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unfactored
assessing airline or other route network each sector is
counted once only, in one direction only, despite fact it is
used in both directions and may form part of from 2 to 48
distinct routes; hence * route mileage, * network.
unfactored Not multiplied by a factor, eg factor of
safety; hence * load = limit load. See next.
unfactored performance That expected from average
aircraft, flown by average pilot, with no safety factors.
unfavourable unbalanced field One whose clearway
allows takeoff at increased weight at which TOD to 35 ft
exceeds accelerate/stop distance.
UNFCCC United Nations Framework Convention on
Climate Change [1994–] (Int.).
unfeather To restore propeller from feathered state to
normal operative state with engine transmitting power
and blades in positive pitch.
unfeathering accumulator Source of stored fluid [liquid
or gas] pressure to guarantee ability to unfeather after
failure of primary propeller control system.
unfilmed IIT not coated with protective ion barrier in
order to improve resolution and SNR.
Unfo Undergraduate Naval Flight Officer (USN).
UNGA 1 United Nations General Assembly.
2 Unione Nazionale Giovanile Aeronautica (I).
UNICE, Unice Union of the industrial federations of
the EEC countries (English translation).
Unicom Private radio communications service on five
frequencies based at airports, heliports etc, with or
without tower in addition; used for various advisories
other than ATC purposes (US).
unidentified aerial phenomena UAP, the official British
term for UFOs.
unidentified flying object UFO, something seen in the
sky which, by virtue of shape or behaviour, cannot be
identified as something known to humanity.
unidirectional aerial Single well-defined direction of
maximum gain.
unidirectional composite All fibres are parallel, usually
aligned with direction of applied load.
unidirectional current Flowing in one direction only, eg
signal pulses or d.c. with superimposed a.c.
unidirectional solidification Techniques for obtaining
strongly preferred direction of crystalline grains on solidification
of alloy from melt such that each crystal forms
long string or column aligned with maximum applied
load, transverse intercrystalline joints being rare. In most
applications, eg turbine rotor blades, a step on route to
single-crystal material.
Unido UN Industrial Development Organizations.
unified control This usually means unified flight control,
which in turn usually means governing the trajectory of a
fixed-wing aerodyne via a single three-axis inceptor, typically
a wheel or cycle-type handlebar. Blériot (1908) has
been followed by 60+ schemes, several of which have been
flown (Clark, de Valroger, Chrislea, Ercoupe, Davis).
unified fuel control Control system for supersonic
airbreathing engine governing engine acceleration, pilot
input response, Mach, nozzle and Plap.
unified system Generalized term for TTC (tracking,
telemetry and command) system handling all digital,
video and voice signals in integrated system for larger or
complex air vehicle or space payload. Also applied to
simpler satellites, missiles and RPVs, eg unified-pulse
systems in which each command pulse train comprises
unit deformation
vehicle address, message ident and message, synchronized
with radar ranging pulses; thus one ** handles all vehicles.
Unified thread Standard 60° screwthread (US, UK,
Canada).
uniform acceleration Time-invariant, giving straight line
on V/T plot.
uniformly distributed load One imposing constant force
on each unit area of horizontal floor.
uniformly varying load Magnitude varies directly with
distance along straight-line axis from reference point.
uniform photo-interpretation report Third-phase
machine-formatted intelligence report of particular
objective containing detailed information extracted from
photo sensor imagery (USAF).
uniform velocity Time-invariant speed and direction.
Unihedd Universal head-down display; standardized
cockpit display of information from many sources and
sensors with high brightness.
unijunction transistor Bar of doped semiconductor with
p-n junction near centre, normally forward-biased, giving
sharp peak of emitter V for small emitter current; used in
pulse generators and sweep circuits. Also called doublebase
diode.
unilateral instrumentation In unyawed flight each halfaircraft
behaves as mirror image of other and, therefore,
full information can be obtained by fitting pressuresensing
heads, transducers, and other experimental
equipment on one half only; ** should not be used during
yawed flight.
unipole Hypothetical aerial radiating equally in all
directions.
Unishear Fixed or portable high-speed shear for thin
sheet.
unison ring Ring linking and driving all IGVs or stator
blades [vanes] in one stage of a variable-stator engine.
Unisor United Nations International Strategy for
disaster Reduction.
unit 1 Fundamental subdivision of any numerical
measure. Nearly all industrial countries have in theory
adopted SI system. Base * of seven fundamental quantities
are: length, metre (m); mass, kilogram(me) (kg); time,
second(s); electrical current, ampere (A); thermodynamic
temperature, kelvin (K); luminous intensity, candela (cd);
and amount of substance, mole (mol). SI * of electricity
or charge is coulomb. For payment of electricity supply,
kWh.
2 Military element whose structure is prescribed by
component authority; normally applied only to small
organizations at field level, eg squadron, or to element of
airborne force, eg two or three aircraft.
3 One complete item from production, eg
production *, * sales.
unit aircraft Those provided to an aircraft unit for
performance of a flying mission (DoD).
unit area That equal to square of unit length on each
side.
unitary Having a single warhead, as distinct from
dispensed or clustered munitions.
unit cost 1 Airline’s total costs divided by generated
RPKs or RTKs.
2 See Average flyaway *, average procurement
*, program acquisition *.
unit deformation Deformation divided by original
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