STATIC & DYNAMIC BALANCING
When the weight distribution about the propeller axis is equal, with the propeller in any position, it is said to have static balance.
On fixed pitch propellers an unbalanced condition (Fig. 93) can be rectified by the removal of material from heavy blades or by the addition of extra coats of paint on the lighter blades. Some propellers have weights attached to the propeller boss.
On variable pitch propellers, balance is corrected by the addition of weights at the hub, or by the installation of lead wool or washers in the hollow blade roots.
Static: Balanced when the centre of gravity acts through the Axis or Centre of Rotation.
A propeller possessing static balance may cause vibration due to the non symmetrical disposition of the mass within the propeller. Unequal weight distribution about the propeller axis can only be corrected by repeated ground runs following the addition of weights to the propeller.
Dynamic: Balanced when the blades' centres of gravity are in the Plane of Rotation.