naval guns

CHAPTER 2

NAVAL GUNS

Most naval ships and aircraft are fitted

with various kinds of guns.

Guns may be used against surface,

shore, and air targets.

Ship guns designed for engaging

both air and surface targets

Dual-Purpose Systems

In automatic, gun recoil ejects the

fired powder case and reloads the

gun.

A weapon consisting of a metal tube

or barrel closed at one end, with

mechanical attachments from which

projectiles are shot by the force of an

explosive.

Gun

Gun Components

Gun Components

The loading cycle for a large baval breech loader. Notice that there is a

Series of interlocking doors that never permit an open path from the

Gunhouse, down, which a flash might travel to the magazine.

Gun Barrel Rifling

Spiral grooves cut in the inner

surface of the gun barrel to give

the projectile a rotating motion

and thus a more precise trajectory

Rifled Barrel

The system of rifling spiral

grooves cut inside the bore

Rifling Lands

Rifling causes the projectile to spin in

flight, which keeps the projectile from

tumbling after it leaves the barrel, thus

providing greater accuracy.

BARREL

Rifling

Gun Measurement

The diameter of the bore of a gun

taken as a unit of measurement

Caliber

Gun Measurement for Barrels

over 3" in Diameter

Caliber = barrel length ÷ bore

diameter in inches.

A 20-millimeter machine gun has a bore

diameter of 20 millimeters. A .32-caliber

revolver has a bore diameter of .32 inches.

20–millimeter .32–caliber

A gun having a bore diameter of 5 inches and

a barrel 190 inches long is designated 5-inch,

38-caliber (written 5/38).

What is the designation of a gun

having a bore diameter of 5 inches

and a barrel 270 inches in length?

What is the designation of a gun

having a bore diameter of 5 inches

and a barrel 270 inches in length?

It is called a 5-inch, 54-caliber gun

(5/54).

Gun Elevation

The total vertical arc through which a

gun barrel can be raised and lowered

Arc of Elevation

Gun Train

The total horizontal arc through which

a gun mount may be rotated

Arc of Train

Cutout cams prevent guns from being fired

into the ship’s or aircraft’s structure.

The entire structure between

the gun and ship’s structure

Gun Mount

Battery

A group of gun

mounts of the

same size, normally

controlled from the

same point

Consists of the largest size gun

on board a ship

Main Battery

Consists of dual-purpose guns,

or guns of the next smaller size

Secondary Battery

Effective range depends

on:

• Initial velocity

• Weight of projectile

• Caliber of the gun

• Fire control system

5" Projectile

Projectile range on larger caliber gun

projectiles can be extended by rocket

assistance.

5" Rocket Assisted Projectile

They are designed to extend the

range of the projectiles and are

filled with high explosive (HE)

material.

Rocket-Assisted Projectiles (RAP)

Less than 8 inches

and larger than 4

inches

Less than 4 inches

in diameter

5"/54 Caliber Gun Mount MK 45

5"/54 Caliber Gun Mount MK 45

Firing rate — 40 rounds per minute

Maximum Range — 24,500 yards

(23,700 meters)

5-inch Projectile

Weight – 72 pounds

Oto Melara 76mm/62–Caliber

MK 75 Gun Mount

Oto Melara 76mm/62–Caliber MK 75

Gun Mount

Firing rate — 80 – 85 rounds per minute

Maximum Range — 17,800 yards

(19,200 meters)

Phalanx Close–in

Weapons System

(CWIS) 20mm Gun

System

A last-ditch

weapon against

an antiship

cruise missile

Search Radar

Tracking Radar

6 – 20mm

gun

barrels

Ammunition

drum – 900+

rounds

The six-barrel

Vulcan Gatling

gun can fire

3,000 rounds

per minute.

The gun is

computer

controlled.

Gun Ammunition — Principal

Components:

Propelling charge

Projectile

An object fired from a gun with an

explosive propelling charge, such

as a bullet, shell, rocket, or grenade

Projectile

Bag Ammunition

Case Ammunition

DER

Semifixed Ammunition

Fixed Ammunition

Refers to a round that consists of a

projectile and a separate case charge

loaded one after the other

Semifixed Ammunition

Refers to a round in which the projectile

and powder case are permanently

attached (standard in 3‖ and smaller guns)

Fixed Ammunition

Propellant Components

PRIMER

IGNITERMAIN CHARGE

PRIMER

IGNITERMAIN CHARGE

Propellants are chemical compounds

that burn at a rapid rate rather than

detonate or explode.

