The Cambridge Aerospace Dictionary Episode 11 ppt

V MCP Speed, usually EAS, at maximum continuouspower in level flight; VHis more commonly used.. V r Radial velocity, eg component of velocity alongsightline to target rate of change of r

lowest frequency, or (depending on dimensions,

mounting, impressed forces, coupling and other factors)

at any of numerous modes having different visual pattern

and higher frequency Fundamental mode usually

longi-tudinal over length or thickness, flexural over width or

thickness, and shear over thickness or face

vibrator 1 Mechanical source of high-power sinusoidal

vibration for test purposes; also called vibration generator

2 Rapid-action switch for alternately reversing

polarity of transformer primary fed from d.c to give raw

a.c output; also called vibrator converter

vibratory torque control Mechanical coupling for rotary

output, eg from piston engine, which at low rpm locks

drive into hydraulically stiff configuration but at higher

rpm unlocks and allows drive to be taken through slender

quill shaft

vibrograph Seismic instrument giving record of

vibration displacement/time

vibro polishing Immersion in a vat of small abrasive

particles vibrated at a selected frequency

Vic, vic Formation of aircraft all in same horizontal

plane having shape of V flying point-first; minimum

number of aircraft 3

vicious cycling Standard maintenance procedure for

Ni/Cd battery in which charge is violently drained and

replaced; also called deep cycling

Vickers pyramid Hardness testing machine in which

precise force drives pyramid-point diamond into

specimen, hence * Number = measure of surface hardness

Vicon Visual confirmation (of voice instruction or

clear-ance, especially to take off)

Victor airway Airway linking VORs, thus virtually all

airways in US and many other countries; identified by

prefix V (from 1952)

VID 1 Visual identification, or VID required.

2 Virtual (confusingly, also visual) image display.

video Generalized adjective or noun for electronic

trans-mission of visual information

video compression Returning of video from primary

radar so that each radial trace is briefly stored and then

written more quickly; this allows time for cursive writing

of synthetic data

video detector Diode which demodulates video signal

video display Electronic display which, whether or not it

presents alphanumerics, symbology and other

infor-mation, presents pictures

video extractor System for analysing all signals,

selecting all that form part of useful image (eg in TV or

radar) and excluding all others; in SSR usually

synony-mous with plot extractor

video link Telecom system conveying pictorial

infor-mation

video map(ping) Superimposition on radar display of

fixed information or picture, usually derived from

fine-grain photo plate scanned in synchronization with

rotation of radar aerial or from computer memory, eg in

GCA to show exact relationship of aircraft to surface

obstructions

video signal Telecom signal conveying video

infor-mation

Videotex System of computerized self-service

infor-mation terminals giving complete inforinfor-mation (usually

without charge) to all users, eg passengers at airports

vidicon Most common form of video (TV) picture

(camera) tube, in which light pattern is stored on conductive surface; this is then scanned by electron beam,which deposits electrons to neutralize charge and thusgenerate output signal

photo-Vidissector Modern form of pioneer Farnsworthcamera tube; used in space TV surveillance (ITT)

VIDS Visual integrated [or information] display set [orsystem]

VIE Video image exploitation

Les Vieilles Racines French association of aerospacepioneers and professionals

Les Vieilles Tiges French association of pioneer pilots

Vierendeel Girder (truss) comprising upper/lowerchords and verticals, without diagonals or shear web,designed for flexure

view Opinion; thus ‘to take a dim *’ = to oppose orregret a decision or situation (RAF WW2)

VIEWS, Views 1 Vibration indicator early-warning

system

2 Virtual integrated EW simulator.

VIF Vertical integration facility (space launch vehicle)

viff, VIFF Vectoring in forward flight; pilot control oftrajectory by direct control of propulsive thrust axis ofjet-lift V/STOL aeroplane, selecting downwards for lift(normal acceleration) and forward of vertical for de-celeration, thus performing combat manoeuvresunmatchable by any conventional aircraft Hence verb toviff, viffing etc

Vigil Vinten integrated IR linescan

Vigo pad Small concrete pan preferably surrounded byconcealing trees (STOVL)

VIGV Variable-incidence (or inlet or integral) guidevane[s]

VII Viscosity index improver

VIIRS Visible/IR imaging radiometer suite

VIM 1 Vacuum-induction melting.

2 Vendor information manual.

V IMD Speed (IAS) for minimum drag

V IMP Speed (IAS) for minimum power, not necessarilysame as above

V i-mp Speed corresponding with lowest power at whichboth height and speed can be maintained, ie minimumspeed for continuous cruise (not current use)

V∞ V-infinity, ie free-stream velocity

V (Int) 2

Vehicle integrated intelligence

vinyl ester Low-viscosity solventless liquid resin used asalternative to epoxy in wet lay-up of FRC materials

VIO Violent, meaning heavy static or other radio ference, normal code VLNT for other meanings

inter-violet Route(s) into and out from target area on colourradar

VIP 1 Value improvement programme.

2 Common meaning, very important person.

3 Video integrated processor, or presentation (see next

entry)

4 Vehicle improvement programme.

5 Variable installation position (engines).

6 Voice over internet protocol.

VIP levels Those of video processor yielding weatherecho intensity for precipitation, from * 1 (weak) to * 6(extreme)

Viper Video-input encoder

VIPPS Visual-imaging pass-production system,controlling personnel access

virage Tight turn (pre-WW1).

virga Streaks of water or ice particles falling from cloud

but evaporating before reaching surface

virgin fibre Continuous tow, long staple

VIRSS Visual and IR sensor systems

virtual airline Air carrier created only as legal entity to

facilitate franchising agreement

virtual cockpit One offering no natural external view,

only displays from sensors

virtual collaborative engineering Links users at remote

locations into conference [eg, all can have input to a

drawing]

virtual gravity Terrestrial acceleration acting on parcel

of atmosphere, reduced by centrifugal force due to

parcel’s relative motion; symbol g* = approx 99.99% g

virtual height Apparent height of ionized atmospheric

layer calculated from time for radio pulse to complete

vertical round trip

virtual image One visible in mirror but not projectable

on surface

virtual image display Small CRT binocular colour

high-resolution image of surface target, which appears to be

935 mm (36.9 in) behind face of magnifying lens

virtual inertia That part of inertia forces acting on

oscil-lating body due to surrounding fluid (eg air) and

proportional to fluid density

virtual level Energy level of subatomic nuclear system

for which excitation energy exceeds lowest

nuclear-particle dissociated energy

virtual manufacturing Integration of available

tech-nologies to get right information to right people at right

time to increase speed and accuracy of decisions

virtual mass Actual mass plus apparent mass

virtual piston Pumping effect caused by collapse of

launch tube by explosive lens

virtual star Created by laser illuminating diffuse sodium

c100 km above Earth to give continuous readout of

atmospheric distortion of telescope optics

virtual stress See Reynolds stress.

virtual temperature Temperature parcel of air would

have had had it been entirely free of water vapour, symbol

Tv= (1 + 0.61 q) T where T is measured temperature and

q is specific humidity

VIS Voice-interactive subsystem

V IS Lowest selectable airspeed

vis Invariably means visibility, but ambiguous

Visa Vertically interconnected sensor array

viscoelasticity Behaviour of material which has

heredi-tary or prior stress-history memory and exhibits viscous

and delayed elastic response to stress superimposed on

normal instantaneous elastic strain

viscosimeter Instrument for measuring viscosity;

Saybolt and Engler * are simple calibrated containers with

narrow orifice, result being obtained by timing run-off;

accurate (absolute) * include Stokes (falling speed of small

sphere), rotating-cylinder (outer cylinder drives inner via

fluid interface whose drive torque is measured), capillary

tube (Poiseuille), and oscillating disc (parallel and close to

plane surface)

viscosity 1 Dynamic * can be considered internal

friction in fluid; property which enables fluid to generate

tangential forces and offer dissipative resistance to flow,

defined as ratio of shear stress to strain; in air almost

un-affected by pressure but increases with temperature

Symbol µ; unit Ns/m2

= 1,000 cP; for air 1.78593 × 10–5

Ns/m2

(in traditional units 3.73 slug/ft-s)

2 Kinematic * is µ/ρ where ρ is density; varies with

pressure as well as temperature, units are m2/s = 106cSt;also called dynamic * Symbol ν

viscosity coefficient Synonymous with viscosity

viscosity index Usually synonymous with viscosity, orits variation with temperature

viscosity-index improver Long-chain waxy polymer[s]which stay thick at elevated temperatures

viscosity manometer Instrument for measuring very lowfluid pressure by torque exerted on disc suspended onquartz fibre very close to spinning disc; examples areDushman and Langmuir gauges

viscosity valve Liquid-system control valve controlled

by viscosity of medium, eg in bypassing lube-oil cooler

viscous aquaplaning Occurs when the runway is merelydamp, with a water film not penetrated by tyres;important on smooth surfaces, especially coated withdeposited tyre rubber; persists to low speeds

viscous damping Energy dissipation in vibrating system

in which motion is opposed by force proportional torelative velocity

viscous flow Flow in which viscosity is important; can belaminar or turbulent but criterion is that smallest cross-section of flow must be very large in relation to mean freepath At very low R inertia becomes unimportant andflow is governed by Stokes equations

viscous fluid One in which viscosity is significant

viscous force Force per unit mass or volume due totangential shear in fluid

viscous stress Fluid shear stress, symbol τ = µdu/dy(Newton’s law) where u is velocity distant y from surface

or other reference layer

Visgard Polyurethane conductive coating for parencies, anti-fog, anti-scratch, anti-static

trans-visibility Distance at which large dark object can just beseen against horizon sky in daylight (DoD, NATO, see

RVR, RVV).

visibility meter Instrument for measurement of bility, visual range, eg telephotometer, transmissometer,nephelometer etc

visi-visibility prevailing Distance at which known fixedobjects can be seen round at least half horizon

visibility value Distance (see visibility) along runway, inmiles and tenths

visible horizon Circle around observer where Earth andsky appear to meet (USAF) Also called natural horizon

visible light EM radiation to which human eye responds,typically with wavelength from 400 to 700 mm, 0.4 to0.7µ

visible line Full line on drawing representing a linevisible in assembled subject item

visible radiation See visible light.

visible spectrum See visible light.

visionics Collective term for optical and electronicdevices, operating at many EM wavelengths, whichenhance human vision, especially at night and in badweather or smoke or other adverse conditions

vision-in-turn window Eyebrow window in roof of flightdeck or cockpit

visitor Person entering a foreign state for period lessthan three months

Vismir Visible to medium infra-red

Visol Butyl ether + 15% aniline; rocket fuel with Salbei

(G)

visor 1 Pivoting or translating fairing for forward-facing

cockpit windows of supersonic or hypersonic aircraft, in

latter case with thermal-protection coating

2 Hinged screen, transparent clear or tinted,

protecting eyes against solar radiation and/or

micro-meteorites in space exploration

Visrep Visual report by reconnaissance pilot

VISSR Visible IR spin/scan radiometry (or radiometer)

Vista 1 Very intelligent surveillance and target

acquisition

2 Variable-stability inflight-simulator test aircraft.

3 Virtual integrated software testbed for avionics.

4 Visual imagery simulation training aid.

Visual Visual imaging system for approach and landing,

based on a 3.5-µ Flir

visual See visual contact.

visual acuity Human ability to see clearly, as tested by

letter card

visual approach Landing approach conducted by visual

reference to surface, esp by aircraft on IFR flightplan

having received authorization

visual approach path indicator Simple Vasi for private

pilots with red/amber/green sectors (Lockheed-Georgia)

visual approach slope indicator Systems of visible lights

arranged in pattern at landing end of runway providing

descent (and limited lateral guidance) information Basic

* comprises downwind and upwind bars each of three

lights on each side of runway (in US, total of 2, 4 or 12),

each light projecting red lower segment and white upper

When correctly on glidepath, as close as possible to ILS

glidepath, pilot sees pink For long or LEW aircraft extra

light bars are added in 3-bar *, 3-bar Avasi, T-Vasi and

AT-Vasi FAA-adopted 1970

visual arrow Modern equivalent of finger four

(fingertip), too tight for tactical use but common on

recovery to airfield

visual/aural range See VAR.

visual contact To catch sight of, or a sudden good view

of, target or Earth’s surface

visual cue Visual contact of object outside vehicle, esp

Earth, sufficient to give pilot orientation and position

information; eg first glimpse of ground through cloud

during letdown in remote place far from electronic aids

visual descent point Optional point on final approach

course of non-precision landing, identified by a navaid,

from which VASI should be visible

visual envelope Plot of flight-deck window areas

showing range of P1 vision

Visual Flight Operations Panel Permanently reviews

what is permissible in each class of airspace (ICAO)

visual flight rules Those rules as prescribed by national

authority for visual flight, with corresponding relaxed

requirements for flight instruments, radio etc; in US

typically demands flight visibility not less than 3 st miles

(1 outside controlled airspace) with specified distances

from any clouds; * on top gives a VFR clearance to an IFR

flight above the weather or cloud

visual head-up image Imagery created outside simulator,

focused at infinity; alternative or addition to terrain

visualization Making fluid flow visible, eg by injection ofcarbon tetrachloride or other liquid, smoke, tufting,schlieren, spark photo, hot wire, china clay on surface,liquid films etc

visually coupled Night/all-weather sensor(s) are slaved

to pilot’s helmet-mounted system, so pilot appears to ‘see’normally (field of regard and FOV impose limitations)

Visually Coupled System Specific system linked withTiara, providing monochromatic overlain with aircraftperformance data, on pilot’s HMD

visual meteorological conditions Generally UK part to VFR, requiring visibility 5+ miles and 1,000 ftvertical and 1 n.m horizontal from any cloud [variations

counter-if a/c below 3,000 ft a.m.s.l.]

visual/optical countermeasures Those directed againsthuman eyesight, ranging from reduction of night adapta-tion to blinding

visual photometry Luminous intensity judged by eye

visual range Distance under day conditions at whichapparent contrast between specified target and back-ground becomes equal to contrast threshold of observer

(there is also night *) (see RVR, RVV).

visual reference Earth’s surface, esp that clearly fied and thus giving geographical position as well asattitude and orientation guidance, used as reference incontrolling flight trajectory, if necessary down to touch-down

identi-visual report Identical to hot report but based solely onaircrew observations; answers specific questionsconcerning target for which sortie was flown (ASCC).(ASCC adds ‘not to be confused with inflight report’,while DoD states ‘not to be used; use inflight report’)

visuals Lifelike scenes viewed through windows ofsimulator, almost always wholly synthetic and computer-generated (but in old simulators achieved by optics movedover a large model)

visual separation Basic method of avoiding collisions inTMAs or on ground by seeing and avoiding; normallyinvolves conflicts between arrivals and departures and can

be accomplished by pilot action or tower instruction

VIT Vision in turn

vital actions Rigorously learned sequences instilled intoall pilots, either specific to type or, more often, as generalgood airmanship; necessary eg before entering aircraft,upon entering cockpit, on starting engine, before taxiing,before takeoff, etc On simple aircraft generally remem-bered by mnemonics, eg Bumpf (check brakes, u/c,mixture, pitch, flaps) or HTMPFFG (hood/harness,trim/throttle friction, mixture, pitch, fuel cocks, flaps,gills/gyros)

vital area Designated area or installation to be defended

by air-defense units (DoD)

VITC Vertical-interval time code

Vitreloy Dense ‘metallic glass’ (proprietary, Howmet)

vitrifying Transformation of ceramic from crystallinephase into amorphous or glassy state

Vitro-Lube Ceramic-bonded dry-film lubricant withwide temperature range

VITS Video-image tracking system

VIU 1 Video interface unit.

