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power plant, powerplant
power plant, powerplant 1 Those permanently installed
prime movers responsible for propulsion, including their
number; thus * of L-1011 TriStar is three RB.211 turbofans
(some authorities would add ‘plus ST6 APU’).
2 One prime mover, of any type, in complete form plus
accessories, silenced nozzle, propeller and associated
subsystem and, in some cases, surrounding cowling. This
is a different meaning from (1).
power port Socket beside passenger seat for laptop or to
charge switched-off mobile.
power press Any press whose actuation force does not
derive from human muscle; need not have vertical motion.
power processing unit Converts electricity from solar
panels into power for a Hall-effect thruster.
power rating Rating (1).
power-recovery turbine Driven by exhaust gas from
piston engine to put extra power into crankshaft or other
output.
power section Gas-generator part of engine, especially
where two share a common output gearbox and drive.
power shear Shear for cutting heavy sheet or plate, with
hydraulic ram(s) moving blade.
power spectral density The assumption that a random
[Gaussian] process can be made up of an infinite number
of sinusoidal components of infinitesimal amplitude and
frequency difference.
power spectrum Plot of Sa(f), signal amplitude against
frequency, normally symmetrical about peak at fc and
with form varying with modulation.
power/speed coefficient 1 Function in propeller performance
calculation, introduced by F.E. Weick;
C s = –––––
J ρ 0.2 V
0.2 = ––––––
2C P 0.2 n 0.4
p
where J is advance ratio, C P power coefficient, ρ density,
V slipstream velocity, P power consumption and n
rotational speed.
2 Variation of installed power or thrust with airspeed,
esp. for jet engine; normally plotted at constant air
density.
power take-off Shaft from which power is available to
drive accessory or other item.
power train Assembly of gearwheels, shafts, clutches
and possibly other items for transmitting shaft power.
Generally synonymous with transmission.
power transfer unit Interconnection between otherwise
totally separated hydraulic systems, eg Green and Yellow,
which enables power to be transfered from one to the
other.
power turbine Mechanically independent turbine (ie
connected to engine only by shaft bearings and gas path)
driving propeller gearbox of turboprop or output shaft of
turboshaft.
power unit 1 Power plant (2) (not recommended).
2 Device which either generates electrical or EM
radiative power or produces required currents or signals
from raw AC or DC input.
3 Source of energy, other than propulsion, for missile,
RPV or spacecraft where there is no shaft-driven alternator
or other supply.
4 Prime mover of APU or EPU/MEPU.
power venturi Venturi used to operate air-driven instruments
or other devices relying on suction.
PPL
POWS Proximity operations work-station (NASA
Ames).
PP 1 Descent through cloud (ICAO code).
2 Present position.
3 Pilot production.
4 Peak-to-peak, also p.p.
5 See P/P.
6 Pre-production aircraft.
7 Probability percentage.
8 Polypropylene.
P/P 1 Private, or pupil, pilot.
2 Push/pull.
P P Polar Pacific.
p.p. Peak-to-peak.
PPA 1 Pre-planned attack.
2 Passengers per annum.
3 Pre-production aircraft.
PPAC Product performance agreement center (US).
PPARC Particle Physics & Astronomy Research
Council [Swindon SN2 1SZ] (UK).
P/PATM Passengers per air transport movement.
PPB 1 Program/planning/budgeting; ES adds evaluation
system, S adds system (US).
2 Parts per billion; (M) adds by mass, (V) by volume.
3 Passenger protective breathing; E adds equipment.
PPB&E Planning, program review, budgeting and
execution[s].
PPC 1 Production possibilities curve.
2 Pulse position code [uplink/downlink].
PPCR Product and process confirmation review.
PPD Proximity/point detonating.
PPDU Physical-layer protocol data unit.
PPE 1 Passengers (per year) per employee.
2 Personal protective equipment.
PPF 1 Production-phase financing.
2 Payload processing facility.
PPFRT Prototype preliminary flight rating test.
P/PFRT Pupil-pilot flight rating test.
PPG 1 Planning policy guidance.
2 Powered para-glider.
3 Pacific Proving Ground[s] (USA).
4 Pulse pressure gain [combustion].
PPH, pph Pounds or, less commonly, pints, per hour.
PPhA Passive phased-array radar.
PPHE Prefragmented preprogrammable high explosive.
PPI 1 Plan-position indicator.
2 Power performance index.
3 Photo production and interpretation.
4 Personal Proficiency Index.
5 Public/private initiative[s].
PPIF Precision photographic interpretation facility
(pre-1980, photo processing [or production] and interpretation
facility).
PPINA PPI (1) not available.
PPINE PPI (1) normal, no echoes observed.
PPIOM PPI (1) out for maintenance, or inoperative.
PPL 1 Private Pilot’s Licence; (A) adds aeroplane, (AS)
airship, (B) balloon, (G) gyroplane/autogyro, (GR)
ground examiner, (H) helicopter, (IR) instrument rating,
(microlight), (R) examiner, (SLMG) self-launching
motor-glider, (X, followed by appropriate suffix) examiner
authorized to conduct flight and ground tests (CAA).
2 Polypropylene.
3 State airports enterprise (Poland).
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