Efficiency of a propeller is defined as the ratio of available power to the engine power which is. . (3). Note, that this definition for efficiency contains the velocity v, which means, that the efficiency approaches zero as the flight speed goes to zero, because the thrust cannot become infinitely large. So this definition is not useful for the special case of static thrust.
1 Compound Fracture: A compound fracture is a fracture in which the injured bone sticks through the skin. 2  Also known as an open fracture, a compound fracture can be a bit more serious in nature.
A fracture is a break or a crack in a bone. A fracture occurs when force exerted against a bone is stronger than the bone can structurally withstand. The most common sites for bone fractures are the wrist, ankle and hip. Treatment includes immobilising the bone with a plaster cast, or surgically inserting metal rods or plates to hold the bone pieces together.