2 Voloclub Italiano Ultraleggeri (ultralights).

Vivid Video verification and identification

V JVelocity of propulsive jet, normally measured relative

to vehicle

VKIFD Von Kármán Institute for Fluid Dynamics

(Int.)

VKS Military space force[s] (R)

VL 1 Vertical landing, or lift, or launch.

2 Tunnel velocity × characteristic model length.

V/L VOR/localizer

V L Relative velocity of flow on underside of aerofoil

VLA 1 Very light aircraft.

2 Very large aircraft.

3 Vertical line array.

4 Variable lever arm (flight-control ratio changer).

VLAAS Vertical-launch autonomous attack system

VLAC Vertical-Lift Aircraft Council (US Aerospace

Industries Association)

VLAD Vertical line-array Difar

Vladimir Very-large-array demonstration imager for

IR

VLAR Vertical [attitude] launch and recovery

VLBI Very long baseline interferometry

VLBTI Very-long-burning target indicator

VLC Very low clearance

VLCHV Very low cost harrassment vehicle

V L / D , V l / d Best lift/drag speed

VLE Virtual learning environment

V LE Maximum speed with landing gear locked down (E

= extended); flight manual specifies whether main gear

only or all units Always significantly higher than VE

values

VLEA Very-long-endurance aircraft, powered by solar

cells charging fuel cell(s) for continuous flight of months

or years

VLED Visible LED

VLES Very large eddy simulation

VLF Vectored-lift fighter; also see next

v.l.f. Very low frequency See Appendix 2

v.l.f Omega Global system of long-range navigation

using v.l.f radio

V LG No longer used; was vague maximum landing- gear

speed, now replaced by VEI, VLE

VLNT Violent

VLO Very low observability

V LO US term, maximum speed for landing-gear

operation; synonymous with UK VE

V LOF Lift-off speed, at which aeroplane becomes

airborne; suggest = VT

VLR 1 Very long range [1942–45, ranges today

con-sidered modest]

2 Telecom code for long-range search/rescue aircraft.

3 Velocity/length Reynolds number.

4 Very light rotorcraft.

VLS 1 Visible light sensor.

2 Vertical launch system.

3 Veiculo Lancador de Satelittes (Brazil).

VLSI Very-large-scale integration

VLSIC Very-large-scale integrated circuit

VLSIPA Very-large-scale integration photonics

4 Visual [target] marker.

5 Heading to a manual termination.

V M Speed at which precipitation (esp slush) drag ismaximum; always well below aquaplaning speed

V m 1 Volume fraction of composite material occupied

by matrix

2 Missile velocity.

V/M See VM(2), (3)

VMA Code, fixed-wing attack squadron (USMC)

VMAD Vertically mounted accessory drive

V max Maximum CAS for clean aircraft

VMC 1 Visual meteorological conditions.

2 Vehicle management computer.

V MC Minimum-control speed; more precisely specified

as following three entries:

V MCA Minimum speed at which aeroplane can becontrolled in air; defined as limiting speed above which it

is possible to climb away with not more than 5° bank andwith yaw arrested after suffering failure of critical engine

in takeoff configuration, with engine windmilling and c.g

at aft limit There are usually suggested limits of requiredrudder-pedal force and on absolute value of *

V MCG Minimum speed at which aeroplane can becontrolled on ground; defined as that above which pilotcan maintain directional control after failure of criticalengine without applying more than 70 kg pedal force,without going off runway and if possible while holdingcentreline, with 7+ kt crosswind and wet surface

V MCL Minimum speed at which aeroplane can becontrolled in the air in landing configuration, whileapplying maximum possible variations of power onremaining engine[s] after failure of critical engine

V MCL 2 As above but with any two engines inoperative

V MCP Speed, usually EAS, at maximum continuouspower in level flight; VHis more commonly used

VMDI Vector miss-distance indicator

VME 1 Virtual memory environment.

2 V.h.f management entity [bus].

3 Versa module Eurocard [bus].

V ME Airspeed of sailplane for maximum endurance

VMECC Versa module Eurocard card cage

VMF 1 Code, fixed-wing fighter squadron (USMC).

V min Minimum CAS for basic clean aircraft

V M(LO) Minimum maneuver speed (US)

VMM 1 Veille Météorologique Mondiale = World

Weather Watch

2 Vehicle management module.

VM3, VM 3 , VMMM Versatile mass media memory, 4RTMMs

VMO Variable metering orifice

V MO Maximum permitted operating speed under anycondition, higher than VNEand less than VDFbut latter iswholly exceptional limit not intended to be reached exceptduring certification flying

VMS 1 Vehicle management system.

2 Vehicle monitoring system (robotics).

3 Vertical motion simulator.

4 Vehicle motion sensor.

5 Variable metering sleeve.

V MS Minimum EAS observed during normal symmetric

stall, usually less than Vs

VMU 1 Voice management [or message] unit.

2 Velocity measurement unit.

3 Marine Air Group (USMC).

V MU Minimum demonstrated unstick speed, at which

with all engines operating, and without regard to safety,

noise-abatement or any other factor, aeroplane will leave

ground and hold positive climb

VN 1 Speed multiplied by (or plotted against) normal

acceleration; more commonly V-n

2 Vinyl/nitrile (PVC nitrile-based rubber).

V n Component of wind acting perpendicular to

heading; also called normal wind, normal component or

(loosely) crosswind component

V-n Flight speed (usually EAS) multiplied by or plotted

against normal acceleration; hence * diagram, of which

two forms; basic manoeuvring envelope and basic gust

envelope

V NA Noise-abatement climb speed, usually synonymous

with V4(1st segment) but also commonly used for 4th

segment Fuss

V-Nav, VNAV, V/NAV Vertical navigation; generalized

topic of control of flight trajectory in vertical plane; now

becoming automatic in transport-aircraft

energy-managing flight systems In a specific system, an add-on

to LNAV giving glideslope guidance down to 350 ft AGL

(WAAS)

V NE Never-exceed speed; an exceptional permitted

maximum beyond VMOof which captain may avail

himself in unusual circumstances Implication is that *

must be reported and explained

VNII All-union research institute [EM adds

electro-mechanics, RA radio engineering] (R)

V90 Category of off-base airstrips usable by fighters

(Sweden)

VNIR Visible to near-IR

V NO Maximum permitted normal-operating speed,

generally replaced by VMO; in smooth air can be exceeded

‘with caution’

VNR V.h.f navigation receiver

VNRT Very near real time

VNTSC Volpe National Transportation Systems

Center (US DoT)

VNV ALPA (Netherlands)

VO 1 Visual optics.

2 US piston engine code, vertical crankshaft, opposed.

V o Operational speed (airspeed in FCS calculations)

VOA 1 Velocity of arrival.

2 Vsesoyuznoe Obshchestvo Aviastroitelei

(aero-nautical society, USSR, R)

3 Volatile organic analyser.

VOB Vacuum optical bench

VOC 1 Validation of concept.

2 Visual optical countermeasures.

3 Volatile organic compound[s].

Vocational Tax relief Granted by Inland Revenue

against cost of some commercial-pilot training (UK)

Vocoder Voice coder; device responding to spoken input

(usually previously stored) to generate synthetic speechoutput

VOCRAD Voice radio

VOCS Voice-operated carrier suppressor

VOD 1 Vertical-on-board delivery; usually

synony-mous with vertrep

2 Vertical obstruction data.

3 Video on demand.

Voder Device with keyboard input controlling tion of electronic sounds, esp synthetic speech output

genera-VODR Has been used to mean VOR

VOF Volume of fluid

VÖFVL Verband Österreichischer Flugverkehrsleiter(Austria)

Vogad Voice-operated gain-adjusting device; autovolume compressor or expander

Voice Voice optimal interrogator (USN)

voice frequency Normally taken as 25 Hz to 3 kHz fortelecommunications, much greater range for hi-fi

voice-grade channel Covers about 300–3,000 Hz, forspeech, analog, digital or facsimile

voice keying System enabling telecommunications touse common R/T transmit and receive sites and similarfrequencies but with voice-operated carrier suppressorand delay network to switch outgoing signal to trans-mitter and incoming to receiver Remote stationsnormally switch automatically to receive mode exceptwhen user is speaking

voiceless homing Any electronic homing system notusing speech; traditionally meant radio range (arch.)

voice message unit Software-controlled systemproviding voice or tone warnings of faults, sensor activityand other occurrences

voice-operated relay See voice keying.

voice rotating beacon Short-range radio navaid mitting stored-speech headings (usually QDMs) whichdiffer from 000° round to 359°; a form of talking VOR,also called talking beacon, abb VRB (arch.)

trans-void Undesired gap in welded joint

void fraction 1 Percentage of total frontal area of jet

engine through which airflow passes

2 Also several meanings in composite materials and

structures

Voigt effect Double refraction (associated withZeeman) of light passing through vapour perpendicular tostrong magnetic field

VOIR Venus-orbiting imaging radar

Voiska-PVO Troops of air defence of homeland(USSR, R)

Voispond Proposed Calsel function that would matically identify an aircraft by a voice recording

auto-VOL 1 Vertical on-board landing.

2 Volume.

volatile 1 EDP (1) memory which dissipates stored

information when electrical power is switched off; thus,next morning or after weekend all bits must be restoredbefore computer operation Also means electricaltransients cause corruption (though this may be onlytemporary) Hence * data, * memory, volatility

2 Having high vapour pressure, and thus low boiling or

subliming temperature at SL pressure; hence volatility

vol à voile(s) Gliding, soaring (F)

vol d’abeille Beeline, straight-line distance (F)

Volmet Routine ground-to-air broadcast of

meteoro-logical information (ICAO) Today such broadcasts are

Metars and apply to a designated list of airfields

Volocan Radar tracking/computing of flight paths to

solve stacking problems (USAF 1953)

vol piqué Dive (F)

vol plané Planing (inclined) flight, ie glide by powered

aeroplane (arch except in F)

volt SI unit of EMF, = W/A

voltage amplifier Delivers small current to high

im-pedance to obtain voltage gain

voltage-dependent resistor Ohms = f(V); resistance

varies directly with applied voltage

voltage drop PD across any impedance carrying current

voltage-fed aerial (antenna) Fed from one end, where

signal potential is maximum

voltage gain Ratio of output/input voltages

voltage standing-wave ratio Ratio maximum/minimum

V along waveguide or coaxial

volt-ampere SI unit of alternating-current power,

symbol S, made up of power component P watts and

P2

+ Q2; see power factor.

voltmeter Instrument for measuring potential

= 60.9756 in3; cm3(cc) = 0.06102 in3; UK gal [Imp gal]

= 1.20095 US gal; US gal = 0.83267 UK gal

volume fraction 1 Proportion, usually %, of reinforced

composite (FRP) occupied by reinforcing fibres

2 Generally, proportion of whole volume occupied by

particular substance

3 For aerostats see air *, gas *.

volumetric efficiency Volume of combustible mixture (in

diesel, air) actually drawn into cylinder of piston engine

on each operating cycle divided by capacity (swept

volume) of cylinder, usually expressed as % Symbol ην

or eν

volumetric loading Also called * density, total volume of

solid rocket motor propellant divided by total volume of

unloaded case, usually expressed as % Symbol λ

volume unit Measure of audio volume to be outputted by

electrical current, expressed in dB equal to ratio of

magni-tude of electrical waves to magnimagni-tude of reference volume,

usually 1 mW; abb VU

volute Spiral or planar helix; thus, spiral casing of

centrifugal compressor or supercharger impeller

Vom Volts/ohms/milliamps tester

Vomit Comet Aircraft, e.g KC-135, used for

zero-gravity tests

Von Brand Standard method of measuring jet smoke by

passing measured gas volume through filter and then

recording intensity of calibrated light reflected by filter

pad Gives quantified measure of particulate matter

trapped by chosen filter Hence * scale for visible smoke

von Kármán street See street (also called Kármán street).

VOP Variation of price

VOR V.h.f omnidirectional radio range, announced by

RCA in 1941 and forced through by US to become

universal global [except USSR] radio navaid Comprises

fixed beacon emitting fixed circular horizontal radiation

pattern at 108–118MHz on which is superimposed

rotating directional pattern at 30 Hz giving output whose

phase modulation is unique for each bearing from beacon.Thus airborne station can read from panel instrumentbearing of aircraft from station, called inbound oroutbound radial Each fixed station identified by three-letter keyed intermittent transmission (sometimes voice).See Doppler *

VOR/DME VOR steering guidance with DME distanceinformation

Vorgen Voltage generator

VOR/ILS Linkage of VOR signals to aircraft ILS sothat left/right steering guidance is given by ILS panelinstrument Latter often called * deviation indicator, orVorloc

Vorloc, VOR/Loc Panel instrument giving steeringguidance from received VOR signals; can be complete ILSindicator or (esp in light aircraft) simple VOR receiverwith localizer needle only

VORMB, VOR/MB VOR marker beacon

Vormet Sends scripted pilot’s weather reports to flying aircraft

vortex Fluid in rotational motion (possessing vorticity),

eg streamed behind wingtip or across leading edge ofslender delta See line *, point *, trailing *

vortex breakdown Sudden separation of large vortexfrom leading edge of slender delta (naturally followed byits decay) at particular AOA (higher than stalling AOAfor most wings); essentially represents stall of slender-delta wing

vortex burst See vortex breakdown.

vortex dissipator Bleed-air jet(s) blown down below andahead of jet-engine inlet to prevent ingestion of materialfrom unpaved airfields or contaminated runways

vortex drag Drag caused by vortex formation; notnormally a recognized part of aircraft drag

vortex filament Line along which intense (theoreticallyinfinite, at R = 0) vorticity is concentrated; either closedloop or extending to infinity

vortex flap Hinged along its leading edge just behindleading edge of wing on upper surface Opened to 45°traps vortex to increase lift

vortex flow Fluid flow combining rotation with lational motion

trans-vortex generator Small flat blade perpendicular to skin

of aircraft or other body set at angle to airflow to causevortex which stirs boundary layer, usually to increaserelative speed of boundary layer and keep it attached tosurface; also called turbulator

vortex hazard Danger to aircraft, esp light aircraft,from powerful vortices trailed behind wingtips of largeaircraft; also called wake hazard, wake turbulence

vortex lift Lift generated by slender delta or similar winghaving sharp, acutely swept leading edge (subsonicrelative velocity normal to leading edge): large andpowerful vortex is shed evenly on left/right wings, adding

major non-linear increment to lift; also postpones stall to

lower speed and extreme AOA, but with high drag

vortex line Line whose direction at every point coincides

with rotation vector, all of whose tangents are parallel

with local direction of vorticity Must be closed curve or

extend to infinity, or to edge of fluid or to a point on an

infinitely intense vortex sheet

vortex ring Vortex forming closed ring (eg smoke ring);

collar vortex, and formed by helicopter as it slows to the

hover

vortex-ring state Operating state of rotorcraft (esp

heli-copter) main rotor in which direction of flow through

rotor is in opposite sense to relative vertical flow outside

rotor disc and opposite to rotor thrust Occurs in

auto-rotative landing, and can occur with rotor under power if

rate of descent equals rotor downwash velocity

vortex separation Filtration of different types of particle

from fluid by different centrifugal forces in vortex motion

vortex sheet Theoretical infinitely thin layer of fluid

characterized by infinite vorticity; in practice layer of

finite thickness formed by large number of small vortices,

eg as trailed behind lifting wing (where much of vorticity

is quickly rolled up into two large tip vortices)

vortex street See street.

vortex strength Circulation round any body or other

closed system, symbol Γ, constant at all points on a vortex

filament

vortex trail Visible (white) trail from wingtip, propeller

tip etc, caused by intense vortex

vortex tube Device devoid of moving parts in which

pres-sure difference induces fluid flow through tangential slots

into tube; violent vortex divides flow into surrounding

warm flow and cold (about 40°C cooler) core

vortex turbine Mounted in optimum location at wingtip

to extract power from tip vortex

vorticity Vector measure of local rotation in fluid; in

uniformly rotating fluid proportional to angular velocity

(in UK, exactly defined as twice angular velocity) Symbol

q = V¯ V where V¯ is del (mathematical operator) and V is

vector velocity (° curl V in US; often called rot V, from

rotation, in Europe)

vorticity component Circulation around elementary

surface normal to direction of vorticity divided by area of

surface; more strictly, limit of circulation as area of

element approaches zero

vortillon Name coined by McDonnell Douglas to

describe fence around underside of DC-9 wing leading

edge controlling boundary-layer direction

VORW VOR without voice

VOS 1 Velocity of sound.

