the Aviation Dictionary

roll . rotor streaming
roll - The motion of an aircraft about its longitudinal
axis. This motion is controlled by the ailerons.
roll cloud - The dense and horizontal cloud band
occasionally found parallel to gust fronts. Also used to
describe the rotor clouds associated with mountain lee
waves.
roll pin - A pressed-fit pin made of a roll of spring steel.
The spring force tending to unroll the pin holds it tight
in the hole.
roll threading - Applying a thread to a bolt or screw by
rolling the piece between two grooved die plates, one
of which is in motion, or between rotating grooved
circular rolls.
roller bearing - An antihiction bearing with hardened
steel rollers between two hardened steel races.
rollout RVR - The RVR (Runway Visual Range)
readout values obtained from RVR equipment located
nearest the rollout end of the runway.
root - The supporting base or structure, as in the wing
root, connected to the fuselage.
root mean square (RMS) - The value of direct current
equivalent to an alternating current sine wave. The
value is 0.707 times the peak value of one alternation.
rosette weld - A weld made through a small hole in a
piece of steel tubing to weld an inner tube to the outer
tube to prevent relative movement.
rosin -A light yellow-colored resin. Rosin remains after
oil of turpentine has been distilled from the oleoresin of
pine trees.
rosin core solder - A soft solder made chiefly of tin and
lead alloys used primarily for bonding copper, brass,
and coated iron. Rosin core solder is a hollow wire
filled with rosin. During the soldering process the rosin
serves to clean corrosion from the components being
soldered in order to make a sound bond.
rosin joint - A soldered electrical connection in which
the rosin, not the solder, holds the connection. Rosin
joints are not considered to be airworthy connections.
rotary breather - A rotating set of vanes or a centrifuge
device through which oil laden air from the vent
cylinders, crankcase, and propeller all rotated and the
crankshaft remained stationary.
rotary solenoid - An electromagnet whose movable
core is rotated by current through the coil.
rotary switch - A switch that consists of one or more
circular wafers, each with multiple contacts. A central
shaft rotates a wiper from contact to contact, switching
connection from one circuit to another. When multiple
wafers are stacked on the shaft, multiple circuits can be
selected simultaneously.
rotating wing - The rotors of a helicopter.
rotation - The act of turning about an axis.
rotational velocity - In rotorcraft, the component of
relative wind produced by the rotation of the rotor
blades.
rote learning - A basic level of learning where the
student has the ability to repeat back something
learned, with no understanding or ability to apply what
was learned.
rotor - 1. The rotating
element in an
alternator. It is excited
by direct current, and
the interlacing fingers
on the faces of the
rotor form the
alternating north and
south poles. 2. The rotating blades of a helicopter. 3.
The portion of a turbine compressor that spins. 4.
Either compressor or turbine. A rotating disk or drum
to which a series of blades is attached. 5. In
meteorology, a turbulent circulation under mountainwave
crests, to the lee and parallel to the mountains
creating the wave. Glider pilots use the term rotor to
describe any low-level turbulent flow associated with
mountain waves.
rotor brake - A device used to stop the rotor blades of a
rotorcraft on shutdown. This can be either a hydraulic
or mechanical mechanism.
rotor disc - The area within the tip path plane of a
helicopter's rotor. Also referred to as the disc area.
subsystem Deaeration takes place and the oil is rotor disc area - In rotorcraft, the area swept by the
returned to the sump while the air exits back to the blades of the rotor. It is a circle with its center at the
atmosphere.
hub and has a radius of one blade length.
rotary pick-off - A device attached to a rotating object rotor force - The force produced by the rotor in a
that generates a signal proportional to the amount of gyroplane. It is comprised of rotor lift and rotor drag.
rotation.
rotor streaming - In meteorology, a phenomenon that
rotary radial engine - An aircraft engine popular in occurs when the air flow at mountain levels can be
World War I, in which the propeller was attached to the sufficient for wave formation, but begins to decrease
crankcase and the pistons were attached to a crankshaft with altitude above the mountain. In this case, the air
mounted on the airframe. When the engine ran, the downstream of the mountain breaks up and becomes
turbulent, similar to rotor, with no lee waves above.
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