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aircraft (eg Aggressor role) takes over when predecessor
is at bingo.
rolling instability Lateral instability; depending whether
neutral or positive instability, an upset about OX will fail
to be restored or become divergent.
rolling moment Component about longitudinal (OX)
axis of couple due to relative airflow; measured positive if
rotates right-wing down, negative if vice versa.
rolling plane Vertical plane normal to OX axis, ie
containing line through both wingtips.
rolling radius Effective radius of landing wheels
allowing for deflection (function of aircraft weight, speed
and tyre inflation pressure).
rolling tailplane Taileron.
rolling take-off Any take-off by helicopter, tiltrotor or
other VTO aircraft which, for any reason, accelerates
forwards before leaving ground.
rolling vertical take-off Take-off with vectored nozzles
aft for short distance (USAF 50 ft, in practice more helps),
at which point nozzles are vectored to 60° or thereabouts
for near-vertical ascent. Often shortened to rolling
take-off.
roll-in point Point in space where aircraft enters diving
attack.
roll jet Reaction-control jet for roll.
roll off Uncommanded roll when at high AOA (eg due
to climb at low speed) due to contamination by ice or
other matter).
roll off the top See Immelmann.
roll-on landing Helicopter landing with substantial
forward speed, eg following loss of tail rotor.
roll on top Half loop followed by 360° roll followed by
remaining half of loop.
rollout 1 Ground roll after landing, esp. when continued
to later turnoff to ease brake wear.
2 Emergence of new aircraft, especially first of new
type, from factory, often carefully staged ceremony.
3 Termination of flight manoeuvre designed to place
(normally combat-type) aircraft in optimal position for
completion of intended activity (USAF).
rollout RVR Readout values from RVR equipment
located nearest runway end (FAA).
rollover Apart from generalized meaning in business
investment, replacement of airline line equipment by
larger aircraft, in response to or anticipation of increased
traffic.
roll-over stand Maintenance stand for engine [rarely,
other items] providing hand-crank gearbox to rotate unit
for all-round access.
Rollpin Press-fit pin made of roll of spring steel, forming
self-retaining bearing pivot, axle or hinge-pin.
roll post Strange US term for the reaction-control jets
needed for lateral control on jet STOVL aircraft, esp. the
F-35B. Each comprises a downward-pointing nozzle with
an electrically powered valve controlling high-power
bleed air from the main engine (maximum 6% of mainengine
airflow per nozzle). The previously existing terms
were puffer jet and RCJ.
roll pylon Strong structure on ag-aircraft to give protection
to pilot’s head in event of aircraft becoming inverted
on ground.
roll ratcheting Uncommanded oscillation of lateral
controls, typically at 2–3 Hz, caused by human neuroroll-angle
steering
2 To move across surface on takeoff or landing.
3 The length of * (2).
roll-angle steering Autopilot mode based on CAS6
giving automatic correct bank at fixed altitude.
rollback 1 Pushback.
2 Engine rundown or spooldown.
roll bar, roll cage See roll pylon.
roll cloud See rotor cloud.
roll coupling See inertia coupling.
roll damper Flight-control damper operating on
ailerons or differential spoilers, either to preclude Dutch
roll or because aircraft is difficult to hold wings-level in
turbulence.
roll electrodes Freely rotating mating discs used for
resistance-welding continuous seams or evenly spaced
spots.
roller 1 Landing by tailwheel aircraft with fuselage
substantially level, eg because three-pointer is difficult or
risks severe bounce, or because of gusty conditions.
2 Touch-and-go (RAF).
roller/ball transfer Movement of container[s] or pallet[s]
over ballmats.
roller bearing Shaft bearing providing precise diametral
[radial] location only.
roller-blind instrument Panel instrument whose display
makes use, usually as backdrop, of roller blind (eg giving
black/white sky/Earth indication of horizon). Not
synonymous with tape instrument, which is analog linear
scale.
roller cloud See rotor cloud.
roller drive Patented (TRW) reduction or stepup gear in
which gear teeth and most bearings are eliminated,
smooth preloaded rollers (Sun and two-step rings of
planets) transmitting torque without lubrication.
roller-map display Navigation display based on moving
map (usually air topographic printed on film at reduced
scale) projected by optics on circular screen on which
heading appears as vertical central line (usually with
present position as small ring near 6 o’clock position). In
advanced forms, eg Ferranti Comed, combined with electronic
displays and information readouts.
rolleron Flight control serving as primary for pitch or
pitch/yaw and roll, esp. in radial-winged missiles, which
have four * to handle all manoeuvres.
rollgang Any of many makes of roller system for facilitating
movement of cargo, especially in removable floor
panels of standard size.
rolling Engaged in roll (1, 2).
rolling balance Tunnel balance measuring forces and
moments while model rolls about axis parallel to airflow.
rolling ball Compact two-axis human input to dynamic
system, eg ATC or SSR radar, air-defence plot or
computer display, in which partially recessed sphere
drives two potentiometers giving rotary output proportional
to rotation of ball about each of two
perpendicular horizontal axes; output can be analog
voltage or digital pulses. Smallest types fit on end of
cockpit levers to command panel displays or HUD. In US
ATC called track ball.
rolling-element bearing Shaft bearing in which sliding
friction is eliminated, the commonest types being ball,
roller, tapered-roller and needle.
rolling engagement Air-combat training in which one
roll ratcheting
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