Report presenting the utilization of the differential equation of Chaplygin's jet problem to give a systematic development of particular solutions of the hodograph flow equations, which extends the treatment of Chaplygin into the supersonic range and completes the set of particular solutions. The solutions serve to place on a reasonable basis the use of velocity correction formulas for the comparison of incompressible and compressible flows.

Lift characteristics and pressure distribution for a NACA 230 wing were investigated for an angle of attack range of from -10 to +24 degrees and Mach range of from 0.2 to 0.7. Maximum lift coefficient increased up to a Mach number of 0.3, decreased rapidly to a Mach number of 0.55, and then decreased moderately. At high speeds, maximum lift coefficient was reached at from 10 to 12 degrees beyond the stalling angle. In high-speed stalls, resultant load underwent a moderate shift outward.

Report presenting tests in the two-dimensional low-turbulence pressure tunnel to study the interference effects of various pusher-propeller shaft-housing combinations on a low-drag airfoil. Thirty different combinations were tested, variations being made in shaft size, shape, angle, and fillet.

Report presenting the magnitude of slipstream contraction, which provides information about the conditions of the ultimate wake. Curves and tables are given for the contraction coefficient of two-blade and four-blade propellers for various values of the advance ratio; the contraction coefficient is defined as the contraction in the diameter of the wake helix in terms of the wake diameter at infinity.

Report presenting simple and exact expressions for the efficiency of single- and dual-rotating propellers with ideal circulation distribution as given by Goldstein functions for single-rotating propellers and by the new functions for dual-rotating propellers from part I of this series. Efficiency is found to depend primarily on a defined load factor and on an axial loss factor. Tables and graphs are included for practical use of the results.

Report presenting a cascade investigation in two-dimensional flow in the 5-inch cascade tunnel and the 1-inch turbine-element testing apparatus to obtain a satisfactory bucket design for use in a modern aircraft turbosupercharger. Results regarding the root sections, pitch sections, and tip sections are provided.

Report presenting cast-iron piston rings that were run in nitrided-steel cylinder barrels under scuffing conditions and showed a coating material on the scuffed areas. Only a few of the 14 etching reagents that were tried attacked the coating chemically, indicating good corrosion resistance. Results regarding the occurrence of coating, metallurgical characteristics, and chemical characteristics are provided.

Report presenting the results of tests of a model of a single-engine airplane with two different tilts of the propeller axis. The results indicate that on a typical design, a 5 degree downward tilt of the propeller axis will considerably reduce the destabilizing effects of power.

Report presenting an investigation in the 7- by 10-foot wind tunnel of an NACA 23012 airfoil with a 15-percent-chord and a 25-percent-chord balanced split flap of Clark Y profile. The primary purpose was to determine the aerodynamic section characteristics of the airfoil as affected by the size, nose location, and deflection of the flap.

Report presenting a consideration of the general problem of stalling as affecting the safety of airplanes. The increased difficulties associated with modern efficient wings, particularly highly tapered wings and high-life devices, are discussed and means are considered for avoiding these difficulties.

Report presenting a description of an experimental model of a flight instrument that utilizes infrared radiations for detecting and indicating the location of clouds at night. A preliminary investigation is made of data in the scientific literature. A table and chart are developed that make it practical to determine the magnitude of the net exchange of radiation for any particular atmosphere of known composition and distribution of temperature.

Report presenting an investigation of the flow downstream from a two-dimensional grid formed of parallel rods. The nature of the flow was determined primarily by means of total-head measurements. Preliminary tests were made in both the closed-duct and open, two-dimensional configurations, but it was found that the same phenomenon occurred in both cases.

Report presenting testing in the 8-foot high-speed wind tunnel to determine the effect on external drag and pressure distribution of air inlet openings on the stagnation point of a streamline body. The results showed that external drag of the body with suitably designed nose-inlet and tail-outlet openings over a wide range of rates of internal air flow was no higher than the drag of the streamline body. Specific results for the streamline body, nose-inlet openings, outlet openings, and inlet-outlet combinations are provided.

Report presenting pressure distribution testing of an NACA 66,2-216, a = 1.0 airfoil equipped with a blunt nose balance aileron and a sealed internal-balance aileron and of an NACA 23012 airfoil equipped with a Frise aileron and a blunt nose balance aileron in the stability tunnel. Results regarding the section pressure distribution and section loads and moments are provided.

Report presenting a consideration of the possibility of using conducting rubber as the conductor in aircraft ignition cable. The effects of stretch, temperature, and continuous and impulsive currents on the resistance of several conducting-rubber test strips of the same position were determined. Two types of experimental conducting-rubber cable were tested.

Report presenting an investigation of the effects of 0.20-aileron-chord tabs on an NACA 66,2-216 airfoil equipped with a 0.20-airfoil-chord plain sealed aileron. Basic data are presented from which the effect of tabs can be calculated for specific cases. The data are sufficient for the solution of problems of fixed tabs with a differential linkage, as well as simple and spring-linked balancing tabs.

Report presenting an investigation of a long column continuous over three supports to determine its critical load when the center support was given varying amounts of initial displacement. During each test, the middle support was hinged so as to be free to move parallel to the column axis during buckling. The critical loads predicted from load-deflection readings were different for the upper and lower spans.

"Flight tests were conducted on the XP-41 airplane, equipped with a Pratt & Whitney R1830-19, 14-cylinder, air-cooled engine, to determine the increase in flight speed obtainable by the use of individual exhaust stacks directly rearwardly to obtain exhaust-gas thrust. Speed increases up to 13 miles per hour at 20,000 feet altitude were obtained using stacks having an exit area of 3.42 square inches for each cylinder. A slight increase in engine power and decrease in cylinder temperature at a given manifold pressure were obtained with the individual stacks as compared with a collector-ring installation" (p. 1).