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ight ascension
right ascension Angular distance measured E from
vernal equinox; arc of celestial equator, or angle at celestial
pole, of given celestial body measured in hours (h) or
degrees (°).
right-hand circuit Circuit (1) with turns to right, clockwise
seen from above (unusual).
right-hand rotation Clockwise; in case of engine/
propeller, seen from behind. No ruling exists for pusher
engines, one school claiming that ** engine is unchanged
when installed as pusher and another claiming that **
means seen from direction in which propeller is beyond
engine.
righting moment Restoring moment.
right wind One blowing on aircraft from right, causing
drift to left (suggest arch.).
rigid airship One having rigid framework or envelope to
maintain desired shape at all times.
rigid frame One having fixed joints, and thus statically
indeterminate.
rigidity Property of gyro of maintaining axis pointing in
fixed direction; also called gyroscopic inertia.
rigid rotor 1 Rotor of helicopter (in theory also autogyro)
whose blades have no lead/lag [drag] or flapping
hinges but can rotate to change pitch.
2 Bearingless helicopter lifting rotor, in which all
control input is reacted by root attachment flexible in
bending and torsion.
RIGV Respaced inlet guide vanes.
RII Required inspection item [must be certified independently].
RIIA Royal Institute of International Affairs [London
SW1Y 4LE] (UK).
RIIS Route integration instrumentation system
(SAC 1).
rill Deep, narrow depression across lunar surface.
Rilsa Resident integrated logistic support activity.
RIM US guided-missile designation prefix, shiplaunched
for aerial interception.
Rimcas Runway-incursion monitoring and conflictalert
subsystem.
rim cavities Peripheral spaces either directly
surrounding the blades of an axial turbine rotor, or
connected thereto.
rime Icing type; rough, milky and opaque, formed by
instantaneous freezing of super-cooled water droplets.
Definition of BS, under heading ‘frost’: ‘ice of feathery
nature on windward side of exposed objects when frost
and fog occur together’.
Rimpatt Read impatt diode.
RIMS 1 Replacement inertial measurement system [or
set].
2 Ranging and integrity monitoring station [navsats].
RIN The Royal Institute of Navigation [1947–, office,
London SW7 2AT] (UK).
ring 1 Common structural part of most gas turbines.
Compared with a disc it has little or no inner web, and in
the latest engines may include the blades in a monolithic
whole.
2 Frame of fuselage of circular or oval section.
ring and bead sight Rudimentary gunsight in which
aimer aligns target with bead foresight and correct part of
ring backsight for required aim-off.
ring around Self-interrogation of beacon due to insufficient
isolation between transmitter and receiver, or to
ripcord
triggering of airborne transponders at close range by
unwanted sidelobes; in either case result is disastrous ring
around display origin. Suppressed by ISLS.
ring counter Three or more bistable devices and gates so
interconnected that only one is ON at one time; input
pulses advance ON around ring.
ring cowling Simple ring, usually with concave inner
profile (in longitudinal plane) and convex outer,
surrounding radial engine (see Townend ring, from which
stemmed long-chord NACA cowl).
Ringelman Basic method of assessing jet smoke by
subjective opinion, in use since 1896 for matching smoke
plumes against grey (gray) tones; hence * number,
numbered scale from white to black. Said to be free from
subjective variation but affected by angle, eg if four
exhaust plumes are seen from the side.
ring-fin tail rotor Helicopter tail rotor mounted in
profiled duct in centre of tail fin (vertical stabilizer).
ring-frame Main transverse structural frame(s) of rigid
airship.
ring gauge Hand gauge for checking outside diameter of
circular work, in some cases threaded; can be go/no-go
type [US = gage].
ring laser gyro Measures rotation, and rate of rotation,
by sending laser light in both directions round closed
circuit [in parked aircraft, outputs rotation of Earth].
ring main Continuous pipe surrounding passenger cabin
supplying emergency oxygen to passengers.
ring rolling Forming rings, eg for engine, by rolling on
specially set-up machine which produces required radius.
rings Black/white stripes on cuffs or shoulders denoting
rank (RAF).
ring-sail parachute One having construction based not
on gores but on rings, usually arranged in form of upper
disc and large skirt ring with separating gap. Unlike
ribbon parachute, there is usually only one gap (sometimes
two).
ring seal Shaft seal with small freedom to move in closefitting
static housing.
ring-slot parachute Family of parachutes with basic ring
construction with concentric slots, merging into ribbon
form.
ring spring Spring assembled from stack of steel rings
with mating chamfered edges whose friction on compression
reduces rebound.
Ringstone Ceramic or jewel pivot for instrument arbor
(shaft).
ring topology Linkage of terminals by two fibreoptic
rings, one sending unidirectional messages or data clockwise,
the other anticlockwise. The ring continues to
function following the failure of any terminal.
ringworm Cracked dope on fabric, especially in concentric
circles, caused by local pressure or impact.
Rint Radiation intelligence.
RIO Radar intercept officer (USN aircrew).
RIO/RI/O Remote input/output.
riometer Relative ionospheric opacity meter.
RIP 1 Resin impregnation, or resin-impregnated
plastics.
2 Remote instrument package.
ripcord 1 Cord which deploys parachute, pulled by
wearer, static line or automatic (eg barostat control)
system.
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