RC-helicopter that can be controlled easily may be required on use of farm work in future. In this paper, four-rotor type RC-helicopter was tried to develop and the results of some flight tests were reported.
The trial RC-helicopter had four rotors which were driven by DC motors, The pitch angle was fixed and the revolutional speed of each motor was controlled by way of PWM (pulse width modulation). They revoluted in the opposite direction each other in order to defeat the reaction torque of the body caused by the revolution of rotors. The flight stability of the RC-helicopter could be controlled automatically by two gyroscopes.
From the test resullts, the best pitch angle of the rotor was 10 degrees. The maximum lifting force of trial RC-helicopter with the best pitch angle was 15.9 N at 1170 rpm in rotor revolution.