Are helicopters inherently unstable?
In summary, a helicopter is statically stable and dynamically unstable in all three axes in hover and forward flight except yaw in forward flight where it is dynamically stable.
What normally causes a low frequency helicopter vibration?
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 the most stable helicopter?
Known for its reliability, sturdiness and unparalleled record for safety, the Bell 206B-3 is among the most exceptional turbine helicopters ever built. With a proven track record and low operating costs, the Bell 206B-3 is among our most popular aircraft and a economical, cost-friendly option for chartered air travel.
What makes a helicopter stable?
This stability is explained by the fact that the main rotor at an increase of the airspeed in a direction opposite to the thrust reduces its thrust, and conversely, when this speed decreases—increases the thrust, thus creating a damping force in the direction of the axis of rotation.
What is static stability in a helicopter?
Abstract. The static stability of a rotary-wing aircraft is established by observing its immediate response following a disturbance from a trimmed flight condition. For a helicopter, this can include rearwards, sideways, forwards, and hovering trimmed flight at constant altitude or in a climb or descent.
What causes high frequency vibrations in helicopters?
High frequency vibrations are associated with the engine bearings, cooling blower fan blades, the tail rotor driveshaft, or any other component spinning at high revolutionary speeds. Main rotors rotate at close to 360 revolutions per minutes (r.p.m.), with tail rotors generally spinning six times faster than that.
What causes ground resonance in a helicopter?
Ground resonance is a specific self-excited oscillation of the helicopter and is caused by the interaction between the main rotor blades and the fuselage structure. Inertia forces of the blades perform an out-of-phase lagging motion, which reacts with the elastic landing gear of the helicopter.