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stoves and as a base for turbine engine fuel, and is commonly called coal oil.
The name kerosine was originally spelled kerosene, but the “ene” ending wrongly implied that
kerosine is made of unsaturated compounds (compounds having atoms bound together with more than one
bond). To keep the spelling of the name from giving the wrong idea of the chemical composition of the
material, the spelling was changed in 1957 by petroleum chemists to kerosine.
Ketts saw (sheet-metal cutting tool). A power-operated saw used for cutting various thicknesses of metal
sheet. The metal is cut with a small-diameter circular saw blade mounted in the head of this hand-held tool.
Kevlar. A patented synthetic aramid fiber noted for its flexibility and light weight. It is to a great extent
replacing fiberglass as a reinforcing fabric for composite aircraft construction.
key (telegraph). A form of electrical switch used to break a continuous wave of radio-frequency
alternating current into a series of dots and dashes for use in continuous wave (CW) radio transmission.
The key allows the operator to send the dots and dashes in the sequence needed to transmit information by
Morse code.
key (verb). To initiate an action by depressing a key or a button.
keyhole saw. A small handsaw with a stiff, tapered blade. The blade of a keyhole saw can start its cut
through a small hole drilled in the material. A key-hole saw is a form of compass saw.
keyway. A lengthwise groove cut in the outside of a shaft. A similar keyway cut into the side of the hole in
the hub that fits on the shaft is aligned with the keyway on the shaft, and a rectangular piece of metal called
a key locks the keyways together, preventing the hub turning on the shaft.
Printed from Summit Aviation's Computerized Aviation Reference Library, 2/7/2007
Page 339
K-factor (sheet metal layout). A factor used in sheet metal work to determine the setback for other than a
90° bend. K-factors are found in charts in most sheet metal working handbooks.
Setback = K • (bend radius + metal thickness).
For bends of less than 90°, the value of K is less than 1; for bends greater than 90°, the value of K
is greater than 1.
kHz. The abbreviation for kilohertz (1,000 cycles per second).
kickback (reciprocating engine operation). A condition of engine operation in which the engine tries to
run backward when it is being started. Kickback is caused by the ignition spark occurring while the piston
is moving slowly upward on the compression stroke. Since the piston is moving slowly, the pressure from
the expanding gases is applied to the piston before it passes over top center of the compression stroke.
Kickback is prevented by timing the ignition so the starting spark occurs late.
kick-in pressure (hydraulic system operation). The pressure at which an unloading valve causes a
hydraulic pump to direct its fluid into the system manifold.
kick-out pressure (hydraulic system operation). The pressure at which an unloading valve shuts off the
flow of fluid into the system pressure manifold and directs it back to the reservoir under a much reduced
pressure.
kilo (k). The metric prefix that means 1,000. A kilogram is one thousand grams, a kilometer is one
thousand meters, and a kilohertz is one thousand cycles per second.
kilogram. One of the commonly used units in the metric system for measuring mass. One kilogram is the
mass of one thousand cubic centimeters of pure water. In the International Bureau of Standards in Paris,
France, there is a cylinder of platinum having a mass of exactly one kilogram. It is known as the standard
kilogram.
kilomega (kM). A term that has, in the past, been used to represent the quantity 1,000,000,000 or 1 x 109.
The prefix giga is now used in place of kilomega.
kindling temperature. The temperature to which a material must be heated for it to combine with oxygen
from the air and burn. The kindling temperature of a material is also called its ignition temperature, or its
kindling point.
kinematic viscosity. The ratio of the absolute viscosity of a fluid to its density. Kinematic viscosity is
measured in centistokes.
kinetic energy. Energy in an object caused by its motion. Kinetic energy is equal to one half the mass of
the body times the square of its speed.
EK = (M · V2) / 2
kink (form of metal damage). A sharp bend or twist in a piece of wire, tubing, or sheet metal.
Kirchhoff’s current law. One of the basic laws of electrical circuits, stating that the sum of the current
flowing away from any point in an electrical circuit is equal to the sum of the current flowing to that point.
Printed from Summit Aviation's Computerized Aviation Reference Library, 2/7/2007
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航空术语词典Dictionary of Aeronautical Terms 中(99)
