Report presenting a study to determine the effect of several methods of increasing the knock-limited power on critical cylinder temperatures. The knock-limited indicated horsepower and cylinder temperatures were determined for a Wright R-2600-8 cylinder under specified operating conditions. The most satisfactory method of increasing knock limited power was found to be internal cooling with water and the least satisfacotry was increasing the engine speed.

Report presenting a combination oil sump and scavenge pump constructed to eliminate some of the oil-system difficulties in an aircraft engine that result from the aeration of the scavenged engine oil and air-lock of the scavenge pump. Information regarding test results and design recommendations are provided.

Report discusses the results of an investigation into the effectiveness of water injection into the combustion end zone of a spark-ignition engine cylinder for the suppression of knock. The injection angle was found to be very important for obtaining maximum results. The results of various angles and amounts of water were examined.

Report presenting an investigation to determine the knock-limited power obtainable by injecting water solutions of monomethylamine and dimethylamine as internal coolants into a CFR engine using AN-F-28, Amendment-2, fuel.

Report presenting simple curves by which the basic pressure-drop characteristics of unheated tubular radiators can be corrected to operating conditions in which the radiator is heated and in which the Mach number of the tube flow is of appreciable magnitude. The only data required for the use of the curves are the radiator dimensions, the rate of heat input, the pressure and temperature ahead of the radiator, and the rate of mass flow of air through the radiator.

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 flight tests of a Curtiss No. 714-102-12 four-blade propeller on a Republic P-47C airplane in climb and at high speeds.

Report presenting an investigation of the possibility of using internal cooling instead of fuel enrichment to suppress knock and to estimate the fuel savings that will result. Data from four different sources was examined and an analysis of the fuel consumption was conducted. Four different types of coolants were explored.

From Summary: "A method is outlined for determining in flight the weight rate of air flow to the engine equipped with a Bendix-Stromberg injection-type carburetor. The method has the advantage that no additional equipment need be inserted in the charge-air system and only a few simple measurements are necessary. The analysis of an air-box calibration of the carburetor to be used in interpreting the flight measurements is shown by an example."

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.

"The lubrication of a piston ring is treated as though the ring were a rigid slider of finite width. An expression is obtained for pressure distribution which takes into account the effect of oil leakage from the ends of the ring and which has the convenient form of an end correction to the pressure-distribution formula for an infinite slider. The important formulas are summarized for convenience and two examples are included of their use in finding the pressure pattern over wide sliders" (p. 1).

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 discusses an investigation into piston and ring friction as compared to total engine friction under natural operating conditions. Several test conditions were explored, including the effect of scuffing and excess cylinder-wall lubrication on friction. A device for measuring ring tensions and an apparatus for transforming pressure-crank angle indicator diagrams into pressure-volume indicator diagrams are also described.

Report presenting testing in the pressure tunnel to determine the yaw characteristics of a scale model of a single-engine, fighter-type airplane with six-blade single-rotating and dual-rotating propellers. Force and moment characteristics are presented for several model and power conditions.

Report details the methods of determining the heat-transfer rate, pressure drop, and drag power of high-altitude radiators. Performance charts are provided for a wide range of design variables.

Engine tests, together with estimates made at Langley Memorial Aeronautical Laboratory, indicate that a 25-percent increase in take-off power can be obtained with present-day aircraft engines without increasing either the knock limit of the fuel or the external cooling requirements of the engine. This increase in power with present fuels and present external cooling is made possible through the use of an internal coolant inducted through the inlet manifold. Estimates on aircraft indicate that this 25-percent increase in power will permit an approximate usable increase of 8.5 percent in the take-off load of existing military airplanes. This increase in load is equivalent to an increase in the weight of gasoline normally carried of between 30 and 65 percent.

Report presenting a paper in a series about the cooling of aircraft-engine installations with special reference to the difficulties of cooling at high altitudes. This particular paper discusses the properties of NACA standard air and Army summer air, with corresponding stagnation conditions for a range of flight speed, as summarized in tables and figures.

Report presenting the heat-transfer theory for air-cooled engines and an analysis of the cooling pressure drop for the case in which the pressure drop is an appreciable fraction of the absolute pressure. A chart is given for the simple determination of the cooling pressure drop predicted on the basis of the usual type of sea-level cooling-correlation tests.

Report presenting a detailed analysis to take account of the high cooling-air velocity occurring in high-altitude radiators. Methods are developed for determining the heat-transfer rate, the pressure drop, and the drag power. Radiator performance charts based on the analysis are presented for a wide range of the design variables.

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.

Report presenting an investigation to determine the possibility of attaining or approaching critical-altitude power at altitudes considerably higher than the critical as limited by the supercharger by the use of oxygen in conjunction with internal coolants.

Report presenting an analysis of the effect of cooling-air blowers on thrust power using an assumed airplane. Results indicated that when aviation-engine heat exchangers are used above their design altitude, blowers may be used to give additional available pressure and to increase jet thrust. Results regarding airplane speed, altitude, fin width, physical significance of the heat cycle, and thermodynamic efficiency are provided.

From Introduction: "The purpose of this report is to show that it is practical to apply a least-squares method to the correlation of engine-cooling data."

Report discussing some calculations made for the effects of water in cooling the inlet air of aircraft-engine cylinders. From Summary: "The estimates indicate that the cooling effect of the water on the inlet air can be more extensive than the cooling now obtained with the intercoolers or aftercoolers in the air-induction system. In connection with water recovery from the exhaust gas, the estimates indicate that sufficient water can be recovered from 50 percent of the exhaust gas to provide an inducted water-fuel ratio of 0.5."