the Aviation Dictionary

J -jet thrust
jack pads - Structural locations capable of supporting
the weight of an aircraft when being jacked from the
ground.
jacket - A metal blanket or shroud used to insulate a
portion of a turbine engine.
jacks - The hydraulic or mechanical devices used to lift
an aircraft off of the ground for testing or servicing.
jackscrew - A threaded, hardened steel rod that can be
rotated to lift an object or to apply a force.
jagged edge - An irregularly shaped edge on a piece of
metal, wood, or plastic material.
jam acceleration - The rapid movement of the power
control lever of a gas turbine engine. Done when
measuring the RPM acceleration rate.
jam nut - A thin check-nut screwed down against a
regular nut to lock it in place.
jamming - Electronic or mechanical interference that
can disrupt the display of aircraft on radar or the
transmission/reception of radio
communications/navigation.
J-block - A precision block ground to an accuracy of
approximately 0.00001", used as a reference in
precision machining operations.
Jeppesen Information Services - A subscription
service, for pilots, which provides revisions for several
flight information publications including the Jeppesen
AIM, Jeppesen FARs for Pilots, the Jeppesen Airport
Directory, JeppGuide, and the GPSILORAN
Coordinate Directory
jerry can - A specially designed five gallon container
used for carrying fuel.
jet - 1. A calibrated, restricted orifice in the fuel passage
of a carburetor used to control the amount of fuel that
can flow under a given pressure. The size of the hole
(jet) determines the amount of flow through the jet. 2.
A forceful stream of fluid discharged from a small
nozzle. 3. An aircraft powered by a turbojet engine. 4.
The hot, high velocity gas stream issuing from the
tailpipe of a gas turbine engine.
Jet A - A kerosene-type turbine engine fuel similar to
the military JP-5. It has a very low vapor pressure and
a relatively high flash point.
Jet A-1 - A kerosene-type turbine engine fuel similar to
the military JP-8 fuel with additives to make it usable
at very low temperatures of approximately -58°F.
Jet Assist Takeoff (JATO) - An auxiliary means of
assisting a heavily loaded aircraft to takeoff,
particularly on a short runway. The JATO consists of
small rockets attached to the aircraft and provides the
required additional thrust needed for takeoff.
Jet B - A wide-cut blend of hydrocarbon fuels for use in
turbine engines. Used primarily in the military as JP-4
fuel.
jet blast -Jet engine exhaust (thrust stream turbulence).
jet emux - The gas flowing from the exhaust nozzle.
jet engine - A reaction engine that derives its thrust
from the acceleration of an air mass through an orifice.
There are four common types: rocket, ramjet, pulsejet,
and turbojet.
jet fuel control (JFC) - The fuel metering system for a
turbine engine. Measures the operating conditions of
the engine and meters into the burners the correct
amount of fuel for the condition.
jet nozzle - A specially designed device shaped to
produce a jet stream.
jet nozzle area - The area in square feet of the opening
through which the engine exhaust gases pass to the
atmosphere.
jet propulsion - The propulsion produced when a
relatively small mass of air is given a large amount of
acceleration
jet pump - A pump that operates by producing a low
pressure through a venturi. Seen in oil scavenge
systems as oil pumps and fuel systems as vapor
eliminators.
jet route - A route designed to serve aircraft operations
from 18,000 feet MSL up to and including flight level
450. The routes are referred to as "J" routes with
numbering to identify the designated route; e.g., J 105.
jet silencer - A device used to reduce and modify the
lower frequency sound waves emitting from an
engine's exhaust nozzle, and thus reducing the noise
factor.
jet streak - A portion of the jet stream where wind
speeds are greater than in regions up- or downstream.
Jet streaks are several hundred to 1,000 miles long.
jet stream - A narrow band of high speed winds (speeds
exceed 60 knots). Normally found near the tropopause.
jet stream axis - The line of maximum winds (>60
knots) on a constant pressure chart.
jet stream cirrus - Associated with an extratropical
cyclone, these anticyclonically curved bands of cirrus
clouds are usually located just downstream of the upper
trough.
jet stream front - High-level frontal zone marked by a
sloping layer below the jet core.
jet thrust -The
thrust produced by a jet.
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