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Return to Terminology
L
- Laminac
- A (proprietary) plastic binder
material, the general class term is "unsaturated polyester."
- Lands
- Raised portion between grooves in the bore of a rifled gun.
- Lanthanide Series
- Rare - Earth Metals with
atomic numbers 58 through 71 in group IIIb of the Periodic
Table. They are, in order of increasing atomic number, Cerium, Praseodymium,
Neodymium, Promethium, Samarium, Europium, Gadolinium, Terbium, Dysprosium, Holmium,
Erbium, Thulium, Ytterbium, and Lutetium. Although they closely resemble Lanthanum and
each other in their chemical and physical properties, lanthanum (at. no. 57) is not always
considered a member of the series.
- Lanyard
- A cord, wire, etc. for firing certain fuze.
- LASER
- An acronym for Light Amplification By Stimulated Emission Of
Radiation. Laser is made up of light waves that are nearly parallel to each other, all
traveling in the same direction. Lasers emit beams of coherent light of a single color or
wave length and frequency.
- Lateral Deviation
- Horizontal distance between the point of impact or burst and
the gun-target line.
- Lead (Rhymes with "feed").
- An explosive train component which consists of a column of
high explosive, usually small in diameter used to transmit detonation from one detonating
component to a succeeding high explosive component. It is generally used to transmit the
detonation from a detonator to a booster charge. Also called "explosive lead."
- Lead Azide
- Very sensitive high explosive used in small quantities to
initiate other less sensitive high explosives. This agent has largely replaced mercury fulminate in military ammunition.
- Leading (Lead) Lines or Wires
- The wire(s) connecting the electrical power source with the
circuit containing electric detonators ( Firing Line).
- Leaflet Shell
- Usually consists of standard-base ejection smoke shell, of any
caliber, with smoke canisters removed and propaganda substituted therefore.
- Leakage Resistance
- The resistance between the blasting circuit (including lead
wires) and the ground.
- LEDC
- Low energy detonating cord commercial version of mild
(miniature) detonating fuse.
- Legwires
- The two single wires or one duplex wire extending out from an
electric detonator, which are permanently attached to the electric detonator.
- Lens
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A device for forming an image of an
object by the refraction, or bending, of light. In its simplest form it is a disk of
transparent substance, commonly glass, with its two surfaces curved or with one surface
plane and the other curved. Generally each curved surface—called convex if curved
outward and concave if curved inward—of a lens is made as a portion of a spherical
surface; the center of the sphere is called the center of curvature (C) of the surface.
All rays of light passing through a lens are refracted except those that pass directly
through a point called the optical center. A divergent lens (thicker at the edges than at
the center) bends parallel light rays passing through it away from each other. The image
formed by a diverging lens is always erect (upright), smaller than the object, and virtual
(located on the same side of the lens as the object). A convergent lens (thicker at the
center than at the edges) bends parallel light rays toward one another; if they are
parallel to the principal axis of the lens, they converge to a common point, or focus (F),
behind the lens. The image formed by a converging lens depends on the position of the
object relative to the lens's focal length (distance between the focus and the optical
center) and its center of curvature. |
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- Lifting Plug
- Threaded eyebolt which fits into the fuze cavity, permitting
heavy shells to be handled by means of a winch.
- Light
- Light, that part of Electromagnetic
Radiation to which the human eye is sensitive. The wavelengths of visible light range
from c.400 to c.750 nanometers. If white light, which contains all wavelengths, is
separated into a Spectrum, each wavelength is seen to correspond to a different Color.
