Air-consumption Parameters for Automatic Mixture Control of Aircraft Engines

Data obtained from Nary calibration tests of an 18-cylinder, two-row, radial engine of 8350-cubic-inch displacement and a 14-cylinder, two-row, radial engine of 2600-cubic-inch displacement {carburetor types) were analyzed to show the correlation between the air consumption of these engines and the parameters that evaluate the air consumption from intake-manifold temperature and pressure, exhaust back pressure, and engine speed. The analyses showed that, for the speed range reported, the air consumption of these engines could be represented as a continuous single-valued function of intake-manifold temperature, and pressure, exhaust back pressure, and engine speed. This function was shown to be adaptable for automatic mixture control ov an engine with a continuous injection system. The analyses indicated that even better adaptability existed for a timed injection system. Design information required for the construction of controls for a fuel-injection system using the foregoing type of automatic mixture control was presented for the two engines. The analyses also showed that the parameters varied for different engine designs and that calibration tests would therefore be required for each design.