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splash lubrication
splash lubrication Use of small lips or vanes on
connecting rods or crankpins to splash oil inside
crankcase; rare in aviation.
splatter 1 Adjacent-channel interference in pulsed transmissions,
measured as amount of spectrum energy that
can appear in adjacent channel; varies greatly with
different pulse waveforms.
2 Cloud of canopy fragments after MDC detonation.
splice Structural joint made by plate overlapping both
members, plus doubler.
spline 1 Axial groove in shaft for meshing with driven
member; hence splined shaft has entire periphery formed
into splines, invariably of involute or even rectangular
section.
2 Flexible non-structural strip (various materials) bent
to required curvature in construction of fairing.
splinter Fragment of casing from exploded bomb or h.e.
shell.
split Verb, to divide an engine into modules, notably
into fan and core, hence *-engine shipping, etc.
split-altitude profile Flight-profile has two main flight
levels.
split-axle gear Landing gear on simple low-performance
aircraft in which there is no axle or other linking transverse
member. Also called divided gear.
split basing Division of tactical-aircraft unit’s resources
between two operating bases.
split cameras Two or more cameras fixed so that
imagery of one overlaps that of neighbour(s) by selected
amount.
split charter Commercial flight flown on charter to two
companies, each providing part of payload.
split-compressor engine Gas turbine in which compression
is performed by two separate rotating assemblies
running at different speeds; can be axial + centrifugal,
while term two-spool suggests axial + axial.
split courses See multiple courses.
split distance Two friendly fighters fly apart for mutual
interception practice, usually head-on.
split flap Flap formed from only underside of aerofoil,
depressed with plain hinge leaving upper surface unaltered;
gives high drag but little extra lift.
split-flow engine Turbofan in which fan air is diverted to
blow wing or flaps and core jet is used for propulsion (and,
if vectoring is added, for lift).
split gear Landing-gear trucks (B-52) attempt to steer
some left and some right simultaneously.
split landing gear See split-axle gear.
split line Small flash-projecting ridge round surface of
die forging.
split load Drop of firefighting retardant at two locations
in same mission.
split mission Several meanings, including (1) profile part
hi and part lo, (2) task includes recon and attack, (3) task
includes two surface targets, (4) transport flight carries
loads for two destinations, and (5) part subsonic and part
supersonic dash.
split needles Various flight-instrument indications for
aeroplane (eg dual engine-speed indicator with one engine
at flight idle) or helicopter [eg, gross disharmony between
speeds of engine and rotor system].
split pair See split vertical photography.
split patch Patch for reinforcing end of surface (eg fabric
air inlet) at junction with airship envelope.
spoiler
split-plane manoeuvring Air-combat manoeuvring for
mutual support following a defensive split.
split-S Flight manoeuvre comprising half flick (snap)
roll followed by second half of loop, resulting in loss of
height and 180° change in heading.
split-surface control Powered flight-control surface
subdivided into two or three portions, each of same area
and each driven by its own independent power unit (thus,
VC10 has four elevators and three rudders).
splitter 1 Fixed or laterally movable surface dividing
fluid flow in duct, eg to feed two engines, or to divide each
flow element in a centrifugal compressor or to pass into
bypass duct and compressor in a turbofan.
2 Machine which divides or apportions signals, shaft
power or other services among selected recipients.
splitter fairing The streamlined fairing over a shaft
taking the drive from inside a gas turbine to a unit
mounted externally or on a fan case.
splitter box Divides one rotary input among two outputs
in variable proportions, eg to control either or both of
two-roll-control or DLC spoilers.
splitter gearbox 1 Splitter box.
2 Gearbox dividing input along two channels, eg from
reverser PDU (3) to left/right half-rings of slave actuators.
splitter panels Sound-absorbing panels, usually radial
struts or concentric rings, to reduce noise from jet-engine
inlet.
splitter plate On centreline of single-surface rudder.
split vertical photography Simultaneously triggered
reconnaissance cameras, each tilted same angle to left or
right of centreline, with small centreline overlap.
split wheel Made in inner and outer halves to facilitate
changing tyre.
split-work blade Gas-turbine fan blade comprising inner
(compressor supercharging) portion separated from outer
(fan) portion by part-span shroud.
SPLR Spoiler.
SPM 1 System planning manual.
2 Solar-proton (or particle) monitor.
3 Solid propellant motor.
4 Security protection module (networks).
5 Superalloy powder metallurgy.
6 Scanning-probe microscope, or microscopy.
7 Surface-position monitor.
8 Stabilizer position module[s].
9 Stochastic process model.
spm Shots per minute.
SPMS Special-purpose manipulator system.
SPN/GEANS Standard precision navigator, gimballed
electrostatically, aircraft navigation system.
SPO 1 System program office.
2 Safety petty officer (carrier catapult).
3 Single-pilot operation.
4 Strategic plan of operation [see SPT].
SPOC Single point of contact (Sarsat).
SPOH Since part, or propeller, or partial, overhaul.
spoil To reduce, not necessarily to zero (eg lift or thrust).
spoiler 1 Hinged or otherwise movable surface on upper
rear surface of wing which when open reduces lift, and
usually also increases drag. Most are essentially flat plates
hinged at or beyond leading edge and power-driven to
open upwards, either symmetrically to incline flight path
downwards or differentially to command or augment roll.
Supersonic combat aircraft often have no other roll
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