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ND point
ND point Nominal deceleration point (SST).
NDRC National Defense Research Committee (US,
WW2).
NDS Nuclear detection system.
NDT Non-destructive testing.
NDTA National Defense Transportation Association
[office, Alexandria, VA] (US).
NDTS Non-Destructive Testing Society (UK).
NDU Navigation display unit.
NDV Nuclear delivery vehicle.
NdYAG Nd-doped YAG.
NE 1 No echo [radar weather].
2 Network element.
N/E 1 Neon/ethane mixture (for flushing payload
compartments in space).
2 Northings and eastings.
Ne Neon.
N e 1 Number of engines.
2 Shaft power (USSR, R).
NEA 1 National Electronics Association (US).
2 Nuclear Energy Agency (OECD).
3 Nitrogen-enhanced, or enriched, air.
4 Near-Earth asteroid [R adds rendezvous, T tracking,
TS tracking system].
5 Non-effective airframe (RAF).
NEAC Noise and Emission Advisory Committee
(IATA).
NEACP National-emergency airborne command post
(US).
NEA4 Nitrogen-enriched air with 4% oxygen and other
constituents.
Neal-Smith Criterion for assessing pitch control:
lead/lag pilot model with time delay 0.3s [adjusted to
aircraft] provides closed-loop resonance and phase lead
for comparison with opinions of real pilots.
NEADS NorthEast Air Defense Sector (US).
NEAM New England Air Museum (Windsor Locks).
Neame Gunsight for use at night, with illuminated ring
backsight and red dot foresight, 1917 (UK).
NEAN North European ADS-B network.
Neap Northern European CNS/ATM (7) application
project (Euret).
NEAR Near-Earth Asteroid Rendezvous (NASA).
near encounter Close fly-by of planet or other body.
near field 1 Shockwave region close to source (hence **
signature).
2 Sonic boom area closest to SST track.
near-field effects With jet aircraft, include entrainment
of free stream, blockage behind the nozzles and [STOVL]
suck-down.
near-hit Airmiss.
near-IR Usually defined as 0.75-1.5µ.
near miss DoD term for airmiss.
near space Region between 100,000 and 120,000 ft
[30.48 – 36.58 km], regarded by USAF as a “not used”
region which could be exploited. Hence NSMV.
Near-term data radio A restricted LOS1 system that
relies on terrestrial relay to cover long distances (USA).
NEAT North European Aerospace Test facility
(Kiruna, Sweden).
Neat, NEAT Near-Earth asteroid tracking.
neatlines Parallels and meridians surrounding body of
map (NATO); also called sheetlines.
NEB 1 National Enterprise Board (UK).
negative g
2 National Energy Board (C).
3 Nuclear exo-atmospheric burst (DoD).
4 National Examiner Board (US).
NEC Network-enabled capability.
NECI Noise exposure computer/integrator.
neck Lower tube-like portion of gas-balloon envelope.
necking Local reduction in cross-section of member due
to plastic flow under tension.
necking down Reducing the diversity of types, e.g. on a
carrier.
necklace vortex Formed at a junction between a quasiflat
surface, such as the local skin of a fuselage, and a bluff
projection, such as the leading edge of the wing. Unable
to penetrate the adverse pressure-gradient, the fuselage
boundary layer separates and forms a *, coiling above and
below the wing. In most applications the same as a horseshoe
vortex.
neck moment Bending moment on neck on entering slipstream
in ejection.
NED North/east/down co-ordinate system.
NEDO English rendition of New Energy and Industrial
Technology Organization (Japan).
NEDS Narcotics eradication delivery system (US).
NEEC Noise-excluding ear capsule.
needle Rotary ‘hand’ of traditional dial-type instrument;
but see plural.
needle and ball See turn and slip.
needle beam Extremely directional radio beam with
suppressed sidelobes (difficult for enemy to detect).
needles Generalized term for instrument (esp. flight
instrument) readings; thus ‘the * all dropped to zero’.
needle split Divergence between helicopter engine and
rotor speed indications, with normally superimposed
needles.
needle valve One offering fine adjustment of fluid flow
by linear translation of tapering pointed rod centred in
orifice.
NEF Noise exposure forecast.
NEFC NATO electronic-warfare fusion cell.
NEFD Noise equivalent flux density.
Nefma, NEFMA NATO European Fighter
Management Agency (Int.).
NEG Negative.
“negative” Voice communications word meaning “no”.
negative altitude Angular distance below horizon;
depression (ASCC).
negative area 1 Area on tephigram enclosed between
path of rising particle at all times colder than environment
and surrounding air.
2 Generally, vague area (volume) surrounding colder
air that happens to be rising.
negative camber Usually interpreted as concave on
upper surface.
negative feedback 1 Signal either reversed in sense or
otherwise out of phase and thus tending to increase departure
from original condition.
2 Transfer of part of amplifier output in reverse phase
to input.
negative flow Through an axial compressor, flow from
delivery to inlet.
negative g Subject to acceleration in the vertical plane in
the opposite-to-normal sense, eg aircraft in sustained
inverted flight or in pushover from steep climb to steep
dive; wings are bent ‘downwards’ (relative to aircraft atti-
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