When a two-blade propeller is checked on a balancing beam, what will vertical imbalance cause?

When a two-blade propeller is checked on a balancing beam, what will vertical imbalance cause?

• A. the blade to rise to a vertical position
• B. the blade to stay at mid-position
• C. the blade tends to come to rest in a horizontal position
• D. the blade to move unpredictably

Answer: (C)

Vertical imbalance means one blade is heavier than the other in the plane of rotation, shifting the prop’s center of gravity away from the hub. That creates a gravitational torque about the balancing supports. The system will rotate until that torque is neutralized, settling in the orientation that minimizes potential energy. For a two‑blade propeller, the stable equilibrium under gravity is when the blade pair lies in a horizontal plane, with the heavier blade positioned at its lowest point. This makes the torque zero and prevents further rotation. Hence, the blade tends to come to rest in a horizontal position. The other outcomes would not produce a stable, gravity-free state given the uneven mass distribution: a persistent vertical tilt or continual motion would imply ongoing torque, while a mid-position rest would indicate balance, which vertical imbalance does not provide.

Vertical imbalance means one blade is heavier than the other in the plane of rotation, shifting the prop’s center of gravity away from the hub. That creates a gravitational torque about the balancing supports. The system will rotate until that torque is neutralized, settling in the orientation that minimizes potential energy. For a two‑blade propeller, the stable equilibrium under gravity is when the blade pair lies in a horizontal plane, with the heavier blade positioned at its lowest point. This makes the torque zero and prevents further rotation. Hence, the blade tends to come to rest in a horizontal position.

The other outcomes would not produce a stable, gravity-free state given the uneven mass distribution: a persistent vertical tilt or continual motion would imply ongoing torque, while a mid-position rest would indicate balance, which vertical imbalance does not provide.