What causes ground resonance in helicopters?
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 unbalanced centrifical force that gets in phase with the natural frequency of the aircraft rocking on it’s landing gear.
What causes low frequency vibration in a helicopter?
Low-frequency vibrations are often caused by disturbances in rotor revolution, while medium-frequency vibrations can typically be attributed to loose components that affect the rotor system.
What is special about Chinook helicopter?
The Boeing CH-47 Chinook is a tandem rotor helicopter developed by American rotorcraft company Vertol and manufactured by Boeing Vertol. The Chinook is a heavy-lift helicopter that is among the heaviest lifting Western helicopters.
Can you Autorotate a Chinook?
Yes-not being able to autorotate means no sale The fundamental design principal at work is, in plain language: You need for those in the damaged helicopter, or when the engines quit, to have a chance to walk away from it.
How do you fix ground resonance?
The wait-and-hope approach is only sometimes successful, so a better solution to ground resonance is to prevent it. 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.
How do you recover ground resonance?
When it does occur, recovery is often possible if action is taken quickly. If sufficient rotor RPM exists, immediate takeoff can restore rotor balance by allowing the airframe to freely move and help damp the oscillation. If rotor RPM is very low during a ground resonance incident, complete shutdown may be sufficient.
What are the 4 types of helicopter vibration?
1 – Reduce collective pitch. 2 – Increase rotor RPM. 3 – Reduce forward airspeed. 4 – Minimize maneuvering.
What causes lateral vibration in helicopter?
Lateral vibrations are often the result of worn, loose or cracked parts or a lateral imbalance such as a span-wise imbalance, a chord-wise imbalance or a combination of both. Vertical vibrations typically occur when a rotor blade is out of track.
Can a Chinook helicopter fly on one engine?
The Chinook is powerful enough to fly with one engine, so pilots are able to shut down one engine and activate the other if it fails, he said.
What happens if a helicopter loses power?
Actually, helicopters have a built-in mechanical control called the collective pitch lever that allows them to descend slowly and land even if the engine dies. This maneuver is called autorotation.