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surface acoustic wave
4 2-D layer in any plane corresponding to particular electronic
radiation pattern or time difference.
5 Hinged or extendable area for flight control, lift
augmentation or drag augmentation.
6 Generalized term for Earth’s *, hence * target = one on
land or water.
surface acoustic wave Travelling across polished piezoelectric
substrate at controllable microwave frequencies.
surface actuator Device which physically moves a surface,
eg control surface; need not embody any form of control
function.
surface boundary layer Atmosphere in contact with
Earth’s surface, extending up to base of Ekman layer
(anemometer level).
surface burning Combustion of fuel for propulsion on
outside of aeroplane, proposed for variable-geometry
aircraft for Mach numbers of about 5, using variable body
profile for ramjet effect.
surface cooler See surface radiator.
surface corrosion Galvanic (non-mechanical) attack on
surface, eg by salt spray, often under paint film.
surface discharge Most common type of gas-turbine
igniter, in which semiconductor [usually SiC] permits leak
from tungsten electrode to body, ionizing path for main
high-energy flashover.
surface effect Effects on air-supported vehicle of close
horizontal surface beneath (synonymous with helicopter
ground effect), hence ** vehicle ( = air-cushion vehicle), **
ship (US usage in latter cases).
surface-friction drag Drag due to all forces tangential to
surface, notably shearing of boundary layer; added to form
drag makes profile drag; added to pressure drag makes
total drag.
surface gauge Gauge (US, gage) in form of precision
stand moved about on surface plate carrying adjustable
scriber for transfer of exact height measures, eg in marking
out or in checking finished workpieces.
surface inversion Atmospheric inversion with base at
Earth’s surface.
surface loading Mean normal force per unit area carried
by a particular aerofoil under specified aeroydynamic
conditions (BS); in case of wing term is wing loading;
suggest few cases where ** needed.
surface management system Looks into near future to
manage departures and avoid congestion or other
problems.
surface movement One vehicle (eg aircraft, or even
bicycle), in motion on airfield movement area. Hence **
indicator, usually a PPI radar.
surface of discontinuity Sloping demarcation between
warm and cold air masses.
surface operations In the US civil community, any movement
on airport/airfield surface.
surface plate Steel table with extremely flat and smooth
surface.
surface power unit Surface actuator embodying control
functions, eg control valves, feedback inputs, summing
units and possibly redundancy provisions.
surface radiator Mounted to form integral part of
external surface of vehicle, with no change in profile.
surface sampler Device for scooping up specimen of planetary
or other surface for analysis or other study (eg to
investigate for presence of life).
surface tape Pinked-edge strips of fabric doped over all
surge line
seams, rib-stitching and edges of fabric covering. Also
called finishing tape.
surface target One on land or sea.
surface tension Tendency of a liquid/gas surface to minimize
its area [because all the attractive liquid molecules are
on one side of the surface], symbol γ.
surface-to-air missile Missile launched from surface (6)
against target above surface (DoD). Hence ** envelope,
that airspace within kill capabilities of particular SAM
system; ** installation, a ** site with system installed; **
site, prepared plot of ground designated for but not
occupied by SAM system.
surface-to-surface missile Surface (6)-launched missile
designed to operate against target on surface (6), including
those underground.
surface visibility At eye level.
surface wave 1 Radio wave travelling round surface (6);
most effective propagation mode of LW/LF.
2 Acoustic wave in surface-wave device.
surface-wave device New family of electronic devices
based on surface acoustic waves sent across piezoelectric
slab or other substrate; originally (1970s) used for delay
lines and now for complex signal processing.
surface wind Generalized term for wind measured at
surface (6); in US gradually switching from 20 ft (6.5 m)
anemometer level to ICAO 10 m (32.8 ft) level.
surface zero See ground zero.
surfacing Improving low-drag quality of vehicle surface
(in general task called stopping and *), eg by perfecting flatness
and smoothness.
surfactant Surface active agent, material (usually liquid
or particulate) which alters surface tension and/or performs
other tasks at boundaries between dissimilar materials, eg
detergent.
surfing Riding with enhanced L/D ratio on the field of
increased pressure created by a hypersonic vehicle’s own
shockwaves.
surge 1 Gross breakdown of airflow through compessor,
normally of axial type, resulting from local stall and usually
characterized by muffled bang and sudden increase in
turbine temperature; hence * line, * point. Often used
synonymously with stall.
2 Various abnormally large currents, signal amplitudes
or voltages in electrics or radio, eg on first switching on or
caused by lightning or static discharge.
3 Planned large increase in flying rate of military unit, eg
to explore ultimate potential of personnel and hardware
over short or longer term under crisis conditions.
4 Unplanned transient increase in flow of fuel in aerial
refuelling, sometimes causing a disconnect.
5 General change in atmospheric pressure at surface
apparently superimposed on predicted diurnal or cyclonic
change.
6 Fore/aft linear motion (simulator).
surge box Term used for various kinds of device in aircraft
fuel system to reduce pressure/flow excursions caused by
fuel momentum either in tanks (sloshing) or in pipelines,
esp. during high-rate refuelling.
surge diverter Protective semiconductor device having
negative resistance/temperature coefficient to earth voltage
surges.
surge line Boundary between gas-turbine operating
region and region where surge of compressor is certain. In
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