but basic types of spot-welded test pieces made from 24S-T alclad. The primary purpose of the investigation was determining the mechanism of fatigue failures in the different types of test pieces.

Report presenting an investigation to find a means of obtaining undiluted exhaust-gas samples from a Wright R-2600-B aircraft engine equipped with short individual stacks. Preliminary tests to aid in determining the best design, location, and orientation of orifices ranging in size. Results regarding the Briggs & Stratton engine tests and Wright aircraft engine tests are provided.

Characteristics are determined for various modifications of 0.155-chord blunt-nose aileron on semispan model of tapered fighter plane wing. Ailerons with 40 percent nose balance reduced high-speed stick forces. Increased balance chord increases effectiveness and reduces high-speed stick forces. Increased balance chord increases effectiveness and reduces adverse effects of gap at aileron hose. Increase of nose radii increased negative slope of curve hinge-movement coefficient plotted against deflection. Extended deflection range decreased aileron effectiveness for small deflections but increased it at large deflections. Peak pressures at noses of ailerons are relatively high at moderate deflections.

Report presenting tests in the propeller research tunnel to determine the characteristics at low blade angles of propellers for which high blade angles are already available.

Report presenting compression testing on several series of flat panels with Z-section stiffeners with varying relative dimensions. The data presented show the effect of dimension ratio on the buckling stress for the sheet and on average stress at maximum load.

Report presenting corrections to the velocities near a cowling-flap tip in order to determine jet-boundary corrections to cowling-flap-outlet pressures. The presence of the low-energy air leaving the flap opening was taken into account by so shaping the nacelle model that its outer surface represented the stream surface leaving the flap tip. Copper was found unsatisfactory for use as electrode material.

Report presenting measurements in the full-scale tunnel of the pressure distribution over the horizontal tail surface of a typical pursuit airplane in order to determine the effects of propeller operation and angle of yaw on the tail load distribution. Most of the tests were made with the propeller operating to simulate climb conditions, high-speed dives, and pull-ups to various normal accelerations for a range of angles of yaw. Results regarding chordwise pressure distributions, spanwise distributions of normal-force coefficient, airflow measurements, and tail-load asymmetry are provided.

Report presenting an extension of tables of stiffness and carry-over factor to include the stiffness of a member with the far end subjected to a moment equal and opposite to the moment applied at the near end. The formulas used in calculation to determine the values are also provided.

Report presenting testing made on a Wright 1820-G single-cylinder engine to determine the effect of operating variables and the effect of shape and size of the exhaust stack on the visibility of exhaust gases for individual-stack installations. Flame damping was improved by decrease in nozzle-exit area, increase in stack length, and reduction in hydraulic diameter of the exhaust jets. Results regarding the characteristics of exhaust flames and damping of exhaust flames are provided.

Report presenting performance tests of the thermal ice-prevention equipment developed for the B-17F airplane at the NACA Ice Research Project. Temperatures of the heated surfaces, structure, and circulating air and the air-flow rate and quantity of heat through the system were obtained during flights in dry air and in natural icing conditions. Results regarding the wing outer panel, wing tip, wing inner panel, carburetor and intercooler inlets, horizontal stabilizer, vertical stabilizer, windshield, windows, and engine cowls are provided.

Report re-examining known procedures for handling general resistance testing on flying-boat hull models, with particular attention paid to saving test time and improving the usefulness of the results to designers. While specific testing will likely always be needed, the procedures given in the report for condensing resistance data should make data analysis easier to apply to design.

Report presenting an investigation conducted with alcohol used in conjunction with a windshield wiper as a means of affording protection against ice formation on the windshields of aircraft when operating in inclement weather. Flight tests established the most economical flow rate of isopropyl alcohol to provide adequate ice prevention. The optimum location and size of the alcohol-distribution tube and orifices were determined for the specific installation investigated.

"The relation between the elevator hinge-moment parameters and the control forces for changes in forward speed and in maneuvers is shown for several values of static stability and elevator mass balance" (p. 1). Factors affecting stability positively and negatively are presented and potential modifications to the elevator control system are provided. The amount of solid friction present was found to be one of the greatest predictors of instability.

Report presenting an attempt to establish a correlation of the cooling characteristics of the Wright R-2600-8 engine with water as an internal coolant and to investigate methods of introducing the water. A cooling correlation, including the effect of water as an internal coolant, was established by use of the NACA cooling-correlation method. Results regarding the cooling-performance predictions and engine condition are provided.

Report presenting an investigation of a special single-cylinder test engine constructed with provision for operation with three different lengths of piston stroke. Results regarding the air capacity of the engine, extent to which the spark must be retarded in order to prevent detonation, and brake mean effective pressure are provided.