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weight and balance sheet
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), that
number written into original agreed specification; jobpackage
target/bogey, series of targets for each * group
parts-breakdown; current, also called current status, that
representing best available information, obtained by
adding to previously reported status all subsequent
revisions.
weight and balance sheet Document carried with transport
(military/civil) recording distribution of weight and
c.g. at takeoff and (military) landing.
weight breakdown Subdivision of aircraft weight
(usually a design gross) into broad headings: structure
(itself divided into wing group, tail group, fuselage and
landing gear), power-plant, equipment services, and
disposable load (latter divided into fuel/consumable items
and payload).
weight coefficients Dimensionless ratios BF/TOW,
BF/ZFW, RSV/LW, RSV/ZFW, TOW/LW and
TOW/ZFW.
weight distributors In a large gas-turbine engine the fuel
pressure is equalised all round the combustor by a system
of masses and springs, the latter being in unison at ‘6
o’clock’ and in opposition at the top.
weight flow See mass flow.
weight gradient Required change in weight, eg MTOW,
for unit change in temperature, usually expressed in
kg/°C, in such corrections as QNH variation, air-conditioning
and anti-icing.
weight in running order Traditional measure of pistonengine
weight in which radiator/coolant/pipes/controls
were added, plus oil within engine, but excluding tanks/
fuel/oil/reserve coolant/exhaust tailpipes/instruments.
weightless Condition in which no observer within
system can detect any gravitational acceleration; can be
produced 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 by
restriction on aircraft MTOW or ZFW and not by available
space.
weight-on-wheels Signal sent to landing-wheel brake
system confirming oleo struts are compressed, enabling
brake [and, if fitted, lift dump] system to function.
weight per horsepower Usually incorrectly called
power/weight ratio, basic measure of piston or other
shaft-output engine; dry weight divided by maximum
power (latter can be 2½-minute contingency).
weight per unit thrust Dry weight (mass) of jet engine
divided by a specified measure of thrust (for
wet
turbojets/turbofans usually SLS/takeoff); in SI it is not
possible to divide a mass by a force, but a meaningful ratio
is still obtainable provided units of both are compatible
and specified.
weightshift control Controlling aircraft [micro, hang
glider, or similar] by pilot moving his/her c.g. laterally or
longitudinally.
Weir tables Azimuth diagram and tables for interpreting
radio direction finding (obs.).
weld bead Metal deposited along welded joint.
weld bonding Combination of resistance spot-welding
and adhesive bonding with properties superior to either
alone.
weld continuity Specified as tack, intermittent, continuous.
welded patch Thin sheet-steel patch welded over local
damage in steel tubular airframe.
welded wing Pair of aircraft in unvarying side-by-side
formation about 500 ft apart.
welded steel blade Propeller blade assembled by edgewelding
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.
WEPSS Wideband enhanced passive surveillance
system (USAF).
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 [see wet thrust].
3 Of station or pylon, plumbed for fuel, or carrying a
tank.
4 Fuel included [hire cost per hour].
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