Report presenting an investigation by lifting-surface theory of a thin elliptic wing of aspect ratio 6 in a steady roll by means of the electromagnetic-analogy method. The results obtained by lifting-surface theory indicate that the damping in roll for a wing of aspect ratio of 6 is 13 percent less than that give by lifting-line theory and 5 percent less than that given by lifting-line theory with the edge-velocity correction derived by Robert T. Jones applied. Simple practical methods of applying the results of the investigation to wings of other plan forms are given.

Report discussing tests of a model of the XP-55 to determine which modifications would prevent trim at large positive and negative angles of attack. The model was found to not trim at flat attitudes if the large wing tips with an extension of the wing-tip trimmers and a large elevator are installed on the airplane.

Report presenting the results of spin-tunnel testing of 65 models indicating that when a single-engine type airplane was simulated with mass distributed along the fuselage, the rudder was the predominant control for recovery. The primary focus of this investigation is to determine the spinning characteristics of the airplane and to develop a useful criterion for predicting the optimum control manipulation for recovery.

Report presenting two blending equations that have been derived from an analysis based on certain assumptions relative to the cause of fuel knock. The main purpose of this study was to investigate the possibility of developing a method of predicting the knock ratings of fuel blends.

Report presenting data obtained when a float with both horizontal and vertical velocity contact on a water surface. The report is confined to a presentation of the relationship between resultant velocity and impact normal acceleration for various float weights when all other parameters are constant.

Report discusses some unusual velocity-acceleration records on transport airplanes, which the report defines as "records of accelerations experienced in flight that resulted from causes other than atmospheric gusts" (from Summary). The analysis of the records, which is required for determining proper classification, is described, and the sorting of the records into gust- or maneuver-related is described. The report also discusses the importance of receiving this data from flight operators in addition to the routine information they provide.

Report presenting an investigation to develop methods and equipment for the measurement of operating stresses in aircraft-engine crankshafts and connecting rods. The results indicate that the measurement of stresses in connecting rods is feasible. Results regarding stresses in the crankshaft and stresses in the master connecting rod are provided.

"Friction and heat-dissipation data are presented for use in determining the load-carrying capacity of 2- by 1.25-inch bearings with the following types of lining: copper-lead, lead-indium-coated silver, and lead-coated copper-lead. The tests were made in a four-bearing friction machine and covered operation with three clearances using three oils of different viscosity at three oil-inlet temperatures. Values are computed to indicate the safe loads at various speeds for bearings lined with each of the three types of material" (p. 1).

Report presenting tests to determine the thermal and pressure-drop performance and durability of a cross-flow, internally finned, tubular exhaust-heat exchanger. The test covered a range of exhaust-gas flows, cooling-air flows, and exhaust-gas temperatures.

Report presenting testing to determine the stresses and bending moments required to break pieces 1 inch or less in length from the ends of cast-iron, keystone, compression piston rings. Strain gages were used to determine the stress pattern for various modes of vibration. The maximum-stress points of vibrating piston rings were at the antinodes or points of maximum deflection.

"At the request of the Bureau of Aeronautics, Navy Department, tests were made in the 7- by 10-foot wind tunnel of the 1/8-scale model of the Brewster F2A airplane with full-span slotted flaps. The object of the tests was to determine the power-on static lateral and longitudinal stability of the complete model with a new wing which had a full-span slotted flap and a plain and slot-lip aileron for lateral control" (p. 1).

Report investigating the theoretical sea-level performance of an explosion jet-propulsion engine similar to the German flying bomb to show the effects on performance of heat added and supercharging and a comparison was drawn between the performance of the explosion engine and the constant-pressure engine. The explosion engine was found to be more efficient than the constant-pressure engine at compressor pressure ratios below 3.0 when the maximum gas temperature of the constant-pressure engine is 1600 degrees Fahrenheit.

Report presenting a report illustrated by photographs and vibration records on the failure of the P-47 rudder in the high-speed tunnel at a true speed of 468 miles per hour and a density corresponding to 9000 feet altitude. The fin-rudder unit was tested as being at least representative of the tail design of the P-47 airplane.

Report presenting samples of 17S-T and 24S-T aluminum alloys subjected to accelerated corrosion tests in which the corrosion period was established at 6 hours for samples that had been etched to produce a uniform surface. The results indicate the types of corrosion attack, which are described in standard terminology, and may form a basis for estimating the resistance of the material to corrosion by a comparison of the relative depth and frequency of the corrosive attacks.

Report discussing an investigation to determine the effect of omitting some of the fuel constituents in AN-F-28 Amendment 2 fuel that are normally lost in flight on fuel-vapor loss. Removing the components was found to decrease the fuel-vapor loss and increase the critical altitudes.

Wind-tunnel tests, investigating low drag wing performance in small-scale tests, showed a large increase in minimum drag coefficient, and a decrease of maximum lift coefficient occurred with decreasing Reynolds Number above certain designated values. The lift-curve slope varied up to 6% between high and low turbulence levels. Low Reynolds Number test data are unreliable for low drag airfoils either to estimate full-scale characteristics or to determine merits of airfoils for higher Reynolds numbers.

Report presenting a discussion of the problem of establishing a rational unsymmetrical gust load criterion from available data on gust structure and it is indicated that the problem cannot be solved at the present state of knowledge without more analysis.

Report presenting a generalized drag curve providing an estimate for the drag rise due to compressibility as obtained from an analysis of wind-tunnel data of several airfoils, fuselages, nacelles, and windshields at speeds up to and above the wing critical speed. Results regarding drag characteristics and terminal-velocity calculation are provided.

Report presenting an investigation to determine the permissible increase in engine power by using various internal coolants from the consideration of fuel knock and cylinder cooling. The internal coolants tested were water, 30-70 methyl alcohol-water volume percent mixture, 70-30 methyl alcohol-water volume percent mixture, methyl alcohol, and 80-20 ethyl alcohol-water volume percent mixture.

Report discussing spin tests performed on a scale model of the Curtiss-Wright XP-55 airplane. A large elevator with increased deflections and large wing tips with extensions were installed to improve the longitudinal-trim characteristics. Information about the spins, attitude after rotation, and recommended technique for spin recovery is provided.

Report discuss the results of force tests, yaw-trim tests, and power-off tests to compare the stability and control characteristics of a powered airplane model in the erect and inverted flight attitudes. Due to the violent and uncontrollable maneuvers that sometimes occur after flight in the inverted attitude, more information was requested about stability and control characteristics in this position. Testing found that with the power on, a serious reduction in longitudinal and directional stability occurred in inverted flight.

Report on the NACA recommended method for comparing the performance of centrifugal compressors. The most important indices of compressor performance are the adiabatic temperature rise ratio or adiabatic efficiency, the adiabatic shaft efficiency, and the pressure ratio, which incorporate many other parameters. Recommendations for reporting on compressor effectiveness and characteristics are provided.

Report on the NACA test-rig installation, measurements, instrumentation, test procedure, methods of calculation, and presentation of data for rating and testing centrifugal superchargers. Special precautions for certain portions of testing are also provided.

Report presenting static tests on four full-scale two-bladed propellers differing only in blade sections at blade angles from 0 to 20 degrees at the three-quarters radius. Two of the propellers were also tested as three-bladed propellers. For all of the propellers tested, the highest value of the static thrust figure of merit occurred at a tip-speed ratio between 0.7 and 0.9; the highest efficiency in flight may be expected in the same range of tip-speed ratios.