DICTIONARY OF AVIATION 189
in planes parallel to the vertical plane passing thru the line of the direction of flight.
double rudder, any rudder having two planes or surfaces.
flexible rudder, a rudder which is made flexible or capa- ble of being bent so as to present curvd surfaces to the air.
forward rudder, same meaning as front rudder.
front rudder, a rudder, usually horizontal, located at the front or fore part of an airship; a forward rudder; an ele- vating-plane; an elevator.
horizontal rudder, a rudder, commonly at the front or rear of a flying-machine, whose axis of rotation is hori- zontal and which is used for up-and-down steering and to effect, or aid in maintaining, longitudinal equilibrium; an up-and-down rudder; an altitude-rudder; an elevating- plane; an elevator.
lateral rudder, a rudder, as in the rear of an aeroplane flying-machine, used to effect, or aid in maintaining, lat- eral equilibrium; a vertical rudder-plane designed to aid in balancing a flyer laterally; a right-and-left rudder.
pivoted rudder, a rudder which is pivoted so as to turn upon an axis, usually horizontal or vertical.
right-and-left rudder, same meaning as lateral rudder, vertical rudder, side-to-side rudder.
side-to-side rudder, same meaning as right-and-left rud- der.
stabilising rudder, a rudder or rudder-like aerofoil, as at either wing-tip of an aeroplane flying-machine, used for stabilizing or stedying the craft; a balancing-plane; an aileron.
twisting rudder, a flying-machine rudder which is capa- ble of being ttuisted, warpt, or revolvd and flext at the same time, and thus acting upon the air in every possible direction, after the manner of the tail of most birds.
up-and-down rudder, same meaning as horizontal rudder, altitude rudder.
vertical rudder, a rudder whose axis of rotation is ver- tical arid which is used for right-and-left steering and to effect, or aid in maintaining, lateral equilibrium; a right* and-left rudder; a lateral rudder.
2. a rudder-fether.
rudder-feather 'zAd9z,fed9z n. [also spelt rudder-fether\ one of the rectjices or principal f ethers of a bird's tail; a '-true tail-f ether; a rudder.
rudder-frame 'z/vdaz^fseem n. the frame of the rudder of an airship.
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