Windsock.  A truncated cloth cone open at both ends and  mounted on a freewheeling pivot that indicates the direction  from which the wind is blowing.  V$_{YSE}$.  Best rate-of-climb speed with one engine inoperative.  This airspeed provides the most altitude gain in a given  period of time in a light, twin engine airplane following an  engine failure.  Wing.  Airfoil attached to each side of the fuselage and are  the main lifting surfaces that support the airplane in flight.  Wing area.  The total surface of the wing (square feet),  which includes control surfaces and may include wing area  covered by the fuselage (main body of the airplane), and  engine nacelles.  Wake turbulence.  Wingtip vortices that are created when  an airplane generates lift. When an airplane generates lift,  air spills over the wingtips from the high pressure areas  below the wings to the low pressure areas above them. This  flow causes rapidly rotating whirlpools of air called wingtip  vortices or wake turbulence.  Waste gate.  A controllable valve in the tailpipe of an aircraft  reciprocating engine equipped with a turbocharger. The valve  is controlled to vary the amount of exhaust gases forced  through the turbocharger turbine.  Weathervane.  The tendency of the aircraft to turn into the  relative wind.  Wing span.  The maximum distance from wingtip to wingtip.  Wingtip vortices.  The rapidly rotating air that spills over an  airplane’s wings during flight. The intensity of the turbulence  depends on the airplane’s weight, speed, and configuration.  It is also referred to as wake turbulence. Vortices from heavy  aircraft may be extremely hazardous to small aircraft.  Wing twist.  A design feature incorporated into some wings  to improve aileron control effectiveness at high angles of  attack during an approach to a stall.  Weight.  A measure of the heaviness of an object. The force  by which a body is attracted toward the center of the Earth (or  another celestial body) by gravity. Weight is equal to the mass  of the body times the local value of gravitational acceleration.  One of the four main forces acting on an aircraft. Equivalent  to the actual weight of the aircraft. It acts downward through  the aircraft’s center of gravity toward the center of the Earth.  Weight opposes lift.  Yaw.  Rotation about the vertical axis of an aircraft.  Yaw string.  A string on the nose or windshield of an aircraft  in view of the pilot that indicates any slipping or skidding  of the aircraft.  Weight and balance.  The aircraft is said to be in weight and  balance when the gross weight of the aircraft is under the max  gross weight, and the center of gravity is within limits and  will remain in limits for the duration of the flight.  Zero fuel weight.  The weight of the aircraft to include all  useful load except fuel.  Zero sideslip.  A maneuver in a twin-engine airplane with  one engine inoperative that involves a small amount of bank  and slightly uncoordinated flight to align the fuselage with  the direction of travel and minimize drag.  Wheelbarrowing.  A condition caused when forward yoke  or stick pressure during takeoff or landing causes the aircraft  to ride on the nosewheel alone.  Wind correction angle.  Correction applied to the course to  establish a heading so that track will coincide with course.  Wind direction indicators.  Indicators that include a  wind sock, wind tee, or tetrahedron. Visual reference will  determine wind direction and runway in use.  Wind shear.  A sudden, drastic shift in windspeed, direction,  or both that may occur in the horizontal or vertical plane.  Windmilling.  When the air moving through a propeller  creates the rotational energy.  Zero thrust (simulated feather).  An engine configuration  with a low power setting that simulates a propeller feathered  condition.   G-20 Z Y W