Report presenting a method for making lifting-surface calculations by means of magnetic measurements of an electromagnetic-analogy model. The method is based on the perfect analogy between the strength of the magnetic field around a conductor and the strength of the induced-velocity field around a vortex.

Bulletin presenting a short investigation in the 19-foot pressure tunnel to determine the aerodynamic characteristics of a rectangular wing model constructed to NACA 0012 airfoil sections. Tests were run with the air in the tunnel at 2 different pressures: atmospheric and 35 pounds per square inch absolute.

Report discusses the results of two tests: "1) aerodynamic tests to determine the effect of the slipstream and thrust from the powered propellers on the lift and trimming-moment characteristics, and 2) hydrodynamic tests to determine the effect of the powered propellers on the range of stable locations of the center of gravity (from Introduction)." Large differences in the stable range between half-thrust and full-thrust conditions were observed. Three effects of power were also involved in the location of the stable range of the center of gravity.

Report presenting a detailed method for determining the jet-boundary corrections for reflection-plane models in rectangular wind tunnels. The principal effects of aerodynamic induction and boundary-induced curvature of the streamlines are considered. An example is included to illustrate the method.

Report presenting tests on a scale model of a four-engine transport airplane to determine the stability characteristics, empennage control-surface effectiveness, the effect of propeller rotation on longitudinal stability, and a method for carrying spare wing panels under the fuselage. The effect of two models of wing power operation on the characteristics of the model was studied. The results indicate that the model possess satisfactory stick-fixed longitudinal stability for all normal flight conditions except for high power with flaps extended.

Report discussing the effects of Mach number on the aerodynamic characteristics of an Allison powered single-engine pursuit airplane. Information about the lift, drag, pitching-moment characteristics, stability, tail effectiveness, and elevator effectiveness with Mach number is provided.

Report presenting an investigation of the size and distribution of ice particles on the wings of aircraft and how they affect the aerodynamic characteristics. A simulated ice formation was generated from survey information received from aircraft pilots and was tested to determine the impact on the lift characteristics.

Report presenting an investigation to develop an instrument for the determination of rain densities in this range in flight. The major requirements for the instrument are ease of operation, minimum weight and bulk, rapid response, and simplicity of installation.

Report discusses the "effects of oil introduced into the combustion chamber and of oil-spray piston cooling on the knock-limited performance of aircraft engines" (from Summary). A CFR engine and Allison V-1710 cylinder were used to test the rate of oil consumption, knock, and knock-limited brake mean effective pressure.

"General relationships for the lead susceptibilities of paraffins, cycloparaffins, and olefins are presented. Methods are described by which the lead response may be estimated for these hydrocarbon classes, whether the lead response is indicated by octane number, critical compression ratio, or indicated mean effective pressure as limited by knock" (p. 1).

Report presenting tests conducted to determine the performance of two pressurized shunt-type cooling systems for liquid-cooled aircraft engines using a mixture of 30 percent AN-E-2 ethylene glycol and 70 percent water as the coolant. Results regarding effect of engine speed on coolant-flow rate, effect of expansion-tank pressure on coolant-flow rate, relation between pump-inlet pressure and expansion-tank pressure, variation of coolant-flow rate with pump-inlet pressure, flow rate through the shunt lines, effect of coolant-flow rate on pressure drop, effect of venturi on performance of the cooling system, and the system operating experience are provided.

Report discussing a study of automatic nonreturn air valves for use in an intermittent-jet engine. Four valve-spring materials, three valve-grill materials, and five types of valves were used. Valve A, which was made out of aluminum, was found to perform the best and last the longest.

Report discussing a study of the heat-transfer processes in liquid-cooled engines, an equation that has been developed based on the testing, and additional tests on an Allison V-3420-11 engine to determine the accuracy of the equation and the cooling characteristics of the engine. The equation was found to predict heat rejection to a coolant with good accuracy.

Report presenting the results of aerodynamic tests of seven-blade propellers which were considered as a possible arrangement to avoid vibration difficulties. Variations of relative blade angle and rotational speeds of the front and rear components of a six-blade dual-rotating propeller were also investigated.

"Strain surveys were made on the stringers reinforcing a D-section box loaded in torsion and restrained from warping at the root. On the basis of the tests, a procedure is suggested for estimating the bending stresses due to torsion that occur near the flange of a D-section box. A similar test of a triangular-section box showed that for such a section there were no significant bending stresses due to torsion, a fact which was also shown theoretically" (p. 1).

"Column and plate compressive strengths of extruded 14S-T aluminum alloy were determined both within and beyond the elastic range from tests of flat-end H-section columns and from local-instability tests of H-, Z-, and channel-section columns. These tests are part of an extensive research investigation to provide data on the structural strength of various aircraft materials. The results are presented in the form of curves and charts that are suitable for use in the design and analysis of aircraft structures" (p. 1).

Report discussing the results of testing on the suitability of six aromatic amines as fuel additives. Antiknock effectiveness, availability, physical properties, and chemical properties for knock tests were explored. The six aromatic amines were xylidines, cumidines, N-methylxylidines, N-methylcumidines, N-methylaniline, and N-methyltoluidine in 28-R aviation fuel.

Report presenting a method of correlating the effects of compression ratio and inlet-air temperature on the knock limits of aviation fuels. Knock-limited performance tests of several fuels were run to check the method.

"A rain-repellent lacquer was submitted to the National Advisory Committee for Aeronautics by Captain K.H. Kalberer, of Lorr Laboratories, and preliminary tests and observations have been made to determine its value in improving the vision through an airplane windshield during rain. The tests and observations were carried out at Ames Aeronautical Laboratory, Moffett Field, California, over a period of about a week. The results are reported herein" (p. 2).

"The knock-limited performance of blends containing General Motors triptane in S reference fuel and in an S plus M base fuel was determined in 17.6, F-3, F-4, and full-scale (single cylinder) engines. The results obtained are presented and are compared with published data from similar tests of 12 aromatics, 10 paraffins (including highly purified triptane), and 2 olefins. The comparison of fuels - which is based on a consideration of (a) antiknock blending sensitivity, (b) lead susceptibility, (c) temperature sensitivity, and (d) comparison of small-scale and full-scale engine data - is presented by means of bar graphs" (p. 1).

Tests show that at inlet-air temperatures of 250 deg F and 100 deg F the knock-limited performance of the base fuel of blends, leaded with 4 ml TEL per gallon and containing 20 percent spiropentane, was reduced at fuel/air ratios below 0.085. The 20 percent methylenecyclobutane reduced the knock-limited power of the base fuel at fuel/air ratios below 0.112. Di-tert-butyl ether, methyl-tert-butyl ether, and triptane increased the knock-limited power of the base fuel at all fuel/air ratios and at both temperatures.

Report presenting an investigation to determine the knock-limited performance in a full-scale aircraft-engine cylinder of leaded blends of 10 pure hydrocarbons and a base fuel.

Report presenting an investigation to obtain force-test data on a wing design suitable for high-speed guided missiles, especially data on rolling moments produced in yawed and pitched attitudes. Force tests were conducted on two models of a wing design of low aspect ratio and 20 degree triangular plan form. Results regarding the application of results, four-unit wing design, and six-unit wing design are provided.

Report presents and discusses the improvements in hydrodynamic and aerodynamic performance of a seaplane with a retractable planing flap instead of a conventional main step. A type of flap that could be used is described and tested for hydrodynamic stability. Results regarding the trim limits of stability, limiting positions of the center of gravity, and skipping are provided.