Report presenting force tests of the NACA 23012 and 23012-64 airfoils of 24-inch chord in the high-speed wind tunnel at a range of Mach numbers. The results show the variation with mach number of lift, drag, and pitching-moment coefficients at a range of angles of attack.

Report presenting an investigation in the 7- by 10-foot wind tunnel of a large-chord NACA 23021 airfoil with a 15-percent-chord and a 25-percent-chord balanced split flap of Clark Y profile, to determine the aerodynamic section characteristics of the airfoil-flap combinations as affected by the size, nose location, and deflection of the flaps.

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).

Summary presenting information on flush-riveted joints for aircraft construction, including the strength, occurrence of defects, and effect of the angle of rivet head. The current tests covers specimens from 15 manufacturers of which 5 series have been completed and are described in this report.

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.

"The measurement of pressure distribution may be accomplished rapidly for any number of locations deemed necessary in model or full-scale investigations by use of the 'belt' method. Reasonable accuracy may be obtained by careful use of this method" (p. 1).

Report presenting a thermal ice-prevention system for the B-24D airplane. The report includes a description of the design and an outline of the method of design analysis. Results of performance tests of the installation will be presented in a supplementary report.

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 testing of the flutter characteristics of the SB2U-2 airplane. The secondary purpose of the test, which ended up being the primary purpose, was to study the behavior of the airplane just below the flutter speed. Results regarding flutter amplitude, frequencies, and energy-absorbing qualities are provided.

Report presenting an investigation of the effect of wing loading, power loading, and aspect ratio on the performance of pursuit airplanes. The study is based on data combined from specifications, wind-tunnel, and flight tests of various airplanes and presented in graphs.

Report presenting tests on a scale model of a four-engine cargo airplane, which was tested in the high-speed wind tunnel. The high-speed characteristics of the airplane, particularly the longitudinal stability and control in dives were investigated. Test results indicated that no important changes in longitudinal stability or controllability occurred until the speed exceeded the predicted maximum level-flight speed by more than 38 percent.

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.

Report presenting a method utilizing the Doppler effect on radio signals for determining the speed and distance traveled of an airplane. The method is called the NACA radio ground-speed system and uses the standard radio transmitter already found in most aircraft. Flight tests were made in which the method was used and the results were consisted with calibrated airspeed indications and stop-watch measurements.

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 analysis of the pressure drop that is required to cool a typically baffled radial engine, which shows that a total pressure drop of 58 pounds per square foot is necessary at sea level and 112 pounds per square foot is required at an altitude of 40,000 feet.

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 discusses an investigation that was conducted to compare the strength and tightness of machine-countersunk flush-riveted joints assembled with NACA flush rivets and a type of commercial flush rivet. A comparison was also generated between the strength and tightness of counterpunched flush-riveted joints assembled with the same types of rivet. NACA's flush-riveted joints tended to be stronger and tighter than the commercial joints.