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.

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.

What Robinson wrestled with is ground resonance, a demon that has demolished helicopters and killed pilots, passengers, and bystanders.

Ground resonance has not been "solved", and is still a big concern for anyone who flies a helicopter with a fully-articulated rotor system. It basically is an out-of-balance condition in the rotor system of a helicopter on the ground that rapidly increases in frequency until the helicopter shakes itself apart.

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.

Ground resonance is a phenomenon that occurs in helicopters like the Seasprite with a fully articulated rotor-head, a dampened undercarriage and, usually, on helicopters with inflatable tyres.

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.

Jul 2, 2024 · Ground resonance is a dynamic instability that can occur in helicopters, particularly during ground operations. This phenomenon arises when the natural frequencies of the helicopter’s rotor system coincide with the frequency of …

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.

Helicopter ground resonance is a potentially destructive phenomenon that can produce catastrophic damages and result in the complete destruction of the helicopter.

Ground resonance is taken to mean the self-excited oscillations (swinging) of a helicopter on the Earth, due to the specific dynamic instability. A number of cases are known in the history of helicopter construction when the phenomenon of ground resonance has led to total destruction of helicopters [9, 10].

Ground resonance is one of the most dangerous situations a helicopter pilot can face. This emergency situation can result in the entire hull being ripped apart by the air-craft ’s own extreme oscillations.

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.

Sep 1, 2002 · Since helicopter ground resonance is well understood, and linear methods are sufficient to accurately predict its onset, what purpose does performing a nonlinear analysis of this phenomenon achieve? There are two excellent reasons for obtaining the nonlinear solution of the ground resonance problem.

Jan 1, 2000 · We present a method to analyze the ground resonance phenomenon for a one-main rotor helicopter on the basis of a complete set of nonlinear differential equations, known in flight mechanics....

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.

Jan 23, 2019 · What Are Ground Resonance Vibrations? These kinds of vibrations are seen as the most serious, as they have the potential to destroy aircraft. Unlike other kinds of vibrations listed here, ground resonance vibrations occur only when a helicopter is grounded (rather than when it’s in the air).

Oct 26, 2023 · Self excited vibrations of helicopters on the ground have been the cause of several accidents It is, therefore, essential that the means of ensuring freedom from such phenomena should receive serious attention.

Oct 1, 2014 · In helicopters with hinged blades an unstable dynamical phenomenon known as ground resonance may occur during take-off and landing and lead to the total destruction of the aircraft. Predicting the phenomenon is necessary to determine the stability of …

Jan 1, 2020 · Abstract: Aeromechanical instabilities arising due to frequency coalescence of different modes of a helicopter rotor and fuselage system is investigated. The focus is on removing the small angle approximation typically used for ground resonance analysis and perform simulation of the resulting nonlinear model.