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notched cone nozzle
notched cone nozzle Promising primary nozzle in
ejector-lift system in which primary flow is discharged
through row(s) of fishtail (lozenge-section) nozzles generating
plumes orthogonal to long axis of duct.
notched elevators Cut away at trailing edge for rudder
movement.
notch effect Shortcoming of early (1960s) all-flying
tailplanes or slab tails in which demands tended to be in
noticeable increments [pilot often reverted to flying on
trimmer].
notch flap Leading-edge flap extended from fuselage.
notifiable accident One which cannot legally go unreported,
where any person suffers injury, third-party
property is damaged or public are in any way put at risk;
variable rules governing scale of damage to aircraft.
no-transgression zone Airspace where aircraft under
positive electronic IFR control must not penetrate, esp.
region 900+ m/2,000+ ft wide between aircraft making
ILS approaches on to parallel runways.
NOTS Naval Ordnance Test Station [China Lake,
Inyokern, etc, now NWC] (USN).
Notus Notice to users (Arinc).
Nourishment Key word which, in extremes [following
failure of other communications] would launch an attack
with NW (UK 1953–77).
Nova Networked open versatile architecture.
NOV-AB Non-persistent Toxic-B gas bomb (USSR).
Novcam Non-volatile charge-addressed memory.
NOVE Networked operations in a virtual environment.
Novoview Range of CGI(2) visual systems, some
textured (Rediffusion).
Novram Non-volatile RAM.
Nowcast Report on current weather.
no-wind position Geographical position aircraft would
have occupied had wind velocity been zero.
NOx, NOX Nitrogen/oxygen breathing mixture
(normally means supplied in absence of atmosphere).
NO x Shorthand for all oxides of nitrogen resulting from
combustion of fuel in air.
noy, Noy Subjective measure of noisiness in bandwidths
of one-third octave (see noise).
NOZ No operating zone.
nozpos Nozzle position[s], ie angle.
nozzle 1 In jet-propulsion or reaction-jet control, aperture
through which fluid escapes from system to
atmosphere and in which as much energy as possible is
converted to kinetic energy (see choked, con/di).
2 Wind-tunnel section immediately upstream of
working section.
3 Primary aperture through which fuel is injected into
gas-turbine engine combustion chamber [US usage].
4 Section of fluid flow duct upstream of axial turbine,
in which flow is controlled to enter turbine at favourable
direction, pressure and velocity. Form depends on
whether turbine is impulse/reaction or pure impulse.
5 Incorrectly, nozzle guide vane.
nozzle blade See nozzle guide vane.
nozzle block See nozzle (2).
nozzle box Assembly of nozzle guide vanes (all, or a
group filling portion of periphery) and surrounding walls
of gas duct.
nozzle bucket See nozzle guide vane.
nozzle contraction ratio Ratio of flow cross-section area
NPP
at inlet or start of nozzle (esp. con/di or rocket) to area at
throat.
nozzle diaphragm Nozzle (4) as complete assembly.
nozzle efficiency Usually ratio of actual change in
kinetic energy across nozzle to ideal value for given inlet
conditions.
nozzle exit area Area of cross-section of flow at exit.
nozzle expansion ratio In supersonic nozzle, ratio of exit
area to throat area.
nozzle guide vane Radial aerofoils upstream of axial gas
turbine, convergent passages between which form
nozzle (4) through which gas is directed on to turbine
rotor blades. Also called turbine stator.
nozzle insert Small blocking body fixed inside nozzle (1)
to trim exit area; colloq. = mice.
nozzle ring Complete 360° assembly of nozzle guide
vanes.
nozzle throat Region of con/di nozzle having smallest
cross-section area.
nozzle thrust coefficient Usually defined as actual
achieved thrust divided by product of chamber pressure
and throat area (rocket).
NP 1 Noise-preferential.
2 North Pacific region (ICAO).
3 Noisy phenotype [optimization variables].
N/P Navigator plotter.
N p 1 Number of passengers.
2 Speed (rpm) of power turbine or, confusingly,
propeller.
3 Power-turbine number of cycles.
np – Yawing moment coefficient due to rolling.
NPA 1 Notice of proposed amendment (FAA, JARs).
2 National Packaging Authority (UK).
3 National Pilots’ Association [trade union; office,
Washington, DC] (US).
4 Non-precision approach.
NPB 1 Nuclear-powered (or propelled) bomber.
2 Nadge Policy Board.
NPC 1 No-paper cockpit.
2 National Petroleum Council (US).
NPD Need and planning documents.
NPDU Network protocol data unit.
NPE Navy preliminary evaluation (USN).
NPF Net propulsive force.
NPG 1 No performance group type aircraft (CAA).
2 Nuclear planning group.
3 Non-unit personnel generator.
NPI Non-precision instrument.
NPIAS National Plan of Integrated Airport Systems
(US).
NPL National Physical Laboratory [1899–; Teddington
TW11 0LW] (UK).
n pll Positive load limit, maximum permissible load
factor.
NPLOs NATO production and logistics organizations.
NPL tunnel A closed-jet tunnel, original * = return flow,
standard * = non-return flow.
NPO Scientific production union (USSR, R).
NPOESS National, later (2002) changed to New, polarorbiting
operational environmental satellite system
(NASA, NOAA, USAF).
NPP 1 Research and production enterprise (R).
2 NPOESS preparatory project.
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