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floor vents
floor vents Pass used cabin air to pressurized or nonpressurized
lower fuselage.
flops Floating-point operations per second, hence M-*,
Giga-*.
FLOT, Flot Forward line of own troops (formerly
called Feba, forward edge of battle area).
flotation Quality of a wheel landing gear of operating
from soft ground.
flotation bags, collars Inflatables used to provide buoyancy
and stability for sea-recovered spacecraft.
flotation gear 1 Inflatable bags carried inside RPV,
target or missile test vehicle to provide buoyancy after
ditching.
2 Emergency inflatable bags surrounding landing gear
of shipboard helicopter [or, historically, carried on, or in,
carrier-based landplane].
Flo Trak Patented arrangement of large-area plates
fitting around landing-wheel tyre for enhanced flotation,
esp. to permit combat aircraft to use soft surface.
flow augmenter Usually means ejector, but also applied
to inducer at entry to centrifugal pump.
flowback Runback of water from wing leading edge in
icing conditions.
flow chart Graphical symbolic representation of
sequence of operations.
flow control Measures designed to maintain even flow of
traffic into airspace or along route. Chief feature is
acceptance of each aircraft into pre-booked slot at entry
to controlled airspace, at agreed gate time, to provide
orderly ATC service which does not become overloaded.
flow control system One form of main control for gasturbine
engine: fuel-pump delivery pressure is function of
rpm, output being controlled to maintain set dP across
throttle valve for any set air-inlet condition; ancillaries
take care of transients and limitations. See proportional *.
flow disrupter Small hinged or retractable plate intended
to promote intentional stall.
flowdown The multi-stage process by which a set of
requirements are progressivly subdivided into the
smallest indivisiable hardware items. Essentially synonymous
with Work breakdown structure.
flow fence Kevlar fabric shield surrounding top and
sides of ejection-seat occupant.
flowmeter Instrument which measures fluid (gas or
liquid) flow; numerous types based on venturi pressure
drop, speed of free-spinning turbine, pitot pressure and
many other principles; measure can be velocity at point,
near-average velocity or, with density input, mass flow.
See integrating *.
flow rake See rake.
flow regime Particular type of fluid flow (see continuum
*, free-molecule *, laminar *, slip *, turbulent *.
fl oz Fluid ounce.
FLPFM Foot-launched powered flying machine, eg,
wheelless micro or engined parachute.
FLPP Future Launcher[s] Preparatory [or Preparation]
Programme (2002, ESA+R).
FLRCM Future long-range cruise missile (UK).
FLR Forward-looking radar.
FLRE Flare.
FLS 1 Foreign Liaison Staff (MoD).
2 Fuel-level sender.
FLT, Flt Flight (unit).
FLTA Forward-looking terrain-avoidance.
flush air-data system
FLTCAL Flight calibration.
FLTCK Flight check.
FLT CON, Flt Ctrl Flight control.
FLTP Future launcher technology programme (ESA,
1999, never implemented).
Flt Pln Flight plan.
FLTR Flightline tape-reader.
FLTS Flight Test Squadron (USAF).
FltSatCom Fleet satellite communication system; also
clumsily written all capitals (USN).
FLTWO Flight watch outlet.
FLUC Fluctuating.
fluerics See fluidics.
fluid Liquid or gas.
fluid dynamics Study of fluid motion.
fluid element Second or supporting element in fluid four.
fluid four Tactical formation in which second element is
loosely spread in both vertical and horizontal planes to
enhance manoeuvrability, look-out and mutual support.
fluid gallon See gallon.
fluidic nozzle Jet-engine nozzle in which fluidic control
is used to vary vectoring, profile and area.
fluidics Branch of technology akin to electronics but
using instead of electrons air or other fluid flowing at low
pressure through pipes, valves and gates for control of
external systems; one advantage is relaxed upper temperature
limit.
fluidity Reciprocal of viscosity.
fluidized bed Container of finely divided solid particles
supported in liquid-like state by upcurrent of air or other
gas.
fluid mechanics Study of static or moving fluids and
reactions on bodies (includes aerodynamics, aerostatics,
hydrodynamics, hydrostatics).
fluid ounce Non-SI unit of volume, UK * = 1 /160 Imp.
gal. = 28.4131 cc; US * = 1 / 160 US gal. = 23.6588 cc.
fluid resistance See drag.
fluid seal Normally refers to a labyrinth shaft seal in
which the peripheries of the sealing rings on the inner shaft
are slightly immersed in oil in a rotating outer casing. See
hydraulic seal.
fluorescein Proprietary chemical supplied as solid block
attached by lanyard to aircrew dinghy. When dropped
into sea stains surface fluorescent greenish yellow.
fluorescence Emission of photons, esp. visible light,
during absorption of radiation of different wavelength
from other source; photoluminescence (see luminescence,
phosphorescence, scintillation).
fluorescent testing Examination of item coated in
fluorescent ink by UV light, to reveal crack as a bright
line.
fluorine Reactive yellow-green gas, used as liquid (BPt
–188°C) oxidant in rockets (Isp 410 with LH 2 ) or in many
cryogenic compounds such as oxygen difluoride (OF 2 );
* -18 is radionuclide of half-life 110 min.
fluorocarbons Generally resemble hydrocarbons, but F
instead of H makes them more stable; many uses.
fluoroscope Instrument with fluorescent screen supplied
by processed signals from X-ray tube, used for immediate
indirect viewing inside metal or composite structures.
fluoroscopy X-ray TV.
flush air-data system One whose sensors do not protrude
beyond the skin of the aircraft.
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