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software-enabled control
packs, esp. those installed in aircraft. This usage is potentially
misleading.
software-enabled control Systems giving intelligent
UAVs ability to respond autonomously to external
threats and internal faults.
Software Speicification Review A parallel procedure to
the hardware SDR, if anything running slightly later to
incorporate upgrades or limitations resulting from refinement
of the hardware design.
SOG 1 Special Operations Group (US).
2 Singlet oxygen generator, supplies excited oxygen for
high-power COIL.
SoGR School of General Reconnaissance.
SOH 1 Since overhaul.
2 Start of header.
Soho Solar and heliospheric observatory.
SOI 1 Space object identification (Norad).
2 Silicon-on-insulator (Mosfet).
3 System operator instructions.
4 Saturn orbit injection.
SOIA Simultaneous offset instrument approach.
SOIC Small outline integrated circuit.
SOICA The State Organization for Iraqi Civil Aviation.
SOIR Study Group, operations on parallel instrument
runways.
SOIS 1 Silicon on insulating substrate.
2 Space-object identification system.
SOIT Satellite operational implementation team
(FAA).
SOJ Stand-off jammer, or jamming.
SOL Solenoid valve.
sol, Sol 1 Martian day, 39 min 35 s longer than Earth day.
2 Solenoid.
SOLAP Shop-order location and reporting.
Solar Shared on-line automated reservation system.
solar apex Point on celestial sphere towards which Sun
is moving.
solar array Large assembly of solar cells, on rigid frame,
folding, in roll-up sheet or other geometric form.
solar atmospheric tides Cyclic variations in atmospheric
pressure ascribed to Sun’s gravitation, with primary 12-h
component (about ± 1.5 mb at Equator, 0.5 in mid-latitudes)
and much smaller 6-h and 8-h effects.
solar battery See solar cell.
solar cell Photoelectric (photovoltaic) device converting
sunlight direct into electricity, usually by liberating electrons
and holes in silicon p-n junction.
solar chamber Test chamber in which is simulated solar
radiation outside atmosphere.
solar constant Rate at which solar radiation is received
outside atmosphere on unit area normal to solar radiation
at Earth’s mean distance from Sun, about 1.38769 kW/m 2 .
solar cycle Approx 11-year cycle in sunspot frequency.
solar day 1 Time between two successive solar transits of
same meridian, ie time for Earth to rotate once on its axis
with respect to Sun (mean or apparent), see sidereal year,
solar year.
2 Time for Sun to rotate on its axis with respect to fixed
stars.
solar electric Propulsion based on jet of ions accelerated
magnetically, thrust measured in grams but specific
impulse typically 1,500.
solar flare See flare (2).
Solar Happ Solar high-altitude powered platform.
solid propellant
solari board Usual type of large electromechanical
display at airports indicating flight arrivals and
departures.
solar noise Solar radiation at RF frequencies.
solar paddle Solar-cell array on fixed frame resembling
paddle.
solar panel Any fixed planar solar array.
solar-particle alert network Global observation system
to warn astronauts of solar flares.
solar propulsion Loose term sometimes used for rocket
systems based on electric power, which can be derived
from solar cells, but best restricted to solar sailing using a
sail (2).
solar radiation Solar constant.
solar simulator Device for simulating solar radiation
outside Earth’s atmosphere.
solar wind Plasma radiating from Sun, assumed equally
in all directions, which in vicinity of Earth has T about
200,000°K, V about 400 km/s and density of 3.5
particles/cm 3 ; grossly distorts terrestrial magnetic field,
causing upstream shock front; another effect is to blow
comet tails downstream from Sun.
Solas Safety of life at sea.
solar year 365 days 5 h 48 min 45.5 s.
solderless splice Joint made by crimping or machinewrapping.
SOLE 1 Start-of-life efficiency of thermoelectric
module or other progressively degraded powerconversion
device.
2 Society of Logistics Engineers (US).
solenoid 1 Range of simple electromagnetic devices in
which current in a coil (usually of cylindrical form) moves
iron core, eg to operate a switch.
2 Tube formed in space by intersection of two surfaces
at which a particular quantity (eg pressure, temperature)
is everywhere equal.
Solic Special-operations low-intensity combat.
solid Apparently immovable [flight controls, especially
ailerons].
solid angle Portion of space viewed from given point and
bounded by cone whose vertex is at that point, measured
by area of sphere of unit radius centred at same point cut
by bounding cone. SI unit is steradian.
solid conductor One containing single wire.
solid fuel Preferably reserved for fuel not used as propellant
but as energy source, eg for EPU. For rocket, see solid
propellant.
solidification By 2003 a common word meaning the
firming-up of a [initially USA] plan of action.
solidity 1 Ratio of total area (not projected area but
integral of chord lengths across length of blade) of
propeller or rotor to disc area. Basic measure of proportion
of disc occupied by blades. See chord length ratio.
2 At standard radius, ratio of sum of blade chords to
circumference, which is not same as (1) since blades of
different rotors or propellers are not all same plan shape.
solid motor Rocket filled with solid propellant.
solid nose Term to distinguish aircraft nose with metal
skin or radome from others of same aircraft type which
are glazed (colloq.).
solid propellant Rocket propellant containing all ingredients
for propulsive jet in solid form, either in cast,
extruded or otherwise prepared grain or in granular,
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