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pure pursuit-course lead Course in which velocity vector
of attacking aircraft is always directed towards instantaneous
position of target (ASCC).
pure research In case of aircraft, one whose purpose is to
obtain knowledge of general application; aircraft
employed may be specially designed or modified version
of familiar type.
Purex Plutonium/uranium extraction.
purge 1 To clean and flush device, eg liquid-propellant
rocket, by high-rate pumping of inert gas, eg dry nitrogen.
This removes potentially dangerous propellants and helps
preserve hardware; secondary function may be to trigger
various valves and leave inert gas occupying internal
chambers and piping. Term also sometimes used to mean
inhibiting.
2 To prevent admission of air to space above fuel in
aircraft tank by continuously pumping in inert gas
(usually dry nitrogen).
purity Volume percentage of lifting gas in aerostat gas
cell.
Purolator Patented lubricating-oil filter of conventional
form.
Purple Air-intercept code: unit is suspected of carrying
nuclear weapons (DoD).
Purple Airway Special temporary airway established
and promulgated in Notams for Royal flight(s) in UK and
certain other areas. Also Purple airspace.
pursuit aircraft Interceptor (US, term faded from use in
WW2).
pursuit course Course in which attacker must maintain
a lead angle over velocity vector of target to predicted
point in space at which gun- or rocket-fire would intercept
target (ASCC) (see pure pursuit).
pursuit missile One which can be fired only from astern
of air target, eg because IR homing head is unreliable from
any other aspect.
PUS Permanent Under-Secretary of State (UK).
pushback Transfer from gate to clear area or taxiway by
tractor [AM or tug] attached to NLG, hence * clearance,
* crew, * time [usually = OBT], * tug.
pushboom Very long rigid sleeve ahead of aircraft nose,
carrying surface radiating elements.
pushbutton indicator Pushbutton which when depressed
illuminates.
pushdown effect Generalized rule that new commercial
transports enter service on densest routes, pushing older
types down to lesser markets; new type is itself then
pushed down over 10 to 20 years.
pusher See stick-pusher.
pusher aircraft One with pusher propeller(s) only.
pusher propeller One mounted behind engine so that
drive shaft is in compression.
push fit Fit just requiring light force to assemble.
push-off drift See kick-off drift.
pushover Nose-down manoeuvre commanded by stickpusher;
in effect same as pitchover.
push/pull 1 Throttle, eg on lightplanes, having linear
motion sliding through panel.
2 Amplifier having two similar valves or transistors
connected in anti-phase and with I/O circuits combined
about earthed centre.
3 Installation of tractor and pusher propellers in
tandem, posibly separated by entire fuselage.
push-push actuator Linear actuator having unipulse
sorter
pulse sorter ECM device which selects one pulse from
many for detailed measurement.
pulse spike Erroneous sharp super-peak superimposed
on pulse.
pulse-time modulation CW carrier is modulated by pulse
train of lower frequency which in turn is modulated with
variable characteristic, which may be amplitude, duration,
PRF or position.
pulse train Succession of pulses.
pulse width Unlike duration, this measure of CW signal
is normally defined as width (time) between half-power
points.
pulse-width modulation CW signal is translated into
train of constant-amplitude pulses whose widths are each
proportional to corresponding amplitude of original
signal. (Width in this context has no relevance to halfpower
points).
pulsometer Visual indicator of fluid flow, especially
lubricating oil, often showing doses in glass dome calibrated
08-18 [trad. engineering meaning is not used in
aerospace].
pultrude Fabrication process combining pulling
through die and extrusion under back-pressure (eg Grafil
CFC).
pultrusion Raw material or finished section made by a
pultrude-type process.
pulverized fuel ash From coal-burning power stations
[utilities], brings aircraft to a stop in overrun area with
little damage.
Puma Parallel unstructured maritime aerodynamics;
program to generate flow data, eg to predict noise from
helicopter landing gear and other complex shapes.
PUMP Pre-upgrade maintenance programme (RAF).
pump unloading Automatic opening of the fuel-system
spill valve to enable HP delivery to recirculate after shutdown.
pump-up time Time taken to inflate gas storage in blowdown
tunnel.
PUN ICAO code: prepare new perforated tape for
message.
punch, punch out 1 To eject.
2 Confusingly, to start engine(s).
punch welding Poke welding.
pundit 1 Aerodrome beacon with Morse identifying
sequence (arch.).
2 Portable ultrasonic non-destructive digital indicating
tester.
punkah, punkah louvre Fresh-air jets in passenger cabin,
of whatever geometry and location. Typically, overhead
each seat, controlled by passenger.
PUP 1 Pitch-up, or pull-up, point in pop-up delivery.
2 Performance update programme.
3 Principal-user processor.
pupil pilot General British term for student pilot, other
terms being (US) undergraduate pilot, trainee and PUT.
Pilots seeking higher qualifications are not *.
purchase Single grip on yoke, spectacles or other aileron
input; thus full aileron may be two-* task.
purchase cable That connecting pendant to arresting
gear under flight deck.
Pure-clad Trade name (Reynolds) for Alclad-type
material.
pure jet Not defined, but usually meant turbojet as
distinct from turboprop (arch.).
push-push actuator
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