rotary actuator /r.υt.ri
ktjue.t./ noun an actuator which rotates and operates a screw jack, e.g. to extend flaps
rotary inverter /r.υt.ri .nvt./
noun a DC motor driving an AC gener-ator, the output of which must be regu-lated to give constant voltage and fre-quency
rotary wing aircraft /r.υt.ri w.. e.krɑft/ noun an aircraft with a rotor which provides lift, such as a helicopter
rotate /r.υte.t/ verb to turn around on an axis or centre . In the event of flame extinction in flight, the engine will continue to rotate, due to the air-

199 rudder
flow through it caused by the forward speed of the aircraft. . The aircraft should be rotated to the recommended nose-up attitude for touch down. . Counter-rotating propellers rotate in opposite directions. . rotation
rotation /r.υte..(.)n/ noun 1. the act of moving the control yoke or stick aft to raise the nose of an aircraft during the take-off run to facilitate the aircraft becoming airborne . Rotation should begin at about 60 knots. 2. the act of turning around an axis or centre . the rotation of the earth . crankshaft rota-tion . The speed of rotation determines the frequency of the generator output.
COMMENT: The aircraft rotates around three axes: pitch = rotation around the lateral axis; roll = rotation around the longitudinal axis; yaw = rotation around the vertical axis.
rotational /r.υte..(.)n.l/ adjective
rotating . rotational movement of the camshaft . The rotational movement of the propeller blades creates lift at right angles to the blade.
rotor /r.υt./ noun a device which turns about an axis or centre . The rotor blade of a compressor.
rotor blade /r.υt. ble.d/ noun a
long thin aerofoil on a helicopter rotor
rotorcraft /r.υt.krɑft/ noun same as rotary wing aircraft
rough /rf/ adjective 1. not smooth, having an irregular surface. Opposite smooth . rough air turbulent air . rough running referring to a piston engine which is not operating correctly
2. not fully detailed . a rough estimate an approximate calculation, good enough for a given purpose . a rough drawing a quick drawing usually used to illustrate or explain
roughness /rfn.s/ noun uneven-ness of a surface . The strength of tur-bulence near the Earth’s surface depends largely on the surface temper-ature, the surface wind, and the rough-ness of the surface.
rough terrain /rf t.ra.n/ noun
uneven ground
round /raυnd/ adjective circular . a round life raft . adverb in a circular movement . The pointer swings round.