The Cambridge Aerospace Dictionary Episode 11 ppt

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 information (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 photo- conductive surface; this is then scanned by electron beam, which deposits electrons to neutralize charge and thus generate output signal. Vidissector Modern form of pioneer Farnsworth camera tube; used in space TV surveillance (ITT). VIDS Visual integrated [or information] display set [or system]. VIE Video image exploitation. Les Vieilles Racines French association of aerospace pioneers and professionals. Les Vieilles Tiges French association of pioneer pilots. Vierendeel Girder (truss) comprising upper/lower chords and verticals, without diagonals or shear web, designed for flexure. view Opinion; thus ‘to take a dim *’ = to oppose or regret 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 of trajectory by direct control of propulsive thrust axis of jet-lift V/STOL aeroplane, selecting downwards for lift (normal acceleration) and forward of vertical for de- celeration, thus performing combat manoeuvres unmatchable by any conventional aircraft. Hence verb to viff, viffing etc. Vigil Vinten integrated IR linescan. Vigo pad Small concrete pan preferably surrounded by concealing trees (STOVL). VIGV Variable-incidence (or inlet or integral) guide vane[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 necessarily same as above. V i-mp Speed corresponding with lowest power at which both height and speed can be maintained, ie minimum speed 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 as alternative to epoxy in wet lay-up of FRC materials. VIO Violent, meaning heavy static or other radio inter- ference, normal code VLNT for other meanings. violet Route(s) into and out from target area on colour radar. 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 weather echo intensity for precipitation, from * 1 (weak) to * 6 (extreme). Viper Video-input encoder. VIPPS Visual-imaging pass-production system, controlling personnel access. vibrator VIPPS 691 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 T v = (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/m 2 = 1,000 cP; for air 1.78593 × 10 –5 Ns/m 2 (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 m 2 /s = 10 6 cSt; also called dynamic *. Symbol ν . viscosity coefficient Synonymous with viscosity. viscosity index Usually synonymous with viscosity, or its variation with temperature. viscosity-index improver Long-chain waxy polymer[s] which stay thick at elevated temperatures. viscosity manometer Instrument for measuring very low fluid pressure by torque exerted on disc suspended on quartz fibre very close to spinning disc; examples are Dushman 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 merely damp, with a water film not penetrated by tyres; important on smooth surfaces, especially coated with deposited tyre rubber; persists to low speeds. viscous damping Energy dissipation in vibrating system in which motion is opposed by force proportional to relative velocity. viscous flow Flow in which viscosity is important; can be laminar or turbulent but criterion is that smallest cross- section of flow must be very large in relation to mean free path. At very low R inertia becomes unimportant and flow is governed by Stokes equations. viscous fluid One in which viscosity is significant. viscous force Force per unit mass or volume due to tangential shear in fluid. viscous stress Fluid shear stress, symbol τ = µ du/dy (Newton’s law) where u is velocity distant y from surface or other reference layer. Visgard Polyurethane conductive coating for trans- parencies, anti-fog, anti-scratch, anti-static. visibility Distance at which large dark object can just be seen against horizon sky in daylight (DoD, NATO, see RVR, RVV). visibility meter Instrument for measurement of visi- bility, visual range, eg telephotometer, transmissometer, nephelometer etc. visibility prevailing Distance at which known fixed objects can be seen round at least half horizon. visibility value Distance (see visibility) along runway, in miles and tenths. visible horizon Circle around observer where Earth and sky 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 to 0.7 µ . visible line Full line on drawing representing a line visible in assembled subject item. visible radiation See visible light. visible spectrum See visible light. visionics Collective term for optical and electronic devices, operating at many EM wavelengths, which enhance human vision, especially at night and in bad weather or smoke or other adverse conditions. vision-in-turn window Eyebrow window in roof of flight deck or cockpit. visitor Person entering a foreign state for period less than three months. Vismir Visible to medium infra-red. virage Vismir 692 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 model or CGI. visual hold[ing] Over fixed feature easily recognized from altitude. visual identification Control (ATC) mode in which aircraft follows a radar target and is automatically positioned to allow visual identification (NESN); ie inter- ceptor pilot looks at other aircraft and, if possible, identifies type and registration or other identity. visualization Making fluid flow visible, eg by injection of carbon 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 with Tiara, providing monochromatic overlain with aircraft performance data, on pilot’s HMD. visual meteorological conditions Generally UK counter- part to VFR, requiring visibility 5+ miles and 1,000 ft vertical and 1 n.m. horizontal from any cloud [variations if a/c below 3,000 ft a.m.s.l.]