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.
Compound may refer to: 1  Chemical compound, combination of two or more elements. 2  Compounding, the mixing of drugs in pharmacy. 3  Compound (enclosure) , a cluster of buildings having a shared purpose, usually inside a fence or wall. 4  Compound (fortification) , a version of the above fortified with defensive structures.