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PDG
PDG 1 Precision-drop glider.
2 Président directeur-général (F).
3 Programmable display generator.
4 Pilot’s display group.
PDI 1 Powered descent insertion.
2 Primary direction indicator.
PDID Pulse-doppler identification.
PDL Program design [or description] language.
PDM 1 Pulse-duration modulation.
2 Primary development model.
3 Programmed depot maintenance.
4 Presidential decision memorandum.
5 Product-data management.
6 Pilot decision-making.
7 Propulsion deorbit module.
P-DME Precision DME.
PDMF Programmable digital matched filter(s).
PDMM Pulse-Doppler map matching.
PDMS Point-defense missile system.
PDN 1 Public data network.
2 Pulse-Doppler navigation.
PDNES Pulse-Doppler non-elevation scan; surveillance
down to surface, without indication of target height.
PDO Pendulum dynamic observer.
PDOP 1 Phase degradation of performance.
2 Position dilution of precision (GPS).
PDOS Powered-door operating [or opening] system.
PDP 1 Program(me) decision package.
2 Plasma, or performance, display panel.
3 Portable data processor [S adds system].
4 Project definition phase.
5 Polar-diagram plotter.
PDQ 1 Photo-data quantiser (or quantifier).
2 Pre-defined qualities.
PDR 1 Preliminary design review.
2 Pulse-Doppler radar.
3 Pilot’s display recorder (Ferranti).
4 Predetermined routeing.
5 Primary defect rate.
6 Preferential departure route.
7 Programmable digital radio.
8 Pressure-drop regulator.
9 Program-development review.
PDRC Pressure-drop ratio control.
PDRJ Pulse-Doppler radar jammer.
PDRR Product/program/project definition and risk
reduction.
PDS 1 Passive detection system.
2 Prestocked dispersal site.
3 Pulse-Doppler search mode.
4 Passenger distribution system.
5 Post-design service(s), or support.
6 Primary display system.
7 Project definition study.
8 Portable data store.
PDSTT Pulse-Doppler single-target track mode.
PDT 1 Pyrotechnic door [or deployment] thruster.
2 Pacific Daylight Time (US).
3 Pliable display technology.
PDU 1 Pilot[’s] display unit.
2 Power drive, or distribution, unit.
3 Pneumatic drive unit.
4 Protocol data unit.
PDV 1 Pressurizing and dump valve.
Pectenometers
2 Parafoil-delivered, or -deployed, vehicle, for MOP(5).
3 Pressure-drop valve.
PDVOR Precision DVOR.
PDW 1 Pulse-detonation wave [rocket] or ramjet.
2 Priority delayed weather.
PDWC Post-departure weather change.
PDWE Pulse-detonation wave engine.
PDZ Parachute dropping zone.
PDZC Pathfinder drop-zone control.
PE 1 Procurement Executive [MoD, Abbey Wood,
Bristol BS12 7DU] (UK).
2 Position error, also p.e.
3 Pilot error.
4 Piston engine.
5 Program, or processing, element (DoD).
6 Professional engineer (US).
7 Permanent echo.
8 Ice pellets.
9 Pre-emptive.
10 Precision engagement.
11 Polyethylene.
12 Passive element [warning system].
P E Pressure in core-engine jetpipe.
Pe See Péclet number.
P e Total installed power of shaft-drive engine[s].
PEAD PE(10) assessment definition.
peak 1 In production programme, time or rate of
maximum output.
2 In aerospace vehicle, highest points in sine-wave
flight, typically 200,000 ft.
peaking circuit Extends frequency response of video
amplifier at highest frequencies.
peak suction Lowest pressure on upper surface of wing
or on 2-D aerofoil profile; rarely, lowest pressure on other
convex surface of aerodynamic body.
peak/trough ratio Peak (usually summer) traffic rate
divided by lowest (usually winter) traffic rate.
peaky Aerofoil section (profile) of traditional type
causing large acceleration of flow over leading edge and
hence very low pressure (large peak suction) over narrow
strip at 8–15% chord; opposite to supercritical or rooftop.
PEAT Procedural event analysis tool.
PEC 1 Personal equipment connector.
2 Pressure, or position, error correction.
3 Pulsed eddy current.
4 Precision-engagement capability.
PECHS Percussion/electric conversion hardware
system [ammunition].
pecked line Broken or dashed line in graphics or
artwork.
pecking Touching ground with propeller tips, esp. on
takeoff.
Péclet number Pe = –––
Vl
where V is fluid flow velocity,
λ
l a length and λ thermal conductivity; applies in heat
transfer at low airspeeds.
PECM 1 Passive electronic countermeasures.
2 Pulsed electro-chemical machining.
PECP Primary entry control point, to hostile airspace.
PECT Peer entity contact table.
Pectenometers Class of aerodynes weighing c6.5g, 0.23
oz, which fly like, e.g., butterflies, by clapping aerofoils
together, ejecting air rearwards. On separation, air is
sucked in from the front (NRL).
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