the Aviation Dictionary

reverse question ridgelridge line
reverse question - A response to a question. Rather
than give a direct answer to the student's query, the
instructor can redirect the question to another student
to provide the answer.
reverse riveting - A process of driving aircraft rivets in
which the manufactured head is bucked by holding it in
a rivet set supported in a bucking bar and upsetting the
shank with a flush rivet set.
reverse-current relay - A relay incorporated into a
generator circuit to disconnect the generator from the
battery when the battery voltage is greater than
generator voltage.
reverse-flow annular combustor - A combustor design
that forms an S-shaped path in which the gases flow
from the diffuser to the exhaust. This design shortens
the entire engine length because the liner is coaxial to
the turbines rather than in front of them as in a
conventional annular combustor.
reversible-pitch propeller - A propeller system with a
pitch change mechanism that includes full reversing
capability. When the pilot moves the throttle controls
to reverse, the blade angle changes to a pitch angle and
produces a reverse thrust, which slows the airplane
down during a landing.
reversing mechanism - A linkage that reverses the
direction of movement between two parts.
review and evaluation - The fourth and last step in the
teaching process, which consists of a review of all
material and an evaluation of the students. In the
telling-and-doing technique of flight instruction, this
step consists of the instructor evaluating the student's
performance while the student performs the required
procedure.
revision - In mechanical drawings, a change in
dimensions, design, or materials.
revision block - That portion of an aircraft drawing that
contains a record of all of the revisions. symbols are
used to indicate changes and their locations.
revolutions per minute (RPM) - The number of
complete revolutions a body makes in one minute.
revolved section - A detail on an aircraft drawing in
which the external view shows the shape of a part's
cross section as though it were cut out and revolved.
Reynolds Number - A dimensionless ratio that relates
how smoothly a fluid flows. At low velocities fluid
flow is smooth or laminar. As the fluid flows more
rapidly, it reaches a velocity, known as the critical
velocity, at which the motion changes from laminar to
turbulent, with the formation of eddy currents and
vortices that disturb the flow.
RF alternating current - Radio frequency (RF) is a
term that refers to alternating current (AC) that, when
fed into an antenna, generates an electromagnetic field
suitable for communications. These frequencies range
from nine kilohertz (9 kHz) to thousands of gigahertz
(GHz).
rheostat - A variable resistor having only two terminals.
It is normally used in a circuit to drop voltage by
dissipating some of the energy as heat.
rhetorical question - A question asked to stimulate
group thought. Normally answered by the instructor, it
is more commonly used in lecturing rather than in
guided discussions.
rhomboid - A parallelogram in which the angles are
oblique and the adjacent sides are unequal.
rhumb line - In navigation, a rhumb line crosses all
lines of longitude at the same angle.
rib - The structural member of an airfoil that gives it the
desired aerodynamic shape.
rib cap - A thin, narrow strip of material usually glued
to wooden ribs or riveted to metal ribs to enlarge the
contact surface for the attachment of skin to the wing
or flight control surface.
rib lacing - The attachment of fabric to an aircraft
structure with rib stitching cord. A series of loops
around the structure and through the fabric are secured
with seine knots. Also referred to as rib stitching.
rib stitching - The attachment of fabric to an aircraft
structure with rib stitching cord. A series of loops
around the structure and through the fabric are secured
with seine knots. Also referred to as rib lacing.
rib stitching cord -A strong cotton, linen, or polyester
fiber cord used to stitch or lace fabric to an aircraft
structure.
ribbon direction - In composites, on a honeycomb core,
the way the honeycomb can be separated. The direction
of one continuous ribbon.
ribbon parachute - A parachute that consists of strips
or ribbons of material instead of a solid fabric. This
type of chute is used in instances where it is desirable
to have less opening shock, since air escapes between
the ribbons.
rich flameout - A condition of turbine engine operation
in which the fire goes out in the engine because the
fuel-air mixture is too rich to support combustion.
rich solvent - A slow-drying solvent.
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ridgelridge line - In meteorology, an elongated area of
relatively high atmospheric pressure; usually associated
with and most clearly identified as an area of maximum
anticyclonic curvature of the wind flow (isobars,
contours. or streamlines).
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