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 broken bone. Fractures can range in severity from a crack (known as a hairline or greenstick fracture), to a complete break and separation of a bone that may protrude through your skin (known as an open or compound fracture). closed fracture is one in which the bones do not break the skin, while in an open (also known as compound) fracture, one or more bone fragments protrudes through the skin.