Foldable Propeller Hub Mechanisms Based on Rolling Elements

A propeller hub connectable to a rotatable motor shaft, the propeller hub comprising:

• a slidable structure that is slidable between a first position and a second position;
• a spring that urges the slidable structure toward the first position;
• and
• at least one sphere that is selectively moveable within at least one corresponding groove or channel to selectively lock a propeller in a predetermined angular position relative to the shaft depending on the slidable position of the slidable structure.

An aircraft comprising:

• a wing,
• a motor applying torque to a shaft;
• a first propeller connected to the shaft;
• and
• a propeller hub connected to the shaft, the propeller hub transmitting torque from the shaft to a second propeller,
• wherein the propeller hub is configured to change angular position of the second propeller relative to the shaft,
• wherein the propeller hub includes at least one spherical connector that selectively moves into or through a corresponding channel or groove to selectively lock the second propeller in a predetermined changed angular position to generate thrust for the aircraft.