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prepware
prepware Software, usually paper and DVD, for selfinstruction
in PPL, IR or other qualification.
pre-rotation gear Landing gear whose wheels are spunup
before touchdown.
pre-rotation vanes Upstream of fan in wind tunnel to
impart swirl which is eliminated by fan.
PRES, Press Pressure.
Preselect Autopilot mode to capture desired condition,
usually altitude.
presentation 1 Geometric form, character and style of
display, esp. one of electronic nature; eg PPI plus alphanumerics,
line plot plus cursive writing or TV picture plus
alphanumerics.
2 Presentation flight.
3 Putting up a target to be shot at with guns, SAMs or
by fighters; each * can be racetrack, snaketrack, straight
line or other form.
présentation The merge (F).
presentation flight First showing of new type of aircraft
to Press/customers/public, usually [unlike demo flight] in
sedate flypasts.
preset guidance Pre-programmed autopilot determining
mission in advance.
PRESFR Pressure falling rapidly.
pre-simulator training Training on Technamation and
similar animated displays, with mainly dummy controls,
to ensure familiarity with systems and procedures.
PRESRR Pressure rising rapidly.
Press 1 Pacific Range electromagnetic signature study
(USAF, DARPA).
2 Project review, evaluation and scheduling system.
3 Pressure.
Presselswitch Pressure selector with manual input.
press fit Loose term which usually means interference
fit.
press tooling Tooling for use in presses, such as rubber
or mating male/female dies for making finished or nearfinished
parts in sheet; not usually applied to tools for
applying curvature to plate.
press to transmit Pushbutton on control wheel or other
inceptor enabling pilot to use R/T whilst flying manually.
press-ups Jet STOVL training: vertical takeoffs and
landings repeated on same spot.
pressure Force per unit area. The SI unit is the pascal,
1Pa= Nm –2 = 0.02089 lbf/ft –2 ; 1 lbf/ft 2 = 47.8303 Pa;
1 kPa = 0.29530 in Hg; 1 in Hg = 3.38639 kPa; 1 MPa =
0.0675 UK tonf/in 2 = 151.2 lbf/in 2 ; 1 lbf/in 2 = 6.89476
kNm –2 = 6,894.76 P a = 0.0689476 bar = 2.03602 in Hg; 1
in Hg = 0.49115 lbf/in 2 = 3.38639 kNm –2 ; 1 in H 2 O=
249.089 Nm –2 = 5.2023 lb/ft 2 ; 1 bar = 10 5 Nm –2 = 750.08
mm = 29.5307 in Hg; 1 ata = 101.325 kNm –2 = 1.01325
bar = 14.6959 lb/in –2 = 760.01856 mm = 29.922 in Hg.
pressure accumulator Device for storing energy in form
of compressed fluid, typically by gas (nitrogen or air)
trapped above liquid (eg hydraulic system).
pressure altimeter Conventional altimeter driven by
aneroid capsule(s) and measuring not height but local
atmospheric pressure.
pressure altitude 1 Height in atmosphere measured as
vertical distance above standard sealevel reference plane
defined in pressure terms, invariably 1013.2 mb; thus
height indicated by pressure altimeter set to QNE and
corrected for IE (2) and PE (2).
pressure garment assembly
2 Altitude in standard atmosphere corresponding to
atmospheric pressure in real atmosphere.
3 That simulated in pressure (vacuum) environmental
chamber.
4 That at which gas cell(s) of aerostat become full.
pressure-balance seal Disc carried by gas-turbine shaft
acted upon by internal air pressure to maintain positive
forward load on shaft location bearing.
pressure breathing Respiration of gas (eg O 2 or mixture)
at pressure greater than ambient surrounding wearer of
mask; hence * mask. Converse of demand breathing.
pressure bulkhead One sealed to serve as boundary of
pressure cabin or pressurized section of fuselage.
pressure cabin Volume in aircraft occupied by human
beings in which pressure is always maintained at or above
selected level (eg equivalent to atmospheric height of
2,500 m or 8,000 ft) for comfort of occupants no matter
how high aircraft may ascend. Term derives from early
(c1930–40) usage when ** was entity installed in fuselage.
Today inappropriate for civil transports where entire
fuselage is pressurized except for nose tip, extreme tail and
cut-out for wing; preferable simply to use adjective pressurized.
pressure chamber Strictly, one in which environmental
pressure is raised above atmospheric; decompression
chamber is preferred.
pressure coefficient Local pressure (eg measured on
surface of body such as wing) divided by dynamic
pressure, thus Cp = P/½ρV 2 .
pressure cooling Cooling of heat-generating device (eg
piston engine) by liquid maintained under pressure to
raise boiling point.
pressure-demand system Demand oxygen system
supplying at above wearer’s local pressure.
pressure differential Difference in pressure between two
volumes, eg pressurized fuselage and surrounding atmosphere,
dP.
pressure door Sealed to form part of boundary of pressure
cabin or pressurized cargo compartment.
pressure drag Drag due to integral (summation) of all
forces normal to surface resolved along free-stream direction;
most wings in cruising flight have small ** because
adverse pressures on and immediately below leading edge
are largely countered by helpful pressures over rear
portion.
pressure-drop control Called a * valve, * orifice or *
system, this turbofan fuel-control unit comprises sliding
variable-aperture orifices moved by a centrifugal
governor controlling transmission of primary to main fuel
pressure.
pressure error Instruments using a pitot/static system
suffer from *, made up of compressibility error and
position error.
pressure face Side of propeller or helicopter-rotor blade
formed by lower surfaces of aerofoil elements, over which
pressure is usually greater than atmospheric.
pressure fatigue Structural fatigue induced in pressurized
fuselage by repeated reversals of pressurization stress.
pressure flap Large fabric inwards- (rarely, outwards-)
relief valve(s) in skin of airship to allow air to flow in
during descent so that internal pressure shall never be
significantly below that of surrounding atmosphere.
pressure garment assembly NASA terminology for types
of space suit, without PLSS.
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