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ceiling balloon
below 6000 m/20,000 ft covering 50+ per cent of sky
(ICAO).
4 Amount above which FFP contract cannot be implemented.
ceiling balloon Small free balloon, whose rate of ascent
is known, timed from release to give measure of ceiling (2).
ceiling climb Aircraft flight authorised for express
purpose of measuring ceiling (1).
ceiling height indicator Device for measuring height of
spot produced by ceiling projector.
ceiling light See ceiling projector.
ceiling projector Source of powerful light beam
projected vertically to form bright spot on underside of
cloud.
ceiling unlimited Sky clear or scattered cloud, or base
above given agreed height (in US 9,750 ft, 2,970 m).
ceiling zero Fog.
ceiliometer Device for measuring ceiling (2), esp. ceiling
projector, in later types a lidar, whose beam oscillates
about horizontal axis like metronome, linked with photocell
with readout in tower.
CEL 1 Centre d’Essais des Landes (F).
2 Capacitatively-enhanced logic, speed enhanced by
incorporation on to chip of capacitor(s).
3 Component evolution list.
Celar Centre Electronique de l’Armement (F).
celestial altitude Altitude (2) of heavenly body or point
on celestial sphere.
celestial body Meaning arguable, but normally all
bodies visible or supposed other than Earth and manmade
objects. Diffuse bodies (eg nebulae) often called
‘structures’.
celestial equator Great circle formed by extending Earth
equatorial plane to celestial sphere.
celestial fix See astro fix.
celestial guidance Guidance of unmanned vehicle by
automatic star tracking.
celestial horizon Great circle formed on celestial sphere
by plane passing through centre of Earth normal to
straight line joining zenith and nadir.
celestial mechanics Science of motion of celestial bodies.
celestial meridian Meridian on celestial sphere.
celestial navigation See astronavigation.
celestial pole Terrestrial pole projected upon celestial
sphere.
celestial sphere Imaginary hollow sphere of infinite
radius centred at centre of Earth (for practical purposes,
at eyes of anyone on Earth).
celestial triangle Spherical triangle on celestial sphere,
esp. one used for navigation.
cell 1 Combination of electrodes and electrolyte generating
EMF; basic element of battery.
2 Portion of structure having form of rigid box, not
necessarily completely enclosed.
3 In biplane or other multi-wing aircraft, complete
assembly of planes, struts and wires forming structural
box.
4 Gasbag of aerostat, esp. in airship having multiple
bags in outer envelope.
5 In EDP, elementary unit of storage.
6 Self-contained air mass of violent character (eg TRS).
7 In military operations, smallest tactical aircraft
element flying together (often three); another definition is
a small unit of airborne military aircraft which can if
necessary operate independently.
8 Compartment forming an element of large internal
bomb bay.
Cellophane Early cellulose-base transparent plastics
film.
cell-textured See textured visuals.
cellular logic image processing Each pixel has its own
dedicated logic element to which are attached its eight
adjacent pixels in parallel architecture. Thus each instruction
is executed by all processing elements simultaneously.
cellule Cell (3) or assembly of two or more wings on
either side of centreline.
Celluloid Early transparent plastics film from nitrocellulose
treated with camphor.
cellulose Carbohydrate forming major structural
constituent of plants; precursor of many aeronautical
materials.
cellulose acetate Thermoplastic from cellulose and
acetic acid; used in rayon, film, lacquer, etc.
cellulose dope See dope.
cellulose nitrate Thermoplastic from cellulose and nitric
acid; used in explosives, dopes and structural plastics.
Celsius Scale of temperature, symbol °C. Unit is same as
SI scale K, but numbers are lower by 273. Until 1948
called Centigrade.
CELT Combined emitter location (or locator) testbed.
CELV Complementary expendable launch vehicle, ie in
addition to Shuttle (US).
CEM 1 Centre d’Essais de la Méditerranée (F).
2 Combined-effects munition (cluster dispenser).
3 Conventional enhancement modification.
4 Concept evaluation model.
5 Core exhaust mixer.
6 Control-, or contract, equipment manufacturer.
7 Computational electromagnetics.
8 Controlled-emissivity material.
Cementite Iron carbide; carbon form in annealed steel.
Ceminal Cost/effective manufacturing in new aluminum
(aluminium) alloys (US).
CEMS Centre d’Etudes de la Météorologie Spatiale (F).
CEMT Conférence Européenne des Ministres des
Transports.
CEN 1 Centre d’Etudes Nucléaires (F).
2 Comité Européen Normalisation [Int. standards].
CENA Centre d’Etudes (formerly d’Expérimentation)
de la Navigation Aérienne (F).
CENC China-Europe Global Navigation Satellite
System Technical Training and Co-operation Centre
(from September 2003).
Cenelec Comité Européen pour la standardisation de
l’Électrotechnique (Int.).
Cenipa Centro de Investigaçao e Prevençao de
Acidentes Aeronáuticos (Braz.).
cenospheres Microscopic hollow ceramic spheres.
Cenrap Center radar processing (terminal ATC).
Centag Centre Army Group (NATO, formerly).
centi Prefix, 10 -2 (one hundredth), symbol c (non-SI).
Centigrade See Celsius.
centilitre Cl, 0.01 litre, measure of volume contrary to SI.
centimetre, centimeter
contrary to SI.
centimetre Hg
centimeter Hg
0.01 metre; measure of length
Used as unit of pressure = 1.33 kPa.
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