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earing chamber
between parts having relative motion, with minimum
frictional loss of energy or mechanical wear.
bearing chamber Annular chamber surrounding shaft
bearing, in gas-turbine engine as far as possible in cool
location and incorporating low-friction sealing.
bearing compass Portable and hand-held, used for determining
magnetic bearing of distant objects.
bearingless rotor Helicopter rotor in which all control is
effected by flexibility in the blade attachments.
bearing-only launch Missile is launched along approximate
known bearing of target and seeker is switched on to
search sector ahead, thereafter following various
commands depending on whether or not target is
acquired.
bearing plate Simple geometric instrument for
converting bearings of distant objects into GS (1) and
drift.
bearing projector Powerful searchlight trained from
landmark beacon or other point towards nearby airfield
(obs).
bearing selector See omni-*.
bearing stress In any mechanical bearing, with or
without relative movement, load divided by projected
supporting area.
bear pads Horizontal plates added to prevent helicopter
skid sinking into snow. See ski pad.
bear paws Short skis [fixed-wing aircraft].
beat 1 Vibration of lower frequency resulting from
mutual interaction of two differing higher frequencies.
Often very noticeable in multi-engined aircraft.
2 One complete cycle of such interference.
beat frequency Output from oscillator fed by two
different input frequencies which has frequency equal to
difference between applied frequencies. (Other outputs
have higher frequencies, such as sum of applied
frequencies.)
beat-frequency oscillator Oscillator generating signals
having a frequency such that, when combined with
received signal, difference frequency is audible. Such ** is
heterodyne, used in CW (1) telegraphy. Another is superheterodyne,
in which local ** produces intermediate
frequency by mixing with received signal.
beat reception Heterodyne reception, as used in CW (1)
telegraphy.
beat-up 1 Aggressive dive by aircraft to close proximity
of surface object.
2 Repeated close passes in dangerous proximity to
slower aircraft.
Beaufort notation System of letters proposed by Rear-
Admiral Sir Francis Beaufort (1805) to signify weather
phenomena.
Beaufort scale System of numbers proposed by Beaufort
to signify wind strength, ranging from 0 (calm) to 12
(hurricane).
beaver tail Tail of fuselage or other body which has
progressively flattened cross-section.
beavertail aerial Radar aerial emitting flattened beam
having major beam width at 90° to major axis of aerial.
BEC Boron-epoxy composite.
BeCA Belgian Cockpit Association.
BECMG Becoming.
becquerel SI unit of radioactivity; Bq = 1 disintegration
/s, = 2.7×10 –11 Ci.
Be/Cu Beryllium-copper.
bend
bed See zeolite.
Beddown Process of introducing major new weapon
system to combat duty, esp. aircraft (eg B–2) at first operating
base.
BEEF, Beef Base emergency engineering force (USAF).
beefing up Strengthening of structural parts, either by
redesign for new production or by modification of hardware
already made. Thus, beef (= added material), beefed
(US colloq.).
beehive Small formation of bombers with close fighter
escort (RAF pre-1945).
beep box Station for remote radio control of activity or
vehicle, such as RPV (colloq.).
beeper 1 Personal radio alerting receiver.
2 RPV pilot.
3 Manual two-way command switch, eg electric
trimmer or cyclic-stick thumbswitch for fuel valve
control.
BEES, Bees Battle-force electromagnetic interface
evaluation system.
before-flight inspection Pre-flight inspection (NATO).
behavioural science Study of behaviour of living organisms,
especially under stress or in unusual environments.
Beier gear Infinitely variable mechanical transmission
accomplished by stacks of convex discs intermeshing with
stacks of concave discs, drive ratio being varied by
bringing parallel shafts closer together, for extreme ratios,
or further apart.
bel Unit for relative intensity of power levels, esp. in
relation to sound. One bel is ratio of power to be expressed
divided by reference power, expressed as logarithm to
base 10. Numerically equal to 10 decibels.
BELF Breakeven load factor (BLF also common).
Belgospace Trade association for space industry companies
and organisations [B-1050 Brussels] (Belgium)
Belleville washer Washer, usually of thin elastic metal in
form of flat or convex/concave disc, which offers calibrated
resistance to linear deflection of centre,
perpendicular to plane of washer.
Bell-Hiller stabilizer Two masses on short arms
attached to hub of two-blade main rotor of helicopter in
plane of blades, crossing at 90°.
Bellini-Tosi First directional radio stations, using triangular
loop antennas.
bellows Aneroid capsule(s).
belly Underside of central portion of fuselage.
belly-in, belly landing To make premeditated landing
with landing gear retracted or part-extended; belly-in is a
verb.
below minima Weather precludes takeoff or landing.
BEMT Helicopter blade-element momentum theory.
bench Static platform or fixture for manual work,
system testing or any other function requiring firm temporary
mounting (need not resemble a workshop *).
bench check Mandatory manual strip, inspection,
repair, assembly and recalibration of airborne functional
parts, made at prescribed intervals and by station and
staff certificated by airworthiness authority and/or hardware
manufacturer.
bench engine For bench testing, not cleared for flight.
bench test Test of complete engine or other functional
system on static testbed or rig.
bend To damage an aircraft, especially in a crash, hence
bent (UK colloq.)
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