Aeronautical Terms beginning with R

Ramp Weight

The total weight of the aircraft while on the ramp. It differs from takeoff weight by the weight of the fuel that will be consumed in taxiing to the point of takeoff.

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Reciprocating Engine

An engine that converts the heat energy from burning fuel into the reciprocating movement of the pistons. This movement is converted into a rotary motion by the connecting rods and crankshaft.

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Reduction Factor

A number, usually 100 or 1,000 by which a moment is divided to produce a smaller number that is less likely to cause mathematical errors when computing the center of gravity.

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Reduction Gear

The gear arrangement in an aircraft engine that allows the engine to turn at a faster speed than the propeller.

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Reference Datum

(GAMA) An imaginary vertical plane from which all horizontal distances are measured for balance purpose.

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Region Of Reverse Command

Flight regime in which flight at a higher airspeed requires a lower power setting and a lower airspeed requires a higher power setting in order to maintain altitude.

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Registration Certificate

A State and Federal certificate that documents aircraft ownership.

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Relative Wind

The direction of the airflow with respect to the wing. If a wing moves forward horizontally, the relative wind moves backward horizontally. Relative wind is parallel to and opposite the flightpath of the airplane.

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Residual Fuel

Fuel that remains trapped in the system after draining the fuel from the aircraft with the aircraft in level flight attitude. The weight of this residual fuel is counted as part of the empty weight of the aircraft.

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Rigging

The final adjustment and alignment of an aircraft and its flight control system that provides the proper aerodynamic characteristics.

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Roll

The motion of the aircraft about the longitudinal axis. It is controlled by the ailerons.

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Rudder

The movable primary control surface mounted on the trailing edge of the vertical fin of an airplane. Movement of the rudder rotates the airplane about its vertical axis.

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Ruddervator

A pair of control surfaces on the tail of an aircraft arranged in the form of a V. These surfaces, when moved together by the control wheel, serve as elevators, and when moved differentially by the rudder pedals, serve as a rudder.

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