Numerical simulation of helipad considering downwash effects during landing and takeoff of the helicopter

Abstract

The main objective of the paper is to design the man portable and modular helipad structure. The weight of helicopter & downwash effect during landing & take-off are considered while designing the helipad. The size of helipad is 5 m × 4 m suitable for Cheetah /Chetak helicopter and it is made in eight modules. Each module weighs around 40 kg. The material of helipad is glass fibre reinforced polymer (GFRP). Computational fluid dynamics (CFD) analysis of the helipad is done at rotor speed of 314 rpm. Hovering condition is considered at height of 4 m with the angle of attack of rotor blades as 17.50. The velocity and pressure of the wind acting on the helipad during landing and take-off is determined through CFD simulation. The maximum pressure on helipad due to airflow is estimated to be 407 Pa during downwash. The structural analysis of helipad is then performed in two phases, (1) applying the weight of helicopter as 5.5 ton (53955 N) and maximum downwash pressure of 407 Pa to design the structural members (2) applying an upward force of 8140 N (407 Pa × 20 m2) on the joints to check the strength of joints. The helipad panels made of GFRP material using I section bars (25 mm × 15 mm × 3 mm) in longitudinal direction along with circular bars (12 mm in diameter) in transverse direction are enough stiff and strong to sustain weight of helicopter and downwash effects.