Powerplant

Biological propulsion systems such as those in animals use muscle contractions as the powerplant, and appendages such as limbs, legs, wings, fins or tails as the propulsors, while microorganisms evolved sophisticated membrane proteincomplexes that act as molecular motors to power flagella as propulsors. Technological systems such as motor vehicles typically use one or more engines (motors) as the powerplant, and wheels and axles, propellers or a propulsive nozzle to generate the propulsion. Drivetrain components such as clutches, gearboxes and drive shafts may be needed to connect the motor to axles, wheels, or propellers. In additional to internal powerplants, a machine system may sometimes use external forces as power sources to act upon propulsors, such as the use of human- or animal power to propel non-motorized vehicles and watercrafts, the capture of wind power to drive sails or tethered power kites, and the use of gravity to drive the forward motion of gliders.