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ZHR
ZHR Zenithal hourly rate (measure of meteor shower).
ZHUD See Z-HUD.
Zhukovsky theory Original (1907) description of airflow
round wing in which viscous effects transmit disturbance
far from solid surface and lift is direct function of airflow.
ZI Zone of the Interior (US).
zinc Zn, blue-white metal, density 6.92, MPt 907°C,
cheap and important in alloys for casting (esp. diecasting)
and dies, form blocks and other press tooling, see
Prestal, and in surface galvanizing, and electric batteries
(see next).
zinc/air Electrical battery in which KOH (potassium
hydroxide) electrolyte is pumped through cell with Zn
cathode (converted to oxide) and anode of porous Ni
through which is pumped air (oxygen). Much higher
energy density than lead/acid.
zinc chromate ZnCrO 4 , yellow pigment used as basis for
yellow-green * primer; mixed with alkyd resins to give
strongly adhering anticorrosive treatment almost
universal in metal aircraft construction whose chromate
ions are released by moisture.
zinc sulfide ZnS, important phosphor in electronic
screens and lighting.
zinger Snag (US colloq., especially in air combat).
zip fuel Exotic or high-energy fuel for airbreathing
engines, esp. ethyl diborane and other liquids based on
boron compounds.
ZIPO Zone indicate [or indicating] position officer
[helicopter landing].
zipped, zipped up Blast/radiation shields in place over all
glazed areas of bomber after release of NW.
Zipper 1 Target CAP (combat air patrol) at dawn or
dusk (DoD).
2 ZIPO.
ZIPS See XIPS.
zip strap Sharp-edge adhesive sealing strip covering gap
or joint in LO aircraft, renewed after maintenance.
zipstring Something simple and cheap.
zirconia Zirconium oxide ZrO 2 , important refractory
(MPt 2,500+°C) ceramic and abrasive.
zirconium Zr, white, ductile metal, density 6.48, MPt
1,857°C; important as alloying element and in nuclear
applications.
ZL 1 Freezing drizzle.
2 Zero-lift.
ZLA Zero-lift angle.
ZLα Zero-lift angle of attack.
ZLBH Zero-lifed bare hull.
ZLDI Zentralstelle für Luft- und Raumfahrt-dokumentation
und Info (G).
ZM 1 Z-marker, v.h.f. station location.
2 Zettametre, see zetta.
zm Zeptometre, see zepto.
Z mo Maximum operating height [usually expressed in
feet].
ZN Azimuth.
Zn Zinc.
ZNKJRK All-Japan Air Transport and Service
Association.
ZnSe Zinc selenide.
Z o Drift (1).
ZOC Zone of convergence (Eurocontrol).
zodiac Band of celestial sphere centred on ecliptic
extending 8° on either side and containing Sun, Moon and
zoning
all planets used for navigation purposes (except, sometimes,
Venus).
zodiacal counterglow See gegenschein.
zodiacal light Faint cone of light seen (esp. in tropics)
pointing towards ecliptic after sunset or before sunrise.
ZOE Zone of exclusion.
zogging Directing accompanying aircraft by means of
hand signals [from 1915] (UK).
ZOH Zero-order hold in FCS sampling.
ZOK Factory for experimental construction (USSR).
Zombie Soviet strategic-reconnaissance aircraft
intruding [legally] into Western airspace.
ZOMP Weapon(s) of mass destruction (USSR).
zonal comfort system Use of evaporative cooling to
manage moisture in passenger compartment (trademark,
CTT).
Zonal Drying Removal of water condensate from
thermal and acoustic insulation of transport aircraft
(CTT).
zonal wind In N hemisphere, wind’s westerly component.
Zone 1, 2 and 3 Surface skin areas whose smoothness
and perfect profile are of high [1], medium [2] or low [3]
sensitivity for causing aerodynamic drag.
zone 1 Administrative region of airspace, esp.
controlled airspace.
2 Portion of drawing (see zoning).
3 Quadrant of radio range, portions of (early-type)
Decca coverage and other navaid subdivisions.
4 Sector of Earth sharing common time, bounded by
two standard meridians; there are 24.
5 Circular areas centred on NW explosion: I, within
MSD (minimum safe distance), within which all friendly
forces evacuated; II, all personnel maximum protection:
III, minimum protection.
6 Regions of aircraft surface: * 3 combines thick
boundary layer with modest local flow velocity; * 2 is
intermediate; * 1 combines thin boundary layer with high
local velocity, and is acutely sensitive to any disturbance
[eg, caused by a rivet head].
7 Portion of aircraft/spacecraft with separately
controllable ECS.
zone marker See Z-marker.
zone numbers Those locating an item on zoned drawing.
zone of intersection Portion of civil airway overlapping
or lying within any other airway (US chiefly, eg CAR
60.104).
zone of protection Within cone of 45° total apex angle
whose apex is top of lightning conductor (eg on airport
building or tower).
zone signals Radio-range quadrant signals (see zone
[3]).
zone time 1 Civil time of meridian passing through
centre of a time zone.
2 Time kept in sea areas in 15° zone of longitude or
multiple of 15° from prime meridian (ASCC).
zoning 1 Dividing large engineering drawing into
numbered/lettered grid so that items can more quickly be
located by assigning each a grid reference.
2 Division of parts of aircraft into *, esp. for fireprotection
purposes.
3 “Delimitation of areas surrounding an aerodrome to
permit freedom of flight to aircraft approaching and
leaving” [1936, suggest archiac].
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