. visual/optical countermeasures Those directed against human eyesight, ranging from reduction of night adapta- tion to blinding. visual photometry Luminous intensity judged by eye. visual range Distance under day conditions at which apparent 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 identi- fied and thus giving geographical position as well as attitude and orientation guidance, used as reference in controlling flight trajectory, if necessary down to touch- down. visual report Identical to hot report but based solely on aircrew observations; answers specific questions concerning 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 of simulator, almost always wholly synthetic and computer- generated (but in old simulators achieved by optics moved over a large model). visual separation Basic method of avoiding collisions in TMAs or on ground by seeing and avoiding; normally involves 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 into all pilots, either specific to type or, more often, as general good 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 crystalline phase into amorphous or glassy state. Vitro-Lube Ceramic-bonded dry-film lubricant with wide temperature range. VITS Video-image tracking system. Visol VITS 693 VIU 1 Video interface unit. 2 Voloclub Italiano Ultraleggeri (ultralights). Vivid Video verification and identification. V J Velocity 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 V E 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 V EI , V LE . VLNT Violent. VLO Very low observability. V LO US term, maximum speed for landing-gear operation; synonymous with UK V E . V LOF Lift-off speed, at which aeroplane becomes airborne; suggest = V T . 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 architecture. VLV Valve. VLY 1 Volley. 2 Valley. VM, v.m. 1 Velocity modulation. 2 Voltmeter (also V/M). 3 Voter/monitor (also V/M). 4 Visual [target] marker. 5 Heading to a manual termination. V M Speed at which precipitation (esp. slush) drag is maximum; 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 be controlled in air; defined as limiting speed above which it is possible to climb away with not more than 5° bank and with 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 required rudder-pedal force and on absolute value of *. V MCG Minimum speed at which aeroplane can be controlled on ground; defined as that above which pilot can maintain directional control after failure of critical engine without applying more than 70 kg pedal force, without going off runway and if possible while holding centreline, with 7+ kt crosswind and wet surface. V MCL Minimum speed at which aeroplane can be controlled in the air in landing configuration, while applying maximum possible variations of power on remaining 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 continuous power in level flight; V H is 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). 2 Navy (USSR). VMFA Code, fixed-wing fighter/attack squadron (USMC). V MG Vertical main landing gear strut load at MRW and with full aft c.g. 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, 4 RTMMs. VMO Variable metering orifice. V MO Maximum permitted operating speed under any condition, higher than V NE and less than V DF but latter is wholly exceptional limit not intended to be reached except during certification flying. VMS 1 Vehicle management system. VIU VMS 694 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 V s . 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 V 4 (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 V MO of 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 V MO ; 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 speech output. 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 genera- tion of electronic sounds, esp. synthetic speech output. VODR Has been used to mean VOR. VOF Volume of fluid. VÖFVL Verband Österreichischer Flugverkehrsleiter (Austria). Vogad Voice-operated gain-adjusting device; auto volume compressor or expander. Voice Voice optimal interrogator (USN). voice frequency Normally taken as 25 Hz to 3 kHz for telecommunications, much greater range for hi-fi. voice-grade channel Covers about 300–3,000 Hz, for speech, analog, digital or facsimile. voice keying System enabling telecommunications to use common R/T transmit and receive sites and similar frequencies but with voice-operated carrier suppressor and delay network to switch outgoing signal to trans- mitter and incoming to receiver. Remote stations normally switch automatically to receive mode except when user is speaking. voiceless homing Any electronic homing system not using speech; traditionally meant radio range (arch.). voice message unit Software-controlled system providing voice or tone warnings of faults, sensor activity and other occurrences. voice-operated relay See voice keying. voice rotating beacon Short-range radio navaid trans- mitting stored-speech headings (usually QDMs) which differ from 000° round to 359°; a form of talking VOR, also called talking beacon, abb. VRB (arch.). 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 with Zeeman) of light passing through vapour perpendicular to strong magnetic field. VOIR Venus-orbiting imaging radar. Voiska-PVO Troops of air defence of homeland (USSR, R). Voispond Proposed Calsel function that would auto- matically identify an aircraft by a voice recording. 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 restored before computer operation. Also means electrical transients cause corruption (though this may be only temporary). 