What is described as extremely high on a spinning propeller?

• A. The color brightness.
• B. The weight.
• C. The loads on the propeller.
• D. The noise level.

Answer: (C)

When a propeller is spinning, the blade must carry very large forces due to both rotation and aerodynamics. The centrifugal force pulls each blade outward, and the aerodynamic lift acting along the blade adds to that stress. Together, they create substantial bending and shear loads, especially at the blade root where the blade attaches to the hub. These loads increase with RPM and engine power, making them the most critical factor the propeller must withstand in operation. Color brightness is unrelated to operating stresses, the weight doesn’t become extremely high just from spinning, and noise level doesn’t reflect the structural stresses on the blade. So the description refers to the loads on the propeller.