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Arcads Armament control and delivery system.
Arcal Aircraft, or airborne, radio control of airfield
lighting.
Arcan Aeronautical Radio of Canada.
arc and plug See plug aileron.
ARCC 1 Airworthiness, or airframe, Requirements Coordinating
Committee (UK).
2 Aeronautical Rescue Co-ordination Centre (RAF
Kinloss, UK).
ARCH Agricultural remotely controlled helicopter.
Archie Colloq., anti-aircraft gunfire, 1915–18 (allegedly
from ‘Archie! Certainly not’, music-hall song; archaic).
archway Airport-gate detector requiring passenger to
pass through sensitive magnetic field, usually alongside
baggage screening; also called AMD or WTMD.
ARCM Anti-radiation countermeasures.
Arcmas Automatic real-time cable monitoring and
analysis system.
arc-minute, arc-second See angular measure.
ARCO, Arco Airborne remote control officer (RPVs).
ARCP 1 Air refuelling control point.
2 Aerodrome Reference Code Panel (ICAO).
ARCS 1 Acquisition radar and control system.
2 Aerial rocket control system.
3 Airline request communication, or computer,
system.
ARCSS Autonomous rendezvous and capture sensor
system.
Arctic air mass Major class of air mass most highly
developed in winter over ice and snow, although surface
temperature may be higher than that for Polar masses.
Arctic minimum Densest of standard model atmospheres
assumed in aircraft performance calculation.
Arctic smoke Surface fog essentially caused by very cold
air drifting across warmer water.
ARCTS Automated radar-controlled terminal system.
ARD 1 Anti-radar drone.
2 Atmospheric re-entry demonstrator.
3 ATC-related delay.
4 Advanced requirement[s] definition.
ARDC Air Research and Development Command
(USAF, established 1 February 1950, became Systems
Command 1 April 1961).
ARDC model atmosphere Devised by ARDC, published
1956 (see model atmosphere).
Ardec Armament Research Development and
Engineering Center (USA).
ARDF Airborne radio direction-finding.
Ardhan Association pour la Recherche de
Documentation sur l’Histoire de l’Aéronautique Navale
(F).
ARDS Airborne radar demonstration system, links
J-Stars, Astor, Orchidée.
ARDU Aircraft Research & Development Unit
(RAAF).
ARE 1 Airborne radar extension (surveillance C-130).
2 Altitude-reporting equipment (towed target).
3 Admiralty Research Establishment.
4 Algebraic Riccati equation for LQR [1724].
area SI unit of plane area is square metre (m 2 ); to
convert from ft 2 multiply by 0.092903; from hectares by
10 4 ; from sq yd by 0.836127.
are Non-SI unit of area = 10 -2 m 2 .
ARES
area, aerospace surfaces See gross wing *, net wing *,
disc *, equivalent flat-plate *, control-surface *.
area bombing Bombing in which target occupies large
area, such as built-up area of city, with aiming point
loosely defined near centre (when expression was current,
WW2, marked at night by TIs or TMs).
area defence system In general, anti-aircraft or AAW
system capable of providing effective defence over large
area (dispersed battlefleet, task force, ground battlefield
or large tract of country containing several cities) rather
than point target.
area-denial munition Explosive device, usually
dispensing cluster bombs each with time-delay fuze, to
deny area to enemy ground forces.
area-increasing flap Wing flap which in initial part of
travel moves almost directly rearwards to increase wing
chord, without significant angular movement.
area loading Mass divided by gross projected area W/S
[lifting-body aircraft].
area navigation, R-nav, RNAV Navaid that permits
aircraft operations on any desired course within coverage
of station-referenced navigation signals or within limits of
self-contained system capability (FAA); thus, does not
constrain aircraft to preset pathways.
area-navigation route Established R-nav route, predefined
route segment, arrival or departure route
(including RNAV SIDs and STARs). Route, based on
existing high-altitude or low-altitude VOR/DME
coverage, which has been designated by Administrator
and published (FAA).
area ratio 1 In rocket thrust chamber, usually ratio of
idealised cross-section area at nozzle to minimum crosssection
area at throat; also called expansion ratio. In
general, chambers designed to expand products of
combustion into atmosphere have ** 10:1 to 25:1; those
for use in upper atmosphere may exceed 50:1; SSME for
Space Shuttle has ** 157:1.
2 For a wing, S/b 2 , area divided by span squared,
reciprocal of aspect ratio.
area rule Formulated by Richard T. Whitcomb at
NACA in 1953. For minimum transonic drag at zero lift
aircraft should be so shaped that nose-to-tail plot of gross
cross-section areas should approximate to that of ideal
body for chosen flight Mach number. Thus, addition of
wing should be compensated for by reduction in section
of body (which gave some early area-ruled aircraft “wasp
waists”, which are generally undesirable). Obviously,
streamlines cannot be sharply deflected; it is not possible
to have perfect area-ruling both with and without bulky
external stores. In 1954–55 rules extended to Mach 2 by
plotting cross-section area distributions on sloping axes
approximately aligned with Mach angle.
area sterilization Seeding part of sky with chaff of such
extent and density that radar operation is impossible.
AREF, ARef Air Refueling Squadron (USAF), also
ARS.
Arens A remote control system in which push/pull
commands are transmitted by a steel cable tightly
surrounded by a guiding coil spring, the whole sliding in
a tube.
Arento National telecommunications organisation
(Egypt).
ARES 1 Adaptable radar-environment simulator.
2 Airborne radar emitter simulator.
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