Abstract
An RC-helicopter that can be controlled easily may be required for the use of farm work in the future. In this paper, a four-rotor type RC-helicopter was made for experiment and the results of its performance tests were reported. The trial RC-helicopter had four rotors which were driven by DC motors. The pitch angle was fixed, and the rotational speed of each motor was controlled by way of PWM (pulse width modulation). They rotated in the opposite direction of each other in order to defeat the reaction torque of the body caused by the rotation of rotors. The test results were as follows: 1. The horizontal adjustment effect of free gyroscope installed on the trial RC-helicopter was good when the tilt angles were -10 to 10 degrees. 2. The maximum lifting force of the trial RC-helicopter was 38.66N when the pitch angle of the rotor was 12 degrees and the rotational speed of the rotor was 1312 rpm. The lifting force of all four rotors was 2.3 times larger than one rotor.
