Wind Tunnel Studies on Hover and Forward Flight Performances of a Coaxial Rigid Rotor

The aerodynamic performance of a reduced-scale coaxial rigid rotor system in hover and steady forward flights was experimentally investigated to gain insights into the effect interference between upper lower rotors influences advance ratio, shaft tilt angle lift offset. featured by 2 m-diameter, four-bladed hingeless installed test rig. Experiments were conducted ?3.2 m wind tunnel at China Aerodynamics Research Development Center (CARDC). tested states collective pitches ranging from 0° 13° it also ratios up 0.6, with specific focus on offset sweeps. To ensure that operating similar manner real flight, torque difference trimmed zero whilst constant coefficient maintained flight. An isolated single-rotor configuration same pitch setting rotor. results demonstrate figure merit (FM) value is than rotor, both are single Moreover, can contribute better efficiency under blade loading (CT/?). In effective lift-to-drag (L/De) ratio does not monotonously change as increases. Increases required power drag case high 0.6 leads decreasing L/De Meanwhile, relatively when tilted backward. increasing tends result reduced an increase drag. When greater increased drag, increases benefit significantly but much less influenced low ratio. poorer which different