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ubbing strip
members actually in contact; usually at least one mating
face is carbon.
rubbing strip Numerous non-structural parts whose
purpose is to accept impact from doors, ground equipment
(eg steps and vehicles) and abrasion by inlet
blanking plates or rescue winch cable.
rub indicator Sensor giving cockpit indication of eccentric
running of rotating assembly, eg engine shaft.
rub rail Mount and launch rail for missile shipped and
launched from canister; sometimes four, each locating a
wingtip.
RUC Rapid update cycle (weather).
rudder Primary control surface in yaw; when nosemounted,
prefaced by nose- or fore-. Term also includes
fixed fin of kite balloon, usually ventral, providing
weathercock stability.
rudder bar Centre-pivoted bar providing pilot rudder
input in simplest ultralights and historic aircraft.
Traditional term for rudder input even when linear pedals
are fitted.
rudder-bias strut Simple engine-out device comprising
piston in rudder circuit with engine-bleed air piped to each
side; failure of either engine causes immediate application
of rudder.
rudder lock Potentially dangerous flight condition with
rudder locked at maximum deflection. Caused by reversal
of aerodynamic moment at large sideslip angle [suggest
simple manual rudder only].
rudder pedal Left/right pedals for pilot’s feet acting as
manual input to rudder, and in modern aircraft to wheelbrakes.
rudder post Traditional (suggested arch.) term for
leading-edge member of rudder carrying hinges; with
modern inset hinges place taken by internal spar.
rudder reversal Roll reversal using rudder only, usually
in maximum-performance high-alpha air-combat
manoeuvres.
rudder roll Unwanted roll produced solely by coarse use
of rudder.
rudder torque Twisting moment exerted by rudder on
rear fuselage.
ruddervator Movable flight-control surface of butterfly
tail, combining duties of rudder and elevator. It may or
may not be downstream of a fixed surface. Sometimes
‘ruddevator’.
ruddervon Control surface, usually of traditional
trailing-edge form, able to serve as rudder, aileron or
elevator on so-called tailless aircraft. In most applications,
outboard of elevon[s].
RUF Rough.
ruling dimension Basic measure, almost impossible to
alter, e.g. diameter of fuselage.
ruling material That used for most of airframe structure.
RUM Ship-launched anti-submarine missile (USN
code).
rumble 1 Rocket combustion instability audibly
obvious from low growl or *.
2 Unstable pulsing at low frequency [300–700 Hz] in jet
engine or afterburner.
3 Prolonged flat landing approach under power, to * in.
rumble seat Occasional seat, eg for flight-deck observer
or for stewardess on landing/take-off.
run 1 Ground or distance traversed by wheels, or water
by floats/hull, on takeoff and landing.
run-out
2 Number of production articles built to common type,
or elapsed time to produce same.
3 Single flight over target (also called pass) for assessment,
release of ordnance or operation of reconnaissance
sensors.
4 Single flight past designated point(s), eg in attempt on
speed record.
runaway Undesired operation of device, eg PFCU,
when not commanded; in dangerous extreme case continuing
to limit of travel, giving hard-over condition.
runback ice Very dangerous accretion of ice which forms
on LE, is melted by deicing system or kinetic [ram-energy]
heating, and refreezes further back.
Run black Order to extinguish all externally visible
lighting [interceptor squadrons] (US).
rundown 1 Fall off to zero rpm after normal closure of
shut-off valve or HP cocks, or flameout or engine failure
(also called spool-down).
2 Decay in production rate due to falling demand or
imminent termination.
rundown time Time for engine to come to rest, giving
rough indication of internal rubbing.
run-flat tyre Various aircraft tyres, pioneered by
Goodrich, designed for high-speed landings after deflation
caused by take-off blowout, fire or combat damage.
Runge-Kutta Possibly the most widely used integration
routine in digital flight control.
running fit Slight clearance between mating parts
allowing rotation or other relative motion.
running fix Approximate fix obtained by taking a
bearing of fixed station, or in any other way obtaining PL,
then obtaining second PL and adjusting to common time.
running in Act of running newly built or completely
overhauled engine or other machine to ensure parts run
together under controlled gentle operating conditions.
running landing 1 Helicopter landing made into wind
with groundspeed and/or translational lift at touchdown;
with skid gear demands careful collective after touchdown
to avoid abrupt stop.
2 Jet V/STOL landing with significant forward speed.
running mate New transport aircraft type, usually
smaller, to accompany trunk-route type already in service
and offering same advanced-technology appeal.
running order Traditional condition for measuring mass
of piston engine: including radiator, coolant, internal oil,
external pipes and controls, but excluding fuel, oil, tanks,
reserve coolant, exhaust tailpipes and instruments.
running rigging Rigging for kite balloon or other aerial
object which by system of vee-lines and pulleys automatically
adjusts to direction of pull.
running take-off 1 Started without lineup and hold,
speed never slackening on arrival at runway in use.
2 By helicopter or other VTO aircraft making preliminary
ground run.
runoff area Strip or pad beside runway where arrivals
can clear quickly for following traffic (also run-off, run
off).
run-on landing Roll-on landing.
run-out 1 Distance travelled by carrier aircraft between
engaging hook and coming to stop, also called pull-out.
2 Distance travelled by aircraft after encountering
runway barrier, drag wire, decelerating bed [such as
EMAS] or other arresting system.
3 Distance travelled by gun or barrel, on recoil stroke.
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