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). V MS vol d’abeille 695 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 reactive component Q; S = ͱ⒓⒓⒓⒓⒓⒓⒓ P 2 +Q 2 ; see power factor. voltmeter Instrument for measuring potential differ- ence, ie V. volume SI unit is m 3 (conversion factors for non-SI measures, from ft 3 × 0.02831684, UK gal × 0.004546087 and US gal × 0.003895411); litre (dm 3 ) = 0.035287 ft 3 = 60.9756 in 3 ; cm 3 (cc) = 0.06102 in 3 ; 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 η ν or e ν . 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 magnitude 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 instrument bearing of aircraft from station, called inbound or outbound radial. Each fixed station identified by three- letter keyed intermittent transmission (sometimes voice). See Doppler *. VOR/DME VOR steering guidance with DME distance information. Vorgen Voltage generator. VOR/ILS Linkage of VOR signals to aircraft ILS so that left/right steering guidance is given by ILS panel instrument. Latter often called * deviation indicator, or Vorloc. Vorloc, VOR/Loc Panel instrument giving steering guidance from received VOR signals; can be complete ILS indicator or (esp. in light aircraft) simple VOR receiver with localizer needle only. VORMB, VOR/MB VOR marker beacon. Vormet Sends scripted pilot’s weather reports to over- flying aircraft. Vorpostenboot Flakship (G). Vortac Combination of VOR and Tacan (occasionally written VOR/TAC) offering from one fixed station VOR az, Tacan az and Tacan (DME) distance information; ident codes prove VOR and Tacan signals are both from same fixed station. Normally * is end-product of trying to integrate civil (VOR/DME) with military (Tacan) navaids, latter being u.h.f. and therefore inherently incompatible. vortex Fluid in rotational motion (possessing vorticity), eg streamed behind wingtip or across leading edge of slender delta. See line *, point *, trailing *. vortex breakdown Sudden separation of large vortex from leading edge of slender delta (naturally followed by its decay) at particular AOA (higher than stalling AOA for most wings); essentially represents stall of slender- delta wing. vortex burst See vortex breakdown. vortex dissipator Bleed-air jet(s) blown down below and ahead of jet-engine inlet to prevent ingestion of material from unpaved airfields or contaminated runways. vortex drag Drag caused by vortex formation; not normally a recognized part of aircraft drag. vortex filament Line along which intense (theoretically infinite, at R = 0) vorticity is concentrated; either closed loop or extending to infinity. vortex flap Hinged along its leading edge just behind leading edge of wing on upper surface. Opened to 45° traps vortex to increase lift. vortex flow Fluid flow combining rotation with trans- lational motion. vortex generator Small flat blade perpendicular to skin of aircraft or other body set at angle to airflow to cause vortex which stirs boundary layer, usually to increase relative speed of boundary layer and keep it attached to surface; also called turbulator. vortex hazard Danger to aircraft, esp. light aircraft, from powerful vortices trailed behind wingtips of large aircraft; also called wake hazard, wake turbulence. vortex lift Lift generated by slender delta or similar wing having sharp, acutely swept leading edge (subsonic relative velocity normal to leading edge): large and powerful vortex is shed evenly on left/right wings, adding Volmet vortex lift 696 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 of financial reward (usually in increased annual earning power) from cutting each unit of mass (kg or lb) from empty weight; eg VOWS for Concorde in 1974 currency was £50/lb. VOx Vanadium oxide. VOX See Vox. Vox Voice (communication, keying or activation). VP 1 Variable-pitch. 2 Code: fixed-wing patrol squadron (USN); suffix B adds bomber. 3 Vector processor. 4 Video processor. 5 Combat helicopter regiment (R). 6 Validation parameter. 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, r o is 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). VR 1 Resultant velocity. 2 Vernier radial (thruster). 3 Visual reconnaissance. 4 Volunteer Reserve. 5 Veer[ring]. 6 Visual route, rules or range. 7 Vortex ring. 8 Virtual reality. 9 Voice recognition. V R 1 Rotation speed, at which PIC starts to pull back on yoke to rotate aeroplane in pitch; normally determined by one of following: not less than 1.05 V MCA ; not less than 1.1 V MS ; not less than 1.05 or 1.1 V MU ; and it must allow 1.1 V MCA or 1.2 V MS to be achieved at screen after one engine failure. 2 Radar velocity, i.e., of aircraft in which it is mounted. 3 Heading to a radial (US wording). = ǰ˭˭˭˭˭˭˭˭˭˭ K 2 –– r o – 1 –– a vortex line V R 697 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 V s 0 (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. 2 Vestigial sideband. 3 Velocity search (radar). 4 Vane set. 5 Vertical speed (also V/S, VSP). 6 Versus. 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 V MCA ). 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 V s1 ]. VSIP Virtual-system implementation. V6, V16 Vasi with 6 or 16 boxes, the 16-box being on both sides of the runway. VSJ Vazduhoplovni Savez Jugoslavije, aeronautical sport 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 engine diagnostic 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 other than clean. V s1g Stalling speed under 1 g vertical (normal) accelera- tion; obtained from V s by correcting for any imposed normal acceleration that may have been present during an actual measured stall; a ‘pure’ V s not normally entering into performance calculations. 