Horizontal joint helicopter rotor blades
To avoid attachment or, in other words, to improve the stability of the helicopter between the blade and the sleeve is set apart from the hinge axis, has a horizontal hinge (GSH).
In this case, according to certain rules of mechanics we can move the lift of each blade parallel to itself on the axis of a horizontal hinge, adding to it a moment acting on the sleeve with all of the blades, folding constitute the lifting force of the rotor, which in hover is full aerodynamic force R .
Under the influence of this moment the blade will be deflected upward, rising above the plane of rotation.
On the rotating blades are more weight force and the centrifugal force applied to the center of gravity of the blade.
If the blade acted only the weight force, the blade would have been down. If operated only centrifugal force, the blade would pull strongly in the rotation plane.
The actual ratio of the force, like this: lifting force developed blade 10-15 times the weight of the blades and the centrifugal force in 10-12 times more lift. Under these conditions, the deflection angle of the blade (3, referred to as an angle relative to the horizontal flapping hinge is small, only 5-7.
The weight of the blade is constant. Centrifugal force for the speed does not vary too.
During operation, the rotor in place during hovering or vertical rise in lift blade calm during the turnover remains constant. Under these conditions the blade is in equilibrium under the action of the weight, the centrifugal and lift force keeps flapping angle (3 constant. In the presence of translational flight lift the blade during one revolution is undergoing changes due to asymmetric blasting blades due to changes in the speed and angle of attack. Therefore, the blade does not stand in the process of circulation constant angle stroke and performs undulating flapping around a mean angle of stroke.
This average angle stroke easy to calculate approximately, if you know the weight, lift, momentum and the radius of the blade.
Suppose, for example, the blade radius m 6 30 kg weighs, does 200 / min and develops lift in 400 kg. Assume further that the weight force, lifting the centrifugal force applied at a single point, namely, in the middle of the blade (in 3 m from the axis of rotation).
Of the three forces acting on the blade in the vertical plane, known to us only the centrifugal force. We calculate it.
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