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.
When a bone breaks it is called a fracture (say: FRAK-chur). There's more than one way to break or fracture a bone. A break can be anything from a hairline fracture (a thin break in the bone) to the bone that's snapped in two pieces like a broken tree branch. Doctors describe fractures in the following ways: A complete fracture is when the bone has broken into two pieces.