2 Voice-operated switch.

VOT, Vot VOR test signal; ground facility for testing

accuracy of VOR receivers

voter Binary logic element or device which compares

signal condition in two or more channels and changes

state whenever a predetermined signal mismatch occurs,

usually to exclude a minority ‘outvoted’ signal

voter threshold Difference between signals at which

voter is switched or triggered; normally difference

between one selected signal and mid-value signal from all

others in parallel system

voting system System in which outputs of several

parallel channels are sensed and compared by voter so

that any single malfunctioning channel may be excluded

Votol, VOTOL Vertical-only take-off and landing

VOWS, Vows Valuation of weight saved; measure offinancial reward (usually in increased annual earningpower) from cutting each unit of mass (kg or lb) fromempty weight; eg VOWS for Concorde in 1974 currencywas £50/lb

VOx Vanadium oxide

VOX See Vox.

Vox Voice (communication, keying or activation)

V p 1 Propellant volume; that volume occupied by solid

propellant in a rocket motor

2 Propwash velocity, V + v.

v.p. Vapour pressure

VPAC Vapour-phase aluminide coating

V path Vertical path

VPC Vertical-path computer

VPD Virtual product design

VPDS Variable public display system

V % Best angle-of-climb speed (UK usage, US = Vx)

V %SE Best angle-of-climb speed, single-engine (UK)

V peri Perigee velocity, maximum speed of satellite

where K is constant, rois distance to centre of primary and a is semi-axis of elliptical orbit

VPI 1 Vapour-phase inhibitor.

2 Vertical-position indicator.

vpm, v.p.m. Vibrations per minute

VPN 1 Vickers pyramid number.

2 Variable primary nozzle.

3 Virtual private network.

4 Vendor part number.

VPR Voice position report

VPS Vacuum plasma spray

VPTAR See Vaptar.

VPTS Voice-processing training system

VPU 1 Video, or voice, processing unit.

2 Vortac position unit.

VPU(D) Voice processor unit with data mode

VPVO Air-defence troops (R)

V R 1 Rotation speed, at which PIC starts to pull back on

yoke to rotate aeroplane in pitch; normally determined byone of following: not less than 1.05 VMCA; not less than 1.1

VMS; not less than 1.05 or 1.1 VMU; and it must allow 1.1

VMCAor 1.2 VMSto be achieved at screen after one enginefailure

2 Radar velocity, i.e., of aircraft in which it is

mounted

3 Heading to a radial (US wording).

= K––2ro– 1––

V r Radial velocity, eg component of velocity along

sightline to target (rate of change of range) or fluid

speed along radial direction in centrifugal compressor

measured relative to compressor (ie eliminating tangential

component)

VRA Variable-response [research] aircraft

V RA Rough-air speed; maximum recommended EAS for

flight in turbulence

VRAM Video random-access memory

VRB Voice rotating beacon

VRBL Variable

VRC 1 Vendor reject crib.

2 Value relay centre (EC).

VRD Virtual retinal display

V REF 1 Loosely, any reference speed.

2 In jet transports, a typical approach speed at about

1.35 Vs0(chiefly US)

VRF Code: ferry squadron (USN)

VRG 1 Vertical reference gyro, = vertical gyro.

2 VDL(2) reference guide.

vrille Spin (arch.)

VRMT Virtual-reality maintenance trainer

VROC 1 Vertical rate of climb (helicopter).

2 Validated rate of climb.

VRP 1 Visual reporting post or point.

2 Visual refrence point, giving a fix.

VRS 1 Video recording system.

2 Voice response system.

3 VTOL recovery and surveillance [aircraft] (USCG).

4 Vortex-ring state.

VRT Virtual-reality toolkit [& S adds and simulator]

VRU Vertical reference unit

VS 1 USN squadron code: fixed-wing ASW.

V s 1 Stalling speed; IAS at which aeroplane exhibits

characteristics or behaviour accepted as defining stall (in

US, FAA adds ‘or minimum steady flight speed at which

airplane is controllable’, which is not same thing and is

separately defined in UK as VMCA)

2 Velocity of slip (propeller).

3 Slipstream velocity, relative to aircraft.

V/S Vertical speed

VSA By visual reference to ground (ICAO code)

VSAM Vestigial-sideband amplitude modulation

VSAT Very small aperture terminal

VSB 1 Vendor service bulletin.

2 Visible.

vsby Visibility

VSC 1 Video scan converter.

2 Vacuum system control.

VSCAS Variable-stability control-augmentation

system

VSCF Variable-speed constant-frequency

VSCS 1 Voice switching and communications, or

control, system (FAA)

2 Vertical-stabilizer control system (Notar).

VSD 1 Vertical situation display.

2 Video symbology display.

3 VDL(2) specific DTE address.

VSDR Variable-speed digital recorder

VSER Vertical-speed and energy rate

VSFI Vertical-scale flight instrument

VSG Vibrating-structure gyro

VShorad Very short-range air defense (USA)

VSI 1 Vertical-speed indicator, output is rate of climb

or descent

2 Vertical soft-iron; component of Earth’s field.

3 Vapour space inhibitor = VPI.

4 Vacuum superinsulation.

5 Velocity and steering indicator.

6 Variable-swath imagery.

V SI Indicated stalling speed [avoid confusion with Vs1]

VSIP Virtual-system implementation

V6, V16 Vasi with 6 or 16 boxes, the 16-box being onboth sides of the runway

VSJ Vazduhoplovni Savez Jugoslavije, aeronauticalsport union of former Yugoslavia

VSL Vertical-speed limit [A adds advisory, which may

be preventative or corrective]

VSLD Velocity-, or vertical-, search lookdown

V-sled, VSLED Vibration, structural life and enginediagnostic system

VSM Vertical-separation minimum, or minima

V s0 Stalling speed with flaps at landing setting, engine[s]idling

V s1 Stalling speed in a specified configuration otherthan clean

V s1g Stalling speed under 1 g vertical (normal) tion; obtained from Vsby correcting for any imposednormal acceleration that may have been present during anactual measured stall; a ‘pure’ Vsnot normally enteringinto performance calculations

accelera-VSP Vertical speed; VS more common

VSR 1 Very short range.

2 Volume search radar.

3 Valve-seat recession.

VSRA V/STOL research aircraft (NASA)

VSRAD Very short range air defence

VSRS Variable-speed rotor system

VSS 1 Video signal simulator.

2 Variable-stability system.

3 Vehicle systems simulator.

VSSA Variable-stability simulator aircraft

VSSC Vikram Sarabhai Space Centre (India)

V SSE Minimum speed, selected by manufacturer, forintentionally shutting down one engine in flight for pilottraining; in UK and some other countries this is prohib-ited below 3,000 ft (907 m) AGL

VSSG Vertical Separation Study Group (Navsep)

VST Variable-stability trainer; aeroplane with avionicsand flight-control surfaces added to enable it precisely toduplicate flight characteristics of other types

V st One reference states ‘stall or minimum flightspeed, flaps up, no power’; not a normally recognisedabbreviation

V-Star Variable search and track air-defence radar

V/STOL Vertical or short takeoff and landing

VSTT Variable-speed training target

VSV Variable-stator vane, or valve [A adds actuator,

AS adds actuating system]

VSVT CAA of lithuania (1992), in 1994 becameDCA(2)

VSW 1 Vertical speed and windshear; hence VSWI = *

indicator

2 Variable-sweep wing.

3 Verification software.

VSWE Virtual strike warfare environment

VSWR Voltage standing-wave ratio

6 Video tracker [SC adds system controller].

7 Variable time or timing.

4 Threshold voltage, especially that established for

automatic target detection

V t True airspeed, in aerodynamics

VTA 1 Military transport aviation (USSR, R).

2 Vibration tuning amplifier.

3 Vertex time of arrival.

4 Voice terrain advisory.

VTAS 1 Visual target acquisition system.

2 True airspeed.

3 Voice, throttle and stick.

VTC 1 Vectored (or vectoring) thrust control.

2 Vernier thruster control.

3 Variable time-constant.

4 Vibratory torque control (Teledyne Continental).

V TDM Minimum threshold speed demonstrated

V TDP Vectored-thrust ducted propeller

VTK, V TK Vertical track distance

VTL Prefix to aviation fluid specification(6)

VTM Voltage-tunable magnetron

V Tmax Maximum threshold speed, above which risk of

overrunning is judged unacceptable; usually VAT+ 15 kt

V Tmin Minimum threshold speed, below which risk of

stall (esp in windshear) is judged unacceptable; usually

VAT- 5 kt

VTO 1 Vertical takeoff.

2 Varactor-tuned oscillator.

3 Volumetric top-off.

4 Visiting technical officer (UK).

VTOCL Vertical takeoff, conventional landing

VTO grid Vertical takeoff grid designed to reduce

erosion and reingestion problems in operating jet-lift

aircraft from unprepared surfaces

VTOGW Vertical takeoff gross weight

VTOL Vertical takeoff and landing; VTOVL adds

redundant second ‘vertical’

VTOSS Takeoff safety speed (rotorcraft) (FAA)

VTPR Vertical temperature-profile radiometer

VTR 1 Video tape recorder.

2 Vocational training, or tax, relief.

3 Variable takeoff rating.

VTRAT Visual threat recognition and avoidance

trainer

V TRK , V/TRK Vertical track

VTS 1 Video target simulator.

2 Voice telecom system.

V TS Velocity of tunnel test section

VU Volume unit

VTUAV 1 VTOL UAV.

2 VTOL tactical UAV.

VTVL Vertical takeoff, vertical landing [suggest =VTOL]

V U 1 Relative airspeed across upper (positively

cambered or lifting) surface of aerofoil

2 Tangential velocity, eg of flow leaving centrifugal

compressor

3 Utility speed (US usage).

VUAV Vertical UAV

V/u.h.f. Very and ultra-high frequency; Appendix 2

Vulcanoids Hypothetical asteroids within the orbit ofMercury

Vulkollan Hard erosion-resistant thermosetting plasticsmaterial (trade name, F)

V us Unstick speed of marine aircraft

VV 1 Vertical visibility, measured (most countries) in

hundreds of feet, or runway visibility value

2 Valve voltmeter.

3 Validation and verification (sometimes V&V).

4 Velocity vector.

V/V Vertical velocity

VVA 1 Zhukovskiy air force academy (USSR, R).

2 Vietnam Veterans of America; F adds Foundation.

3 Voltage variable attenuator.

VV&A Verification, validation and accreditation

VVI Vertical velocity indicator, suggest = VSI

VVIA VVA engineering academy (USSR, R)

VVR Voice and video recorder

VVS, V-VS Air forces (USSR, R)

VVT Variable valve timing

VW Vortex wake; S adds spacing

V w Tailwind, or tailwind component

VWA Virtual worktop architecture

VWF Verband der Wissenschaftler an instituten (G)

Forschungs-VWP Visa-waiver program (Dept of State)

VWRS Vibrating-wire rate sensor

VWS 1 Vertical windshear.

2 Ventilated wet suit.

VX 1 General code for nerve gases.

2 Test and Evaluation Squadron (USN).

V x Airspeed for best angle of climb, segment not fied (US usage)

speci-VXE Antarctic Development (ie, exploration)Squadron (USN)

VXO Variable crystal oscillator

V XSE Airspeed for best angle of climb, single-engine (USusage)

V Y Airspeed for best rate of climb (US usage)

VYRO, Vyro Vertical yaw and roll

V YSE Airspeed for best rate of climb, single-engine (USusage, also called blueline speed)

VZ Aircraft designator, vertical-lift research (USA1957–62)

V ZRC Airspeed for zero rate of climb, at which with oneengine inoperative drag reduces gradient to zero

W 1 Watt[s], and general symbol for power in SI

countries

2 Weight, loosely synonymous with mass, and mass

flow, esp through jet engine

3 Force of applied load.

4 Energy [work]; E is preferred.

5 Tungsten [from wolfram].

6 Aircraft mission, prefix, electronic search or AEW

(USN 1952–62)

7 Modified mission, suffix, AEW (USN 1944–62);

prefix, weather reconnaissance (USAF from 1958, USN

from 1962)

8 JETDS code: armament, automatic flight or

remotely piloted

9 Weather, and airport with NWS office (US).

10 West, western longitude.

11 Weapon.

12 Wave[s] or Mach-wave angle.

13 IFR flightplan; approved R-nav but no xpdr.

14 Wing [military unit].

15 Prefix, NW warhead.

16 White light.

17 Width, maximum tyre [tire] cross-section.

18 Warning.

19 Indefinite ceiling, sky obscured.

20 Secondary station (Loran).

21 See W-engine.

22 Without voice (radio).

23 Suffix, quenched in cold water.

w 1 Generalized symbol for special fluid velocities, eg

vertical gust, wing downwash, propeller slipstream etc

2 Warm (air mass).

3 Load per unit distance or per unit area.

4 Specific loading.

5 Linear velocity due to yaw.

6 Suffix, wing; thus Ww= wing weight

7 Rate term for weight or mass, eg per unit time.

8 Generalized symbol for work.

9 Range, of values.

W-code W (13): approved R-Nav but no transponder

W-engine Piston engine with three linear banks of

cylinders about 50°–60° apart; also called broad-arrow

W-wing Shaped like W in planform with sweepback

inboard and forward sweep outboard

WA 1 Work authorization.

