the Aviation Dictionary

skin sliu
skin - The smooth outer cover of an aircraft.
skin antenna -An
skin.
antenna that is flush with the aircraft
skin effect - The tendency of high frequency alternating
currents to flow in the outer portion of a conductor.
Skin effect can be reduced by using stranded rather
than solid wire.
skin friction - Aerodynamic drag caused by air flowing
over the surface of the aircraft.
skip distance - The distance from a transmitter to the
point where a reflected sky wave first reaches, the
Earth.
skip welding - A welding technique used to pre/vent
warping of the material. Skip welding is a series of
short welded beads evenly spaced to anchor the entire
length of the weld. The remaining gaps are filled in
after the skip welds are tacked in.
skull-cap spinner - A round nosed cover for the hub of
a fixed-pitch propeller. Normally the same diameter as
the hub, it is usually attached to a bracket secured by
propeller mounting bolts.
skunk works - Slang. A loosely structured corporate
research and development unit formed to foster
innovation. Most famous was Lockheed Aircraft's
Skunk worksB, headed up for years by Kelly Johnson.
sky wave - The portion of a radio wave reflected from
the ionosphere.
Skydrol hydraulic fluid - A synthetic, nonflammable,
ester-base hydraulic fluid used in modern
high-temperature hydraulic systems.
slab - An unfinished bar of metal.
slag - A completely fused and brittle by-product caused
by the flux used in welding. Slag separates from the
metal in the process of welding.
slam acceleration - Improper operation of a turbine
engine when the power control lever is moved forward
too rapidly. A rich flameout is possible because the
fuel is metered before the airflow has increased
sufficiently. More sophisticated fuel controls in recent
turbine engines have minimized this problem.
slant range - In radar, the line-of-sight distance from
radar to target as opposed to ground distance (from
radar to the position on the ground below the target).
Also the line-of-sight distance from an aircraft to a
navigation aid on the ground as opposed to the ground
distance (from a point under the airplane to the
navigation aid).
slant visibility - In weather, the distance fiom an
airborne observer to the farthest point visible on the
ground.
slant-line distance - See slant range.
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slash - A radar beacon reply displayed as an elongated
target.
slat - A movable auxiliary airfoil on the leading edge of
a wing. It is closed in normal flight but extends at high
angles of attack. This allows air to continue flowing
over the top of the wing and delays airflow separation.
slave relay - A relay that operates in response to the
actions of a relay in a primary circuit (activates an
associated circuit).
slaved gyro - Directional gyro slaved to the output of a
flux valve. Gives a directional gyro synchronous
attributes.
sleet - Small, transparent or translucent, round or
irregularly shaped pellets of ice. They can be (1) hard
grains that rebound on striking a hard surface or (2)
pellets of snow encased in ice.
sleeve - A tube or tube-like part that fits over or around
another part.
slide rule - A ruler-like instrument with a center slide.
Both the inner slide and fixed outer sections are
marked with logarithmic scales. Slide rules are used for
mathematical calculations; however electronic
calculators or computers are more widely used.
slide switch - In electricity, a switch that consists of a
slider that moves across contacts to make and break
one or more circuits.
slide valve - A mechanical valve that opens and closes
by sliding a gate across a port.
slide-wire rheostat or potentiometer - In electricity, a
variable resistor that changes resistance by moving a
slider along a length of resistance wire. The amount of
resistance is proportional to the effective length of the
wire.
sliding support - A duct support attached to flexible
bellows. The sliding support allows movement of the
bellows while the duct is under pressure.
sling psychrometer - In weather, a device used to
measure the relative humidity. It consists of two
thermometers, one of which has wetted cloth wrapped
around its bulb. Both thermometers are swung on the
end of a cord. Due to evaporation, the thermometer
with the wetted cloth will iead a lower temperature
than the dry thermometer. A chart of the differences is
consulted to determine the relative humidity.
slinger ring - A tubular ring mounted around the hub of
a propeller where deicing fluid is directed and slung
out onto the blades.
slip - I. Propeller: The difference between geometric
and effective pitch of a propeller. Slip can be expressed
as a percentage of the mean geometric pitch or as a
linear dimension. 2. Aircraft flight maneuver: A
sideways aircraft maneuver used to descend at a steep
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