What causes helicopter ground resonance?
What causes helicopter ground resonance?
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 is ground resonance test?
The current trend in ground resonance testing is aimed at providing aircraft modes of vibration appropriate to the free‐free condition. To achieve this objective the rigid body frequencies of the aircraft on its supports must be low by comparison with the frequency of any mode of distortion.
How do you turn off ground resonance on a helicopter?
Proper maintenance of the helicopter’s damping system components can prevent ground resonance from taking hold. When it does occur, recovery is often possible if action is taken quickly.
Why is the Chinook the fastest helicopter?
Chinook, having two main rotors in tandem, rotating in opposite direction (pic above) cancels out the torque produced by the other rotor, hence eliminating the need of a tail rotor, thus utilizing full power of engines to produce lift & only lift. More the lift (downwash) per unit weight, more the forward speed.
Why do helicopters shake?
A helicopter main rotor is capable of producing vibrations in both the vertical and lateral planes. A vertical vibration is a result of unequal lift produced by the main rotor blades. This vibration is a result of the airframe rolling with the mass effect caused by the unequal vertical lift component.
How does a helicopter lift upwards off the ground?
This shape is called an airfoil. That shape makes air flow over the top faster than under the bottom. As a result, there is less air pressure on top of the wing; this causes suction and makes the wing move up. A helicopter’s rotor blades are wings and create lift.
What is ground effect helicopter?
In Ground Effect (IGE) is a condition where the downwash of air from the main rotor is able to react with a hard surface (the ground), and give a useful reaction to the helicopter in the form of more lift force available with less engine power required.
Why do you have to keep your head down helicopter?
THE ROTOR SYSTEM OF THE HELICOPTER Never carry anything above your head such as an umbrella while walking under the rotor system. Even the lightest contact with the rotor blades on a helicopter may result in permanent damage to the aircraft.
How does ground effect work?
When landing, an airplane will get closer to the ground. The air and pressure distortions between the airplane’s wings and the ground will then create additional lift. At the same time, it will reduce the airplane’s drag. This all-too-common phenomenon is known as the ground effect.
Do Chinooks have weapons?
Armament: two 7.62mm M134 Miniguns and one 7.62mm M60D machine gun.
Can Chinook lift a tank?
CH-47 Chinook: Max Lift Capacity The 26,000 pound capability of the chinook allows the aircraft to lift large HVAC units, utility poles, and large bundles of food, health care supplies, and water to those in need.
What creates lift in a helicopter?
In the case of a helicopter, the object is the rotor blade (airfoil) and the fluid is the air. Lift is produced when a mass of air is deflected, and it always acts perpendicular to the resultant relative wind. A symmetric airfoil must have a positive AOA to generate positive lift. At a zero AOA, no lift is generated.
What is the civilian version of a Chinook helicopter?
The military version of the helicopter has been exported to nations across the world; the U.S. Army and the Royal Air Force (see Boeing Chinook (UK variants)) have been its two largest users. The civilian version of the Chinook is the Boeing Vertol 234.
Did a Chinook helicopter dump water on a nuclear reactor?
“CH-47 Chinook helicopter begins dumping water on nuclear reactor”. The Christian Science Monitor. Archived from the original on 13 November 2014. ^ McKeown, Shawne (17 March 2011). “Concern grows over spent fuel pools as crews spray nuclear plant with water”. CityNews. Archived from the original on 18 March 2011.
Who created the CH-47 Chinook helicopter?
And Boeing Vertol using concepts by Frank Piasecki created the CH-47 Chinooktwin-rotor helicopter. The CH-47D is the current model in the Army’s conventional forces inventory. There is an advanced MH-47E model that is designed to support special operations.
Why did the Chinook become a competitor to the CH-53?
The Chinookwas always a competitor for the CH-53 but the height of the helicopter was enough so that Vertol never did get around to really working out an arrangement where it fit well on the ships. The tandem arrangement of course always gave a nice compact spot, an advantage for shipboard use.