2 Prefix: word after

3 Airmet weather advisory.

W/A Weight per cross-section area (warhead)

W A Equipped airframe weight

W a Air mass flow, eg passing through engine per

second

WAA War Assets Administration (US, 1946 – )

WAAF Women’s Auxiliary Air Force (UK, 1939–49)

WAAM Wide-area anti-armour munition

WAAS 1 Wide-area active surveillance (radar).

2 World airline accident summary (UK CAA).

3 Wide-area augmentation system (GPS, US

3 Wide-angle collimated; S adds system.

4 World Aeronautical Chart (1,000,000 scale).

5 Women’s Army Corps (US, 1943 – ).

WACA World Airlines Clubs Association (Int.)

WACCS Warning and caution computer system

WACD Wide-area change detection (DDB)

WACRA, Wacra World Airline Customer RelationsAssociation (Int.)

WAD 1 Workload assessment device.

2 Wide-angle differential (see *GNSS, *GPS).

WADC Wright Air Development Center (USAF)

WADD Wright Air Development Division

WADDS Wind and altimeter [setting] digital-displaysystem

WADGNSS Wide-area differential global navsatsystem

WADGPS Wide-area differential GPS

WAEA World Airline Entertainment Association(Int.)

WAEO World Aerospace Education Organization(UK)

WAF Women in the (US) Air Force (1948 – )

WAFC World area forecast centre

wafer Complete (near-circular) slice of single crystal(usually epitaxial) semiconductor material on whichnumerous elecronic devices are constructed, subsequentlyseparated by scribing and cleavage to make chips

waffle plate Thin metal sheet stabilized by impresseddimples, often parallel rectangles Same name for morecomplex sandwich structures

WAFS 1 Women’s Auxiliary Ferrying Squadron (US,

1942)

2 World area forecast system.

WAG 1 World average growth.

2 World Air Games, held annually.

WAGE Wide-area GPS enhancement

waggle Rapidly repeated bank to left and right [say,

±20°]

Wagner bar Pioneer spoiler-type flight control withbang/bang solenoid operation for radio commandguidance of missiles (from 1937)

Wagner beam Idealized pure tension-field beamassumed to have zero compressive strength and thus toreact loads as diagonal tensions; generally, a beamdesigned to buckle in operation

wagon wheel See wheel (6).

wagonwheel propellant Solid rocket motor propellantgrain with cross-section having form [positive or negative]

of wagon wheel

WAGS Windshear alert and guidance system

WAHS World Airline Historical Society (US)

WAI 1 Wing anti-ice, anti-icing.

2 Women in Aviation, International (1994 –, office in

Ohio)

W

wailer Unmistakeable warning triggered by autopilot

disconnect without human response

WAIN Wide-area integrated network

waist 1 Amidships portion of fuselage or hull; thus *

gunner, firing laterally (often from rear midships area)

2 Middle portion of gas-turbine engine, esp where

diameter here is less than elsewhere; thus * gearbox for

accessories

waisting 1 Local reduction in diameter caused by plastic

flow under tension, esp at point of failure

2 Local reduction of cross-sectional area of body, eg to

conform to Area Rule

waiting beacon “A low-power omni-directional beacon

used by aircraft waiting their turn to follow the radio

track” (B.S., 1940)

waiver Whereas usual meaning is permanent

relinquish-ment, in air law or certification it is a postponement

WAK Wing adapter kit

wake 1 Fluid downstream of body where total head has

been changed by body’s presence; usually to some degree

turbulent

2 Wingtip vortices left in atmosphere behind aircraft

whose wing is generating lift, in case of large/heavy

aircraft very powerful and persistent, capable of

destroying light aircraft

wake-interaction noise Generated by impingement of

wake from moving blade on object downstream, eg stator;

in gas turbine hundreds of such interactions can generate

noises at blade-passing frequency of each stage of blading,

plus harmonics

wake separation Divergence of wakes (2) behind large

aircraft

wake turbulence Turbulence due to wakes (2), behind

large aircraft with powerful downward motion

wake turbulence classification Applies to conventional

aeroplanes: light aircraft 7 t (15,432 lb); medium =

7–136 t (c 300,000 lb); heavy = 136+ t (ICAO) The UK

has a definition ‘small aircraft’ = 17–40 t

wake vortex Wake (2)

walkaround oxygen Bottle carried by aircrew when

disconnected from system

walkback Return of deck arrester wire (pendant) to

‘cocked’ or ready position

walking 1 To advance engine throttles (power levers) in

asymmetric steps, left/right/left etc

2 To keep straight on takeoff with violent left/right

rudder

walking beam Pivoted beam transmitting force or

power, eg to retract landing gear; secondary meaning

arising by chance from repeated usage is landing-gear

retraction and bracing beam whose upper end is not

pivoted direct to airframe but to a sliding or translating

member, eg long jackscrew

walking in/out Movement of aerostat, esp airship, in or

out of hangar by large ground crew walking while holding

tethering lines

walking-stick 1 Laser used to indicate ground clearance

in descent through cloud with ceiling close to terrain (not

colloq.; name derives from stick of blind person)

2 Gas-turbine vaporizing burner in which fuel is heated

in tube with 180° bend looking like top of *

walk-on service Airline service in which anyone could

walk directly on board, buying ticket from cabin crew [not

after 9-11]

walkway Catwalk or other narrow structure provided inairship (rarely, large aircraft of other type) to providehuman access to other part; hence * girder

wall 1 Sides of tyre, between wheel and tread.

2 Internal boundaries of wind tunnel; not only vertical

sides

wall constraint Distortion of flow round model in tunnelwith closed working section arising from fact that wallsare seldom aligned with streamlines

wall energy Energy per unit area of boundary betweenoppositely oriented magnetic domains

Wallops Flight Facility NASA island complex on USeast coast [Hampton, VA] used for nearly all small rocketlaunches

wallowing Uncommanded motions about all three axes

Walter Emergency locator beacon emitting powered pulses

battery-WAM Window addressable memory

WAMRS Water-activated mask-release system

Wams, WAMS 1 Weapon-aiming mode selector.

2 Women Aircraft Mechanics Service (1942 –) (US).

WAN Wide-area network (distributed systems)

wander See apparent precession.

wandering Slow and apparently steady uncommandedchange in heading; may from time to time reverse itself

Wanganui Blind skymarking of target obscured bycloud: Main Force set zero wind and on a given headingbombed on parachute flare (RAF WW2)

WAP Wireless application protocol [mobile phones]

tele-WAPS, Waps 1 Weighted airman promotion system

(US)

2 Wide-area precision surveillance.

3 Whole-airframe parachute system.

WAR Warning

War Air Service Program American (DoD) plan for civilairline routes, equipment and services following with-drawal of CRAF aircraft

warbird Historic military aircraft, real or replica

WARC World Administrative Radio Conference [suffixMOB added mobile service, ST space telecommunica-tions, and two numbers indicated last two digits of year,

eg 1992] (ITU)

war consumables All essential expendables directlyrelated to hardware of a weapon/support system orcombat/support activity (USAF)

War Executive Officer in squadron responsible fordetailed planning of all combat missions (RAF)

war game Simulation, by whatever means, of warfareusing rules intended to depict real life

war gas Chemical agent designed for use against humanbody directly; eg not used to contaminate water supply.Liquid, solid or vapour

warhead Portion of munition containing HE, nuclear,thermonuclear, CBR (2) or inert materials intended toinflict damage DoD recognizes additional term, *section, as assembled * including appropriate skinsections and related components; thus * alone need notinclude fuzing, arming, safety and other subsystems

Warhorse, War Horse Wide-angle reconnaissancehyperspectral overhead real-time surveillance experiment

warhud Wide-angle raster HUD

warload Generally taken to include expendableweapons, external fuel and external EW

Warloc W-band advanced radar for low-observables

control

Warlord War Executive (colloq.)

Warmaps Wartime Manpower Planning System (US)

war materiel All purchasable items required to support

US and Allied forces after M-day (US)

warm front Locus of points along Earth’s surface at

which advancing warm air leaves surface and rises over

cold air

warm gas thruster Propulsive jet composed of HP stored

gas heated (eg by main rocket combustion) before

ex-pulsion through separate nozzle; various configurations

but common for vehicle roll control

warm sector Portion of depression, esp recently formed,

occupied by warm air

warm-up Generalized term for process, or necessary

elapsed time, in which device is operated solely for

purpose of bringing it to steady-state operating condition,

with steady running speed, temperature, pressure or other

variables Examples: piston engine, gyro

warm-up time Published time for device, eg gyro, to

reach specified performance from moment of energization

Warn Weather-analysis radar network

warned exposed Friendly forces are lying prone with all

skin covered and wearing at least two-layer summer

uniform

warned protected Friendly forces are in armoured

vehi-cles or crouched in holes with improvised overhead

shielding

warning area Airspace over international waters in

which, because of military exercise, non-participating

aircraft may be at risk

warning indicator Device intended to give visual or aural

warning of hazard, eg fault condition or hostile attack

warning in/out Two books in which members record

details of temporary duty elsewhere, leave and other

absence (RAF Officers’ Mess)

warning net Designated telecom system for

dis-seminating information on enemy activity to all

commands

warning order Preliminary notice of friendly action to

follow

warning panel Area of display, eg on aircraft flight deck,

containing numerous designated warning indicators or

captions, with or without attention-getting master *

warning receiver Passive EM receiver with primary

function of warning user his unit/vehicle/location is being

illuminated by an EM signal of interest

warning red Attack by hostile aircraft/missiles imminent

or in progress

warning streamer Brightly coloured fabric strip, flexible

in light breeze, drawing attention to protective cover or

other item which must be removed from vehicle before

flight or launch

Warp Weather and radar processor, a 1990s

develop-ment (FAA)

warp Threads in fabric parallel to selvage, continuous

full length of material

warping Twisting wings asymmetrically to obtain lateral

stability and control; usually imposed by diagonal

down-ward pull on rear of wing near tip to twist (wash-in) and

increase camber

Warps Wing air-refuelling pod system

warp-sheet Standard raw-material form of reinforcing

fibre, esp carbon/graphite, in which broad sheet is made

up entirely of parallel fibres; usually used cut to shape inmultiple laminate structure

warpwheel Pre-1914 lateral control wheel

WARR Wissenschaftliche Arbeitsgemeinschaft fürRaketentechnik und Raumfahrt (G)

war-readiness spares kit Prepared kit of spares andrepair parts to sustain planned wartime or contingencyoperations of weapon system for specified period(USAF)

Warren Structure in form of frame truss comprisingupper/lower chords joined by symmetric diagonalmembers only; hence * bracing, * girder, * struts, * truss

* biplane in front view has only diagonal interplane struts,forming continuous zig-zag along wing

Warren-Young Wing of rhomboid form with sweptbackfront wing joined at tips to swept-forward rear wing

war reserve Inactive stocks, subdivided into nuclear andother, of all forms of supplies (US = materiel) drawn upon

in event of war

Warrior Conceptual American all-arms fighting manable to project force anywhere on the globe

WARS West Atlantic route structure

Warsaw Convention Principal international agreement

on carriage by air, signed 12 October 1929 and quently amended, notably at The Hague in 1955

subse-wartime rate Maximum attainable flying rate based onseven-day week and with wartime maintenance/safetycriteria

warting Pitting of metal surface, esp in gas turbine,caused by combined actions of carbon and atmosphericsalts plus thermal cycling

WAS 1 Weapon-aiming system.

2 Wide-area search, or surveillance.

3 Weapons avionics simulator.

WASAA Wide-area search [and] autonomous-attack:

M adds munition, MM miniature munition

WASD Wide-area surveillance and detection

WASG 1 Warranty and service guarantee.

2 World Airline Suppliers’ Guide.

wash 1 Wake (colloq.).

2 To play upon or around, as ‘the hot jet can * tyres of

washing machine Trainer used by commanding officer

or CFI and thus that in which failed pupil makes last flight(US colloq., arch.)

wash-out, washout 1 Inbuilt wing twist resulting in angle

of incidence reducing towards tips

2 To fail course of flight (pilot) instruction.

3 Failed pupil pilot.

4 Removal of particulate matter from atmosphere by

rain

5 See next.

washout phase Point at which flight simulator can nolonger sustain sensation of acceleration

wash primer Self-etching primer to prepare surface of Al

or Mg for subsequent priming or painting

WASP, Wasp 1 War Air Service Program (DoD).

2 Wide-area special [or surveillance] projectile (USAF).

3 Women Air Service Pilots (US, replaced WAFS

1942–44)

4 Weasel attack signal processor.

5 White alternate sector propeller [black/white to

prevent deaths on the ground]

6 Windshear airborne sensors program (NASA/FAA).

Waspaloy Registered (Pratt & Whitney) nickel alloys

for gas-turbine rotor blading and similar purposes,

typi-cally with about 19% Cr, 14% Co and also Mo, Ti, Al etc

Wassar Wide-angle search synthetic-aperture radar

wastage Those pupils who fail a course of instruction,

esp aircrew; hence * rate, % failing

waste energy Energy not put to use, that in propulsive

jet being W(vj–V)/2g, where (vj–V) is waste velocity.

waste gate Controllable nozzle box for exhaust gas

turbine of turbocharged piston engine; hence ** valve,

which when open allows gas to bypass turbine but which

gradually closes with height until at rated full-throttle or

other selected height valve is closed completely

wastes 1 Human body wastes, esp fecal.