PRIMER

IGNITERMAIN CHARGE

The first stage in a propellant train is called a

primer; it produces a hot flame that sets off

the next stage, called igniter; the igniter sets

off the main charge.

primer

igniter

main charge

The three main parts

of a projectile are:

• Its metallic body

• The fuze that sets

off the main charge

• The explosive

burster charge

Gun Projectile Assembly

Body

Explosive

Charge

ADF

(Auxiliary

Detonating

Fuze)Nose Fuze

Projectile Characteristics

ROTATING

BANDBODY OGIVE

BASE BOURRELET NOSE

The curved nose of a missile or rocket

Ogive

The widest part of the projectile, located

immediately to the rear of the ogive

Bourrelet

Three classes of projectiles:

• Penetrating

• Fragmenting

• Special purpose

Penetrating projectiles are

designed to penetrate the

target before exploding.

Armor-Piercing (AP) Projectile

Fragmenting projectiles are designed

to damage by blast effect and

fragmentation.

These projectiles have relatively thin

walls and large burster charges

A bomb designed to break into many

small, high-velocity shrapnel fragments

when detonated

Fragmentation Bomb

Shell fragments

Shrapnel

Antiaircraft Common (AAC) Projectile

Antiaircraft projectiles are normally fuzed to

detonate in proximity of aircraft with the

fragments penetrating the aircraft skin

BASE DETONATING FUZE

AUXILIARY DETONATING FUZE

MECHANICAL TIME FUZE

High Explosive–Point Detonating

(HE–PD) Projectile

High Explosive–Point Detonating

(HE–PD) Projectiles

These are used against lightly armored

surface targets such as torpedo boats,

shore installations, or personnel.

Special purpose projectiles have

a variety of applications, including

illumination, smoke, chaff, and

target practice, and are not intended

to inflict damage by blast or

fragmentation.

Illuminating (ILLUM) Projectile

PARACHUTE

Illuminating

Projectiles

Often called star

shells, they contain

a bright flare

attached to a

parachute. The

flare is intended

to illuminate an

enemy target or

terrain as it slowly

descends under

the parachute.

Parachute

White Phosphorous (WP) Projectile

A smokeless powder consisting of

nitroglycerine and cellulose nitrate

chiefly in a 40 to 60 percent ratio;

used as a solid fuel for rockets

Ballistite

Chaff Projectile

Strips of metal foil dropped by an

aircraft to confuse enemy radar by

creating false blips

Chaff

Nonfragmenting Projectiles

Produce bursts of various colored smoke

for antiaircraft gunnery practice

Target projectiles contain sand or

other inert material to simulate the

weight and balance of burster

charges; they are used for surface

gunnery practice.

Fuze

A device that detonates the

burster charge

A mechanical or electronic device to

detonate an explosive charge,

especially as contained in an artillery

shell, a missile, projectile, or the like

Fuze

A tube, cord, or the like, filled or

saturated with combustible matter,

for igniting an explosive

Fuse (different spelling)

Fuzes are classified by their function

as:

• Impact

• Time

• Proximity

Fuze

Controlled Proximity (VT) Fuze

A design for detonating a charge, as

in a projectile, within a predesignated

radius of a target

Proximity Fuze

Controlled Variable–Time Fuze (CVT)

Delays projectile arming for a set

time after it is fired

Firing over a Friendly Ship

Note: Impact Backup in VT Mode

Air

Burst

Impact

Burst

Enemy

Mechanical Time Fuze

It contains a clock mechanism that

explodes the projectile after a preset

amount of time elapses.

Antiaircraft guns put up a ―flak‖

screen to protect carrier task forces.

Flak

A heavy antiaircraft barrage through

which aircraft must fly to attack their

target

Artillery projectiles have been produced that

can dispense chemical or biological agents,

and have been used in some of the conflicts

in the Middle East.

Iraqi Chemical Artillery Projectiles

Naval Gunfire Support

Shore bombardment was

common in World War II.

Naval gunfire support for amphibious

operations must be:

• Carefully planned

• Executed with precision

Support roles for naval gunfire include:

• Mine warfare activities

USS Defender

(MCM 2)

• Sea/Air rescue missions

• Reconnaissance and demolition

operations

• Feints

• Raids

• Flak suppression

during air strikes

• In interdiction of coastal

roads, railroads, airfields,

and troop assembly areas

Steady bombardment of enemy positions

and communications lines for the

purpose of delaying and disorganizing

progress

Interdiction

THE END