Description: This report provides a description of the Benz 300 H.P. aircraft engine containing 12 cylinders placed at a 60° angle. It includes a detailed description of the development of the constructional points, particularly the cylinders, pistons, and connecting rods, as well as the engine fitting, lubrication, oil pumps, bearings, oil tank, fuel pump, carburetors, and cooling system. There are seven pages of illustrative figures at the end of the report.

Description: A description is given of a tilting manometer designed to meet the requirements of a manometer for use in the wind tunnel at the Langley Memorial Aeronautical Laboratory. This gauge was designed to meet the requirements of a manometer in use in connection with a static pressure plate to indicate the wind speed in the tunnel. The requirements are noted. The sensitivity of the gauge must be made inversely proportional to the pressure to be measured. The gauge must be accurately and quickly set for any desired pressure. When set at the desired pressure, the extent of variation between the existing and the desired pressures may be readily estimated. In fact, this manometer is quick to adjust, is easy to read, always has the meniscus in the same position, and accurately indicates a large range of air speeds on what is a comparatively compact instrument.

Description: It is argued that there should be an agreement as to what conventions to use in determining absolute coefficients used in aeronautics and in how to plot those coefficients. Of particular importance are the absolute coefficients of lift and drag. The author argues for the use of the German method over the kind in common use in the United States and England, and for the Continental over the usual American and British method of graphically representing the characteristics of an airfoil. The author notes that, on the whole, it appears that the use of natural absolute coefficients in a polar diagram is the logical method for presentation of airfoil characteristics, and that serious consideration should be given to the advisability of adopting this method in all countries, in order to advance uniformity and accuracy in the science of aeronautics.

Description: Issues and techniques relative to the adaptation of aircraft engines to high altitude flight are discussed. Covered here are the limits of engine output, modifications and characteristics of high altitude engines, the influence of air density on the proportions of fuel mixtures, methods of varying the proportions of fuel mixtures, the automatic prevention of fuel waste, and the design and application of air pressure regulators to high altitude flying. Summary: 1. Limits of engine output. 2. High altitude engines. 3. Influence of air density on proportions of mixture. 4. Methods of varying proportions of mixture. 5. Automatic prevention of fuel waste. 6. Design and application of air pressure regulators to high altitude flying.

Description: The technical staff of the NACA at Langley Field, has made a series of free flight tests with a JN4h airplane in order to find the best place for an instrument for measuring the angle of attack. A "neutral zone" was found where the air remains either at rest relative to the undisturbed air beyond the influence of the airplane, or is set in motion parallel to the motion of the airplane. This zone is about midway between the two wings and slightly in front of, or at the vertical plane through the leading edges of the wings but the exact position as well as the outlines of the zone varies considerably as the conditions of flight change.