2 Surplus radioactive equipment and materials.

waste velocity In the propulsion of any aircraft, the

difference between the speed of the propulsive jet (behind

anything giving propulsion, e.g a propeller or helicopter

rotor) and the TAS, i.e (vj–V) At the start of

con-ventional takeoff * is 100%; it would be zero were it

possible for a high-speed aircraft to leave its jet at rest with

respect to surrounding air

WAT 1 Weight/altitude/temperature; factors

inde-pendent of runway which govern each takeoff and

determine whether aeroplane can meet specified positive

climb criteria after engine failure at V1; pronounced

‘watt’, but invariably written all in capitals

2 Western Atlantic (ICAO, RVSM).

WATA World Association of Travel Agents (Int.)

watch office Aerodrome air traffic control centre (UK

1918) Progressively replaced after c 1933 by control

tower, but term still common in 1939–45

WAT curve Graphical plot of WAT limitation for

particular aircraft type; hence WAT limit, limiting

value(s) of WAT at which performance is minimum for

compliance with requirements

water bag Polythene bag carrying water ballast

water ballast Standard ballast carried by competitive

sailplane

water barrier 1 Runway overrun barrier using water as

retarding material

2 Notional barrier to prolonged spaceflight caused by

fact that plants used for fresh food/oxygen continuously

convert more material to water than they return in

consumable form

water bias See sea bias.

water bomber Aircraft designed for surface (eg forest)

firefighting by dropping large masses of water; can be

marine aircraft with means for quick on-water

replenish-ment using ram inlet on planing bottom

water cart Dispenser of water to aircraft on apron, with

supplies of either or both demineralized water for engines

or potable water for passengers

water-collecting sump Low point in any system where

water could collect, esp fuel tank and tray under

vapour-cycle air-conditioning coils, from which water can be

extracted

water-displacing fluid Commercial liquids (eg LPS-3)which preferentially attach themselves to metal surface inplace of local droplets of moisture, thus arresting corro-sion

water equivalent depth Measure of depth of precipitationcontamination on runway; WED = actual depth ×density, thus 20 mm slush with SG 0.5 gives WED 10 mm.For water, *** = actual depth

waterfall Basic model of software life cycle

water flaps Surfaces hinged about near-vertical axis nearafterbody keel of marine aircraft (esp jet) which whenunder water are used differentially for steering andtogether for braking (usually also used as airbrakes)

water gauge Pressure expressed as height of column ofwater; 1 in H2O = 249.089 Nm–2; 100 mm = 980.66 Nm–2

water injection Injection of demineralized water, eitherpure or with 30–67% alcohol or (more commonly)44–60% methanol, into cylinders of piston engine to coolcharge and eliminate detonation at maximum BMEP, orinto compressor inlet or combustor of gas turbine to coolair and thereby increase density and thus mass flow andpower

water jacket Container for cooling water aroundcylinder

water level Generalized term in lofting and aerospaceconstruction generally (except vehicles whose major axis

is vertical, eg most space launchers) to denote measures inthe vertical plane; thus ** 193 = 193 mm above aircraftreference datum for measures in vertical plane, which may

be longitudinal axis OX or some other essentially zontal reference; abb WL Note: in US unit is often stillinches

hori-waterline 1 Intersection of body exterior profile and a

horizontal plane; often used as synonymous with waterlevel, thus WL 0 is lowest point of body and all subsequentslicing planes are parallel to prime longitudinal axis orother horizontal reference Thus * view, * plot (all water-lines drawn on common axis of symmetry)

2 Any horizontal reference other than local Earth

surface used in aircraft attitude instrument or HUD

waterloop Inadvertent turn by marine aircraft on water,

eg after dipping wingtip float at high speed (full ** rarebecause usually aircraft rolls in opposite directionthrough centripetal force)

water/methanol See water injection.

water recovery Recovery of usable water from pulsion exhaust, esp aboard airship for use as ballast

pro-water resistance Drag caused by water to aircraftmoving through it, made up of skin friction and wave-making

water rudder Small surface usually hinged on centreline

of marine aircraft to sternpost or rearstep heel; used fordirectional control on water

waterspout Visible water-filled tornado over sea

water suit Anti-g suit in which interlining is filled withwater which automatically provides approx requiredhydrostatic pressures under large normal accelerations

water tunnel Similar to wind tunnel but using water asworking fluid for large R at low V

water twister Rotary liquid-turbine device whichabsorbs energy in MAG arrested landings

WATOG, Watog World Airlines Technical OperationsGlossary

WATS Wide-area tracking system

watt SI unit of power (not only electrical power), W =

J/s Conversion factors: hp 745.7 exactly, CV 735.499,

Btu/min 17.5725, in each case to convert to * from unit

stated

watt-hour SI unit of energy = 3,600 J

wattless power Reactive power VAR; also called

watt-less component

wattmeter Instrument for measuring electrical power

wave 1 Disturbance propagated in medium such that at

any point displacement = f (time) and at any time

displacement of point = f(position); any time-varying

quantity that is also an f(position) This definition falls

down for light and other EM radiation, which appears not

to need a ‘medium’ for propagation (f = function of)

2 Formation of assault vehicles (land, sea or air) timed

to hit hostile territory at about same time

wave angle Angle between upstream free-stream

direc-tion and an oblique shock created by a real [large source]

supersonic body, symbol α

waveband Particular portion of EM spectrum in

telecommunications frequency region assigned by

national authority for specific purpose

wave cloud Formed at crest of a lee wave

wave crest Peak of waveform

wave disturbance Discontinuity or distortion along a

met front

wave drag Additional increment of aerodynamic drag

caused by shockwave formation, made up of distribution

of volume along length (longitudinal axis) and drag due

to lift; symbol for coefficient of ** CDW

waveform Shape of a repetitive (eg sinusoidal) wave

when plotted as amplitude against time-base or when

displayed on CRT

waveform generator Converts d.c or raw a.c into any

desired waveform output, with any frequency, amplitude

(both time-varying if required) or other characteristic, eg

for testing airborne electronic systems

wave front 1 Leading edge of shockwave group, or of

blast wave from explosion

2 In a repetitive wave, a surface formed by points which

all have the same phase at a given time

waveguide Conductor for EM radiation in reverse sense

to normal conductor in that radiation travels through

insulator (usually atmosphere) surrounded by metal

walls, usually rectangular cross-section, along which

waves propagate by multiple internal reflection Rarer

form is dielectric cylinder along whose outer surface EM

radiation propagates

waveguide modes See propagation modes.

waveguide mode suppressor Filter matching particular

waveguide cross-section designed to suppress undesirable

propagation modes

wavelength Distance between successive wave crests;

symbol λ = v/f where v is velocity of EM radiation (usually

close to speed of light) and f is frequency

wavelet Small shockwave, usually present in large

numbers in boundary layers and around surface of

super-sonic body Sometimes called Mach wave or Mach *

wave lift Lift on lee side of ridge or mountains

wavemaking resistance Drag of taxiing marine aircraft

caused by gross displacement of water in waves; reaches

maximum at about 20–30% of unstick speed

wave motion Oscillatory motion of particle(s) caused by

passage of wave(s), usually involving little or no net

trans-lation, ie particle resumes near-original position afterwave has passed Direction of ** varies with transversewaves (eg EM radiation), longitudinal waves (sound) orother forms, eg surface (water/air interface) waves

wave number Reciprocal of wavelength 1/λ or tively) 2π/λ

(alterna-waveoff, wave-off Any landing prevented, for whateverreason, by a command from the ground terminal orcarrier DLCO

wave period Elapsed time between successive crests, 1/f,where f = frequency

waverider Hypersonic aircraft designed to use waves to increase L/D ratio

shock-Waves Women Accepted for Voluntary EmergencyService (USN, from 1942)

wave soaring Using wave lift

wave trough Point of minimum, or maximum-negative,amplitude, usually half-way between crests

waviness Surface irregularities with spacing greater thanfor roughness; height is mean difference between peaksand valleys and spacing is distance between peaks

way Speed of marine aircraft relative to water surface,also called way on

waybill Document listing description of each item ofcargo, consignor, consignee, route, destination, flightnumber, date and other information

Waymouth unit Capacitance-type fuel contents gauge(tradename)

waypoint 1 Predetermined and accurately known

geographical position forming start or end of routesegment

2 In US, as (1) but with addition ‘whose position is

defined relative to a Vortac station’ (FAA)

3 In military operations, a point or series of points in

space to which an aircraft may be vectored

WB 1 Weather Bureau (US, NOAA).

2 Prefix: word before

W/B Weight and balance

Wb Weber

W-BAR Wing bar [runway lights]

WBC 1 Weight and balance computer.

2 Wideband convertor.

WBD Wideband data, or detector

WBF Wing-borne flight (jet V/STOL)

WBG Wideband gapfiller

WBL Wing buttock [or base] line

WBM Weight and balance manual

WBO Wien-bridge oscillator

WBPT Wet-bulb potential temperature

WBR Wideband receiver

WBS 1 Work breakdown structure.

2 Weight and balance system.

WBSS Wideband switching system

WBSV Wideband secure voice

WBT 1 Web-based training.

2 Wideband transmitter.

WBTM Weather Bureau technical memoranda

WBVTR Wideband video-tape recorder

WC 1 Weather centre.

2 Wire-combed (runway surface).

3 Warnings and cautions (ECAM).

W/C Wavechange

WCA Wind correction angle

WCAN Wideband communications airborne network

WCCS Wireless control and communication system.

WCFB Wide-chord fan blade

WCG Water-cooled garment

WCM Weapon control module

WCMD Wind-corrected munitions dispenser

WCMS 1 Wing-contamination [especially ice]

monitor-ing system

2 Weapon[s] control and management system.

WCNS Weapon control and navigation system

WCO World Customs Organization (Brussels)

W/comp Wind component

WCP 1 Working capital productivity.

2 Weapon[s] control panel.

3 WXR [weather radar] control panel[s].

WCQL Worst-cycle quality level

WCR Weight/capacity ratio

WCS 1 Weapon control system.

2 Waveguide communications system.

3 Writable control store (EDP).

WCSPL Waist-catapult safe parking line, aligned

across deck midway between Cats 2 and 3 (USN)

WCTB Wing carry-through box, joining pivots of

variable-sweep aircraft

WCTL Worst-condition time-lag

WD 1 Wind direction.

2 Warning display.

3 Word or word group.

4 War Department (US, replaced 1947 by DoD).

WDA Weather display adapter

WDAU Weapon-dispenser arming unit

WDC Weapon[s]-delivery computer

WDD Western Development Division (USAF 1954–62,

later Samso)

WDDS Weather-data display system

WDEL Weapons Development and Engineering

Laboratories (US)

WDF Water-displacing fluid

WDI Wind-direction indicator

WDIP Weapon-data input panel

WDL Weapon datalink; A adds archive

WDLY Widely

WDM Wave - [or wavelength-] division multiplexing;

AOR adds area of responsibility

WDNS Weapon-delivery and navigation system

WDS Wavelength dispersive spectrometer

WDSPRD Widespread

WDU Wireless Development Unit (UK, WW2)

WDX Weather-data extractor, or extraction

WE Weekend

W E Mass of propulsion system (from weight of

engine[s])

WEA Weather

WEAA Western European Airports Association (Int.)

WEAAC West European Airport Authorities

Con-ference (Int.)

WEAAP West European Association for Aviation

Psychology (Int.)

WEAG Western European Armaments Group

weakest maintained Weakest fuel mixture at which

under specified conditions maximum power can be

main-tained; also called WMMP

weak link Point at which structure, esp hold-back tie (eg

on aircraft about to be catapult-launched), is designed to

break when normal operating load is applied Catapult

launch ** resists full thrust of aircraft engines but breakswhen catapult thrust is added Occasionally a safetyfeature fracturing only on overload

weak mixture Fuel/air ratio for piston engine belowstoichiometric; economical for cruising but engine runshot Hence ** rating, maximum power permitted forspecified conditions cruising with **; ** knock rating, fuelperformance-number grade under economical-cruiseconditions

weak tie Structural weak link designed to fail in normaloperation (eg holdback on catapult takeoff)

weapon-aiming system That governing launch trajectory

of unguided weapon

weapon bay Internal compartment for carriage ofweapons, esp of varied types, eg AAMs, ASMs, NWs,free-fall bombs, guns, sensors, cruise missiles etc If forone type of weapon preferable to be more explicit.Derived terms include ** door, ** fuel tank, ** hosereelpack

weapon control system Avionics and possibly othersubsystems (eg optics) built into launching aircraft tomanage weapons before release and release them atcorrect points along desired trajectories Should not beused to mean radio command or other form of guidancesystem of missile

weapon debris Residue of NW after explosion; notusually well defined but generally means all solids(assumed recondensed from vapour) originally formingcasing, fuzing and other parts, plus unexpended Pu,U-235 or other fissile material

weapon delivery Total action required to locate target,establish release conditions and maintain guidance totarget if required (ASCC)

weaponeering Process of determining quantity ofspecific weapon necessary for required degree of damage

to particular (surface) target Takes into accountdefences, errors, reliabilities etc

weaponized Modified to carry weapons (USAF UAVs)

weapon line See bomb line.

weapon-replaceable assembly Any item, not necessarilyrelated to weapons, that can be quickly removed andreplaced, such as a PCB

weapons assignment Process by which weapons areassigned to individual air weapons controllers for anassigned mission (DoD)

weapons of mass destruction For arms-control purposes,strategic NW, C, B, R devices with potential of killinglarge numbers of people, but exclusive of delivery systems

weapons recommendation sheet Defines intention ofattack and recommends nature of weapons, tonnage,fuzing, spacing, desired mean points of impact, intervals

of reattack and expected damage

weapons state of readiness In DoD usage, lists ofnumbers of air-defence weapons and reaction times:

2 min, 5 min, 15 min, 30 min, 1 h, 3-h, and released fromreadiness

weapon system 1 A weapon and those components

required for its operation (DoD, NATO) This couldsimply be a part of a manned aircraft, eg radar, HUD,WCS

2 Composite of equipment, skills and techniques that

form instrument of combat which usually, but not sarily, has aerospace vehicle as its major operationalelement (USAF) As originally conceived in 1951,

includes all type-specific GSE, training aids, publications

and every other item necessary for sustained deployment

weapon-systems physical security Concerned to protect

aerospace operational resources against physical damage

weapon/target line Sightline (straight line) from weapon

to target

weather Short-term variations in atmosphere, esp lower

atmosphere

weather advisory Expression of hazardous weather

likely to affect air traffic, not predicted when area forecast

was made

weather beam Emitted by radar operating in weather

mode, conical pencil of approx 5° total angle projecting

horizontally ahead (thus filling whole troposphere about

100 km ahead)

weather categories 1 Traditional **, eg US cat C

(contact), N (instrument) and X (closed), common today

in many countries

2 Precise measures of DH/RVR as they affect arrivals;

Cat 1, DH 60 m/200 ft or better, RVR 800 m/2,600 ft or

more; Cat 2, 60–30 m/200–100 ft, 800–400 m/2,600–1,300

ft; Cat 3a, 0 along runway, 200 m/700 ft in final descent

phase; Cat 3b, 0, 50 m/150 ft; Cat 3c, 0, 0, (visual taxiing

impossible)

weather central Organization collecting, processing and

outputting all local weather information

weathercocking Tendency of aerodynamic vehicle to

align longitudinal axis with relative wind; note that this

affects pitch as well as yaw

weathercock stability Basic directional stability of air

vehicle or re-entering spacecraft; in CCV (eg modern

fighter) this is degraded to ultimate degree and replaced

by synethetic * applied by avionics linking sensors to

flight controls

weather forecast Prediction of weather within area, at

point or along route for specified period

weather map Shows weather prevailing, or predicted to

prevail

weather minima Worst weather under which flight

oper-ations may be conducted, subdivided into VFR and IFR;

usually defined in terms of ceiling, visibility and specific

hazards to flight

weather radar Airborne radar (less often, surface radar)

whose purpose is indication of weather along planned

track; traditional ouput is picture of heavy precipitation,

but modern * can indicate severe turbulence (in

meaning-ful colours) even if precipitation absent

weather reconnaissance Flight undertaken to take

measurements (traditionally = thum = temp + humidity)

at specified flight levels up to near aircraft ceiling; today

rare but also includes all forms of weather research

weather report 1 Broadcast * by national weather

service, eg each hour

2 An actual, transmitted by airborne flight crew.

weather satellite See met satellite.

weathervane US term for weathercock (eg on building),

and for weathercocking tendency of aircraft on ground to

face into wind Hence * effect of vertical tail, which

progressively gives directional stability to VTOL aircraft

as forward speed increases

weathervane stability That provided in flight by fixed tail

surfaces

weave 1 To make continuous and smooth changes of

direction and height while over a period following a

desired track; weaving assigned to proportion of fightersescorting slower aircraft so that continuous watch could

be kept astern and in other difficult areas Hence, weaver

2 Angular wander of spin axis, esp of gyro, radar

scanner, rotary mirror etc

WEB Web effective burn (time)

web 1 Principal vertical member of a beam, spar or other

primary structure running length of wing or fuselage,providing strength necessary to resist shear and keepupper and lower booms (chords) correct distance apart.Occasionally expanded to * member, * plate

2 In solid-propellant rocket, distance through which

propellant burning surface will advance from initialsurface until * burnout as defined by two-tanget method;usually measured as linear distance perpendicular toinitial surface, symbol τw

3 Any material form resembling sheet, either as discrete

pieces or continuous * unrolled from drum or coil; esp.sheet form of prepreg, supplied in standard widths

web average burning-surface area Total volume of solidrocket propellant, excluding slivers, divided by web; thushas dimensions of an area, symbol As

webbing Strong close-woven fabric strip produced tospecified UTS, used eg for securing loose (bulk) cargo

weber, Wb SI unit of magnetic flux; that flux which,linking circuit of one turn, produces EMF of 1 V as it isreduced to zero uniformly in 1 s Symbol Φ To convertfrom maxwell, multiply by 10–8

web fraction Web (2) divided by internal radius of motorcase or chamber; symbol f, expressed as %

web rib Rib fabricated from sheet or plate

WEC World Energy Conference

WECMC Wing electronic-combat management, ormanagers’, course

WECPNL Weighted equivalent continuous perceived

noise level (see noise).

