Experimental Study of the Ground Effects on Performance of Model Tandem-Rotor Helicopter in Hover Flight

The effect of ground proximity on the some performance parameters of tandem rotors was measured using a multifunctional test rig in this study. Trust, produced power and induced power measurements of the rotors were performed in three different overlap values ​​to investigate the effects of ground proximity on these values ​​in hover flight. The results showed that the positive effect of ground proximity on the produced trust of tandem rotors is more than single rotors. In the ground effect, as the amount of overlap of the tandem rotors increased and the effect of the fountain flow recirculated from the ground increased, the amount of thrust increased . The results of power measurements showed that with decreasing the height of the rotors in the ground effect, the amount of induced power as well as the negative effect of aerodynamic interference due to their overlap decreased, These findings lead to a new approach to evaluating the performance of this type of helicopters.