Ground resonance is an imbalance in the rotation of a helicopter rotor when the blades become bunched up on one side of their rotational plane and cause an oscillation in phase with the frequency of the rocking of the helicopter on its landing gear.

Helicopters with multiple-blade rotors have shock-absorbing landing gear with powerful dampers that allow it to soak up the energy that would otherwise set the helicopter shaking.

Ground resonance is a potentially destructive resonance between the main rotor and landing gear on a helicopter. It can only occur when the helicopter is on the ground, and it's typically caused by poor maintenance.

Ground resonance happens in helicopters with lead-lag hinges. It occurs only on the ground. It starts when the blades "bunch up" on one side of the rotor disc where they generate an …

Jan 6, 2021 · Ground Resonance is an aerodynamic phenomenon associated with fully-articulated rotor systems. "Ground" implies the airframe must be in contact with the ground. "Resonance" refers to the natural vibration frequency of the airframe resulting from the design and manufacturing process.

When in contact with the ground (at touchdown), a helicopter with an articulated rotorhead (more precisely, a rotorhead with drag hinges) can get into resonance mode, which has the potential to destroy the aircraft. In this section, we look at what ground resonance is, how it is generated and how to prevent it.

Helicopters with articulating rotors (usually designs with three or more main rotor blades) are subject to ground resonance, a destructive vibration phenomenon that occurs at certain rotor speeds when the helicopter is on the ground.

Feb 25, 2016 · These problems included lead-lag forces from Coriolis effects, high vibrations in the control system, large control forces, and a susceptibility to a destructive aeromechanical problem known as ground resonance – see Section 4.10 and Fig. 4.18.

When a helicopter is resting on the ground with its rotor spining, a condition called "ground resonance" can develop. This is a destructive harmonic vibration caused by a dynamic reaction of the rotor blades to the lateral motion of the helicotper.

Th nks to the investigations carried out, the characteristic features of the phenomenon of ground resonance hav been explained and practical recommendations have been made for the purpose f eliminating these oscillations in helicopters.