WED Water equivalent depth

wedge 1 Air mass having wedge shape in plan, esp such

a mass of high pressure extending between two lows

2 Sharp-edged essentially 2-D * forming one wall of

2-D inlet of supersonic airbreathing engine, extendingahead of inlet so that its shock may be focused on inlet lipand normally extending rearwards as a variable ramp.Hence * inlet

3 Small * added above trailing edge of aileron [rarely,

other control surface] giving blunt trailing edge; sonic equivalent of aileron cord

super-wedge aerofoil Sharp LE and blunt TE, useless except atsupersonic speed where efficiency is high, so confined to

use on missiles See parallel double-*.

WEDS Weapons effects display system

weeds, in the 1 At lowest possible level, on TFR or

wef With effect from

Wefax Weather facsimile format; one selectable mode

of data transmission between weather satellite and groundprintout

Weft Wings/engine(s)/fuselage/tail; most basic ofmnemonics used in early aircraft-recognition instruction

WEG Weapons Evaluation Group (USAF)

Wehnelt Type of cathode whose emissivity is enhanced

by coating of radioactive-metal oxides

Weick Coefficient for calculating propeller

character-istic, also called speed/power coefficient,

Cs= V5

ρ/PN2, where V is velocity of advance, ρ is

density, P is power and N is rpm

weighing Today almost all determination of aircraft

weight is done by moving landing gears over platforms

supported on load cells which measure forces by

strain-gauges, whose output may be summed and displayed

automatically A few aircraft have landing-gear

hydraulics giving a cockpit readout of weight and c.g

position

weighing points Locations, published in engineering

documents and stencilled on aircraft, where jacks may be

applied in weighing process

weighing record Hard copy updated each time aircraft is

weighed; includes c.g position

weigh-off Free ballooning of airship before casting off to

refine trim

weight Force exerted on a mass by Earth’s gravity; thus

a figure unique to a particular location which by

interna-tional agreement is any at which g (free-fall acceleration)

is 9.80665 m/s For modern aeroplane some measures

include: empty, complete aircraft plus systems measured

in accord with specification (eg in US military usage,

MIL-STD-3374); CCDR, empty minus items listed in

STD-25140A such as engine(s), starter(s), electrics and

avionics where removable direct from racking,

wheels/brakes/tyres/tubes; standard empty, bare aircraft

plus unusable fuel, full oil and full operating fluids (thus

excluding potable water); basic empty, standard empty

plus optional equipment; structure, bare airframe without

systems and equipment other than wing/tail movables and

flight-control power units, flap actuation, landing gear

and actuation, and equipped engine installation(s) minus

engines; useful load, those items that when added to *

empty (for transport, OEW) will add up to gross weight

for design mission (transport, MTOW); operating weight

(military), empty plus useful load minus expendable fuel

(internal/external), ammunition and stores; operating

empty (OEW), equipped empty + all consumables (fuel,

lube, filled galleys and bonded stocks, toiletries etc) +

removable furnishings, reading and entertainment

materials, cutlery, flight and cabin crews and their

baggage, ship’s papers; zero-fuel (ZFW), (military)

oper-ating plus ammunition/missiles/stores, (transport)

MTOW minus usable fuel; gross (military), MTOW

(civil), allowable at moment of takeoff; ramp (MRW),

(civil) allowable at moment of starting engines; basic

flight design (military), takeoff with full internal fuel and

useful load for primary mission; minimum flying gross

(military), empty + minimum crew, 5% usable/unusable

fuel (zero for flutter) and lube consistent with fuel;

maximum design, military equivalent of MRW allowing

for full internal/external fuel (in some cases extended to

higher figure still after air refuelling); maximum landing

(MLW, civil), figure specified for each type between ZFW

and MTOW; landplane landing design gross, basic flight

design gross plus empty external tanks and pylons minus

60% internal fuel; maximum landing design gross,

maximum design minus dropped tanks, fuel expended in

one go-around (overshoot) or 3 minutes (whichever is

less) and any items routinely dropped immediately after

takeoff; bogey, also called target bogey, established 4%below specification * (in practice * tends to rise, and bogey

is usually a pious hope); specification (military), thatnumber written into original agreed specification; job-package target/bogey, series of targets for each * groupparts-breakdown; current, also called current status, thatrepresenting best available information, obtained byadding to previously reported status all subsequentrevisions

weight and balance sheet Document carried with port (military/civil) recording distribution of weight andc.g at takeoff and (military) landing

trans-weight breakdown Subdivision of aircraft weight(usually a design gross) into broad headings: structure(itself divided into wing group, tail group, fuselage andlanding gear), power-plant, equipment services, anddisposable load (latter divided into fuel/consumable itemsand payload)

weight coefficients Dimensionless ratios BF/TOW,BF/ZFW, RSV/LW, RSV/ZFW, TOW/LW andTOW/ZFW

weight flow See mass flow.

weight gradient Required change in weight, eg MTOW,for unit change in temperature, usually expressed inkg/°C, in such corrections as QNH variation, air-condi-tioning and anti-icing

weight in running order Traditional measure of engine weight in which radiator/coolant/pipes/controlswere added, plus oil within engine, but excluding tanks/fuel/oil/reserve coolant/exhaust tailpipes/instruments

piston-weightless Condition in which no observer withinsystem can detect any gravitational acceleration; can beproduced either in free fall near a massive attracting body,

eg Earth satellite, or remote from any attractive body

weight-limited Payload that can be carried is limited byrestriction on aircraft MTOW or ZFW and not by avail-able space

weight per horsepower Usually incorrectly calledpower/weight ratio, basic measure of piston or othershaft-output engine; dry weight divided by maximumpower (latter can be 2½-minute contingency)

weight per unit thrust Dry weight (mass) of jet enginedivided by a specified measure of thrust (forturbojets/turbofans usually SLS/takeoff); in SI it is notpossible to divide a mass by a force, but a meaningful ratio

is still obtainable provided units of both are compatibleand specified

weightshift control Controlling aircraft [micro, hangglider, or similar] by pilot moving his/her c.g laterally orlongitudinally

Weir tables Azimuth diagram and tables for preting radio direction finding (obs.)

inter-weld bead Metal deposited along welded joint

weld bonding Combination of resistance spot-weldingand adhesive bonding with properties superior to eitheralone

weld continuity Specified as tack, intermittent, tinuous

con-welded patch Thin sheet-steel patch welded over localdamage in steel tubular airframe

welded wing Pair of aircraft in unvarying side-by-sideformation about 500 ft apart

welded steel blade Propeller blade assembled by

welding two shaped sheets of steel to form aerofoil, also

called hollow-steel

weld fusion zone Width of bead

welding Joining metal parts by local melting, with or

without addition of filler metal to increase strength of

joint, using gas torch, electric arc, electrical resistance,

friction, explosive, ultrasonic vibration and other

methods, often with local atmosphere of inert gas

Techniques generally called diffusion bonding are closely

allied but often require no heat or added metal and rely

upon natural bonding of two clean surfaces in intimate

contact

welding flux Material, eg provided as coating on welding

rod, which melts and flows over joint, excluding oxygen

welding jig Fixture for holding parts to be welded in

exact relative positions while joints are made

welding machine Invariably an electric machine welding

workpieces by spot, roll or seam methods

welding rod Consumable rod of correct metal to act as

joint filler which also conveys current to form arc struck

against workpiece; diameter selected according to current

and usually with flux coating

well 1 Generalized code word (including air intercept) =

serviceable

2 Internal space or compartment for retractable item

such as landing gear, FLIR or radar

Wellington boot Radar viewing vizor

WEM Warning electronic module

WEMA Western Electronic Manufacturers Association

(US)

WEP 1 Weapon effect planning.

2 War emergency power.

WES 1 Warning electronic system.

2 Weapons effects simulation, or system.

Westland-Irving British name for an internally balanced

flight-control surface, esp aileron

wet 1 To come in contact with surface of body; hence

wetted area

2 With water injection.

3 Of station or pylon, plumbed for fuel, or carrying a

tank

4 Fuel included [hire cost per hour].

5 Structure is sealed to house fuel [see * wing, but

adjective also applicable to fuselage, fin or horizontal tail,

eg Airbuses]

wet adiabatic See saturated adiabatic, SALR.

wet and dry bulb See pychrometer.

wet assembly Important technique for modern

aero-space structures in which all primary components are not

only given successive surface treatments but are put

together and joined while their surfaces are still wet; eg

each component would be anodised, then coated with

primer and finally with Thiokol sealer, rivets or bolts also

being coated with Thiokol except in case of

interference-fit bolts (Taper-loks or radius-nose Hi-locks) which fill

holes completely

wet boost Boost pressure permissible for piston engine

with water injection in operation

wet builder Manufacturer employing wet-assembly

techniques

wet-bulb potential Temperature air parcel would have if

adiabatically cooled to 100% RH and then adiabatically

brought to 1,000 mb level

wet-bulb thermometer Has sensitive element surrounded

by muslin kept moist by supply of water, hence readinggives indirect measure of relative humidity

wet emplacement Rocket test emplacement or vehiclelaunch pad whose flame deflector and nearby parts arecooled by deluge of water

wet film Film, usually large-format, used in traditionaloptical camera

wet filter Particles are retained by a liquid film onelement surface

WET FUR Mnemonic for remembering aircraftcomponents for recognition purposes: wings, engines, tail,fuselage, undercarriage, radiators (or radomes) (UK,WW2)

wet H-bomb Thermonuclear device whose fusionmaterial is liquid, cryogenic or otherwise not a dry solid

wet layup Fabrication of composite structure using reinforcements saturated with liquid resin

wet lease Hire of commercial transport from anothercarrier complete with crew (at least flight crew, but oftennot cabin crew) and in effect forming continuation ofprevious operation, with major servicing performed byowner, but with hirer’s logo and insignia temporarilyapplied

wet pad Wet emplacement for launches

wet point, wet pylon Wet station

wet rating Power or thrust with water or water/methanol (rarely, water/alcohol) injection

wet-run anti-icing Surface kept continuously abovetemperature at which droplets freeze

wet sensor ASW sensor dropped or dunked into ocean,

eg sonobuoy

wet start Faulty start of gas turbine in which unburned

or burning fuel is ejected from tailpipe

wet station Plumbed for fuel [or other liquid] carried inexternal tank

wet suit Standard anti-exposure suit for working in sea;

eg in winch rescue

wet sump Piston-engine sump which serves as containerfor entire supply of lube oil

wet takeoff Takeoff with water injection

wetted area Total area of surface of body over whichfluid flow passes and on which boundary layer forms Incase of aircraft usually simplified to visible external skin,ignoring inner surfaces or air inlets, ducts, jetpipes andair-conditioning system

wetted fibre Fibre, eg carbon/graphite/boron/glass,coated with same resin as will be used to form matrix offinished part

wetted surface See wetted area.

wetting agent Surface-active agent which, usually bydestroying surface tension, causes liquid to spread quicklyover entire surface of solid or be absorbed thereby

wet weight Weight of devices plus liquids normallypresent when operating

wet wing Wing whose structure forms integral fuel tank.Note: not merely a wing in which fuel tanks are housed

wet workshop Space workshop launched as operativerocket stage whose propellants must be consumed orremoved prior to equipping as workshop in space

WEU 1 Assembly of Western European Union

(1955 – )

2 Warning electronic unit.

WEWO, Wewo Wing Electronic Warfare Officer(RAF)

WF US mission prefix, weather-reconnaissance fighter.

W F Total weight of fuel

W f Mass flow rate of fuel

WFA WXR [weather radar] flat-plate antenna

WFC 1 Wallops Flight Center (NASA).

2 Wet-film camera.

3 War Finance Corporation (US, WW1).

WFD Widespread fatigue damage

WFG Waveform generator

WFNT Warm front

WFO Weather forecast office

WFOV Wide field of view

WFP Warm front passage

Wg Maximum growth, section width of tyre [tire]

WGD Windshield (windscreen) guidance display,

transport-aircraft HUD for Cat IIIB operations

WGF Wideband gap-filler

WGMD Wire-grid micrometeoroid detector

WGN White gaussian noise

WGS 1 Weapon guidance system (GPS).

2 Followed by 72 or 84, World Geodetic Survey [1972]

WHCA White House Communications Agency

Wheatstone bridge Circuit with known and variable

resistances with which unknown resistance can be

accurately measured

wheel 1 Early aircraft commonly had such an input to

lateral control system (cf ships, road vehicles);

terminology is needed for all forms of stick/control

column/handwheel/yoke/spectacles No modern captain

would say “take the *”

2 Complete turbine rotor, esp single-stage or small

size

3 High-speed gyrostabilizing device (see reaction *,

internal *, gyro *.

4 Verb, change of heading by formation of aircraft.

5 Verb, to introduce 3-D curvature to sheet (see

wheeling).

