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 wind-tunnel testing in two-dimensional flow to investigate the aerodynamic characteristics of a flap balanced by a large overhang linked to deflect more slowly than the flap. Three lengths of blunt-nose overhang were tested linked to a 0.30-airfoil-chord straight-contour flap on an NACA 66-009 airfoil. Results regarding lift, hinge moment, drag, pitching moment, and practical considerations are provided.

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.

"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 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 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.

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 the effect of internal cooling on the knock-limited performance of AN-F-28 fuel in a CFR engine with the following internal coolants: water, methyl alcohol-water mixture, ammonia-methyl alcohol-water mixture, monomethyllamine-water mixture, dimethylamine-water mixture, and trimethylamine-water mixture.

"Two graphical methods are presented for determining the stick-free neutral point, and they are extensions of the methods commonly used to determine the stick-free neutral point. A mathematical formula for computing the stick-free neutral point is also given. These methods may be applied to determine approximately the increase in tail size necessary to shift the neutral point (stick fixed or free) to any desired location on an airplane having inadequate longitudinal stability" (p. 1).

Report presenting an investigation of the effectiveness of suction slots a a means of extending the laminar boundary layer in flight at high Reynolds numbers using an NACA 35-215 airfoil. Tests were made over a range of indicated airspeeds, lift coefficients, and Reynolds numbers. Results regarding boundary-layer control, air-intake distributions, character of the boundary layer, total-intake rate, and profile-drag coefficient are provided.

Report presenting a tabular method for determining the span load distribution at high Mach numbers by utilizing high-speed airfoil section data. This method, which is also called the generalized method, is an easily applied process of successive approximations by which a general application of the lifting-line theory may be used to determine the span load distribution for wings composed of sections with arbitrary lift curves. An example is provided to show how the method is used.

Report discusses tests conducted using a model of a four-engine long-range flying boat with a 30 degree V-step and two different transverse steps of comparable positions and depths. The limits of stability, landing speed, and landing characteristics of the different models are presented.

Report presenting tests in the gust tunnel on a scale model of the XBDR-1 airplane to verify the calculated effective gust factor. Tests were made for three gust shapes, one forward velocity, and one wing loading. The test results and analysis were in good agreement and the results of the analysis indicated that there was an appreciable change in effective gust factor for the center-of-gravity movement considered.

Results are presented for tests of two wings, an NACA 230-series wing and a highly-cambered NACA 66-series wing on a twin-engine pursuit airplane. Auxiliary control flaps were tested in combinations with each wing. Data showing comparison of high-speed aerodynamic characteristics of the model when equipped with each wing, the effect of the auxiliary control flaps on aerodynamic characteristics, and elevator effectiveness for the model with the 66-series wing are presented. High-speed aerodynamic characteristics of the model were improved with the 66-series wing.

"A model of a flying boat was tested to determine the landing characteristics when the depth of the step was reduced to zero by means of a retractable planing flap on the forebody" (p. 4). The results of stability and resistance testing are presented.

"Strength tests were made on two sets of beams having webs with large circular lightening holes. The main conclusion drawn from the tests is that allowable web stressed derived from pure shear tests and allowable flange stresses derived from compression tests cannot be applied in the design of beams without making corrections for interaction" (p. 1). Pure shear tests and beam tests were performed and the circumstances of failure were investigated.

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 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 presenting the calculated performance of four-, six-, and eight-blade single-rotating propellers compared with experimental results for blade angles ranging from 25 to 65 degrees. The data were obtained on propellers mounted in front of a streamline body with a spinner housing the hub.

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 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.

Report presenting an equation based on simple blade-element theory and the assumption of a fixed wake pattern is derived and fitted to available data to show the first-order relation between the parameters of propeller operation and intensity of wake-excited periodic force acting on the blades of a pusher propeller. The derived equation indicates that the effect of power coefficient on the intensity of the wake-excited periodic force is small. Limited data also indicates that the wake-excited vibratory stress in a propeller increases with the drag of the body producing the wake.