Generally, rotorcrafts with multi-blade rotor hub configurations often include a main rotor assembly for supplying forces for flight, and a tail rotor assembly (sometimes referred to as an anti-torque system) that stabilizes and influences the flight direction of the rotorcraft.
Rotor blades in the main rotor assembly rotate at a given speed. In flight, they also change their pitch angle to alter direction of flight, speed, and lift of the rotorcraft. If all rotor blades of a rotor assembly were susceptible to uniform manufacture and installation to specification, then the tips of the rotor blades should all “track” through a same point in space at a given point in the rotation cycle around the hub of the main rotor assembly-thereby providing a rotation track for the rotor blades while the rotorcraft is in operation.
However, no two rotor blades are identical or installed to precise specification. When the rotor assembly of the rotorcraft is spooled up, the rotor blades may appear to run out of balance with each other. In such a case, the rotor blades are generally not within rotation track tolerance (i.e., close enough to the rotation track). Operating unbalanced rotor blades may cause a vibration or beat frequency to be transmitted into the main rotor hub, the transmission, or airframe of the rotorcraft; thereby introducing vibration into other parts of the rotorcraft. Excessive vibration levels can lead to premature wear and failure in various components of the rotorcraft. As a result, there is an increase in maintenance costs and rotorcraft downtime.
In order to correct balancing of any one or more of the rotor blades, the rotor blades are tracked after installation. During tracking, adjustments are made to various components in the main rotor system of the rotorcraft. Tracking continues for multiple operational runs of the rotor blades, and through multiple adjustments, until the rotor blades are sufficiently balanced with each other and stay reasonably close to the rotation track. Therefore, certain mechanisms or indicators may be advantageous to enable installers and maintainers to track each round of adjustment in order to complete the tracking and installation process in a time efficient and effective manner, and to ensure safe operation of the rotorcraft.
USPTO Backgrounds
USPTO Backgrounds