6 Noun, a defensive formation of several aircraft

circling in horizontal plane

wheelbarrow 1 Manoeuvre for airshows in which

aircraft proceeds with nosewheel[s] in contact with

runway and tail high in air (only possible with certain

types of aircraft)

2 To reposition tailwheel-type light aeroplane by lifting

tail and walking

wheelbarrowing Violent oscillation in pitch on ground,

either because of undulating surface or harsh brake

application and rebounds from nose gear (not applicable

to tailwheel aircraft)

wheelbase Distance in side elevation between wheel

centres of nose and main landing gears; where there aretwo sets of MLGs (eg 747, C-5A) measure is to point mid-way between mean points of contact of front and rearMLGs

wheelbrakes Brakes acting on landing-gear wheels

wheelcase Compartment containing train of drive gears

to accessories which are usually mounted thereon, thewhole tailored to fit against or around prime mover, egturbofan There is only a shade of difference between thisand accessory gearbox

wheel door(s) Covers landing wheels when retracted

wheeler Tail-high landing by tailwheel aeroplane, quently sinking into three-point position, also calledwheely or wheelie

subse-wheeling Sheet-metal forming (on * machine) by locallysqueezing it between upper and lower rollers; workpiecehand-positioned to achieve desired 3-D curvatures

wheel landing See wheeler.

wheel load Vertical force exerted by each landing wheel

on ground; hence ** capacity, but this is imprecise incomparison with various soil-mechanics and civil-engineering measures, eg CBR

wheel mode Satellite or position thereof rotates, oftenfairly slowly (5–30 rpm), for attitude stabilization

wheel satellite Made in shape of wheel, normallyrotating either for attitude stabilization or to impartartificial gravity to occupants

wheel trimming By separate [usually small] wheelinceptor[s], requiring pilot to remove hand from flightcontrol

wheel well Compartment in which one unit of landinggear is housed when retracted

which transponder R/T code: please state type oftransponder fitted, IFF, SSR or ATCRBS (DoD)

Whidds War HQ information display and disseminationsystem (USA)

whifferdil Nose up 30°–60°, bank 90°, change heading180° ending in dive

whiffletree 1 Also rendered whippletree, originally

horse-traction linkage, which equalized and distributedpull of many horses at one point; now used to distributepull of one large hydraulic jack or other load applicatorover an area of airframe via array of beams pulled at inter-mediate point (usually mid-point) and transmitting pullfrom both ends to other such beams

2 Also used loosely for any pivoted beam or bellcrank

(US)

whip One meaning is upward jump of carrier pendant orrunway arrester wire after being depressed by passageacross it of landing wheel

whip aerial Flexible aerial (antenna), either wave or of arbitrary length and usually verticallypolarized, projecting at about 90° from skin

quarter-whip stall US term which appears ill-defined; existingdefinitions agree only on fact that * is complete, violentand involves large positive change in pitch attitude; somesuggest it is entered with flick manoeuvre, others makethis impossible by suggesting possible tail-slide at outset.One authority gives tail-slide as alternative meaning.Recent authorities equate * with stall turn

whirl Rotational flow of fluid, esp when in translationalmotion in duct, in which case streamlines follow spiralpaths

whirling arm Large family of instruments or

tions in which object (usually under test) is whirled on end

of balanced beam rotated about vertical axis; originally

used for aerodynamic tests, eg of aerofoils, but now more

often used to apply sustained high-g acceleration to

human beings and devices, sometimes in evacuated

chamber

whirling mode Vibratory mode of shaft in which elastic

bending is suffered, giving severe out-of-straightness

either at end or along length, pronounced only at certain

critical rpm (critical whirling speeds)

whirl-mode flutter Aeroelastic flutter, esp of wing, in

which input energy is derived, at least initially, from

whirling of engine or propeller shaft (catastrophic on one

type of turboprop transport)

whirltower Installation for static testing of helicopter

main rotor, including overspeed conditions Peripheral

net retains separated blades

whirl velocity Peripheral or tangential velocity, eg of

flow in centrifugal compressor

whirlwind Small local tornado in dry air, without cloud

or rain

whirlybird Helicopter (rarely, other rotorcraft)

(colloq.)

whisker 1 Small single crystal, usually lenticular, whose

strength is very close to maximum theoretically

attain-able

2 Sharpened contact pressed against semiconductor in

point-contact transistor or solid-state diode; hence *

resistance

3 See next.

whiskers Multiple weak shocks on surface of real body,

through each of which flow is retarded slightly Hence

whiskering effect

whisper-shout A sequence of ATCRBS interrogations

and suppressions of varying power levels transmitted by

TCAS equipment to reduce severity of synchronous

inter-ference and multipath problems

whistle Annoying high-pitched note, usually slightly

varying in pitch, caused by interference carrier in superhet

reception

whistler RF signal, usually in form of falling note,

gener-ated by lightning; heard on Earth and Jupiter and in

former case bounces to and fro along magnetic-field lines

between N/S hemispheres

Whitcomb body Streamlined body added to aircraft

(eg wing trailing edge) to improve Area Rule volume

distribution; many other names, eg speed bump,

Küchemann carrot

White 1 Not black, hence can be disclosed to public.

2 Friendly, as alternative to Blue.

3 Overseeing authority in war game.

white, white hot TV/video mode giving positive (normal)

picture, which in IR display renders hot as white and cold

as dark

white body Hypothetical surface which does not absorb

EM radiation at any wavelength, ie absorptivity always

2 Commonly used to mean spectrum of generally

uniform level on constant-% bandwidth basis (so-called

broadband noise) without discrete-frequency ponents

com-whiteout 1 Loss of orientation with respect to horizon

caused by overcast sky and sunlight reflecting off snow

2 Zero visibility caused by what one authority calls

ping-pong-ball snow

White Rating Holder of licence is authorized to land incloud base
400 ft, 122 m

white room 1 Super-clean room in which air is

con-tinuously filtered to eliminate micron-size and largerparticles and special rules almost eliminate introduction

of contaminants by human beings or objects (eg rubber, pencils, handkerchiefs, etc, prohibited)

white-scarf syndrome Alleged antipathy towards UAVs

by human pilots (US, esp USAF)

white-tailed 1 Not bearing markings of a commercial air

carrier

2 Available for wet or dry lease with peelable logo and

name

3 Completed but unsold.

4 Company demonstrator (recently including UAV).

White World Ordinary [not black], especially in facturing industry

manu-Whitney punch Hand-operated tool for punching holes

of selected sizes in metal sheet

Whitworth Traditional UK screwthread with radiusedcrest and root and 55° angle

whizzer TV zoom lens

whizzkid Civilian analyst or adviser in DoD

whizzo WSO (colloq.)

WHO World Health Organization (UN agency, HQSwitzerland)

whole-aircraft charter Operator charters completeaircraft for one flight or for a period, in contrast to splitcharter

whole-body counter Nucleonic instrument for ing and measuring body burden (whole-body receivedradiation) of human beings and other living organisms

identify-whole-range distance Horizontal distance between pointvertically below release point and whole-range point

whole-range point Point on surface vertically belowaircraft at moment of impact of bomb released by it,assuming constant aircraft velocity (ASCC)

WI 1 Welding Institute (BWRA).

2 Within.

3 Wallops Island.

WIA 1 Wounded in action.

2 Women in Aviation (US).

WIAS Weather information and display system

WIC 1 Warning information correlation.

2 Women, infants and children.

3 Weapons instructor course.

wick 1 See static wick.

2 Throttle(s); eg to turn up * = increase propulsion

power (colloq.) Invariably used for turbine engine(s), esp.jet(s)

WID Width

WIDE Projection equipment used in simulator to

generate FOV of 150° × 40° (Redifon); WIDE II, five

projectors for 200°

Wide Wide-angle infinity display equipment

wide-area augmentation system Under development

from 1995 to improve GPS accuracy (FAA)

wideband amplifier One offering uniform response over

many decades of frequency

wideband dipole Large ratio diameter/length

wideband ratio Ratio of occupied frequency bandwidth

to intelligence bandwidth

wide body See wide-body aircraft.

wide-body aircraft Commercial transport with internal

cabin width sufficient for normal passenger seating to be

divided into three axial groups by two aisles; in practice

this means not less than 4.72 m (15 ft 6 in) (B.767,

narrowest **)

wide-cut Generalized term for aviation turbine fuels

assembled from wider range of hydrocarbon fractions

than kerosene-type fuels; more accurate term is wide

boiling-point range, for whereas little or no kerosene-type

boils below 174°C, * begins to boil at 52–53° and fractions

continue to boil off at up to about 220° SG well below

0.76, compared with 0.79–0.8 for kerosene-type fuels

Widely held to be dangerous because of high volatility

(arguable) but operational fuel of nearly all air forces and

several airlines

wide-deck Lycoming term for cylinder having wide base

held by hexagonal nuts on large-radius circle; no separate

hold-down rings or plates

widget Any small cunning, fascinating device

Widia German range of sintered tungsten carbides with

3–13% Co

WIDS Weather information display system

width Maximum lateral dimension of lifting-body

aircraft, equivalent to span

width of sheaf Lateral interval between centres of flak

bursts or bomb impacts (DoD)

WIDU Wireless Intelligence and Development Unit

(RAF, from October 1940)

WIE With immediate effect

Wiedemann-Franz law States ratio of electrical to

thermal conductivity for all metals is proportional to °K

(for most metals observed value is slightly higher than **

figure)

Wien bridge Stabilized oscillator whose frequency is

determined by circuits incorporating resistances,

capaci-tances and two triodes

Wien law States wavelength of peak radiation from

hot-body source is inversely proportional to °K

WIFU Weapons interface unit

WIG Wing in ground effect

wigglystrip Rolled [occasionally machined] refractory

strip with endless square-corner up/down form

[combus-tors and afterburners]

WII light Wing ice inspection light

Wilco R/T code: “I will comply with your instruction”

wildfire Forest fire out of control

Wildhaber-Novikov Best known form of conformal

gears with mating profiles formed by convex/concave

circular arcs whose centres of curvature are on or near

pitch circles

Wild Weasel Though original name of specific

programme, now generalized term for dedicated EW

plat-form based on airframe of combat (eg attack or fighter)aircraft

Williot Diagram which graphically portrays deflections

of all joints (panel points) of loaded planar truss; resultcontains small inaccuracies which are removed by Mohrcorrection diagram, result being called Williot-Mohr

will not fire Code sent to spotter or other requestingagency affirming that target will not be engaged by surfacefire

willy-willy Tropical cyclone (Australia)

Wimet British range of tungsten carbides

WIMS, Wims Worldwide intratheatre mobility study

WIN 1 WWMCCS intercomputer network.

2 Web industrial network.

winch launch Launch of glider by winch, usually locallybuilt on road vehicle and driven by latter’s engine

winchman Member of aircrew of rescue helicopter incharge of winching payloads, eg rescuees, and who mayhand winch to colleague and descend to organize pick-up

of incapacitated rescuee from below

winch suspension Rigging joining kite balloon and flyingcable

wind across Horizontal component of wind at 90° tocatapult or centreline of (axial or angled) deck

windage Loss of rpm of rotating device caused by airdrag

windage jump Vertical jump (up or down) of bullettrajectory caused by crosswind, eg firing laterally frombomber or gunship

wind angle Angle between wind direction and truecourse (heading), measured 000–180° L or R of course

wind axes 1 In UK usage, three rectilinear axes (u, v, w)

with origin within aircraft, ususally at c.g., and directionseach representing component of relative wind in longi-tudinal, lateral and vertical planes Traditional names: liftaxis, + upward; drag axis, + to rear; crosswind axis, + toleft

2 In US usage, X, Y, Z, each the exact opposite of drag,

sideforce and lift and acting through c.g to eliminaterotary and translational motions

wind cone See windsock.

wind correction angle Difference between course andtrack

wind diagram US for triangle of velocities

wind direction That from which wind is coming,expressed as number from 000° to 359°

wind down Horizontal component of wind along axis ofcatapult or centreline of (axial or angled) deck

Windee Wind-tunnel data encoding and evaluation(EDP [1])

wind factor Net effect of wind on aircraft progress,expressed as ± knots (USAF)

wind-gauge sight Drift meter; instrument which (BSIdefinition), by determining track on two or more courses,enables air, wind and ground speeds to be represented byvectors (arch.)

wind gradient Rate of change of wind with unit increase

in height AGL; usually factor of interest is component ofwind along runway, thus direct headwind at 150 m/500 ftveering to crosswind at threshold is regarded as changeequal to full wind speed even though actual wind speeddoes not alter See windshear

winding See filament *

WINDMG Wind magnitude

windmill 1 Of inoperative engine, to be driven by

propeller (piston or turboprop) or by ram airflow through

it (turbojet or turbofan); hence windmilling, windmilling

drag etc

2 Small propeller-like * used on older aircraft to drive

electrical generator and occasionally other machines; in

principle like modern RAT but permanently operating

3 Of free-turbine propeller, to spin idly in wind when

aircraft parked (normally prevented by brake)

4 Propeller (colloq.).

windmill-brake state Operating condition of helicopter

rotor in which thrust, flow through disc and flow outside

disc are all in same direction

wind over deck Vector sum of wind plus speed of carrier

window 1 Transparent area in skin for aircraft optics or

IR (in latter case not apparently ‘transparent’)

2 WW2 code for frequency-cut metal reflective slivers,

wire, foil etc that later became better known by US name

chaff (ECM)

3 Launch opportunity, defined as unique and possibly

brief time period in which spacecraft can be launched

from its particular site and accomplish its mission; usually

recurring after a matter of days to months

4 Small band of wavelengths in EM spectrum to which

Earth atmosphere is transparent; there are many such,

though together they account for only small part of total

spectrum, rest being blocked Like (3) this meaning rests

on * being a small transparent gap in a dark continuum

5 Verb, to enlarge local part of drawing or graphic

display, usually to show greater detail

Windpads Wind-profile precision air-delivery system

(para-drop accuracy, USAF)

WINDR Wind direction

wind rose Polar plot for fixed station showing frequency

of winds and strengths over given (long) period from

000°–359°

wind rotor Multi-blade rotor for forced aircooling of

landing-wheel brake, of which it forms part

winds aloft US term for upper winds

windscreen Windows through which pilot(s) look ahead,

called windshield in US Originally on open-cockpit

aero-planes complete assembly of frame and windows ahead of

pilot’s head On modern flight deck less obvious and

generally replaced by such term as flight deck

windows/transparencies/fenestration, which includes side

and roof (eyebrow) windows

windscreen wiper Term confined to mechanical devices

with oscillating blades; rotary-disc and air-blast (eg for

rain-shedding) excluded

windshear Exceptionally large local wind gradient

Originally defined as ‘change of wind velocity with

distance along an axis at right angles to wind direction,

specified vertical or horizontal’ (BSI), which is same as

wind gradient Today recognized as extremely dangerous

phenomenon because encountered chiefly at low altitude

(in squall or local frontal systems) in approach

con-figuration at speed where * makes sudden and potentially

disastrous difference to airspeed and thus lift In practice

pilot must take into account air movement in vertical

plane (see downburst) because sudden encounter with

downward gust is more serious than mere fall-off in

head-wind Often accompanied by severe turbulence and

precipitation which can make traditional ASI under-read

windshear indicator Modern electronic displays will

show * situation well, but with traditional instruments anextra dial is avoided by adding an energy-rate pointer toVSI; this striped needle is driven by combined vertical-speed rate and rate of change of airspeed to show rate ofchange of aircraft energy Pilot can readily work throttles

to keep this needle coincident with VSI needle

windshield See windscreen.

windshield guidance display Optical projector inglareshield giving HUD-type ground-roll guidance afterblind (Cat IIIB) touchdown

wind shift Sudden change in wind direction

wind sleeve See next

windsock Traditional fabric sleeve hung from mast togive rough indication of local wind strength/direction;also called wind sleeve, wind cone

wind star Plot for determining wind by drawing driftsmeasured on two headings (US, arch.)

wind tee White T-shaped indicator displayed in signalsarea to show pilots wind direction; also called wind T See

tee.

wind tetrahedron US counterpart of wind T (which isalso used in US): large pyramid shape indicating winddirection, rotated on pedestal

wind tunnel Any of family of devices in which fluid ispumped though duct to flow past object under test Ductcan be closed circuit or open at both ends Workingsection, containing body under test, can be closed or open(called open jet) Fluid can be air at any temperature/pressure or various other gases or vapours Operation can

be continuous, intermittent or as brief as a millisec.Particular species is spinning tunnel

wind-tunnel balance Apparatus for measuring forcesand moments on object tested in tunnel; originallyincluded actual mounting for object but today usuallyelectrical force-transducers built into sting

wind-tunnel stability axes Considered more helpful termthan mere ‘stability axes’ for data from tunnels

wind-up turn Turn by winged aerodyne that becomesever-tighter [rhymes with mind]

wind vane Small pivoted blade which aligns itself withlocal airflow; usually drives via rotary viscous damper toone or more precision potentiometers to form a flow-angle transmitter for AOA (pivoting on horizontal axis)

or yaw

windy drill Workshop tool driven by high-pressure air(colloquial)

wing 1 Main supporting surface of fixed-* aerodyne;

despite term ‘rotating-* aircraft’ not used in that context,usual word for rotating supporting aerofoils being blade.Normally taken to cover all parts within main aerofoilenvelope, including all movable surfaces Many terms, eg

* jig, * structure, are judged self-explanatory

2 Numerous types of military unit, eg in RAF basic

combat administration organization comprising perhapsthree squadrons, often all sharing same base, but in USusually a larger unit comprising one or more groups withsupport organizations, in Navy a self-contained unit fordeployment of organic air power at sea (one * per carrier)

or land, and in Marines those aviation elements forsupport of one division

3 Extreme left or right of battlefront or aerial

formation

4 To be positioned on *, to be alongside in formation (see wingman).

5 To fly (colloq.).

wing area 1 Area of surface encompassed by planview

outline drawn along leading and trailing edges, including

all movable surfaces in cruise configuration, and

including areas of fuselage, nacelles or other bodies

enclosed by lines joining intersections of leading or

trailing edges with such bodies One expression is

S = where b is span, c chord at distance y across

lateral axis Thus, pods hung below wing are excluded;

wingtip tanks are normally excluded; winglets are

included as they appear in plan view; in case where root

meets fuselage or nacelle at sweep approaching 90° (eg

with forebody strakes) most authorities include these

portions and fuselage up to intersection of leading edge

with fuselage VG ‘swing wing’ is measured at minimum

sweep Foreplane for lifting canard is counted separately

2 Net ** excludes projected areas of fuselage, nacelles

etc Note: US measures of gross * often omit all areas

outside basic wing trapezium, such as exist if taper is

greater at root

wing arrangement 1 Basic configuration of aeroplane.

