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JEFTS
JEFTS Joint Elementary Flying Training School (RAF
Barkston Heath, since 2003 called DEFTS).
JEM 1 Jet-effects model.
2 JTRS enhanced MBITR.
jempers JEMPRS (colloq.).
JEMPRS Joint en-route mission planning rehearsal
system [typically 10 laptops, Ethernet network and
palletized EMS terminal] (US DoD).
Jemtos Jet-engine maintenance task-oriented system.
JENA Jet-engine neural analyser.
Jengo Junior engineering officer (RAF).
Jenisys Joint-effects network-integrated system
solution.
JEPES Joint engineer planning and execution system.
Jeppesen Widely used commercially-sold database of
airway and airport charts and electronic information,
named for Ebroy Jeppesen, whose 1926–40 notes formed
basis.
jerk Rate of change of acceleration, V (esp. in ECM
target or input motion).
jerk offload Extraction of large unit load from airlifter
by sudden pull through ramp door (by parachute, ground
extraction system etc).
Jesus nut Holds main rotor to rotor shaft on helicopter
or, especially, light autogyro.
JET 1 Joint estimate team.
2 Joint experimental toolkit.
jet 1 High-velocity gas flow discharged from nozzle (eg
from * 2 or from open-* wind tunnel).
2 Turbojet engine (loosely, turbofan).
3 Aircraft powered by 2 (loosely, also by rocket).
4 Calibrated orifice(s) in carburettor.
5 To travel by 3.
Jet A Turbine kerosene similar to JP-5; freezes about
-40°C; available US only.
Jet A-1 Turbine kerosene; freezes below -50°C, flash
above 37.8°C; standard commercial fuel.
jet advisory area Specific regions along jet routes
extending 14 nm each side of route segment from
FL240–410 (radar) or FL270–310 + FL370–410 (nonradar).
jet advisory service That offered to certain civil jets in jet
advisory areas; IFR separation or (in radar areas) other
facilities (FAA).
jet age Loosely, era in which jet (3) aircraft became
dominant.
JFTL Joint Future Theater Lift [USA-USAF].
jetavator See jetevator.
Jet B Wide-range distillate fuel similar to JP-4; freezes
below -60°C, vapour pressure 2–3 lb/sq in.
jet blast Disturbance caused by ground running jet
engine, hence need for blast fence.
JETDS Joint electronics type designation system
(NATO).
jet-edge shear Rate of change of velocity per unit radial
distance at outer boundary of jet (1), including on large
scale the velocity profile at edge of atmospheric jetstream.
jet engine Any propulsion system whose reaction is
generated by a jet (1), thus a turbofan, turbojet or ramjet.
Generally used to mean air-breathing, esp.
turbofan/turbojet, and thus arguably not a rocket, and
certainly not applied to space thrusters of ES, ion, plasma
and similar types.
JFCOM
jetevator Small power-actuated flap, spoiler or ring on
skirt or nozzle exit or rocket for TVC.
jet flap Flap through which passes high-energy gas or air
flow, discharged along trailing edge.
jet-fuel starter Main-engine starter burning main-engine
fuel.
Jethete Proprietary refractory sheet metal (high-nickel).
Jeti 1 Jet-engine test instrumentation.
2 Joint European Technology Initiative (Int.).
jet-impingement stagnation pressure That which would
be achieved if a high-velocity jet were to be brought
precisely to rest on a fixed surface.
jet lag Mild temporary symptoms produced in human
beings by fast travel through large meridian difference, ie
through five or more time zones.
jet lift Using jet-engine thrust to support V/STOL
aircraft.
jet noise To a first approximation, the noise caused by
interaction at the edge of a propulsive jet (from a jet engine
or propeller) is proportional to the eighth power of the
relative velocity. See noise.
jetpipe Pipe carrying hot gas from engine core [in a
turbojet, turboshaft or turboprop, from whole engine] to
propulsive nozzle.
jet propulsion Aircraft propulsion by jet engine(s).
jet route High-altitude route system for aircraft with
high-altitude navaids, normally extending from 18,000 ft
AMSL to FL450 (FAA).
JETS Joint effects targeting system.
jet sheet High-velocity fluid flow of essentially twodimensional
nature.
jet shoes Astronaut shoes for weightless walking.
jetstream Quasi-horizontal wind exceeding 80 kt
(148 km/hr) in warm air at sharp boundary with cold, high
troposphere or stratosphere, mid latitudes, predominantly
westerly.
jet tab See jetevator.
jettison Discard fuel, canopy, external stores or other
mass to reduce weight or remove a hazard; hence * pipe(s),
* pump(s), * handle or switch.
Jetts, JETTS Joint effects tactical targeting system, a
software-driven C 2 tool for managing defensive systems
and sensor platforms (UK).
jet vane See jetevator.
jet velocity In turbojet or turbofan core, proportional to
square root of absolute temperature. In rocket, proportional
to square root of absolute temperature divided
by mean molecular weight of jet.
jetway See bridge.
JEWC Joint Electronic Warfare Center (US).
Jezebel Passive acoustic ASW search system (see
Julie) (US).
JFAC Joint Force[s] Air Component; C adds
Commander (US).
J-Fact-SU, JFACTSU Joint FAC Training and
Standardization [in 2007 changed to Support] Unit (RAF
Leeming, UK).
JFASCC JFACC plus space (US).
JFC 1 Jet fuel control.
2 Joint Force, or Field, Commander.
JFCC Joint Functional Component Command[s]
(Stratcom).
JFCOM Joint Forces Command (US).
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