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DIAP
2 Détection identification analyse des nouveaux
emetteurs [helo threat warning] (F).
DIAP Defense Information Assurance Program
(DoD).
diaphragm Fabric partition within aerostat; may be
gastight (ballonet *) or non-gastight (stabilizer *).
diathermy Generation of heat by HF power, usually at
0.5/1.5 MHz.
Diatms DISN interim asynchronous transfer services.
DIB 1 De-icer boot.
2 Digital, or DCGS1, integration nackbone.
3 Dry-ice blasting.
dibber Weapon intended to penetrate concrete runway
before exploding.
DIC 1 Defence Industries Council (UK member of
EDIG).
2 Dynamic-inversion controller.
Dicarps Digital cassette recorder for passive sonar.
Dicass Directional command-activated sonobuoy
system.
dice 1 Semiconductor chips or IC after scribing and
separation.
2 To fly, esp. in exciting manner or on operations
(collog. RAF, WW2). Hence, dicing: ‘op’ is on, not
scrubbed.
dichroic mirror One coated with molecular-thickness
layer of reflector, usually metal, so as to transmit some
EM wavelengths (esp. visible colours) and reflect others.
DICU Display interface control unit.
DID 1 Data-item description [S adds sheet(s)].
2 Digital-image design.
3 Data-insertion device.
diddler CRT auxiliary electrostatic plates which can
collapse elongated blips to sharp spots.
DIE Defense [defence] information environment.
die 1 Press tool, often in mating male/female halves,
which cuts sheet or imparts three-dimensional shape to
workpiece.
2 Shaped tools used in *-casting.
3 Shaped tools used in *-forging.
4 Shaped female mould used in explosive or magnetic
forming.
5 Shaped male tool used in ultrasonic, ECM and related
mechanical, chemical or electrochemical shaping.
6 Tool with shaped aperture used in extrusion.
dielectric Substance capable of supporting electric
stress, sustaining electric field and undergoing electric
polarization; includes all insulators and vacuum.
dielectric constant Ratio of capacitance of material to
same condenser using air or vacuum, or of ratio of flux
densities in the two media. Also called permittivity.
Symbol , but ∆, χ and other symbols can be found.
dielectric heating Generated in dielectric subjected to
HF field, resulting from molecular friction due to successive
reversals of polarization; power dissipated is dielectric
loss.
dielectric strength Measure of resistance of dielectric to
electrical breakdown under intense electric field; SI unit is
Vm –1 ; also known as breakdown potential.
dielectric tape camera TV recording camera (Vidicon)
giving output on tape in form of varying electric field.
DIELI Direction des Industries Electroniques et de
l’Informatique (F).
diffraction-optics HUD
DIEPS Digital imagery exploitation and production
system.
diergolic Non-hypergolic, thus requiring an igniter
system.
diesel IC engine utilising heat of compression to ignite
fuel oil injected in highly atomised state direct into
cylinder, with piston nearly at TDC.
dieseling Any spontaneous ignition of combustible
gaseous mixture due solely to temperature caused by
compression.
diesel ramjet Ramjet operating at Mach number high
enough for fuel to ignite by heat of air compression.
DIF, dif Diffuse weather.
Difar Directional acoustic frequency analysis and
recording (ASW).
difference in depth of modulation Modulation of
stronger [usually ILS] signal minus that of weaker, both
expressed as percentages, divided by 100.
differential ailerons Ailerons interconnected so that
upgoing ailcron travels through larger angle than downgoing.
This increases drag of wing with upgoing aileron
and minimises extra drag of the other wing.
differential ballistic wind In bombing, hypothetical wind
equal to difference in velocity between ballistic and actual
winds at release altitude.
differential controls Control surfaces on opposite sides
of body or fuselage which move in opposition to cause or
arrest roll.
differential fare Difference in airline fare levels usually
reflecting time-saving and passenger appeal of new
aircraft.
differential GPS Operates by placing a receiver at a
point precisely referenced to a point on a runway. It then
makes satellite measurements, from which error signals
are transmitted to the airborne receiver which then
corrects the signals received from the satellite, esp. for
precision approach.
differential laser gyro Two lasers of opposite polarization
operate in same cavity; comparison of outputs
gives twice angular-measure sensitivity of normal laser
gyro.
diffrential pitch Original term for cyclic pitch.
differential positioning See differential GPS.
differential pressure Pressure difference between two
systems or volumes (abb. dP). That of fuselage or cabin is
maximum design figure for pressurization system, beyond
which point spill valves open.
differential spoilers Wing spoilers used as primary or
secondary roll control.
differential tailplane See taileron.
differential tracker Radar that can simultaneously
measure angular separation of target and friendly missile,
so that guidance system can reduce this value to zero.
differentiating circuit Circuit delivering output voltage
in approximate proportion to rate of change of input
voltage or current.
diffraction Phenomena which occur when EM wave
train, such as beam of light, is interrupted by opaque
object(s). Rays passing through narrow slit, or a grating
made of slits, are bent slightly as they pass edges; thus
waves can ‘bend’ around obstacle.
diffraction grating Several forms of grating with lines so
close that they diffract EM wavelengths.
diffraction-optics HUD Uses a precise 3-D array of
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