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SPT-B
4 Signal-processing tools.
SPT-B Selectable-performance target, ballistic.
SPU 1 Short power-up (SAAHS self-test).
2 Intercom (USSR, R).
3 Subsystem power unit.
4 Signal processing unit.
5 Stores power unit.
Spur Space-power unit reactor.
spur gear Gearwheel with straight teeth round
periphery; many dictionaries add ‘parallel to axis of rotation’,
not so, most aero-engines contain helical *.
Sputnik Russian word for ‘fellow traveller’, name of
first artificial satellite, launched 4 October 1957; later
colloq. for any satellite or even any spacecraft.
sputtering Ejection of metal atoms from cold cathode by
evaporation or ion bombardment, either as nuisance, to
form fine coating on substrate or to form colloidal metal
solution.
SPW 1 Self-protection weapon (tactical attack aircraft
AAM, not necessarily fired in forwards direction).
2 Secondary power.
SQ 1 Squall (ICAO).
2 Software, or service, quality.
3 Squelch, squawk.
4 Super-quick [fuze].
5 Square.
SQA 1 Software quality assurance; / CM adds /configuration
management.
2 Service quality agreement.
SQAL Squall.
SQAN Squall line.
SQB Service-quality billing; P adds processor.
SQC Statistical quality control.
SQD Service-quality data.
sq ft Square feet.
SQL Structured query language.
SQLN Squall line.
SQM 1 Software quality metrics, quantified measures
of SQ.
2 Software quality management.
sq m Square metres, m 2 preferred.
Sqn, sqn Squadron.
SQP Sequential quadratic programming.
squadron Any of many types of military or naval unit,
including common administrative unit of combat aircraft;
according to many services ‘consisting of two or more
flights’. Foreign-language equivalents include Staffel (G),
escadron (F), escuadron (S), eskadrilya (USSR, R).
Squadron Uncle Senior officer [e.g., Wg Cdr] who stays
behind when the unit is posted to an overseas conflict
(RAF).
squall Strong but intermittent wind; gust whose effect
lasts minutes rather than seconds and extends a kilometre/
mile or more horizontally.
squall line Line of established or developing thunderstorms.
squarco Radar beam squinting plus area coverage.
square 1 See signal area.
2 Large square marked on remote part of airfield, to be
accurately flown by pupil helicopter pilot, especially in
presence of wind.
3 Of an aeroplane [airplane], having length equal to
span.
4 Of a piston engine, having bore equal to stroke.
squawk normal
square bashing Drill, esp. on barrack square (UK).
square course Airfield circuit (US usage); does not mean
literally square.
square/cube law Basic geometric law: areas of similarshaped
solid bodies are proportional to squares of linear
dimensions, and volumes (ie for equal densities, masses)
to cubes. Thus if two aeroplanes are of same shape but one
has twice linear dimensions, it will have four times wing
area and eight times weight, hence W/S is doubled.
square engine Piston engine whose bore equals stroke.
square foot 0.0929m 2 , 92,903.04 mm 2 .
square inch 645.16 mm 2 .
square mile 2.58999 km 2 .
square parachute One whose canopy is approximately
square when laid out flat.
square search Various standard air/surface search
patterns in form of overlapping rectangles (usually
squares or near-squares) so that after a period aircraft has
examined a large strip or rectangle with minimal duplication.
square stall Stall with wings level throughout.
square thread Thread with vertical faces (unlike Acme)
used for transmitting power as linear thrust in either
direction.
square wave EM or other periodic wave which alternates
between steady positive and steady negative values in time
extremely brief by comparison with steady periods.
square-wing biplane Upper and lower spans equal;
according to some authorities, also without stagger.
squaring shears Hand or power shears for cutting sheet
positioned on marked-out platform.
squash head Warhead for use against hard targets, esp.
those with single thick metallic armour layer; basic
principle is transmission of intense shockwave through
armour, causing transverse acceleration high enough to
spall pieces off inside face.
squat(ting) Downward movement of marine aircraft c.g.
(eg due to trough) in essentially level attitude while
running on water.
squat switch Bistable switch triggered by sustained
(usually 2.5 s) compression of main or nose landing-gear
struts on touchdown, to operate lift dumpers, reversers
and/or other devices. Term also applicable when input is
rotation of MLG bogie beam.
squawk Generalized word for airborne transponder or
IFF operation and keying; when used alone usually a
ground-radar ATC command to switch to normal or to
directed mode. Keying is usually a four-digit number. See
following entries.
squawk alt Switch to active Mode C with auto altitudereporting.
squawk Charlie See squawk alt.
squawk flash Operate IFF I/P switch.
squawk ident Engage ident feature; civil counterpart of
flash.
squawking Air/ground code: showing IFF/transponder
in mode/code indicated.
squawk low Switch to low sensitivity.
squawk Mayday Switch to emergency position; for civil
transponder Mode A, Code 7700; for mil IFF Mode 3,
Code 7700 plus emergency feature.
squawk mike Operate IFF MIC switch and key transmitter
as directed.
squawk normal Switch to normal sensitivity.
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