Experimental Investigation of Performance for Korean Electric Unmanned Helicopter on Ground

Korean Electric Unmanned Helicopter(K-EUH) has been developing to achieve the major performance target of 60 km flight distance with 20 kg payload. The first prototype weighing 126 kgf was manufactured and was tested. Objectives of this ground test is to investigate whether the helicopter has sufficient performance for take-off, and to acquire know-how on the operation of the electric power system. The ground test equipment has loadcells for measuring thrust of the main rotor, and the tail rotor. Rotating power of rotors is supplied by the battery system of nominal DC 355 V. As a result of the test, it was confirmed that the maximum thrust of the main rotor was 1.27 times of MTOW, and the tail rotor also confirmed to have the thrust capable of anti-torque of the main rotor. Experiments have also shown that it is advantageous to configure the electric power system at high voltage. If the required current is low by feeding the high voltage, heat generation and wire thickness can be reduced. The other significant fact is that the voltage drop of battery becomes more severe when the required power is high such as landing approach. Since such a sudden voltage drop reduces the rotating speed of the rotor, a dangerous situation may occur.