2 Height at which monoplane wing is mounted, eg low,

mid etc; see wing position.

wing axis Locus of all aerodynamic centres

wing bar Row of approach lights perpendicular to

runway and starting beyond runway edge (Vasi)

wing bending moment Bending moment Hence ***

relief, reduction afforded by masses (fuel, engine pods)

distributed across span instead of being located in or on

fuselage

wing bending torsion mode Aeroelastic deflection,

sustained or flutter, of swept wing in which bending

intro-duces twist

wing/body fillet Fillet, possibly very large, filling in rear

part of wing/body junction to prevent separation of flow

and possibly reduce peak velocities and suctions

wing box Primary structure of modern stressed-skin in

which all loads are taken by cantilever beams comprising

upper and lower (usually machined) skins joined to front

and rear spars, plus small number of ribs (occasionally

additional spar[s] within *) This strong structure, usually

by far heaviest single piece of airframe, is usually sealed to

form integral tank

wing car Airship car suspended to L or R of centreline

wing cell See cell, cellule.

wing chord See chord.

wing drag When lifting, induced plus profile drags

wing drop Sudden loss of lift on one wing, eg near

stalling AOA, causing rapid roll not recoverable by

aileron

wing fence See fence.

wing fillet See fillet; avoided if possible, but often

intro-duced because of need to accommodate main landing

gears and in some cases combined with air-conditioning

ducts on underside

wing flaps See flap.

wing flutter See flutter.

wing guns Guns mounted within or attached to wing

wing heavy Tending to roll in one direction

wing in ground effect Class of vehicles, arguably aircraft,

supported by a wing riding close above Earth surface

2 Aircraft whose wings have been permanently

removed, to end its days in ground test programmes [eg,catapult/arrest]

winglet 1 Upturned wingtip or added auxiliary

aero-foil(s) above and/or below tip to increase efficiency ofwing in cruise, usually by reducing tip vortex and thusrecovering energy lost therein and improving circulationand lift of outer portion of wing

2 Miniature wing mounted horizontally on fuselage

(not at nose or tail), on interplane struts or elsewhere (egnacelles), often not so much for lift as to carry externalload or connect bracing struts or main gears to fuselage

winglet lift This invariably means the resultant force onthe winglet, which is usually perpendicular to the surface

in the vertical plane and inclined forwards [giving a tive thrust component] in the horizontal plane

posi-wing leveller Simple single-axis autopilot with authorityonly in roll; often with heading lock and VOR/ADFcoupler Generally synonymous with aileron-centringdevice

wing loading Gross weight or MTOW divided by wingarea (1); 1 lb/sq ft = 4.88243 kg m–2

; reciprocal 0.204816

wingman Second in element of two combat aircraft, esp.interceptors; term loosely applied to pilot or aircraft Fliesoff wingtip of element leader except when required toperform manoeuvres, eg day/visual intercept of un-identified aircraft

wingover US flight manoeuvre most briefly defined asclimbing turn followed by diving turn; at apogee aircraft(usually trainer) is almost stalled, and rotation continues

in pitch and roll so that recovery takes place at lower level

by diving out on reciprocal Almost = stall turn

wing overhang See overhang.

wing panel See panel.

wing pivot That on which VG wing (‘swing wing’) isattached

wing plan Shape of wing outline seen from above (see

plan).

wing position Height at which wing (1) is mountedrelative to fuselage, esp as seen from front, eg low,shoulder, parasol etc

wing profile See profile.

wing radiator Cooling radiator mounted on wing, esp.inside wing, fed by leading-edge inlet

wing reactions Those forces applied to fuselage by wing

wing rib See rib.

wing rider A wing walker [and more accurate term]

wing rock See rock (2).

wing root Junction of wing with fuselage (not withnacelle or any other body) Some authorities includejunction of wing with opposite wing, eg on centreline(upper wing of biplane) Hence ** chord, ** fillet, **thickness

Wings 1 Weather information and navigational

graphics system (PC-based, overlays latest Wx on plannedroute by GA pilot)

2 Commander (Flying) on RN carrier.

wing section Appears to be synonymous with foil section, wing profile; only ambiguity caused by

erroneously using term to mean portion of wing, eg centre

section, outer panel

wingset Left and right (port + starboard) wings for same

aircraft

wing setting See angle of incidence.

wingside More specific than airside: in immediate

proximity of parked aircraft

wing skid Protective skid on underside near tip (rare

since 1916)

wing skin Usually refers to large stressed skin forming

upper or lower surface of wing box; largest single piece of

material in aircraft

wing slot Slot built into wing; extends through outer

wing from lower to upper surface with profile generally

similar to that left by open slat

wing spar Principal spanwise member of wing, in

traditional or light aircraft usually isolated but in modern

stressed-skin wing forming one face of wing box which

itself behaves as a spar Always extends full available

depth, unlike stringers In slender delta built

perpen-dicular to longitudinal axis, thus in such wings there are

many spars which terminate not at tip but at points along

leading edge

wing spread See span.

wing strut Primary structural links joining wings of

biplane (interplane struts) or bracing high-wing

mono-plane diagonally to fuselage (such are actually ties in flight

but struts on ground)

wing sweep See sweep.

wing tanks 1 Tanks, normally for fuel, either

accommo-dated in wing or (integral) formed by sealing wing box

2 Wing-mounted drop tanks where aircraft also has

drop tanks elsewhere; thus ** may be dropped first to

permit sweep to be increased

wingtip Outer extremity of wing; either extreme tip or

general area

wingtip aileron Aileron forming entire tip of wing, either

with chordwise inner end or extending inboard along

trailing edge

wingtip extension Increase of span by adding at tip at

same dihedral angle as wing

wingtip fence Winglet of very low aspect ratio

wingtip flare Pyrotechnic attached to wingtip and

ignited by pilot to assist night landing (obs technique)

wingtip float Stabilizing float of flying boat, usually

inboard from wingtip

wingtip handler Person walking beside sailplane being

towed across airfield holding one tip so that wings are

level

wingtip rake See rake.

wingtip sail Winglet, especially prominent

wingtip tank External fuel tank, jettisonable or not,

carried on wingtip

wingtip vortex generator Ducted windmill at wingtip

providing shaft power Does the opposite of generating

vortex

wingtip vortices See vortex; always present off tips of

conventional wings at lifting AOA, and when intense (eg

tight turn) pressure at centre falls so low that moisture

condenses to leave white visible trail

wing truss Wing plus all bracing struts and wires

trans-mitting loads to or from fuselage

wingunder Bunt [suggest unpremeditated]

wing waggle Waggle

wing walk Area marked in upper surface where tenance engineers may walk in soft shoes

main-wing walker Passenger, invariably attractive girl, whoseldom walks but rides standing securely attached toupper centre section of biplane at airshow

wing warping Lateral control by warping; calledprimary on lower wing of biplane, secondary on upper

Relies on wing torsional flexure (see also warping).

wing yawmeter Yawmeter in form of miniature wing,aligned vertically or (for AOA) horizontally, with sensingholes at 0.15 or less chord

WINN, Winn Weather information network (NASA,Honeywell and others)

WINS, Wins 1 Workshop in negotiating skills.

2 Wireless instrumentation station [sometimes WIS].

3 Wireless integrated network sensor.

WINTEM Upper wind[s] and temperature[s]

winterization Process of equipping aircraft for flight inArctic-type environment; obviously includes full anti-icing and de-icing of airframe, engines, propellers andflight-deck windows and extends to landing gears,systems, fluid specifications and many items of GSE

winter solstice Point on ecliptic occupied by Sun atmaximum southerly declination, around 22 December

WIP Work in progress (check if field is open)

wipe-off switch Attached externally under belly orengine pod in most vulnerable place in belly landing; trig-gers safety system, eg tank inerting or fire extinguishers

WIPO World Intellectual Property Organization;handles copyright (eg EDP data); Berne Convention

Wipps, WIPPS Wideband integrated platform tection system

pro-Wire Wide-field IR explorer

wire Misleadingly in common use for the multi-wirecables used to arrest aircraft on carriers

wire braid Woven covering over ignition cables toprevent escape of emissions causing radio interference

wire bundle Large group of electrical wires individuallytagged, clipped together and then attached as a unit tostructure, usually in wireway

wired Wind-tunnel integrated RTIC/RTOC ments and demonstrations

experi-wired program One employing wired storage; also calledfixed program

wire-drawing 1 Manufacture of wire of required

diam-eter by drawing through circular die

2 Part-throttling fluid flow by passage through

constriction (colloq.)

wired storage EDP (1) storage which was originally ally wired in and could be erased only by physicallyremoving it; today any indestructable storage (usually forROM)

liter-wire edge Sharp burr along edge of sheet freshly cut byshear

wire gauge 1 Measure of diameter of wire or thickness of

sheet; in UK by SWG measure based on Imperial(0.001–0.5 in)

2 Hand gauge for measurement of sheet thickness or

conveyed along fine wires unrolled behind vehicle and

used to position surfaces governing trajectory

wireless telegraphy Transmission of Morse by radio

wire link Telemetry in which signals are conveyed by

wire instead of by radio; also called hard-wire telemetry

wire locking Tying a group of nuts with safety wire to

prevent rotation

wiresonde Meteorological balloon at low altitude

trans-mitting data over fine wire(s)

wire-strike kit Measures taken to reduce lethality of

impact between low-flying aircraft, usually small

heli-copter, and electric (eg national grid supply) cable

Simplest form is forward-sloping sharp-edged deflector

Guillotines [as in WW2] appear to be extinct

wireway Large conduit forming secondary structure

along which numerous electrical cicuits (occasionally also

fluid lines) are routed; in civil aircraft under floor or

behind trim

wire-wound Constructed by wrapping

ultra-high-strength (eg tungsten) wire on mandrel and bonding by

plasma spray or other method Usually final part, eg

rocket case or nozzle, has several layers aligned in

different directions; also called wire-wrapped

wire-wrapped connection Connection between single

electrical signal wire and terminal made not with solder

but by crimp wrapping by machine designed for purpose

wiring All internal wires in airship, divided into

structural *, preserving cross-section and other

dimen-sions, and gasbag *, distributing lift and preventing

chafing

WIS WWMCCS information system

Wisp Waves in space plasma

WIST Windshear and turbulence (ICAO study group)

witness 1 Hole, groove, recess or slot cut in reference

plate by each tool used in complete NC program for

producing a large machined workpiece; if each * is

dimen-sionally correct this proves software and cutters and

reference plate is stored as master for that program

2 Marks on surface of structure or component showing

where two surfaces rubbed, scored, impacted, jammed or

became deformed prior to crash of aircraft

WIU Weapon interface unit

Wizard! Expression of approval (RAF WW2)

Wizzo WSO (colloq.uial)

WJAC Women’s Junior Air Corps (1939–, UK, became

W L Actual aircraft landing weight

WL reference Horizontal axis used to define water

levels, usually synonymous with static ground line

(usually not synonymous with longitudinal axis)

WLC Whole-life cost[s]

WLD Welded [pipe or tube]

WLDP Warning-light display panel

WLFL Wet landing field length

WLG Wing-mounted landing gear

WLOP Air-defence and aviation force (Poland)

WMAP Wilkinson microwave anisotropy probe

WMC 1 Warfare management computer.

2 War Manpower Commission (US, WW2).

WMD 1 Weapons of mass destruction [-CST adds US

National Guard civil support teams]

2 Walkthrough metal detector.

WM50 50/50 mix of water and methanol

WMFNT Warm front

WMI Weather-radar indicator mount

WMMP Weak-mixture for maximum power

WMO World Meteorological Organization (UNagency, 1947 –, HQ Switzerland)

W/MOD With modification of vertical profile

WMS 1 World Magnetic Survey (ICSU).

2 Water mist system [fire protection].

3 Wide-area master station.

WMSC Weather-message switching centre; R addsreplacement

WMT Weather-radar mount

WN Week number

W N The Nth root of unity used in expressing coefficients

of Fourier transform in complex notation = e–j2π /N

W-N Wildhaber-Novikov

WNA Wrought nickel alloy

WNC Weapon[s] and navigation computer

WND Wind

WNS Wideband netted sensors

WNW Wideband networking waveform[s]

WOA Warbirds of America

wobble plate See swash plate.

wobble pump Cockpit hand pump, eg for building upfuel pressure before starting piston engine

wobbulator FM signal generator, varied at constantamplitude above/below central frequency

WOC Wing Operations Center (US)

WOD Wind over deck (carrier)

WOFF Weight of fuel flow; usually means per unit time

wolfram Tungsten

Wolf trap Instrument with sample collector andnumerous culture chambers for detecting life in inter-planetary space

Womble Wire-operated mobile bomb-lifting equipment

Wong Weight on nose gear

wooden bomb Hypothetical concept of weapon or devicewhich has 100% reliability, infinite shelf life and requires

no special storage, surveillance or handling (DoD)

wooden round Missile that fails to work when needed(colloq.)

Wood’s metal Low-melting alloy (70°C), typically 50%

Bi, 25% Pb, 12.5% Sn, 12.5% Cd