The scientific study of the behavior of light is called Optics; it covers Reflection of light by a Mirror or other
object, Refraction of light by a Lens or Prism, and Diffraction of light as it
passes by an opaque object. Christiaan Huygens proposed (1690) a theory that explained
light as a Wave phenomenon. Isaac Newton, however, held (1704) that
light is composed of tiny particles, or corpuscles, emitted by luminous bodies. By
combining his corpuscular theory with his laws of mechanics, he was able to explain many
optical phenomena. Newton's corpuscular theory of light was favored over the wave theory
until important experiments, which could be interpreted only in terms of the wave theory,
were done on the diffraction and Interference of light by
Thomas Young (1801) and A.J. Fresnel (1814–15). In the 19th century the wave theory
became the dominant theory of the nature of light. The electromagnetic theory of James
Clerk Maxwell (1864) supported the view that visible light is a form of Electromagnetic Radiation. With the acceptance of the
electromagnetic theory of light, only two general problems remained. It was assumed that a
massless medium, the Ether, was the carrier of light waves, just as air or water carries
sound waves. The famous experiments (1881–87) by A.A. Michelson and E.W. Morley, in
which they tried unsuccessfully to measure the velocity of the earth with respect to this
medium, failed to support the ether hypothesis. With his special theory of Relativity, Albert Einstein showed (1905) that the ether was
unnecessary to the electromagnetic theory. Also in 1905, Einstein, in order to explain the
Photoelectric Effect, suggested that light, as well as other forms of electromagnetic
radiation, travel as tiny bundles of energy, called light quanta, or Photons,
that behave as particles ( Quatum Theory). Light thus behaves as a wave, as in diffraction
and interference phenomena, or as a stream of particles, as in the photoelectric effect.
The theory of relativity predicts that the speed of light in a vacuum (186,282 mi/sec =
299,792.458 km/sec) is the limiting velocity for material particles.
- Light-Year
- Light-year, in astronomy, the distance (5.87 × 1012 mi/9.46
× 1012 km) that Light travels in one sidereal year.
- Lightning
- Lightning, electrical discharge accompanied by Thunder, commonly occurring during a Thunderstorm.
The discharge may take place between two parts of the same cloud, between two clouds, or
between a cloud and the earth. Lightning may appear as a jagged streak (forked lightning),
as a vast flash in the sky (sheet lightning), or, rarely, as a brilliant ball (ball
lightning). The electrical nature of lightning was proved by Benjamin Franklin in his
famous kite experiment of 1752.
- Lignite
- Lignite or brown coal, carbon-containing fuel intermediate
between Coal and Peat, brown or yellowish in color
and woody in texture. Lignite contains more moisture than coal and tends to dry and
crumble when exposed to air. It burns with a long, smoky flame but little heat.
- Limit
- In mathematics, a value approached by a sequence or a function
under certain specified conditions. For example, the terms of the sequence 1/2, 1/4, 1/8,
1/16, … are obviously getting smaller and smaller. Because one can, if enough terms
are taken, make the last term as small, i.e., as close to zero, as one pleases, the limit
of this sequence is said to be zero. If sn denotes the nth term of a sequence, the
equation sn = s (read “the limit of sn as n approaches infinity is s”) expresses
the fact that s is the limit of the sequence; in the example, sn = 1/2n and 1/2n = 0.
Similarly, although the function f(x) = (x - 1)/(x2 - 1) is not defined for x = 1 (where
the denominator would be zero), values of x increasingly close to 1 yield values of f(x)
increasingly close to 1/2. Thus, the limit of f(x) as x approaches 1 is 1/2, which is
symbolized as f(x) = 1/2. Limits are the basis of differential and integral Calculus.
- Linear Burning Rate
- The rate of regression of a burning propellant surface,
measured normal to the surface. Piobert’s Law.
- Liner
- 1) Inner tube, in a cannon, which bears the rifling and which
may be replaced when worn out.
- 2) Cone of material used as an integral part of shaped
charges.
- 3) A material applied to the inside of a solid rocket case
which adheres to both the case and the propellant.
- Liquid Fuels
- Fuels in a liquid state. They may be used with oxidizers to
form explosive materials.
- Lithium
- Lithium (Li), metallic element, discovered in 1817 by J.A.
Arfvedson. A soft, silver-white corrosive Alkali Metal, lithium is
the least dense metal. Lithium compounds are used in lubricating greases, special glasses,
and ceramic glazes; as brazing and welding fluxes; and in the preparation of plastics and synthetic rubber. Lithium is also a
medical antidepressant. Element; Periodic
Table.
