COLLECTIVE PITCH CON- TROL —The control for changing the pitch of all the rotor blades in the main rotor system equally and simultane- ously and, consequently, the amount of lift or thrust being generated. BUNTOVER —The tendency of a gyroplane to pitch forward when rotor force is removed. CONING —See blade coning. CALIBRATED AIRSPEED (CAS) —Indicated airspeed of an aircraft, corrected for installation and instru- mentation errors. CENTER OF GRAVITY —The the- oretical point where the entire weight of the helicopter is considered to be concentrated. CENTER OF PRESSURE —The point where the resultant of all the aerodynamic forces acting on an air- foil intersects the chord. CENTRIFUGAL FORCE —The apparent force that an object moving along a circular path exerts on the body constraining the object and that acts outwardly away from the center of rotation. CENTRIPETAL FORCE —The force that attracts a body toward its axis of rotation. It is opposite centrifu- gal force. CHIP DETECTOR —A warning device that alerts you to any abnormal wear in a transmission or engine. It consists of a magnetic plug located within the transmission. The magnet attracts any metal particles that have come loose from the bearings or other transmission parts. Most chip detec- tors have warning lights located on the instrument panel that illuminate when metal particles are picked up. CHORD —An imaginary straight line between the leading and trailing edges of an airfoil section. CHORDWISE AXIS —A term used in reference to semirigid rotors describing the flapping or teetering axis of the rotor. COAXIL ROTOR —A rotor system utilizing two rotors turning in opposite directions on the same centerline. This system is used to eliminated the need for a tail rotor. FLARE —A maneuver accomplished prior to landing to slow down a rotor- craft. DIRECT SHAFT TURBINE —A shaft turbine engine in which the com- pressor and power section are mount- ed on a common driveshaft. DIRECT CONTROL —The ability to maneuver a rotorcraft by tilting the rotor disc and changing the pitch of the rotor blades. FLAPPING —The vertical move- ment of a blade about a flapping hinge. FLAPPING HINGE —The hinge that permits the rotor blade to flap and thus balance the lift generated by the advancing and retreating blades. DEVIATION —A compass error caused by magnetic disturbances from the electrical and metal components in the aircraft. The correction for this error is displayed on a compass cor- rection card place near the magnetic compass of the aircraft. FEEDBACK —The transmittal of forces, which are initiated by aerody- namic action on rotor blades, to the cockpit controls. DENSITY ALTITUDE —Pressure altitude corrected for nonstandard temperature variations. FEATHERING AXIS —The axis about which the pitch angle of a rotor blade is varied. Sometimes referred to as the spanwise axis. DELTA HINGE —A flapping hinge with a skewed axis so that the flapping motion introduces a component of feathering that would result in a restor- ing force in the flap-wise direction. FEATHERING —The action that changes the pitch angle of the rotor blades by rotating them around their feathering (spanwise) axis. DYNAMIC ROLLOVER —The ten- dency of a helicopter to continue rolling when the critical angle is exceeded, if one gear is on the ground, and the helicopter is pivoting around that point. CYCLIC PITCH CONTROL —The control for changing the pitch of each rotor blade individually as it rotates through one cycle to govern the tilt of the rotor disc and, consequently, the direction and velocity of horizontal movement. DUALROTOR —A rotor system uti- lizing two main rotors. CYCLIC FEATHERING —The mechanical change of the angle of incidence, or pitch, of individual rotor blades independently of other blades in the system. DRAG —An aerodynamic force on a body acting parallel and opposite to relative wind. DISSYMMETRY OF LIFT —The unequal lift across the rotor disc resulting from the difference in the velocity of air over the advancing blade half and retreating blade half of the rotor disc area. CORIOLIS EFFECT —The tenden- cy of a rotor blade to increase or decrease its velocity in its plane of rotation when the center of mass moves closer or further from the axis of rotation. DISC LOADING —The total heli- copter weight divided by the rotor disc area. DISC AREA —The area swept by the blades of the rotor. It is a circle with its center at the hub and has a radius of one blade length. G-2