Contemporary problems of designing engines for military drone propulsion systems, taking into account their unforeseen mechanical failures and technical protection
Contemporary problems of designing engines for military drone propulsion systems, taking into account their unforeseen mechanical failures and technical protection

Summary/Abstract: The operational range and payload of military unmanned aerial vehicles (UAVs) depend strongly on the selected propulsion system. While electric multirotor drives are well suited to shortrange reconnaissance, longrange missions increasingly rely on propellerdriven piston engines. This article examines the suitability of two and fourstroke piston engines for military UAVs and identifies the most frequent failure modes affecting propulsionsystem reliability. The research niche addressed is the reliability-oriented design of small UAV piston propulsion systems based on componentlevel damage analysis. The purpose of the research was to assess whether piston internal combustion engines can meet longrange mission requirements while maintaining acceptable reliability, and it was hypothesised that reliability is primarily constrained by propellerrelated vibration and thermal overload of key engine components. The study combines a literature review with experimental bench and airframemounted tests conducted in the Aircraft Propulsion Laboratory, including thrust and temperature measurements and posttest inspection of components. Damage analysis covered the propeller and hub connection, drivetrain, crank–piston mechanism and exhaust mounting. The results indicate that the propeller, its mounting and transmission elements are the most failureprone parts; defects such as delamination, imbalance and resonant vibrations rapidly propagate loads to bearings, rings and cylinder surfaces, and may contribute to overheating of cylinder heads above 200°C. The paper outlines practical design and technicalprotection measures to mitigate these risks, supporting the use of piston engines for UAVs with ranges of approximately 2000 km and above.

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