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J
J 1 Turbojet (US military engine designation).
2 Jet route in Class-A airspace (civil airways).
3 Joule[s].
4 General EM signal power.
5 RPV direction aircraft (DoD aircraft designation
prefix).
6 Special test, temporary (DoD aircraft designation
prefix).
7 Polar moment of inertia; also inertia matrix.
8 Aircraft category, transport (1926–31), utility
(1931–55) (USN).
9 Life jackets.
10 Current density.
11 Propeller advance/diameter ratio.
12 Torsion constant units = length 4 .
13 Cost function [or italic J].
14 Bessel function of first kind.
j 1 Mass flux (gaseous diffusion).
2 Square root of minus 1.
3 Usually as subscript, fully expanded jet.
4 Operator, 90° (electrical).
J2 Diesel fuel (G, WW2).
J3E Single-sideband suppressed-carrier mode, ie HF
SSB.
J9 Joint Experimental Directorate (USA).
J-band EM radiation 30–15 mm, 10–20 GHz.
J-curves Atmospheric post-stall manoeuvres by thrustvectoring
aircraft [X-31].
J-dinghy Circular, for crew of 6 (RAF, WW2).
J-display Time base is ring near edge of display, echo
blip position varies with range; main use radar altimeters.
J-nose Fixed leading-edge structure.
J-turn Cobra followed immediately by rapid [30°–40°/s]
yaw to reverse direction of flight.
JA Judge-advocate.
JAA 1 Japan Aeronautic Association.
2 Joint Aviation Authorities [2000–, office at 2130 KA
Hoofddorp, Netherlands] (EAAC, Int.).
JAAA Japan Ag-Aviation Association.
JAATT Joint air attack team tactics (outcome of Jaws
[1]); hence JAAT.
Jabo Fighter-bomber (G).
JaboG Fighter-bomber wing (NATO, Luftwaffe).
JAC 1 Joint airworthiness code (AICMA).
2 Junta de Aeronautica Civil (Chile).
3 Joint Air Component [HQ adds headquarters] (UK).
JACIS 1 Japan Association of Air Cargo Information
Systems.
2 Joint applications command information system
(multiservice, UK).
jack 1 Powered linear actuator.
2 Jack box.
jack box Socket for plugging in communications
headset. Except in light aircraft, probably enables any
crew member or ground crew to access intercom.
jack pad Strong plate, usually square, distributing
support of lifting jack into surrounding airframe.
jackscrew Screwthread converting rotary power to
linear (jack) output, usually irreversible (see ball *).
jack stall Aerodynamic load on the surface overcomes
force applied by powered flight-control unit.
jackstay Hinged strut for bracing cowl or other large
panel when in open position.
JACMAS Joint Approach Control Meteorological
Advisory Service.
Jacobs-Relf Original equations for calculation of M crit
and related C p .
Jacola Joint Airports Committee Of Local Authorities
(UK).
JACTS Joint Air Combat Training Squadron
(USAF/USN).
JAE Judge Advocate-General Executive Office (USAF,
Pentagon).
JAEA Japan Aerospace Exploration Agency.
JAF Royal Jordanian air force [UK usage].
JAFE Joint advanced fighter engine (US).
Jafna Joint Air Force/NASA (US).
Jafü Jagdführer, fighter leader (G, WW2).
JAG Judge-Advocate-General.
Jagd Hunt (G), hence Jagdflieger [fighter pilot],
Jagdflugzeug [fighter], Jagdgeschwader [fighter group
(US = wing)], Jagdgruppe [fighter wing (US = group)].
Jago, JAGO Joint air/ground operations [G adds
Group, S School, at Nellis] (USAF).
Jaguar Joint air/ground operations unified adaptive
replanning [or preplanning] (USAF).
JAIC Japanese Aircraft Industry Council.
JAIST Japan[ese] Advanced Institute of Science &
Technology.
JALS JAA-ATPL integrated learning system.
jam Obliterate hostile EM transmission (esp. radar) by
powerful emission on same wavelength(s).
Jamac Joint aeronautical materials activity (USAF).
James Air-damped pendulum driving deceleration (g)
pointer carried in braked truck to give friction measure on
runway (see JBD, JBI).
jammer High-power emitter to jam specific wavelengths.
jammer support receiver Automatically scans through
programmed range of frequencies of interest.
jamming 1 Noise * obliterates by sheer power.
2 Deception * attempts to mislead enemy by causing
false indications on his equipment.
jam nut Thin lock-nut.
JAMSCE Joint Advanced Materials and Structures
Center of Excellence (FAA).
Janap, JANAP Joint Army, Navy, Air Force
Publication (US).
Janet flights Contractor flights bringing staff to classified
Nellis/Tonopah sites.
Janis, janis Joint Army/Navy intelligence studies (US).
jankers Punishment, confined to camp (RAF, colloq.).
JAN-TX Joint Army-Navy technical documentation
(US).
Janus system Doppler radar technique in which
frequency shift is measured as difference between beams
to front and rear.
JAOC Joint Aerospace Operations Center (USAF).
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