- Litmus
- Litmus, organic dye usually used as an indicator of acidity or
alkalinity ( Acids and Bases). Naturally pink in color, it
turns blue in alkaline solutions and red in acids. Litmus paper is paper treated with the
dye.
- Live Ammunition
- Ammunition containing explosives. This is in contrast to drill
ammunition (dummy ammunition), which contains no explosives and is used in training.
- Loading
- Placing explosive material in a blasthole or against the
material to be blasted.
- Loading Density
- The weight of explosive loaded per unit length of borehole
occupied by the explosive, expressed as pounds per foot or kilograms per metro of
borehole.
- Ratio of weight of propellant to available chamber volume.
- Loading Ratio
- The weight of explosive loaded per unit length into a device
to accomplish a breach of a specific area. Total area breached divided by the total charge
weight.
- Logarithm
- The power to which a number, called the base, must be raised
in order to obtain a given positive number. For example, the logarithm of 100 to the base
10 is 2, because 102 = 100. Common logarithms use 10 as the base; natural, or
Napierian, logarithms (for John Napier) use the number e as the base.
- Logic
- The systematic study of valid inference. Classical, or
Aristotelian, logic is concerned with the formal properties of an argument, not its
factual accuracy. Aristotle, in his Organon, held that any logical argument could be
reduced to a sequence of 3 propositions (2 premises and a conclusion), known as a
Syllogism, and posited 3 laws as basic to all logical thought: the law of identity (A is
A); the law of contradiction (A cannot be both A and not A); and the law of the excluded
middle (A must be either A or not A).
- Logic Circuit
- An Electric Circuit whose output
depends upon the input in a way that can be expressed as a function in symbolic Logic; it has one or more binary inputs (capable of assuming either of
two states, e.g., “on” or “off”) and a single binary output. Logic
circuits that perform particular functions are called gates. Basic logic circuits include
the AND gate, the OR gate, and the NOT gate, which perform the logical functions AND, OR,
and NOT. Logic circuits, which are mainly used in digital Computers, can be built from any
binary electric or electronic devices, including Switches, Relays, Electron Tubes,
solid-state Diodes, and Transistors.
- Lot Number
- Code number that identifies a particular quantity of
ammunition from one manufacturer. The number is assigned to each lot of ammunition when it
is manufactured.
- Loudspeaker
- Loudspeaker or speaker, device used to convert electrical
energy into sound. It consists essentially of a thin flexible sheet called a diaphragm
that is made to vibrate by an electric signal from an Amplifier. The vibrations create
sound waves in the air around the speaker. In a common dynamic speaker, the diaphragm has
a cone shape and is attached to a wire coil suspended in a magnetic field. A signal
current in the suspended coil creates another magnetic field that interacts with the
already existing field, causing the coil and the diaphragm attached to it to vibrate.
Quality sound systems employ three different sized speakers. The largest one, the woofer,
reproduces low frequencies; the medium-sized one, called a mid-range speaker, reproduces
middle frequencies; the smallest one, called a tweeter, reproduces high frequencies.
- Low Explosives
- Explosives that are characterized by deflagration or a low
rate of reaction and the development of low pressure.
- Explosive which undergoes a relatively slow chemical
transformation, thereby producing a deflagration or an explosion, the effect ranging from
that of a rapid combustion to that of a low order detonation. It is suitable for use in igniter trains and certain types of propellants. Propellant.
- Low Order Detonation
- Detonation, Low Order.
- Lower Acceptable Mean Maximum Pressure
- For any type gun, that value of the maximum pressure noted in
the propellant specification as the lower limit for the average maximum pressure developed
by an acceptable smokeless propellant, in the form of propelling charges, which will
impart the specified muzzle
velocity to the specified projectile. Smokeless propellant is considered as having
failed to pass the test if, in acceptance tests, it develops an average maximum pressure
lower than this value.
- LSC (Linear Shaped Charge)
- Less flexible, or rigid, version of FLSC.
- Lupersol
- A trade name for a catalyst for
polyesters.
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