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Dufaylite
Dufaylite Airframe sandwich material with core of light
plastics honeycomb.
duff gen Unreliable or incorrect information (RAF,
WW2, colloq.).
dull switch Cockpit push-switch with dull appearance
because never used.
DUM Dominant unstable mode, degree of freedom of
aeroelastic or aeracoustic instability.
Dumas Dual-mode active IR and imaging IR seeker.
dumb Of munition, unguided or “iron”; not smart or
brilliant.
dumb-bell 1 Manoeuvre in vertical plane resembling *,
usually by helicopter, in making repeated low-level passes
over same point.
2 Sign [usually white] in signals area denoting ‘use
paved areas only’. When ends have black bars = no
restriction on taxiing but use runway for landing or TO.
dumb bogie Unimpressive opponent in air combat.
dummy deck Facsimile of aircraft carrier deck marked
out on land.
dummy round Projectile, usually air-to-air or air-toground
missile, fitted with dummy warhead for test or
practice firing.
dummy run 1 Simulated firing practice, esp. air-toground
gunnery or dive-bombing approach without
release of a bomb. Also called dry run.
2 Trial approach to land, to release or pick up a load,
as practice before actually performing operation.
dump 1 Emergency deactivation of whole system.
2 Of computer operation, to destroy, accidentally or
intentionally, stored information, or to transfer all or part
of contents of one section into another.
3 To jettison part of aircraft’s load for safety or operational
reasons, eg * fuel.
4 Of spacecraft, overboard release of waste water,
astronaut waste products, etc.
5 Temporary storage area for bombs, ammunition,
equipment or supplies.
6 To open * vavle of balloon.
dump and burn Awesome airshow entertainment in
which a fighter makes a flypast in full afterburner and
jettisoned fuel ignites in the hot jet[s].
dumper Lift dumper.
dump door Quick-acting hatch under hopper or tank for
emergency release of chemicals, or under water tank
for firefighting.
dump valve 1 Automatic valve which rapidly drains fuel
manifold when fuel pressure falls below predetermined
value.
2 Large-capacity valve fitted to any fluid system to
empty it quickly for emergency or operational reasons.
3 Pilot-controlled valve which releases hot air or gas
from balloon in controlled manner.
dunk To lower [e.g. sonobuoy] into water on tether or
communication cable.
dunker training How to escape from helicopter underwater.
duo Co-ordinated aerobatics by two aircraft.
duo-tone 1 Colour of camouflage scheme with two main
hues.
2 Two notes emitted by variometer.
Dupe Duplicate (Message).
duple burner Basically simple gas-turbine injector which
DUV
covers wide flow range by having two fuel chambers and
two nozzles. See duplex burner.
duplex 1 Circuit or channel which permits telegraphic
communication in both directions simultaneously.
2 The opposite: a radio system requiring separate T/R
channels.
duplex burner 1 Gas-turbine fuel injector with alternative
fuel entries and single exit orifice.
2 Small primary nozzle, used continuously, plus larger
[often annular, surrounding primary] used only at T-O or
other high-power regime.
duplexer Device which permits single antenna to be used
for both transmitting and receiving, with minimal losses.
(See diplexer).
Düppel Chaff (G, WW2).
DUR Duration, during [C adds climb, D descent, also
expressed as DURGC, DURGD].
Durabond Metallic-composite adhesives for joining
aluminium or stainless steel.
duralumin Wrought alloy containing 3–4.5 per cent
copper, 0.4–1.0 per cent magnesium, up to 0.7 per cent
manganese and the rest aluminium. Originally trade
name.
Duramold Low-density structural material of thermosetting
plastic-bonded wood (Clark, Fairchild, 1936).
duration 1 Maximum time aircraft can remain in air.
2 Time in seconds of operation of rocket engine.
duration model Traditional rubber-powered model
aeroplane designed for flight endurance.
Durestos Composite structural material comprising
asbestos fibres bonded with adhesive, usually formed by
moulding under pressure (Aero Research/Ciba).
dustbin 1 Gun turret lowered through aircraft floor to
provide ventral defence (colloq., arch.).
2 Similar retractable container for sensor, esp. radar.
dust devil Small local whirlwind, dangerous to light
aircraft.
dusting Controlled spreading of powder insecticide,
fertiliser or other chemical by agricultural aircraft.
Dustoff Dedicated, unhesitating service to our fighting
forces (US).
DUT Delft University of Technology.
Dutch door Upper portion hinges up, lower portion
hinges down.
Dutch roll Lateral oscillation with both rolling and
yawing components; fault of early swept-wing aircraft.
Especially dangerous at high altitude, when damping is
insignificant. Can be stable [self-decaying], neutral, or
dangerously divergent [unstable].
DUTE Digital universal test equipment (computerguided
probes check circuit boards).
duty crew Crew detailed to fly specific mission.
duty cycle Ratio of pulse duration time to pulse repetition
time.
duty factor 1 In EDP (1), ratio of active time to total
time.
2 In carrier composed of pulses that recur at regular
intervals, product of pulse duration and PRF.
3 Several meanings in electronic jamming, usually
fractions of unit time set is emitting or receiving.
duty ratio In radar, ratio of average to peak pulse power.
duty runway Runway designated for use by aircraft
landing or taking off.
DUV Data under voice.
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