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, for intentionally shutting down one engine in flight for pilot training; 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 avionics and flight-control surfaces added to enable it precisely to duplicate flight characteristics of other types. V st One reference states ‘stall or minimum flight speed, flaps up, no power’; not a normally recognised abbreviation. 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 became DCA(2). VSW 1 Vertical speed and windshear; hence VSWI = * indicator. V r VSW 698 2 Variable-sweep wing. 3 Verification software. VSWE Virtual strike warfare environment. VSWR Voltage standing-wave ratio. VT 1 Vernier thruster. 2 Voltage transient. 3 Vectored thrust. 4 Internal prison, eg for design teams (USSR, 1929–42). 5 Target speed. 6 Video tracker [SC adds system controller]. 7 Variable time. or timing. 8 Validity time[s]. V T 1 Takeoff speed. 2 Confusingly, threshold speed, see V TDM , V T max , V T min . 3 Velocity of target. 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 T max Maximum threshold speed, above which risk of overrunning is judged unacceptable; usually V AT + 15 kt. V T min Minimum threshold speed, below which risk of stall (esp. in windshear) is judged unacceptable; usually V AT - 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 of Mercury. Vulkollan Hard erosion-resistant thermosetting plastics material (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 Forschungs- instituten (G). 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 speci- fied (US usage). VXE Antarctic Development (ie, exploration) Squadron (USN). VXO Variable crystal oscillator. V XSE Airspeed for best angle of climb, single-engine (US usage). 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 (US usage, also called blueline speed). VZ Aircraft designator, vertical-lift research (USA 1957–62). V ZRC Airspeed for zero rate of climb, at which with one engine inoperative drag reduces gradient to zero. VSWE V ZRC 699 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 W w = 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 counter- part to Egnos). WAASA Women’s Aviation Association of South Africa. WAC 1 World Aerobatic Championships. 2 Weapon-aiming computer. 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 Relations Association (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-display system. WADGNSS Wide-area differential global navsat system. 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 which numerous elecronic devices are constructed, subsequently separated by scribing and cleavage to make chips. waffle plate Thin metal sheet stabilized by impressed dimples, often parallel rectangles. Same name for more complex 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 with bang/bang solenoid operation for radio command guidance of missiles (from 1937). Wagner beam Idealized pure tension-field beam assumed to have zero compressive strength and thus to react loads as diagonal tensions; generally, a beam designed to buckle in operation. wagon wheel See wheel (6). wagonwheel propellant Solid rocket motor propellant grain 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 700 [...]... undercarriage (landing gear) WWV NBS exact-time service (US) WWW 1 World Weather Watch (WMO) 2 World Wide Web W(WW) Past weather (ICAO) WX 1 Weather 2 Airborne weather radar 3 Indefinite obscuration WX/C Weather-radar controller WXI Weather-radar indicator WXNIL No significant weather WXP Weather-radar panel WXR Weather radar WXS Weather-radar system WYPT Waypoint altitude X X 1 Longitudinal axis (more... 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... 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... 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 (v j–V) At the start of conventional takeoff... 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... 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... saturated adiabatic, SALR wet and dry bulb See pychrometer wet assembly Important technique for modern aerospace 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... therein and improving circulation and lift of outer portion of wing 2 Miniature wing mounted horizontally on fuselage (not at nose or tail), on interplane struts or elsewhere (eg nacelles), often not so much for lift as to carry external load or connect bracing struts or main gears to fuselage winglet lift This invariably means the resultant force on the winglet, which is usually perpendicular to the. .. front WMI Weather-radar indicator mount WMMP Weak-mixture for maximum power WMO World Meteorological Organization (UN agency, 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 adds replacement WMT Weather-radar mount WN Week number WN The Nth root... Georef, uniform position-fixing and designation system for control of aircraft, targeting of ICBMs and many other functions (USAF) World Weather Watch Scheme to share and disseminate weather-satellite information internationally; also called VMM (WMO) Worm Write once, read many, or multiple wormhole Theoretically achievable short cut between two points [lightyears apart] by warping spacetime Wortmann Family . 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. 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. 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