Naval Weapons Systems

We Know: How the target is detected, How the target is tracked, How the weapon is launched, How the weapon is propelled, How the weapon finds the target, How the weapon knows when to detonate, How the weapon detonates.

The Fire Control Problem Factors affecting the problem: Effects of relative motion during flight Effects of physical phenomena (exterior ballistics)

Relative Motion n Present target position n Relative velocity  Own ship motion  Target motion n Bearing rate n Speed across line-of-sight n Future target position

Relative Motion The apparent motion of an object when viewed from a point. 10 mph 20 mph A B C

Affects of Target Relative Motion on Range and Bearing Present Position Future Position Ship’s Heading Present Range Future Range Range Change Bearing Change Present Bearing

Solving the Relative Motion Problem Launch Platform Sensors Target Position Navigation Systems (location) Gyrocompass (course) Electromagnetic Log (speed) Dead reckoning Analyzer Depth indicator Radar (search and fire control) Sonar Electronic warfare equipment Data Systems (NTDS) INPUT Target Course Target Speed Target Range Target Bearing Output

Exterior Ballistics n Gravity n Drag n Wind n Drift n Coriolis Effect

Effects of Gravity Line of Sight Line of Fire

Effects of Drag Drag is loss of energy of a projectile during flight. Energy is lost through: a. Creation of air waves (function of projectile shape) b. Creation of suction and eddy currents (shape) c. Formation of heat (friction) Drag will change the speed of the projectile - increased flight time - increased curve caused by gravity - changes intercept!

Effects of Drift Drift is caused by the rotation of a projectile. Drift results in a lateral right displacement in flight path. MAGNUS Effect. Vertical Plane Drift Horizontal Plane Line of Fire

Effects of Wind Wind Line of Fire Horizontal Effects Wind Line of Fire Vertical Effects

Coriolis Effect Caused by the earth’s rotation. Results in apparent a right curve in the northern hemisphere, left in southern. 20 mph 10 mph

Fire Control Problem n Input  Target data  Own ship data n Computations  Relative motion procedure  Exterior ballistics procedure

Fire Control Problem Con’t. n Solutions  Weapons time of flight  Bearing rate  Line of Sight(LOS): The course the weapon must follow to intercept the target  Speed across LOS  Future target position  Launch angles F Launch azimuth F Launch elevation  Weapon positioning orders

Block diagram of fire control problem

The Iterative Process to the Fire Control Solution Step 1 Step 2 Step 3Last Step

A 3-Dimensional Problem Horizontal Reference Plane Line of Sight Present Range Target Elevation Gun Elevation

Naval Weapons Systems

Gun Description n Caliber: Measurements of Bore Diameter vs Bore Length n 3 inch and larger guns n 5 inch 54 caliber (5”/54) n 5 inch bore n 54 calibers bore length = 270 inches (54x5)

Uses of 5”/54 n Shore Bombardment n Close In firepower for surface action n Counter Small patrol craft n Political presence (shot across the bow!)

Basic Definitions n Gun: Barrel or whole assembly n Mount: Fixates gun to ship’s structure  Houses Recoil/Counter recoil system n Train: Bearing position of the gun n Elevation: Upward angle from horizon

5”/54 Gun Carriage

Rifling

Bore Deterioration n Corrosion n Dirt n Erosion n Copper Fouling