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DPMC
DPMC Digital-plotter map computer.
DP/MC Display processor and mission computer.
DPMO Department of Defense POW/missing
personnel office (US).
DPNG Deepening.
DPOC Deep and persistant offensive capability (UK).
DPOI Desired point of impact, or interest.
DPP 1 Deferred-payment plan.
2 Development and production phase.
DPPDB Digital point-positioning database (NIMA
DoD).
DPR 1 Dual-port RAM(1).
2 Aeronautical Association (N. Korea).
DPRAM See preceding.
DPRE Designated parachute rigger/examiner.
DPRK Central aeronautical association [N Korea].
DPS 1 Differential phase-shift.
2 Dynamic pressure sensor (brake pedals).
3 Descent propulsion system (LM or planetary lander).
4 Deorbit propulsion stage.
5 Data-processing system, or set.
DPSK Digital, or differential, or differentially coherent,
phase-shift keying.
DPT 1 Durability proof test.
2 Depth.
DPTAC Disabled Persons Transport Advisory
Committee (DTLR).
DPTCA Director, project technical cost-analysis.
DPU 1 Display processor unit.
2 Digital, or data, processing unit.
DQ Design qualification, demo of required reliability.
DQA Directorate of Quality Assurance; TS adds
Technical Support.
DQAB Defence Quality Assurance Board; E adds
Executive (UK).
DQ&R Durability, quality and reliability.
DQAR Digital quick-access recorder.
DQI Digital-quality inertial.
DQTS Data-quality tool set.
DR 1 Dead reckoning.
2 Dispense rate (mass/time) of chaff or aerosol (ECM).
3 Dispatch reliability.
4 Deck run.
5 Direct.
6 Data record[ing], or receptacle.
7 Design Review [followed by number].
Dr Drift.
D R Receiver antenna directivity.
d r 1 Increment of radius, e.g. helicopter rotor blade.
2 Radar resolution in range.
3 Maximum depth of a rib.
DRA 1 Defence Research Agency (part of Qinetic/
DSTL, previously DERA).
2 Direct radar access.
3 Dual-rail adapter.
4 Dual-row airdrop.
5 Direct radiating array.
dracone Large inflatable fluid (eg fuel, water) container,
towable through sea and usable on soft land (strictly,
Dracone).
Drads, DRADS Degradation of radar defence systems
(active jamming by MIRVs).
DRaFT Digital radio-frequency tag (USAF).
drag Retarding force acting upon body in relative
drag rudder
motion through fluid, parallel to direction of motion. Sum
of all retarding forces acting on body, such as induced *,
profile *. Basic equation is D = C D ½ρV 2 S where C D is
drag coefficient, ρ fluid density, V relative speed (e.g.,
TAS) and S total area, or total wing area.
drag area Area of hypothetical surface having absolute
drag coefficient of 1.0.
drag axis Straight line through centre of gravity parallel
to direction of relative fluid flow.
drag bracing Internal bracing commonly used in fabriccovered
wings to resist drag forces; may consist of
adjustable wires, rod or tubes between front and rear
spars or between compression ribs.
drag chute Parachute streamed from aircraft to reduce
landing run, or steepen diving angle. Also called brake or
braking parachute, deceleration parachute drogue parachute
or parabrake.
drag-chute limit Maximum EAS at which drag chute
may be deployed.
drag coefficient 1 Non-dimensional coefficient equal to
total drag divided by ½ρV 2 S where ρ is fluid density, V
relative speed and S a representative area of the body, all
units being compatible.
2 Coefficient representing drag on given body
expressed in pounds on one square foot of area travelling
at speed of one mile per hour (arch.).
drag creep The [undefinable] point at which drag starts
to rise prematurely before M DD is reached. The usual
cause is formation of small shocks round a blunt leading
edge, cured by root extension.
drag curve Plot of lift coefficient against drag coefficient,
also known as drag polar.
drag-divergence Mach number Loosely, that at which
shock formation becomes significant from viewpoints of
drag, buffet and control. A common precise definition is
M at which dD/dM = 0.05; NASA Langley chooses 0.1,
while another definition is simply M 1.2. Also called dragrise
M, M DD’ and M div .
drag hinge Approximately vertical hinge at root of helicopter
main-rotor blade, allowing limited freedom to
pivot to rear in plane of rotation.
drag index Usually means profile drag at 100 ft/s divided
by total wetted area.
drag link Structural tie bracing a body, such as landing
gear, against drag forces.
drag manoeuvre Air-combat manoeuvre in which one of
a pair draws hostile aircraft into a firing position for his
partner; can be used as verb.
drag member Structural component whose purpose is to
react drag forces.
Dragn Dead-reckoning augmented GPS navigator.
Dragon Deployable ram-air glider with on-board navigation
(UAV).
drag parachute 1 See drag chute.
2 See drogue (3).
drag polar Plot of C D against C 2 L .
drag rib See Compression rib.
drag rise Sudden increase in wing drag on formation of
shockwaves.
drag rope Thrown overboard from balloon to act as
brake or variable ballast when landing; also called trail
rope or guide rope.
drag rudder Wing-tip surface capable of imparting drag
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