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The paper presents the results of the experimental research on the combustion process inside the cylinder of a large piston radial aircraft engine with dual spark plug ignition. The tests were carried out on the ASz-62IR-16X radial engine equipped with a double, electronically controlled ignition system with two spark plugs in each cylinder. The constant engine speed tests allowed for comparing the combustion processes with ignition carried out with different ignition advance angle offset between both spark plugs. In the test, the ignition advance angle for one spark plug was changed while leaving the ignition advance angle for the other spark plug. The tests performed for two engine operating points were to change the angle of the front spark plug and the rear spark plug. The analyses were based on the recorded pressure signal from one of the engine cylinders. It has been shown that the ignition advance angle offset significantly affects the combustion process. The obtained results indicate the leading role of the rear spark plug in initiating the combustion process. When ignition is carried out with a steady rear spark plug advance angle, the combustion process practically does not change when the ignition advance angle of the front spark plug changes. However, changing the rear spark plug advance angle at a constant front spark plug ignition advance angle significantly changes the combustion process. [ABSTRACT FROM AUTHOR]

This article presents an analysis of the influence of oil service life on the performance parameters of an aircraft piston engine lubrication system used in an ultralight aircraft. The ageing of oil between oil changes causes a change in its parameters (such as density, viscosity...). These parameters have a strong influence on the level of protection of the lubricated components. Currently, in aircraft, oil changes are carried out according to a time schedule - oil is changed every fixed period (residual life) regardless of its actual condition. The task of this article is to test the possibility of an indirect assessment of oil condition based on analysis of changes in selected parameters of engine lubrication system operation during normal operation. The oil warm-up speed during the pre-start procedure and the dependence of oil pressure on engine speed were assumed for the analysis. The study was conducted on an ultralight rotorcraft during normal operation. Selected first daily flights directly after oil change, and after 17, 32, 50 and 66 hours of operation were analysed. It was shown that the warm-up rate changes in the samples analyzed, but that this change may also be due to factors other than oil operating time. In the case of the oil pressure vs. speed characteristics, different characteristics were shown for different operating time, but no specific dependencies were found. [ABSTRACT FROM AUTHOR]

The paper presents the results of the experimental research on the combustion process inside the cylinder of a large piston radial aircraft engine with dual or single spark plug ignition. The tests were carried out on the ASz-62IR-16X radial engine equipped with a double, electronically controlled ignition system with two spark plugs in each cylinder. The constant engine speed tests allowed for comparing the combustion processes with ignition carried out by both spark plugs, the rear plug only, and the front plug only. The analyses were based on the recorded pressure signal from one of the engine cylinders. It has been shown that the type of ignition significantly affects the combustion process and its nonrepeatability. The obtained results indicate the leading role of the rear spark plug in initiating the combustion process. When the ignition is carried out with the rear spark plug, the induction period is identical to that for dual ignition, but the combustion process is much less intensive. Ignition carried out with the front spark plug only has a longer induction period but a similar intensity of combustion as with dual ignition. Deactivating one of the plugs also improves the nonrepeatability of the combustion process. [ABSTRACT FROM AUTHOR]