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sweepback
measure, of time-base spot scanning across CRT or other
display.
4 One complete cycle of VG wing.
5 Angular deviation of locus of centroids of propeller
blade sections from radial line tangential thereto at
propeller axis projected on plane of rotation (BS).
6 Offensive tactical mission against surface targets,
normally targets of opportunity (WW2).
7 To range over continuous (usually large) band of
frequencies.
8 To employ technical means to uncover covert surveillance
devices (DoD).
sweepback Visibly obvious backwards inclination of
aerofoil from root to tip so that leading edge meets relative
wind obliquely. This is usually done to increase critical
Mach number.
sweepback angle Angle between normal to longitudinal
OX axis (axis of symmetry in most aircraft) and reference
line on aerofoil, normally 0.25 (one-quarter) chord line or,
less often, leading edge; both normal line and reference line
lie in same plane, which is usually that containing centroids
of aerofoil sections from root to tip (thus for canted verticals,
** measured in plane of each surface).
sweepforward Visibly obvious forwards inclination of
aerofoil from root to tip so that leading edge meets relative
wind obliquely; hence * angle, or forward-sweep angle.
sweeping Modifying wing or tail to incorporate sweep (1).
sweeping check Confirming that cockpit flight controls
[inceptors] move freely over full range of travel.
sweep jamming To emit narrow band of jamming able to
sweep (7) back and forth over wide operating band of
frequencies.
sweep oscillator Signal generator whose frequency is
varied periodically by fixed amount at constant amplitude
above and below central fixed frequency; also called
Wobbulator (UK), sweep generator (US) or scanning
generator.
sweep-tip blade Helicopter rotor (main or tail) blade
whose locus of centroids is radial from root to near tip and
then sharply inclines back.
sweet spot Condition in which aircraft can maintain
precise altitude, heading and speed without pilot input or
autopilot.
swept Incorporating sweepback (never used of forward
sweep).
Swerve Sandia winged energetic re-entry vehicle
experiment.
SW/FR Slow write, fast read.
SWG 1 Standard wire gauge (UK); standard range of
sheet thicknesses.
2 Square waffle grid (space structures).
Swift 1 Standoff all-weather radar for inflight terrain
surveillance.
2 Specification of working position in future ATC.
Swift 64 Pioneer mobile connectivity service enabling
mobile phones to be used by airline passengers [2006–].
SWIM, Swim 1 System-wide integrity management
(USAF).
2 System-wide information management (ATC1).
Swims Shallow-water influence minesweeping system.
swing 1 Involuntary and often uncontrollable divergent
excursion from desired track of tailwheel-type aeroplane
running on ground.
2 To turn propeller by hand to start piston engine; if not
switching system
engaged in starting engine, or with turboprop, term is to
hand-turn or pull-through.
3 To calibrate compass deviation by recording its value
at regular intervals, usually 15°, during 360° rotation of
aircraft on compass base.
4 Distortion of radio range; also called night effect.
5 Sudden yaw of aeroplane consequent upon loss of
power of engine mounted away from centreline.
swing-by Close pass of planet or other celestial body by
spacecraft on Grand Tour.
swing force Aircraft or complete combat unit can fly
air/air and air/ground in same mission.
swinging base Compass base; also called deviation clock.
swinging compass Magnetic compass used as standard for
calibrating that in aircraft.
swing-piston engine Various topological families of piston
engine in which two, three or more pistons oscillate around
toroidal cylinder alternately compressing mixture between
them, being driven by firing strokes or, in some, acting as
pumps. Most do not have mechanical drive but supply gas,
eg to drive turbine.
swing-role Often interpreted differently from swing force
in that aircraft and crews can fly offensive missions or (on
different occasions) defensive missions.
swing-wing aircraft Aeroplane with variable sweep (1);
also called VG aircraft (colloq.).
Swinter Study of women in non-traditional environments
and roles, which included military pilot training (Canada).
SWIP 1 Super weight-improvement program (US).
2 Systems weapon improvement program.
Swipe Simulated weapon-impact predicting equipment.
SWIR Short-wave IR.
swirl 1 Gross rotation of flow about axis approximately
aligned with flow direction, eg in propeller slipstream,
upstream or downstream of turbine, downstream of gas
turbine fuel nozzle, or induced by large drive fan in lowspeed
tunnel (removed by straighteners).
2 Rotation of air in whirling-arm room or other nonevacuated
chamber containing high-speed rotating object.
swirl vanes Fixed aerofoils for imparting swirl to a fluid
flow. At inwards-radial entry to a centrifugal compressor
they are ususally miniature wings parallel to axis of rotation.
In turbine-disc cooling air and upstream of fuel
burners they are radial.
SWIS 1 Stall-warning and identification system.
2 Satellite weather information system.
swishtail See fishtail.
SWIT Software integration and test.
switch A specialized aerospace meaning is the rejection of
the target by a missile seeker, which instead locks on to a
decoy; this may be followed by response.
switchblade An oblique flying wing aircraft [colloq.].
switchery Complete array of switches and other inceptors
for on-board systems other than flight controls (colloq.).
switches off Traditional verbal command in handstarting
piston engine to ensure that ignition is inoperative
at start (actually switches normally closed, short-circuiting
HT).
switches on Seldom used; normal call is “contact”.
switch-in deflector For jet lift, shuts off normal jet nozzle
and diverts flow through rotatable side cascade (1957-70).
switching system Automatic switching in large network,
eg military communications, airline reservations or nationwide
computer link; normally electro-mechanical pre-1960
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