Development of low altitude UAV engines, analysis and comparison of engine performance

Today, with the development of UAV (Unmanned Aerial Vehicles) technologies, the use of these vehicles in defense and social issues is increasing. Engines with different cylinder numbers, fuel volume and material properties are used in these vehicles. Especially low altitude (between 1000-2000m) and small scale (wingspan 1.5-5m) two-stroke engines are preferred in UAV productions. These engines have a high carrying capacity and an average of 6 hours of air time. In addition, battery weights and short flight times limit the use of electric powered UAVs. In this study, an UAV with a 61 cc engine displacement was investigated in terms of safety factor, stress variations and factor of safety for different material selections. In the study using Reverse Engineering and FEM (Finite Element Method), it was observed that the single-cylinder engine with the highest 6 hp power and the opportunity to operate at 7500 rpm produces 5.69 Nm torque in the calculations made. It has been calculated that a bursting force of 325.1 N is generated on the piston during detonation. The stress in the piston, crank and crank arm was found to be 24.3 MPa according to the FEM analysis. In the light of these results, safety and fatigue analyzes were made for three different materials, which are thought to be produced for each engine element. In this thesis study, in which ideal material properties were determined, a prototype engine was produced and flight tests of the engine were carried out with a medium-sized UAV. The engine produced in the second stage of the study was subjected to performance tests together with an imported engine. In the tests performed, the thrust produced by both engines for two different propeller types, the engine and exhaust temperature generated during operation, and the fuel and rpm values were examined. This thesis study has shown that a UAV engine capable of competing with imported engines can be developed within university-industry cooperation.