Structural strength analysis of the retractable main landing gear of unmanned aircraft vehicle from impact loads due to vertical landing speed

The landing gear is the main component of an Unmanned Aerial Vehicle (UAV) – Medium Altitude Long Endurance (MALE) to keep the aircraft structure and other components safely or not damaged due to operating loads that occur. The landing gear structure must be strong and safe to withstand the operating load when the aircraft lands. This research analyzes the effect of vertical landing speed on the impact load resistance of the retractable main landing gear using the three-dimensional finite element method. Study stress contour and maximum deformation on main landing gear are caused by the impact load that occurs when an aircraft landing at a certain speed. Stress analysis was done using Pro/ENGINEER software. The main landing gear uses 6061 Aluminum material. The weight of the UAV at landing is 1,330 kg (MTOW) and 85% MTOW at main landing gear or 1,105 kg. Vertical landing speed varies regarding standard design touchdown rates, which were 1.5 m/s, 2 m/s, 2.5 m/s, 3 m/s, 3.5 m/s, 4 m/s, 4.5 m/s, 5 m/s, 5.5 m/s, and 6 m/s. At last, from the results of structural strength analysis to impact loads, the main landing gear is safe to withstand vertical landing speed up to 6 m/s. Based on the modal analysis, natural frequencies are obtained between 10.4823 Hz to 98.2481 Hz with various forms of vibration modes. This is still below the limit of 100 Hz (around 6,000 rpm engine). And from the simulation results show that a Factor of Safety is 7.44 (>1.5) according to the FAR-23 standard.