Which rotor motion is enabled by the Delta hinge system in forward flight?

• A. Yaw
• B. Pitch
• C. Flapping
• D. Roll

Answer: (C)

Forward flight creates dissymmetry of lift, with the advancing blade moving through air faster than the retreating blade. To balance lift across the rotor disk, the blades must move up and down in a flap motion. The Delta hinge system provides a dedicated flap axis, allowing the blade to rise and fall smoothly and passively as the rotor turns. This flap action helps equalize lift between the two sides and keeps the rotor disk aligned with minimal intervention. So, the Delta hinge setup mainly enables flapping in forward flight.