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power-assisted flight control
output current into low impedance to obtain power gain
as distinct from voltage gain.
power-assisted flight control FCS in which power inputs
assist pilot by overcoming major part of hinge moments
while leaving pilot to move surfaces directly and experience
direct feedback, and with difficulty control
aircraft in event of system failure.
power brake US term for sheet-metal press, esp. one
using mating male/female dies or rubber.
power bumping Sheet-metal forming on bumping
hammer.
power by the hour Contract for total support of
customer’s engines at agreed rate per hour flown.
Contractor may be O&M or OEM.
power centroid Point which will be selected by seeker
(radar or IR) as centre of target; in case where both real
target and decoy (eg flare) are visible, ** likely to be in
space between them.
power coefficient In calculating propeller performance
by the Drzewiecki method, a grading curve to torque
component plotted against blade radius may be drawn for
each pitch angle to arrive at function KQ, constant
for each value of advance ratio J; ** equals KQJ 2 , and has
symbol Cp. Total power absorbed is Cpρ n 3 D 5 , where ρ
is air density, n rotational speed and D tip diameter.
power control unit Electronic box on [usually gas
turbine] engine.
power convertor Apron vehicle or trailer converting 50
or 60-Hz current to 400 Hz.
power density 1 Power per unit volume (electronic
device, nuclear reactor).
2 Power per unit area of beam cross-section (radar).
power dive Steep dive with engine at full throttle, suggest
no longer relevant in jet era.
power drive unit 1 In floor of hold, usually electric, for
positioning cargo.
2 Source of mechanical power for secondary power
system, eg to actuate landing gear or flight-control
surface, a recent usage.
3 More specifically, device for converting electric,
hydraulic or pneumatic power into rotary or linear
mechanical power.
powered approach One in which aircraft propulsion is
giving significant thrust.
powered ascent That from lunar or other non-Earth
surface.
powered controls Powered flight-control system.
powered descent That of Lunar Module or other softlanding
device on to surface other than Earth.
powered flight Flight of vehicle while self-propelled.
powered flight-control system Vehicle flight-control
system which uses irreversible actuation such that no
manual reversion is possible, though pilot may have
manual override over AFCS at input.
powered high-lift system High-lift system in which
energy drawn from main propulsion plays direct role,
either by flow augmentation, flap-blowing, USB or other
technique other than jet lift or use of rotors.
powered lift Lift resulting wholly (or in case of CC/BLC
aerofoil, partly) from engine power. Almost all PL
aircraft can fly at very low airspeed or hover.
powered-lift aircraft In 2002 FAA was defining rules for
what were once called convertiplanes, with VTOL
capability but [most] cruising in aeroplane mode.
power performance index
powered-lift regime Flight regime in which sustained
flight at below POSS is possible because lift and control
moments are derived from installed powerplants.
powered slat One positively driven to extended position
instead of being moved by its own aerodynamic lift.
power egg Complete ECU, usually without propeller
(normally piston engine).
power factor 1 That by which product of alternating
current and voltage must be multiplied to obtain true
load, = cos φ where φ is phase angle between current and
voltage. [θ is also common]; p.f. = P [watts]/VI.
2 Measure of dielectric loss of capacitor.
3 In wind tunnel, ratio of driving power to kinetic
energy multiplied by mass flow in working section.
power feedback Feedback in which significant amount
of power (electrical, electronic or acoustic) is transferred.
power folding Folding wings by power actuation,
usually controlled from cockpit and sometimes by
external protected control.
power gain 1 Ratio of power, usually expressed in dB,
delivered by amplifier or other transducer to power
absorbed by input.
2 In any direction, 4π × ratio of radiation intensity sent
out by aerial to RF power input; with strongly directional
(eg pencil beam) aerial close to zero except on axis of main
lobe.
power gearbox In a turboprop engine, that which drives
the propeller.
power head On large machine tool, cutter and associated
drive.
power in, power out Aircraft parks at airport and departs
without use of towing vehicle.
power in, push out Tug is used to push aircraft from
nose-in stand to taxilane.
power jet In traditional carburettor, fuel jet which comes
into operation only when throttle advances beyond
maximum-cruise position.
power lever Throttle, esp. for gas turbine of any kind.
power loading 1 For propeller-driven aeroplane, W/P e ,
total mass (usually taken as MTOW) divided by total
installed horsepower, ehp in case of turboprop; units
lb/hp = 0.60864 kg kW –1 , reciprocal 1.643. Jet
equivalent = thrust loading.
2 Input shaft power divided by projected area of
propeller [not propeller disc].
power-on spin One entered from power-on stall.
power-on stall Normal stall in which propulsive power is
maintained at significant (eg normal cruising) level
throughout; nose is raised higher to lose speed at acceptable
rate and slipstream usually adds to lift, generally
resulting in more extreme attitude and more violent
pitchover when stall finally occurs.
power-optimized aircraft Research programme which
aims to identify, optimize and validate aircraft equipment
which reduces consumption of non-propulsive power
(EC7).
power overlap Overlap of firing strokes in multi-cylinder
piston engine; for four-stroke engine more than four
cylinders are needed to make this concept of continuous
power effective.
power performance index Computerized index of helicopter
engine power corrected for atmospheric
pressure/temperature, altitude, power-turbine temperature
and drive torque.
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