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silver cell
requiring flight of at least five hours, gain in height of at
least 1,000 m (3,281 ft) and straight flight of at least 50 km
(31 miles).
silver cell Silver/zinc.
Silver Flag Exercises training combat support forces to
operate in a hostile bare/austere base environment.
silver iodide AgI, sprayed into clouds to promote rainfall
[seeding].
silver plating This is often resorted to on the tooth faces
of either one, or both mating gears. The soft skin provides
a malleable surface on engine start-up before oil begins to
flow.
silver solder Jointing alloy of silver, copper and nickel.
silver-strip indicator Inserted in fuel filter, detects any
abnormal concentration of sulphur in fuel.
silver tux Astronaut suit (US, colloq.).
silver/zinc Ag/Zn elecric dry battery common in applications
calling for single-shot high-power electric supply.
SIM 1 SAM (1) intercept missile; bomber defence.
2 System improvement modification.
3 Space interferometry mission.
4 Security identification module.
5 Serial interface module [A629].
Sim Simulation, simulator.
SIMA Scientific Instruments Manufacturers
Association of GB (UK).
Simaf Simulation and Analysis Facility (USAF).
SIMD Single instruction, multiple data stream.
simmer On-line flight-simulator player using home PC.
Simmonds-Corsey Mechanical remote-control system in
which push/pull commands are transmitted by flexible
cable in conduit on which are threaded mating tubes and
‘olives’ giving bidirectional control.
Simmonds nut Pioneer stop nut incorporating tightly
held fibre washer.
Simop Simulataneous operation of co-located radios.
Simos Simulator orthogon system.
Simoun Violent hot, dry, sand-laden wind.
Simp Solid isotropic microstructure with penalization.
simple architecture for full electrical Landing-gear
brake-by-wire system in which both main and alternate
[alternative] systems are electric, mainly or wholly eliminating
hydraulics.
simple flap Hinged wing trailing edge, with or without
shroud (4) but without intervening slot.
simple harmonic motion Regular oscillation as exemplified
by alternating current or drag-free swinging
pendulum; projection on any axis in same plane of point
moving round circle with constant angular velocity;
expressed by y = a cos (2π nt + b) where y is distance from
origin (at centre) at time t, n frequency and b a phase
constant such that at t = 0, y = a cos b. A plot of SHM is
a characteristic wavy line, passing through the origin
(displacement zero) with peak velocity, rising to
maximum displacement where velocity passes through
zero and reverses, returning through the origin to describe
a precise mirror-image terminating at the start of the next
cycle. The sum of positive and negative displacements
[peaks plus troughs] is called the amplitude, the time
between successive passes through the same point in the
cycle the period, and the reciprocal of the period [or
number of cycles per unit time] the frequency.
simple stress Either pure tension, pure compression or
pure shear.
simultaneous pitch control
simplex 1 With no provision for redundancy.
2 Communication on a single channel which is unidirectional
in operation; thus, when receiving, cannot
transmit.
simplex burner Simple gas-turbine fuel burner fed by
single pipe leading to nozzle surrounded by air swirl vanes
and with flow proportional to square root of supply
pressure.
simplex communications Communications technique in
which signals pass in one direction only at any one time;
can be single or double channel and switched by press-tospeak,
manual T/R switch or voice-operated.
simplified directional facility ILS localizer (108.1-111.9
MHz) with aerial offset from runway and emitting beam
usually not exactly aligned with it nor providing G/S
information.
simplified passenger travel Attempt from 1999 to
streamline ‘repetitive identity checks at airports’. Since
11 September 2001 emphasis has included new identification
measures (ICAO).
simply supported beam Pin-jointed at both ends.
SIMR Svalbard initial mission recovery.
Sims 1 Secondary-ion mass spectrometry.
2 Signal-identification mobile system.
SIM2 Use of three sets of axes (wind, tunnel stability
and body) for force and moment equations (NASA 1980
onwards).
Simu Single-input multi-unit.
SIMUL Simultaneously (ICAO).
simulated forced landing Includes all actions except
landing.
simulated-operations test Operational test needed to
support statements of new requirements and support
positions and programmes (USAF).
simulated attack profile Typically, lo mission in which
pilot is tasked to find and attack several point targets.
simulator Dynamic device which attempts to reproduce
behaviour of another dynamic device, eg aircraft or
missile, under static and controlled conditions for
research, engineering design, detail development or
personnel training. Those used for research are similar in
appearance to other large electronic items; those for
training often incorporate a complete cockpit or flight
deck carried on hydraulic rams giving motion about all
three linear axes and three rotary axes (eg exactly reproducing
asymmetric swing on take-off engine failure or
buffet at approach to stall with correct fuselage pitch attitudes),
and model-form or electronically generated
external scene for flight in neighbourhood of particular
selected airport(s).
simulator sickness Caused by conflict between sensations,
control inputs and visual cues.
Simulink Versatile software tool for enabling systems
engineer to explore function and performance (Parker
Aerospace).
simultaneous approach Two aircraft land on parallel
runways at the same place.
simultaneous dual field of view Split-screen system generated
by two LOS telescopes focusing IR on single detector
array, converted to formatted electronic picture, half wide
FOV and half magnified narrow FOV (Hughes/Eltro).
simultaneous engagement Concurrent engagement of
target by interceptors and SAMs (DoD).
simultaneous pitch control See collective.
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