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arometric element
barometric element Transmitting barometer carried in
radiosonde payload, variation in aneroid capsules causing
shift in frequency of carrier wave.
barometric fuze Fuze set to trigger at preset pressure
height.
barometric pressure Local atmospheric pressure.
barometric pressure control Automatic regulation of fuel
flow in proportion to local atmospheric pressure.
barometric pressure gradient Change in barometric pressure
over given distance along line perpendicular to
isobars.
barometric tendency Change in barometric pressure
within specified time, usually the preceding three hours.
barometric wave Any short-period meteorological wave
in atmosphere.
barosphere Atmosphere below critical level of escape.
barostat Device for maintaining constant atmospheric
pressure in enclosed volume.
barostatic relief valve Automatic regulation of fuel flow
by spilling back surplus through relief valve sensitive to
atmospheric pressure.
barothermograph Instrument for simultaneously
recording local temperature and pressure.
barotrauma Bodily injury due to gross or sudden change
in atmospheric pressure.
barotropy Bulk fluid condition in which surfaces of
constant density and constant pressure are coincident.
barrage AA artillery fire aimed not at specific targets
but to fill designated rectilinear box of sky.
barrage balloon Captive balloon forming part of
balloon barrage.
barrage jamming High-power electronic jamming over
broadest possible spread of frequencies.
barrel 1 Of piston engine cylinder, body of cylinder
without head or liner.
2 Of rocket engine, thrust chamber of nozzle, esp. of
engine having multiple chambers.
3 Any portion of airframe of near-circular section, even
if tapering; thus Canadair made the CF–18 nose *.
4 Highly dangerous area with strong defences against
attacking aircraft.
5 Non-SI unit of volume, = 42 US gal – 0.15899m 3 .
barrel engine piston engine having cylinders with axes
disposed parallel to engine longitudinal axis and output
shaft.
barrelling 1 Various methods of using rotating drum
filled with abrasive [usually powder] to remove burrs and
other surface imperfections from workpiece.
2 Colloq., to make fast low pass over ground location;
to barrel in.
barrel roll Manoeuvre in which aerodyne is flown
through 360° roll while trajectory follows horizontal
spiral such that occupants are always under positive
acceleration in vertical plane relative to aircraft.
barrel section 1 Portion of transport aircraft fuselage
added in stretching. Alternatively called plug section (but
see barrel (3)).
2 Parallel length of control rod.
barrel wing Wing in form of duct open at both ends and
with longitudinal section of aerofoil shape.
barrette Array of closely spaced ground lights that
appear to form a solid bar of light.
barricade Barrier (USN).
barrier Net mounted on carrier (1) deck or airfield
base leg
runway to arrest with minimal damage aircraft otherwise
likely to overrun. Normally lying flat, can be raised
quickly when required.
barrier crash Incident involving high-speed entry to *
with or without damage. Usually applied to carrier
operations.
barrier pattern Geometrical pattern of sonobuoys so
disposed as to bar escape of submerged submarine in
particular direction.
barring Slowly turning gas-turbine engine by hand.
bar stock Standard form of metal raw material: solid
rolled or extruded with round, square or hexagonal
(rarely, other) section.
Barstur, BARSTUR Barking Sands Tactical
Underwater Range (USN, Kauai, Hawaii).
BAR UK Board of Airline Representatives in the UK
[office, London].
barycentre Centre of mass of system of masses, such as
Earth/Moon system (barycentre of which is inside Earth).
barye Unit of pressure in CGS system. Equal to 10 Nm –2
= 1 dyne cm –2 or 1.4503 10 -3 lb/in 2 or 10 –6 bar (hence
alternative name of microbar).
BAS 1 Bleed-air system.
2 Base allowance for subsistence (US armed forces).
3 Barrier arresting system.
BASA Bilateral Aviation Safety Agreement (FAA +
foreign government).
Basar Breathing air, search and rescue (for diver in helo
crew).
BASE Cloud base height AMSL (ICAO).
BaSE Battlespace synthetic environment.
base 1 Locality from which operations are projected or
supported.
2 Locality containing installations to support
operations.
3 In an object moving through atmosphere, any
unfaired region facing rearwards (eg rear face of bullet or
shell, trailing-edge area of wedge aerofoils, and projected
gross nozzle area of rocket engine after cutoff).
4 Substance constructed of ions or molecules having
one or more pairs of electrons in outer shells capable of
forming covalent bonds.
5 Loosely, substance that neutralises an acid.
6 In transistor, region of semiconductor material into
which minority carriers are emitted (hence, usually,
between emitter and collector).
7 Underside of cloud. With cloud having grossly irregular
undersurface, surface parallel to local Earth surface
below which not more than 50 per cent of cloud protrudes,
and which can be taken as upper limit of VFR. In mist or
fog * intersects Earth.
Basea, BASEA British Airport Services & Equipment
Association [500+ members, office Bournemouth BH8
8EZ] (UK).
base area Aggregate area of unfaired rearward-facing
surface of aerodynamic body.
base check Examination in flight of crew on completion
of conversion to new type.
base drag Drag due to base area experiencing reduced
pressures.
base height Minimum height AGL authorised on lolevel
training sortie, in peacetime typically 200 ft, 91 m.
base leg In airfield circuit, extends from end of downwind
leg to start of turn on to finals.
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