Hover performance of a twin-rotor test model in terms of rotor overlap sweep, blade collective pitch, and blade tip speedwasexaminedexperimentally.The experimental setup consisted of two three-bladed rotors (tandem rotor configuration) with a diameter of1,220 mm and constant chord of 38 mm, giving a blade aspect ratio of 16.05. The blades were of a rectangular planform with NACA 0012 cross-sect...